Correlation of the Aptian Naskapi Member of the Scotian Basin and

Transcription

1 Published in: Canadian Journal of Earth Sciences, 218, Vol. 55, No. 5: pp Available from: if you have a subscription to the Canadian Journal of Earth Sciences This preprint has the same content as the published paper except for copyediting corrections Correlation of the Aptian Naskapi Member of the Scotian Basin and its regional implications Isabel Chavez, David J.W. Piper, and Georgia Pe-Piper I. Chavez and G. Pe-Piper. Department of Geology, Saint Mary s University, Halifax, Nova Scotia, B3H 3C3, Canada D.J.W. Piper. Natural Resources Canada, Geological Survey of Canada (Atlantic), Bedford Institute of Oceanography, P.O. Box 6, Dartmouth, Nova Scotia, B2Y 4A2, Canada Corresponding author: I. Chavez (chavezg.isabel@gmail.com) Keywords: Scotian Basin, Naskapi Member, gamma ray log, correlation, sea level fluctuations 1

2 Correlation of the Aptian Naskapi Member of the Scotian Basin and its regional implications Isabel Chavez, David J.W. Piper, and Georgia Pe-Piper Abstract The Naskapi Member of the Logan Canyon Formation, a 15-m-thick shale dominated unit, lies in between sand dominated units of Upper Missisauga Formation below and the Cree Member above. The great decrease in sediment supply has been suggested as due to tectonic and/or eustatic sea-level changes. Wireline logs and recent biostratigraphy of 3 wells from the Scotian Shelf and Georges Bank, mudstone geochemistry from the Naskapi and Cree Members, and modal composition and chemical variation of detrital heavy minerals in sandstones were examined to better understand the deposition of the Naskapi Member and its regional implications. Minor sandy intervals at the base of the Naskapi Member were correlated based on gamma and sonic log signatures from the type section in the Cree E-35 well to progressively more distant wells, on the assumption that the sands represent periods of lowered eustatic sea level. Correlation was confirmed by the distribution of highstand black shales in washed cuttings and biostratigraphic markers identified in some wells. The geochemistry of mudstones from the Naskapi Member resembles mudstones sourced from the Meguma Terrane, except for higher abundance of elements likely reworked in smaller amounts from the Upper Missisauga Formation. Based on the correlation and geochemistry of mudstones and detrital minerals, we suggest the diversion of Sable River through the Gulf of St Lawrence to either the Orphan Basin or towards western Canada was responsible for the decrease of sediment supply in the Scotian Basin during the deposition of the Naskapi Member shales. 2

3 1 Introduction The Aptian Naskapi Member of the Logan Canyon Formation (McIver 1972; Wade and MacLean 199) is a shale dominated unit overlying the sandy Upper Missisauga Formation (Late Hauterivian Barremian) and is overlain by the sandy Cree Member (Albian) in the Scotian Basin (Fig. 1B). Previous studies have suggested that the significant decrease in coarse-grained sediment that formed this widespread shale unit is an expression of either local tectonic control of sediment supply or eustatic sealevel changes, or a combination of both (Piper et al. 211; Masse and Fenersi-Masse 213; Haq 214; Chavez et al. 216). The tectonic hypothesis suggests that rivers draining Labrador were diverted along the reactivated Cobequid-Chedabucto-SW Grand Banks fault system due to uplift of the Meguma block (Piper et al. 211). This resulted in the diversion of sand delivery through the Bay of Fundy to the Shelburne Subbasin, consequently allowing shales to accumulate farther east in the Scotian Basin. By contrast, the eustatic hypothesis proposes that global high sea-level stand during the Aptian (Peropadre et al. 211; Haq 214) created a fully marine environment for the deposition of the shales of the Naskapi Member, trapping coarser sediment inboard in flood plains and estuaries (Jansa and Wade 1975). This study aims to understand the formation of the Naskapi Member in the Scotian and Georges Bank basins, its regional tectonic implications, and the sedimentation environments and processes during the Aptian. We achieve this by (i) correlating the Naskapi Member based on wireline logs, lithostratigraphy and biostratigraphy across the Scotian Basin and adjacent Georges Bank Basin; (ii) identifying and understanding the significance of key sequence-stratigraphic surfaces and the uncertainties related to these markers; (iii) determining paleoenvironmental conditions and processes during Naskapi Member sedimentation and their implications on a regional scale; and (iv) understanding the source of the thin sand intervals within this shale-dominant member. 3

4 2 Geological setting 2.1 Scotian Basin The Scotian Basin is a Mesozoic Cenozoic passive margin basin offshore eastern Canada (Fig.1A). It initially formed during the breakup of Pangaea and the formation of the North Atlantic Ocean in the Late Triassic to Early Jurassic (Withjack et al. 29). It is divided into subbasins, which are interconnected areas of thick fluvial-deltaic sediments that contain more than 12 km of strata produced from long-term, nearly continuous subsidence (Wade and MacLean 199). Salt tectonics in the Late Jurassic to Early Cretaceous has influenced the entire Scotian Basin, facilitating regional extensional deformation of overlying strata on the outer shelf and upper slope. This resulted in active listric normal faults leading to regional subsidence of an outer shelf ramp during the Early Cretaceous in the central and eastern Scotian Basin (Kendell 212). Until the latest Jurassic, the continental margin developed as the typical sub-tropical passive margin with abundant Jurassic shelf carbonate rocks (Wade and MacLean 199). However, in the Upper Jurassic to Lower Cretaceous a sandy deltaic succession was deposited on the shelf that was several kilometers thick. These deltaic successions are found in the Tithonian to Barremian Missisauga and the Aptian to early Cenomanian Logan Canyon formations (Fig. 1B). The mean sedimentation rate in the Naskapi Member was 1 15 m/ma compared to 4 6 m/ma in the Upper Missisauga Formation and Cree Member, based on thicknesses reported by Wade and MacLean (199) and the Ogg et al. (212) timescale. 2.2 Lithostratigraphy of the Naskapi Member The sediments of the Logan Canyon Formation on the Scotian Margin are Aptian to Early Cenomanian in age (Weston et al. 212) and can be several kilometres thick (Jansa and Wade 1975; Wade and MacLean 199). The Aptian Naskapi Member is a ~15 m thick shale unit deposited at a relatively low sedimentation rate at the base of the Logan Canyon Formation. It consists of shales of 4

5 varied colours, including brown, brownish-grey, or green grey shale, and near the base is commonly reddish brown to pale red (Purcell et al. 1979). This member is commonly interbedded with silty and sandy zones and becomes increasingly sandy along the northeastern part of the basin (Wade and MacLean 199). The depositional environment of the Naskapi Member has been interpreted from macro- and micro-fossils to be tidal estuary to fully marine (Gould et al. 212). The member has been interpreted as a transgressive episode overlying the delta plain environment of the upper member of the Missisauga Formation (Cummings et al. 26). The ongoing transgression is represented at the base of the Naskapi Member with a major lithological change from predominantly sandstone to shale (Wade and MacLean 199), but recent studies have argued for episodes of transgression and regression within the Naskapi Member, with lowstands marked by sandier intervals with brackish water fossils (MacRae 211; Chavez et al. 216). 2.3 Biostratigraphy Albian to Aptian nannofossil assemblages in the basin show variability in abundance and diversity according to Weston et al. (212). The late Albian nannofossil assemblage is typically dominated by Biscutum ellipticum, and Rhagodiscus asper dominates in the early Albian. The Aptian Naskapi Member is characterized by an assemblage that includes Micrantholithus hoschulzii, Micrantholithus obtusus, Orastrum perspicuum and species of Nannoconus (Weston et al. 212). The dinocysts during the Albian to Aptian are characterized by various species, including Criboperidinium, Cyclonephelium, Florentinia, Odontochitina and then (farther downhole) an abundance of Cerbia tabulata (Weston et al. 212). The micropaleontological assemblages show a lower abundance and diversity and are dominated by benthic foraminifera, such as agglutinanted foraminifera Choffatella dicipiens, Verneuilinoides subfiliformis and Haplophragmoides gr. topagorukensis. The Naskapi Member is associated in all wells with high microfossil abundances, but with acmes in planktonic and calcareous benthic foraminifera, nannofossils and dinocysts, which have been interpreted to correspond to 5

6 a widespread maximum flooding surface (MFS) of intra-aptian age (Intra-Aptian MFS) on the Scotian Margin. Based on nannofossil markers, this MFS would equate with the Selli oceanic anoxic event (OAE1a) (Luciani et al. 21; Weston et al. 212). Sequence stratigraphic surfaces that have been previously recognized by Weston et al. (212) in the Aptian include the Albian Aptian boundary MFS, the intra-aptian MFS and the Aptian Barremian unconformity. The Albian Aptian boundary MFS has been picked within the top of the Naskapi Member in some wells and above the Naskapi Member in other wells, implying that the Cree-Naskapi member boundary as defined by MacLean and Wade (1993) and OETR (211) is likely diachronous. Towards the base of the Naskapi Member, a change in biostratigraphy suggests an Aptian Barremian Unconformity between Logan Canyon and Missisauga formations at many locations (Weston et al. 212). 2.4 Lower Cretaceous volcanism Previous studies have shown that Lower Cretaceous volcanic rocks and associated hypabyssal intrusions are widespread off the northeastern United States and southeastern Canada (Jansa and Pe-Piper 1988). The geochemistry and petrography of these volcanic rocks demonstrated the presence of basalt, trachyte, and alkaline rhyolite and microgranite (Pe-Piper et al. 1994). The widespread volcanic activity indicates a regional magma source that resulted in high regional paleo-heat flow (Bowman et al. 212).Higher heat flow is also expected during the extensional rifting between Grand Banks and Iberia and its northward continuation between Labrador and Greenland (Bowman et al. 212). There is direct evidence of volcanism in various parts of the Scotian Basin. In the Orpheus Graben wells and at the Hesper I-52 and P-52 wells, the top Missisauga unconformity is overlain by Naskapi Member sandstones and shales, which are largely marine in Hesper I-52 well and terrestrial in Argo F-38 well (Bowman et al. 212). In these wells, a lower volcanic unit includes basalt flows and an upper volcanic unit is predominantly pyroclastic rocks within the Naskapi Member (Wade and MacLean 199). The age of the pyroclastic unit in the Orpheus Graben was determined by palynology as Albian (Barss et al. 1978), the basalt flows were determined as Aptian-Albian by palynological interpretations of bounding strata above, 6

7 and the uppermost part of the Naskapi shale at Hesper I-52 is Albian (Fig 7 in Bowman et al. 212). Palynological and micropaleontological data in Hesper P-52 were studied by Weston et al. (212), suggesting the Aptian-Barremian unconformity is located slightly below the basalt flows ( m). 3 Methods 3.1 Well selection A total of 3 wells were examined in this study, including eight wells with recent biostratigraphic sampling and analyses by Weston et al. (212). The wells chosen were selected to provide a wide geographic coverage, both inboard and outboard in the basin. The assignment of formation boundaries is based on wireline log correlation, refined by lithologic and biostratigraphic correlation. Wireline gamma ray log plots were obtained from the Geoscience Research Centre of the Canada Nova Scotia Offshore Petroleum Board and from data held under license by the Geological Survey of Canada (Atlantic). The wireline gamma ray logs from Sable Island C-67, North Banquereau I-13, Panuke B-9, Hesper I-52, and 22 other wells (see Table 1) from the Scotian Basin and from the COST G-2 well on Georges Bank were plotted and correlated using key sequence stratigraphic surfaces from Weston et al. (212) and Offshore Energy Technical Research Association (OETR 211) as a guide. Sonic logs were used to recognize clean limestone from clean sandstones. Washed cuttings at 5 1 m intervals from each well were viewed with a binocular microscope to identify lithologies that could easily be correlated; for example, dark, red and green shale intervals. The description of the well cuttings and sidewall cores from well history reports were also used to refine the gamma ray correlation and interpretation. 3.2 Well correlation The low sedimentation rate of the Naskapi Member is mainly influenced by sea level fluctuations and/or tectonically influenced changes in sediment supply. Sandy units at the bottom of Panuke B-9 well, where conventional core is available (Chavez et al. 216), resulted from brief regressions followed 7

8 by transgressions, and are easy to identify in the wireline logs. Once this pattern was established in the gamma ray logs at Panuke B-9, it could be correlated across the basin. Compared to the Naskapi Member, higher sedimentation rates in the Missisauga Formation and Cree Member were influenced by shifting rivers channels and their respective deltas, which is reflected in the gamma ray logs with blocky signature and makes detailed correlation there more challenging. Channel sandstones in the Cree Member are thicker and cleaner than lowstand estuarine sands in the Naskapi Member, and are thus distinctive in washed cuttings samples. 3.3 Markers and boundaries The correlation of sandy interval was based on gamma and sonic log signatures patterns from the type section at the Cree E-35 well. The Panuke B-9 well, which has core in the Naskapi Member, and its correlation to Cohasset L-97 and Alma F-67, which have recent biostratigraphic constraints (Weston et al. 212), were examined and used to correlate to progressively more distant wells. The bottom of the Member is characterized by an abrupt upward change in sedimentation from sandy to shaly, corresponding to the Barremian-Aptian Unconformity of Weston et al. (212) between the Upper Missisauga Formation and the Naskapi Member. Depending on the well, this event can be abrupt (e.g. Cree E-35 and Glenelg J-48) or more gradational. The top of the Member is more complex and its boundary with the sandy Cree Member was picked as diachronous by Wade and MacLean (199), but in most wells, including the type section, the top of the Naskapi and base of the Cree members are roughly synchronous across the studied wells. Erosive surfaces at the Naskapi-Cree boundary interval tend to complicate the correlation (e.g. Panuke B-9 well). The Intra-Aptian MFS from previous biostratigraphic studies (West Esperanto B-78, Glenelg J-48, South Griffin J-13, Evangeline H-98, Cohasset L-97, Chebucto K-9, Alma F-67, Hesper P-52 and Glooscap C-63; Weston et al. 212) was used as a key sequence-stratigraphic surface and its log signature was progressively correlated from the wells in which it was recognised to more distant wells. Limestone intervals in the overlying Cree Member were identified based on descriptions in the well history reports of the studied wells, in addition to the gamma 8

9 and sonic log signatures. Limestones represents conditions of reduced terrigenous sediment input and thus can be locally correlatable between wells. Detailed correlation of limestone is shown in Chavez (217). 3.4 Petrology and mudstone geochemistry Conventional core from Naskapi Member in Sable Island C-67 well and the base of the Cree Member in North Banquereau I-13 well were described using the lithofacies nomenclature of Gould et al. (212). Two sandstone samples from Sable Island C-67 and six from North Banquereau I-13 were analyzed for petrology and mineral chemistry. The samples were divided to obtain core polished thin sections and heavy mineral separates. Heavy minerals from the finer fraction (<18 µm) from each sample were separated with an aqueous solution of sodium polytungstate prepared to a specific gravity of 2.87 g/cm³. Polished thin sections (3 m thickness) were produced from both the core slabs and the heavy mineral separates. They were inspected under a petrographic microscope to select mineral and lithic clasts of interest for chemical analysis. All polished thin sections were analyzed by electron dispersion spectroscopy (EDS) using a Scanning Electron Microscope (SEM) at the Regional Analytical Centre of Saint Mary s University (for more details see Dutuc et al. 217). The geochemistry of Naskapi Member mudstones from conventional core is from a database built by Pe-Piper et al. (28) and expanded by Zhang et al. (214) and Dutuc et al. (217). Details of analytical methods are given by Zhang et al. (214). 4 Results 4.1 Type section and regional correlation Sequential correlation away from the type section We first present the type section of the Naskapi Member, and then summarize how this type section was correlated regionally. More detailed data for each correlated well are then presented. 9

10 The Cree E-35 well (Fig. 2) is the type section for the Naskapi Member (Wade and MacLean 199, p. 219). The top of the Naskapi Member was defined at 248 m and the base at 2582 m (Wade and MacLean 199). The base of the Naskapi Member overlies a blocky-serrated sandstone-related log response. A thin sandy unit that has been correlated to other wells nearby is recognised by this abrupt lithology change (258 m) and represents the top of the sandy Missisauga Formation. Towards the base of the Naskapi Member, the green shales are interbedded with reddish shales. Dark shale intervals are found towards the top of the Member. According to the cutting descriptions from the well history report, these dark shales are overlain by lighter grey shales interbedded with olive green shales. Limestone beds at 213 and 2178 m in the Cree Member provide additional opportunities for correlation. Key log signatures at Cree E-35 well were used to correlate this well to other close wells (dashed lines in Figs. 2-7). The proposed correlation of Cree E-35 well with Panuke B-9 and Cohasset L-97 wells, less than 22 km distant, is shown in Figure 2. The top of the Naskapi Member was picked below a pronounced log response of a sandy unit, which we interpret as Cree Member. The Naskapi-Cree boundary at Panuke B-9 and Cohasset L-97 is likely erosional, complicating the correlation to type section in Cree E-35 well. Since dark or black shale units were widespread and not consistent in the majority of the wells, the presence of limestone units in the lower Cree Member were also used to improve the correlation. Using the description of well cuttings and sidewall cores above and below the picked boundaries for the Naskapi Member, a white to cream cryptocrystalline limestone was correlated among these three wells at 195 m in Panuke B-9, 2177 m in Cree E-35 and 1875 m in Cohasset L-97 wells. The Intra-Aptian MFS is proposed at ~2516 m in Cree E-35, correlating with Intra-Aptian MFS at Cohasset L-97 well defined by Weston et al. (212). In the same area, Glenelg J-48 and Whycocomagh N-9 wells were also correlated to Cree E-35 well (Fig. 3) based on sandy log responses below and above the boundaries of the Naskapi Member. The top and bottom boundaries of the Naskapi Member for Glenelg J-48 in this study differ from those assigned by MacLean and Wade (199) and OETR (211). This well, with detailed biostratigraphy 1

11 (Weston et al. 212) was then correlated eastward to Eagle D-21 and South Griffin J-13 wells (Fig. 4), again resulting in small changes in the position of the base and larger changes in the position of the top of the Naskapi Member compared to previous compilations. Using log signatures, the Intra-Aptian MFS, coloured shales and limestone intervals, Sable Island C-67, Penobscot L-3 and Dover A-43 wells were correlated (Fig. 5). West Esperanto B-78 and Hesper I-52 were correlated to Penobscot L-3 (Fig. 6). The correlation of these wells was challenging due to the greater amounts of sands and thus variable log response of both Penobscot and West Esperanto wells. The recent biostratigraphy at West Esperanto B-78 (Weston et al. 212) allowed for the correlation of signature markers and the Hesper I-52 well allowed correlation with the major basalt unit. Lastly, COST G-2 well in the Georges Bank Basin and the Naskapi N-3 well in the western part of the Scotian Basin were also correlated to the type section Cree E-35 well (Fig. 7). Log responses within the established boundaries for the Naskapi Member are present Allostratigraphic markers Four main markers were correlated across the Scotian Basin and Georges Bank Basin (A to D in Fig. 8). Generally, the top of the Missisauga Formation is characterized by a thick sandy unit overlain by Naskapi shales. Confident correlations include prominent sandstone in the Upper Member of the Missisauga Formation (marker A) in most wells (e.g. Cree E-35, Cohasset L-97, Panuke B-9, Penobscot L-3, Whycocomagh N-9 and COST G-2 wells). In Naskapi N-3, this pick is complicated by interbedded shale and sandstone near the contact, making the contact more transitional. The base of the Naskapi Member is characterized by a commonly abrupt change to shales (marker B), which in most wells are green, red, and dark in colour and a seaward shift in facies (i.e. transgression). Marker B represents a surface within the basal Naskapi Member. Higher in the Naskapi Member, the Intra-Aptian MFS (marker C) is correlated above a siltier unit and below by a uniform shale unit, likely representing a condensed section. It is defined by biostratigraphy and is thus confidently 11

12 identified in wells studied in detail by Weston et al. (212). In general, marker D marks the base of the first clean sand (>4 m thick) of the Cree Member, with its position guided by thickness and correlation of under and overlying units in nearby wells. The Intra-Aptian MFS has not been confidently determined in all the wells. The pick of the marker can vary by ±1 m because of the resolution of well cuttings samples used for biostratigraphic study. 4.2 Naskapi Member in individual wells Panuke B-9 The top of the Naskapi Member at this well is placed at 2152 m and the base is placed at 229 m (Fig. 2). Dark shale intervals are present at the top of core 4, underlain by thinner dark shale intervals in cores 5 and 6 (Chavez et al. 216). Reddish and greenish shale intervals are present at the base of the section. The Intra-Aptian MFS was picked from the log correlation to Cohasset L-97 below the dark shales at the top of core 4 at 2239 m, based on the presence of dark shale with high total organic carbon (TOC: Chavez et al. 216). A limestone bed at 195 m was correlated to the limestone at 2171 m in the type section at Cree E-35, approximately ~2 m above the base of the Cree Member (Fig. 8; detailed correlation of limestone is shown in Chavez 217) Cohasset L-97 The top of the Naskapi Member at this well (Fig. 2) is defined at 211 m by the interval of serrated-blocky gamma response sandstone interbedded with medium grey shales that can also be correlated to the Alma F-67 well (See supplementary data). Two dark shale intervals were picked in the upper Naskapi Member at 2139 and 2151 m. The Intra-Aptian MFS was picked at 216 m by Weston et al. (212). Towards the base of the Naskapi Member, dark grey shales are interbedded with reddish and greenish shales. The top of a ~15 m sand, which is correlated to nearby wells, delineates the boundary 12

13 between the Aptian and Barremian at 2222 m. Limestone beds at m were correlated to nearby wells (Panuke B-9 and Cree E-35; Fig. 8) Glenelg J-48 The Naskapi Member at Glenelg J-48 well (Fig. 3) is mostly grey to dark grey to dark shales with minor interbedded sands. The Intra-Aptian MFS was picked at 3386 m based on biostratigraphy studies (Weston et al. 212). The top of the Naskapi Member was picked at 3273 m, underlying a sandy unit with a serrated-blocky gamma response. Limestone beds at 31, 316, and 318 m were correlated to Cree E- 35 and Whycocomagh N-9. The base was picked at 349 below interbedded red and green shales at the top of a ~1 m sandy unit Whycocomagh N-9 The top of the Naskapi Member is at 272 m and the Intra-Aptian MFS was picked at 279 m, based on the correlation with Glenelg J-48 well. The bottom of the Naskapi Member is picked at 2888m based on correlation to the Cree E-35 well. Limestones described in the well history reports at 2655 and 2765 m were correlated to Glenelg J-48 (Fig. 8; Chavez 217) Eagle D-21 The top of the Naskapi Member at this well is at 3357m below ~2 m of sand of the Cree Member (Fig. 4). This well shows interbedded green and dark shales throughout, and interbedded green and red shales towards the base of the Member. The base of the Naskapi Member is picked at 3555 m. A limestone described in the well reports at 3243 m was correlated to Glenelg J-48 and South Griffin J-13 wells (Fig. 8; Chavez 217) South Griffin J-13 A ~2 m thick sandy unit of the Cree Member is underlain by dark shale, the top of which delineates the Naskapi Cree boundary at 2879 m (Fig. 4). The Intra-Aptian MFS was placed at 322 m, above and below dark shales, based on biostratigraphy (Weston et al. 212). The base of the Naskapi 13

14 Member at this well is at 312 m at the base of an interval of red and green shales, as seen in the Naskapi Member in the majority of wells in the eastern and central part of the Scotian Basin. A limestone bed at 2748 m in the Cree Member was correlated to Eagle D-21 and Glenelg J-48 wells (Fig. 8; Chavez 217) Sable Island C-67 The top of the Naskapi Member is at 2725 m, at the base of a sandy interval from the Cree Member based on the blocky gamma log response (Fig. 5). The Intra-Aptian MFS was picked at 2815 m, based on correlations with nearby wells (South Griffin J-13 in Fig. 4). Correlations to nearby wells Penobscot L-3 and Dover A-43 were also supported by a limestone bed at 263 m. Towards the bottom of the Naskapi Member at 289 m, the dark grey shales are interbedded with red and green shales above a sandstone unit with serrated-blocky gamma log signature interpreted as the top of the Missisauga Formation. The presence of dark shale interval 4 m above the base of the Member correlates with the dark shales at a similar position in conventional core at the Panuke B-9 well Dover A-43 The top of the Naskapi Member at this well is at 1863 m below a ~25 m sandy unit of the Cree Member (Fig. 5). This is one of the most inboard wells in this study, and the Naskapi Member shows a sandier character. The base of the Naskapi Member at 1965 m is underlain by thick (>3 m) sandy unit marking the top of the Missisauga Formation. Limestone beds in the Cree Member at 171 m were correlated to nearby wells (Sable Island C-67 and Penobscot L-3; Fig. 8; Chavez 217). 14

15 4.2.9 Penobscot L The Naskapi Member at this well shows interbedded red and green shales throughout the entire section (Fig. 6). The top of the Naskapi Member was placed at 2138 m and the base at 225 m, overlying a 25 m sandy interval. Dark shales are present at 2172 m and 2212 m. The Intra-Aptian MFS was correlated at 22 m from the pick at Cohasset L-97 by Weston et al. (212). A sandy dolomite at 258 m was correlated to limestone beds at Sable Island C-67 and Dover A-43 wells (Fig. 8; Chavez 217). West Esperanto B-78 The top of the Naskapi is placed at 217 m and the base is at 2275 m (Fig. 6; Weston et al. 212). There is a dark shale unit near the top, which correlates with dark shale units in nearby wells (e.g. Dover A-43 and Sable Island C-67). A siderite cemented mudstone unit (2215 m) is present and correlates with a similar unit at Dover A-43 well (Fig. 5). The Intra-Aptian MFS was picked at 2235 m in a shale dominated interval (Weston et al. 212). The dark shales change towards the base with the presence of green and red shales. A limestone bed at 29 m was correlated with a limestone at Penobscot L-3 and Hesper I-52 wells (Fig. 8; Chavez 217) Hesper I-52 The top of the Naskapi Member at this well starts below a 6 m thick sandstone interbedded with dark shale at 2669 m (Fig. 6). The Intra-Aptian MFS was correlated at 2721 m below a green shale unit and a dark shale unit based on the pick at West Esperanto B-78 at 2235 m and on the nearby Hesper P-52 well (Weston et al. 212). The dark shales are interbedded with red and green shales overlying the basalt flows at m (Bowman et al. 212). The base of the Naskapi Member is picked at 276 m where it is underlain by a 1 m sandy unit, below which are Barremian palynomorphs (Bowman et al. 212). Limestone beds at 265 m in the Cree Member were correlated to West Esperanto B-78 and Penobscot L- 3 wells (Fig. 8; Chavez 217). 15

16 Naskapi N-3 The top of the Naskapi Member in the Naskapi N-3 well is defined in this study by the base of a ~1 m sandy unit of the Cree Member at 129 m (Fig. 7). The bottom of the Naskapi Member is picked below an interval of reddish to dark shales and the start of a sandy interval at 1445 m. The total thickness of the Naskapi Member is 155 m. The Intra-Aptian MFS is either at 1361 or 149 m based on correlation to Glooscap C-63 and Cohasset L-97, respectively.. This sandy unit below the base of the Naskapi Member can be readily correlated to other wells nearby, namely Sambro I-29, Glooscap C-63, and Mohican I COST G Dark shale units described in the well history report for the COST G-2 well on Georges Bank (Amato and Simonis 198) were correlated with wells in the Scotian Basin by matching patterns of the dark shales in the logs (Fig. 7). The Naskapi Member top was picked at 148 m based on the presence of sandstone unit equivalent to the Cree Member and thick shales below. Thin sands recognised on gamma logs correlated remarkably well to thin sands at Naskapi N-3 well. At least two dark shale units were correlated based on nearby wells including Naskapi N-3. The base of the Naskapi Member at 123 m overlies a >1 m thick sandy unit.detrital petrology of Sable Island C-67 and North Banquereau I- 13 wells The understanding of sedimentary environments and probable sediment sources of the Naskapi Member is based on the relative abundance of different heavy detrital minerals, lithic clasts and mudstones, and their chemical varieties. Sable Island C-67 and North Banquereau I-13 wells were chosen for detailed analysis for having conventional core available in or immediately above the Naskapi Member. Panuke B-9 also has conventional core available, and was previously investigated by Chavez et al. (216). Conventional core in North Banquereau I-13 well was identified as Naskapi Member by 16

17 MacLean and Wade (1993), but was recognised in this study as at the base of the Cree Member based on gamma log correlation Modal composition of detrital minerals The modal composition of the detrital minerals in the Sable Island C-67 and North Banquereau I- 13 wells are similar (Fig. 9). Both wells show mineral assemblage with considerable numbers of titania minerals, tourmaline, zircon and chromite and minor amounts of monazite, apatite and xenotime. Sediment in the Naskapi Member and the bottom of the Cree Member tend to have abundant titania minerals that decrease in relative abundance stratigraphically upwards. The lithic clasts present in both wells includes granite, rhyolite, trachyte, altered volcanic ash, schist, quartzite and silty shale (Fig. 1). Overall, North Banquereau I-13 well shows higher number of lithic clasts. Sable Island C-67 well shows the minor presence of altered volcanic clasts (chloritized pumice) Chemical fingerprinting of detrital heavy minerals Four types of tourmaline have been identified (Pe-Piper et al. 29; Tsikouras et al. 211) based on the chemical composition of tourmalines analysed from Lower Cretaceous sandstones from the Scotian Basin, using the works of Henry and Guidotti (1985) and Kassoli-Fournaraki and Michailidis (1994). Type 1 suggests a granitic source; type 2 a metapelitic or calc-silicate rock source; type 3 a metaultramafic source; and type 4 a metapelitic or psammitic source. Tourmaline is a relatively abundant detrital mineral present in these wells. The dominant tourmaline type is type 1 and 4, and rare type 3 and 2 (one grain from North Banquereau I-13 well m) (Fig. 11). The sandstones from these wells contain common muscovite and lesser biotite. Muscovite is mainly of igneous origin, probably from Meguma granites, with rare metamorphic muscovite also from Meguma terrane sources (Fig. 12; cf. Reynolds et al. 212). Some outliers are present in the plot, which could be due to diagenetic alteration of muscovite to hydromuscovite and kaolinite. Even though the best 17

18 muscovite analyses have been selected, this common alteration of muscovite makes it difficult to obtain good chemical analyses of primary detrital muscovite. Spinel compositional variation at the Sable Island C-67 and North Banquereau I-13 compares better with ophiolites of Newfoundland rather than ophiolites of the Quebec Appalachians (Fig. 13). 4.4 Mudstone geochemistry of Naskapi Member The Naskapi Member mudstones from wells in the eastern and central part of the Scotian Basin (Panuke B-9, Sable Island C-67, Hesper I-52, North Banquereau I-13 and Thebaud C-74 wells) tend to have high Ce, moderately high Zr and lower Ti, Ta, P 2 O 5 and Cr compared to Cree Member mudstones (Fig. 14). The Naskapi Member field, shown in light pink, encompasses most of the Naskapi Member samples. Naskapi mudstones from Thebaud C-74 well are the only samples from cuttings, not cores, and may be contaminated by down-hole cavings: they tend to plot distinctively separate compared to the other wells. The Cree Member mudstone from wells in the eastern and central part of the basin (Peskowesk A-99, Panuke B-9, Cohasset A-52, Alma K-85, Glenelg J-48 and Sable Island C-67 wells) are quite different from the Naskapi mudstones, showing higher Ti, Zr, Ta and Ce with considerable amounts of P 2 O 5 and Cr (Fig. 14). The mudstones from the Jurassic and Lower Cretaceous in the wells from the western part of the basin (Mohican I- and Naskapi N-3: Dutuc et al. 217), shown in blue in Figure 14, plot separately from the Naskapi and Cree mudstones. These mudstones tend to have lower Ce, Ta and P 2 O 5 than mudstones in the rest of the basin, but have high Zr (Fig. 14). 18

19 5 Discussion 5.1 Boundaries of the Naskapi Member The regional gamma and sonic log correlation of the Naskapi Member across the Scotian Basin showed log signatures that allow for a good correlation (Figs. 2, 8). In addition to the log signature, four markers are recognised laterally across the wells. The most distinctive correlated signature surface is at the base of the member. This boundary between Missisauga and the Logan Canyon formations, transitioning from clean sandy intervals to shale, reflects an unconformity that represents a variable time interval across the Scotian Margin (Weston et al. 212). This unconformity is more pronounced in inboard wells (Hesper I-52) and in the wells at the western part of the basin (Mohawk B-93 and Sambro I- 29). The common presence of the biostratigraphic hiatus across the unconformity (Weston et al. 212) and the change in sediment facies at the base of the Naskapi Member (Cummings et al. 26; MacRae 211; Gould et al. 212) suggests then that the base of Naskapi is likely to be transgressive. According to Bowman et al. (212), marine sediments accumulated below the basalt flow in Hesper I-52 well, but nonmarine conditions were present in the upper Naskapi Member that correspond to regional erosion of basalt south of the Orpheus Graben. Therefore, it is likely that there were episodes of lowered sea level within the Naskapi Member: it was not exclusively a highstand deposit. The Naskapi Member consists of varicoloured shale at the bottom with minor sandy units and dark coloured shales throughout. The character of the shales varies from east to west. Wells in the eastern and central parts of the basin have interbedded red and green shales units at the base. The western wells have reddish shale units interbedded with darker shale and lack the distinctive green shale in the lower portion of the Naskapi Member. These green and red shales suggest variable redox conditions during or after the time of deposition. In conventional core from Panuke B-9, the green and red shales did not correlate to any paleoclimatic or paleogeographic signals (Chavez et al. 216). In this study, we have not found sufficient evidence to interpret the red colour of some Naskapi Member shales. Studies have shown that such red colouration results from a change in redox conditions on the ocean floor and it is recognised 19

20 by the presence of finely disseminated ferric oxides, which tends to be haematite (Turner et al. 198; Hu et al. 25). Regional oceanographic changes in low sedimentation rate environments, including changes in deep water production, upwelling and bioproductivity, and paleoclimate changes influencing influx of fresh water, could have allowed for the broad geographic occurrence of red shales, which are known from the Caribbean to the central North Atlantic, southern and eastern Europe to Asia (Hu et al. 25). The onshore equivalent of the Logan Canyon Formation, the Lower Cretaceous Chaswood Formation, contains reddish pedogenic mudstones alternating with medium to light grey mudstones, which could be a detrital source for the red shales in the Naskapi Member (Piper et al. 29). Dark shales are recognised throughout the Naskapi Member in most correlated wells. These dark shales are a characteristic lithology of the Lower Cretaceous rock record, which formed during episodes of accelerated global change, fluctuating between arid and humid conditions (Fӧllmi 212), which allowed for the preservation of organic carbon. During humid periods, dys- and anaerobic conditions in deeper ocean waters developed, resulting in the deposition of black shales, such as the Selli Level in the Early Aptian in the Tethys Basin (Fӧllmi 212). Generally, these dark shale units are recognised either below, or above (e.g. Panuke B-9 and Cohasset L-97), or both below and above (e.g. West Esperanto B- 78, Glenelg J-48) the level of the Intra-Aptian MFS (Fig. 8) recognised from biostratigraphy of cuttings samples (Weston et al. 212). The Intra-Aptian MFS correlates with the Selli OAE1a anoxic event based on nannofossil markers (e.g. Panuke B-9 well; Luciani et al. 21; Weston et al. 212; Fig. 2). At Panuke B-9 well, the Selli dark shales corresponded to the upper humid interval of the studied core above the Intra-Aptian MFS and are 1 m thick (Chavez et al. 216). The base of the Cree Member is easily recognised in most wells with the distinctive, multi-metrethick sandy character of the Cree Member overlying the dominantly shaly Naskapi Member (e.g. Cree E- 35, Whycocomagh N-9, South Griffin J-13 and Eagle D-21; Figs. 3, 4). In some wells, such as Cohasset L-97 (Fig. 2) and Dover D-21 (Fig. 5), this surface has an erosional character that differs from the type 2

21 section at the Cree E-35 well (Fig. 2). Limestone beds ~5 to 2 m above the base of the Cree are also recognised and correlated in most wells (Figs. 8). The outboard wells have greater accommodation and accordingly developed a thicker Naskapi Member (e.g. 24 m at Glenelg J-48, Fig. 8). The shales in most of central outboard wells are dark throughout the Naskapi Member (e.g. Evangeline H-98). The inboard wells in the central and eastern basin (such as Dover D-21 and West Esperanto B-78) are more challenging to correlate than distal wells (e.g. Cree E-35, Panuke B-9), due to more lithological and wireline log variability. 5.2 Source of sandstone intervals in the Naskapi Member In the Late Jurassic to Early Cretaceous, thick sandy deltaic successions several kilometres thick were deposited on the shelf, which implied a 3 4 fold increase in terrigenous sediment input compared to the middle Jurassic (Pe-Piper and Piper 212). The river systems were prone to flash flooding and deposited delta-front turbidites, which were responsible for depositing thick sandstones. As a result, the average sedimentation rate in the Cree Member and the Missisauga Formation was 4 6 m/ma, compared to about 1 15 m/ma in the Naskapi Member. Previous studies have suggested that the abrupt decrease in fluvial supply of sediment to the Scotian Basin in the Aptian was the result of the Meguma terrane uplift and diversion of the ancient Sable River that drained the southern Labrador rift. Such diversion was proposed to be westward through the Bay of Fundy to the Shelburne subbasin (Piper et al. 211; Zhang et al. 214). Basin modelling by OETR (211) confirmed that the Naskapi Member deposition could be accounted for by cessation of sediment supply from the Sable River. Correlation of wireline logs in the Aptian Naskapi Member from wells in the Scotian Basin to the Georges Bank shows similarities in key markers and signatures as well as the lack thick sandy intervals in the COST G-2 well in the Georges Bank and in key wells in the SW Scotian Basin. These similarities and relative lack of sands in both the SW Scotian Basin and Georges Bank compared to the 21

22 rest of the Scotian Basin contradicts the hypothesis that the Sable River was diverted southwestwards along the Cobequid-Chedabucto fault system through the Bay of Fundy, which would ultimately have deposited sands in the SW Scotian Basin. Zhang et al. (214) suggested that the Naskapi Member mudstone could have been sourced by the Meguma Terrane and other sources based on similar content of trace elements between the mudstones from the Middle to Upper Missisauga Formation and the Naskapi Member 14). The Meguma Terrane input is reflected in the lower TiO 2 than the Missisauga Formation and the covariation of TiO 2, Ce, Cr and Zr (Fig. 14), suggesting greater polycyclic sources in the Naskapi Member shales. Polycyclic reworking tends to give uniformity of stable heavy minerals (Tsikouras et al. 211) and a linear correlation in selected trace element ratios (Zhang et al. 214). Polycyclic reworking of older formations, such as the sandy Upper Member of the Missisauga Formation, is another source of some sediment in the Naskapi Member. It has been suggested that Upper Jurassic to Lower Cretaceous sediment was reworked, as shown by landward erosional thinning of the Missisauga Formation beneath the base Naskapi unconformity especially on the eastern Scotian Margin (Wade and MacLean 199; Bowman et al. 212). The Naskapi Member has low Ti and Cr content in mudstones and resembles the Upper Missisauga Formation mudstones in the western part of the basin, which are from predominantly Meguma Terrane sources (Fig. 9 in Zhang et al. 214). Based on the interpretation from Dutuc et al. (217; Fig. 14 B), some of the Naskapi Member mudstones plot on the Meguma Terrane trend (blue field) while a few of these mudstones with higher Cr plot closer to the Sable River trend (green field). This suggests that the Naskapi Member is very likely to have multiple sources. In contrast, the Cree Member mudstones show high values in most elements plotted (Fig. 14), suggesting a different sediment supply. Other studies have interpreted Cree Member mudstones as having significant supply from Labrador (Zhang et al. 214). Figure 14B shows most of the Cree Member mudstones at Peskowesk (yellow field) plot distinctly higher in Ti/Al 2 O 3 than the Naskapi Member mudstones, suggesting a different source. The eastern part of the Scotian Basin, including Peskowesk well, has been 22

23 interpreted to have had sediment supplied by a Banquereau River (Piper et al. 212), which could be reflected in the mudstone chemistry. The mudstones from the Upper Jurassic and Lower Cretaceous in the wells from the western part of the basin (Mohican I- and Naskapi N-3) plot on a different trend from the Naskapi mudstones (green field; Fig. 14B), which was interpreted by Dutuc et al. (217) as reworking of polycyclic sediments from the Sable River. Naskapi Member sandstones from the Sable Island C-67 well show abundant chromite, tourmaline type 4 and zircon. In the central and eastern part of the Scotian Basin, chromite is a prominent component of Lower Cretaceous rocks (Pe-Piper et al. 29) and was derived from Newfoundland ophiolites. On the other hand, the western part of the basin lacks a high abundance of chromite, as shown in Mohican I-, Mohawk B-9 and Naskapi N-3 wells (Dutuc et al. 217). Thus, the source for chromite could be ophiolites from Newfoundland, whereas tourmaline and zircons could be the product of reworking of metasediments and granites from the Meguma Terrane. Tsikouras et al. (211) showed that tourmaline type 4 was the most abundant tourmaline in all samples in the central and western parts of the basin, which were derived primarily from the Meguma Terrane granites and metasediments. Basal Cree Member sandstone from the North Banquereau I-13 well shows similar detrital mineral abundance to Sable Island C-67, except for higher tourmaline, monazite and zircon (Fig. 9). Monazite grains in the lower Cree Member in Alma K-85 and Peskowesk A-99 are Devonian, Meso- and Paleoproterozoic in age (Pe-Piper et al. 214) and have been interpreted to be from granites and metamorphic rocks in the Humber and Gander zones of central Newfoundland or northern New Brunswick (Pe-Piper and MacKay 26) and Meso- and Paleoproterozoic rocks of southern Labrador, suggesting the Cree Member had significant supply from Labrador and Newfoundland, presumably transported by the Sable River. The Cree Member shows large variation in mudstone geochemistry compared to the Naskapi mudstones. The presence of volcanic clasts and modal composition of detrital heavy minerals show a 23

24 slight variation from the Naskapi Member sources. Based on detrital mineral abundance from previous studies (Tsikouras et al. 211), the mineral assemblage of the Cree Member stands out with abundant garnet compared to Missisauga Formation and Naskapi Member (Fig. 9). For mudstones, volcanic input can be shown from certain trace elements that concentrate in heavy minerals or are absorbed on clays. In this study, the mudstone from the Cree Member shows higher Ta and Nb than those from the Naskapi Member. Thin sections from conventional core and washed cuttings (from this study and Bowman et al. 212) commonly contain volcanic clasts near the base of the Cree Member (Early Albian). Clasts include felsic volcanic and altered volcanic ash clasts in various wells, including Glenelg N-49, Glenelg J-48, Panuke B-9, Sable Island C-67, Peskowesk A-99 and North Banquereau I-13 (Fig. 15). Sandstone samples from the base of the Cree Member at North Banquereau I-13 show chloritized pumice and trachyte (Fig. 1). The presence of volcaniclastic material in the basal Cree Member is correlative with the pyroclastic unit in the Orpheus Graben that was identified as Albian from palynology (Barss et al. 1978; Bowman et al. 212). Overall, the reworking of proximal Upper Missisauga sands, all of which were derived from the Sable River (Zhang et al. 214), is interpreted to have intermittently supplied sand to the Naskapi Member. The Naskapi Member mudstones resemble mudstones sourced from the Meguma Terrane with lower Cr, Zr and Ta, except Ce is slightly higher. A few Naskapi mudstone samples show higher Cr (Fig. 14B), which resembles the mudstones derived from the Sable River. This suggests that the mudstones are a mix of supply from the Meguma Terrane and reworking of smaller amounts of mudstone from the Upper Missisauga Formation. 5.3 Lower Cretaceous sedimentation environments and processes The shale-dominant character of the Naskapi Member suggests a dominantly marine depositional environment with lower energy that would allow for fine clays to deposit. Thinly bedded silts and finesands interbedded with the shales imply a constant but limited supply of sediment from local rivers draining the Meguma terrane, based on the mudstone chemistry. Thinner overall Naskapi Member in 24

25 inboard wells and thicker sands also implies persistence of some sandstone input despite the overall transgressive nature of the unit. The lower Naskapi Member core section at Panuke B-9 well shows at least 9 small scale (1 2 m) relative sea level cycles expressed by thin sandstones alternating with shales. Each sandstone is generally followed by an erosive transgressive surface and condensed sections (Chavez et al. 216). These fluctuations of relative sea level could have been responsible for anoxic conditions that produced the dark coloured shalesas well as for the reworking of sediment from the Missisauga Formation by local subaerial exposure in more proximal, inboard areas. In Hesper I-52 well, in the eastern part of the basin, marine conditions were present in the sediments below the basalt flow. This volcanic flow stopped at the paleoshoreline and evidence of erosion of basalt south of the Orpheus Graben (Bowman et al. 212) suggests that during late Aptian and early Albian the Canso Ridge was exposed to the surface. The palynological data from the Argo F-38 well in the Orpheus Graben shows that the Naskapi Member is mostly nonmarine in that area (Bowman et al. 212). During regression, the exposed surface would have been eroded and reworked, which could explain the similarities between Upper Missisauga and Naskapi heavy mineralogy. At the base of the Naskapi Member at Sable Island C-67, prodeltaic mudstones with siltstone and sandstone beds (lithofacies b, m, and g; Fig. 9) are overlain by a transgressive, condensed unit (lithofacies 3i). Marine shales (lithofacies 1) follow this thin transgressive surface. These thin-bedded sandstones and mudstones ( m) at Sable Island C-67 well can be compared to the sands ( m) at Panuke B-9 well, which are also overlain by a transgressive condensed interval (Chavez et al. 216). The basal Cree Member at North Banquereau I-13 consists of prodeltaic mudstone with siltstone and sandstone beds (lithofacies b) underlying alternating river mouth turbidite sands, tidal flat and estuarine sandy and silty mudstone (lithofacies 9, 5, 4; Figs. 9 and 16). This gradual increase in sand 25

26 could represent a regression due to progradation since there was greater sediment supply. Trachyte and pumice lithic clasts found in the Cree sands from the North Banquereau I-13 well supports the brief and localized volcaniclastic supply in the eastern part of the Scotian Basin in the Lower Cretaceous from erosion or reworking of Aptian volcanoes (Fig. 16). 5.4 Regional tectonic implications The known rates of deposition in the under- and overlying sandy deltaic sequences from the Naskapi Member are quite different. Thick sands in the Naskapi Member are lacking in wells on the southwestern Scotian margin and in the COST G-2 well on Georges Bank. Rather, the shales show similarities of key markers and overall thickness within the Naskapi Member between the Scotian Shelf and Georges Bank wells. This implies that the Sable River was not diverted through the Bay of Fundy as proposed by Piper et al. (211; Fig. 17). Based on the observations in this study, including the regional correlation of the Naskapi Member and the lack of sediment input derived by the Sable River in the western Shelburne Subbasin and the Georges Bank Basin, we propose two alternatives for where the Sable River could have diverted to. In the Late Jurassic, Newfoundland appears to have been uplifted prior to the onset of the rifting between the Grand Banks and Iberia (Driscoll et al. 1995). From the Early to Late Cretaceous, the onshore Chaswood Formation in Nova Scotia shows evidence of deformation and sediment accumulation resulting due to uplift from northeast-trending faults, extending from New England to Labrador (Stea and Pullan 21; Pe-Piper and Piper 212). The Sable River may have been directed from the Gulf of St Lawrence northeastwards along the Humber Valley fault system to the Orphan Basin (Fig. 17), where Aptian sands are found (L. Dafoe, personal communication 217). Alternatively, since Early Cretaceous detrital zircons from fluvial sandstones of the Western Canada Sedimentary Basin (WCSB) indicate contributions from the Appalachian Mountains (Blum and Petcha 214). The detrital zircon assemblage showed the signature of Grenville ( Ma) and Appalachian (5 3 Ma) ages (Benyon et al. 214). Thus, the Sable 26

27 River could have diverted to the west and contributed sediment to the WCSB through what is now the St. Lawrence River valley. 6 Conclusions 1. The Naskapi Member was correlated across the Scotian Basin using lithostratigraphy, biostratigraphy and available literature on the wells, which allowed us to recognize correlatable markers, including the sandy upper strata of the Upper Missisauga Formation, the basal strata of the Naskapi Member with varicolored shales; the Intra-Aptian MFS and related black shales; and the sandy base of the Cree Member. 2. Similar key markers and overall thickness within the Naskapi Member between the Scotian Shelf and Georges Bank wells were recognized. The expected thick sandstones from diversion of the Sable River through the Fundy Basin were not recognized in the southwest part of the Scotian Basin and in the Georges Bank Basin, suggesting a different cause for the decrease in sediment supply represented by the Naskapi Member. 3. Reworking of the Upper Missisauga Formation sediment supplied sand to the basin during Naskapi Member deposition. The mudstone geochemistry suggests that the Naskapi Member was sourced from a diversity of new local sources and reworking. Lower Ti in Naskapi mudstones reflects Meguma Terrane input and the covariation of TiO 2, Ce, Cr and Zr reflects greater polycyclic sources. 4. The base and top of the Naskapi Member are approximately synchronous surfaces, representing a change from the higher sediment supply of the deltaic Missisauga Formation, to lower sediment supply and deposition in the Naskapi Member and a return to deltaic deposition and higher depositional rates in the overlying Cree Member. The top of the Naskapi Member is redefined in several outboard wells based on the new correlation with the type section.. 5. The base of the Cree Member shows moderate to abundant volcanic detritus input in various wells in the eastern and central part of the basin. Volcanic lithic clasts and mudstone geochemistry supports a different source for the Cree Member compared to the Naskapi Member. 27

28 6. In this study we suggest the tectonically-controlled diversion of the Sable River through the Gulf of St Lawrence northeastwards to the Orphan Basin or westwards into what is now the St. Lawrence River valley as alternative possibilities for the decrease in sediment supply in the Scotian Basin during the deposition of the Naskapi Member shales. 7 Acknowledgements This work was funded by a grant from the Nova Scotia Offshore Energy Research Association (OERA) to GPP and additional funding from NSERC Discovery Grants to GPP and DJWP. We thank the staff of the Canada-Nova Scotian Offshore Petroleum Board for their assistance in providing samples for the study. Two anonymous reviews and advice from the associate editor improved this paper. 8 References Amato, R.V. and E.K. Simonis, (eds.) Geologic and Operational Summary, COST No. G-2 Well, Georges Bank Area, North Atlantic OCS: U. S. Geological Survey Open-File Report 8 269, p Barss M.S., Bujak J.P., and Williams G.L Palynological zonation and correlation of sixty seven wells, Eastern Canada. Canada Geological Survey. Paper pp BASIN Database. Natural Resources Canada. basin.gdr.nrcan.gc.ca/index_e.php Benyon, C., Leier, A., Leckie, D.A., Webb, A., Hubbard, S.M., and Gehrels, G.E Provenance of the Cretaceous Athabasca Oil Sands, Canada: Implications for continental scale sediment transport: Journal of Sedimentary Research, 84: , doi:1.211/jsr Blum, M. and Petcha, M Mid-Cretaceous to Paleocene North America drainage reorganization from detrital zircons. Geology, 42(7): Bowman, S. J., Pe-Piper, G., Piper, D. J.W., Fensome, R. A., and King, E. L Early Cretaceous volcanism in the Scotian Basin. Canadian Journal of Earth Sciences, 49(12):

29 Chavez, I Early Cretaceous sand supply to offshore SW Nova Scotia: tectonic diversion of the Sable River during Naskapi Member deposition. M.Sc. Thesis, Saint Mary s University, Halifax, Nova Scotia, pp Chavez, I., Piper, D.J.W., Pe-Piper, G., and Zhang, Y North Atlantic climatic events recorded in Aptian Naskapi Member cores, Scotian Basin. Cretaceous Research, 6: Cummings, D.I., Hart, B.S. and Arnott, R.W.C. 26. Sedimentology and stratigraphy of a thick, areally extensive fluvial marine transition, Missisauga Formation, offshore Nova Scotia, and its correlation with shelf margin and slope strata. Bulletin of Canadian Petroleum Geology, 54(2): Driscoll, N.W., Hogg, J.R., Christie-Blick, N. and Karner, G.D Extensional tectonics in the Jeanne d Arc Basin, offshore Newfoundland: implications for the timing of break-up between Grand Banks and Iberia. Geological Society, London, Special Publications, 9(1): Dutuc, D. C., Pe-Piper, G., and Piper, D. J.W The provenance of Jurassic and Lower Cretaceous clastic sediments offshore southwestern Nova Scotia. Canadian Journal of Earth Sciences, 54(1): Föllmi, K Early Cretaceous life, climate and anoxia. Cretaceous Research, 35: Gould, K. M., Piper, D. J.W., and Pe-Piper, G Lateral variation in sandstone lithofacies from conventional core, Scotian Basin: Implications for reservoir quality and conductivity. Canadian Journal of Earth Science, 49: Haq, B. U Cretaceous eustasy revisited. Global and Planetary Change, 113: Henry, D. J., and Guidotti, C. V Tourmaline as a petrogenetic indicator mineral- An example from the staurolite-grade metapelites of NW Maine. American Mineralogist, 7(1 2):

30 Hu, X., Jansa, L., Wang, C., Sarti, M., Bak, K., Wagreich, M., and Sotak, J. 25. Upper Cretaceous oceanic red beds (CORBs) in the Tethys: occurrences, lithofacies, age, and environments. Cretaceous Research, 26(1): 3 2. Jansa, L.F., and Pe-Piper, G Middle Jurassic to Early Cretaceous igneous rocks along eastern North American continental margin. AAPG Bulletin, 72: Jansa, L. F., and Wade, J. A Paleogeography and sedimentation in the Mesozoic and Cenozoic, southeastern Canada. Canada's Continental Margins and Offshore Petroleum Exploration- CSPG Memoir 4: Kassoli-Fournaraki, A., and Michalidis, K Chemical composition of tourmaline in quartz veins from Nea Roda and Thasos areas in Macedonia, northern Greece. The Canadian Mineralogist, 32(3): Kendell, K. L., Variations in salt expulsion style within the Sable Canopy Complex, central Scotian margin. Canadian Journal of Earth Sciences, 49(12): Luciani, V., Cobianchi, M., and Jenkyns, H. C. 21. Biotic and geochemical response to anoxic events: the Aptian pelagic succession of the Gargano Promontory (southern Italy). Geological Magazine, 138(3): MacLean, B.C., and Wade, J.A Seismic markers and stratigraphic picks in Scotian Basin wells. East Coast Basin Atlas Series, Energy, Mines and Resources Canada, p McIver, N. L Cenozoic and Mesozoic stratigraphy of the Nova Scotia shelf. Canadian Journal of Earth Sciences, 9(1):

31 MacRae, R Age and paleoenvironmental significance of macrofossils and sedimentary facies from the Alma K-85 and Panuke B-9 wells, Early Cretaceous, Upper Missisauga and Logan Canyon formations, offshore Nova Scotia. Unpublished report to OETR. Masse, J.P., and Fenerci-Masse, M Drowning events, development and demise of carbonate platforms and controlling factors: The Late Barremian-Early Aptian record of Southeast France. Sedimentary Geology, 298: OETR (Offshore Energy Technical Research Association) 211. Play Fairway Analysis Atlas - Offshore Nova Scotia. Nova Scotia Department of Energy Report , 349 p. Also available online at: Ogg, J.G., Hinnov, L.A., and Huang, C Cretaceous. Ch. 27 in Gradstein, F.M., Ogg, J.G., Schmitz, M., & Ogg, G. (eds.). The Geologic Time Scale 212. Elsevier, p Pearce, J.A., Barker, P.F., Edwards, S.J., Parkinson, I.J., and Leat, P.T. 2. Geochemistry and tectonic significance of peridotites from the South Sandwich arc-basin system. Contributions to Mineralogy and Petrology, 139: Peropadre, C., Liesa, C. L., and Meléndez, N High-frequency, moderate to high-amplitude sealevel oscillations during the late Early Aptian: Insights into the Mid-Aptian event (Galve subbasin, Spain). Sedimentary Geology, 294: Pe-Piper, G., and MacKay, R. M. 26. Provenance of Lower Cretaceous sandstones onshore and offshore Nova Scotia from electron microprobe geochronology and chemical variation of detrital monazite. Bulletin of Canadian Petroleum Geology, 54(4): Pe-Piper, G. and Piper, D. J. W The Impact of Early Cretaceous Deformation on Deposition in the Passive-Margin Scotian Basin, Offshore Eastern Canada, in Tectonics of Sedimentary Basins: 31

32 Recent Advances (eds C. Busby and A. Azor), John Wiley and Sons, Ltd, Chichester, UK. doi: 1.2/ ch13 Pe-Piper, G., Jansa, L. F., and Palacz, Z Geochemistry and regional significance of the Early Cretaceous bimodal basalt-felsic associations on Grand Banks, eastern Canada. Geological Society of America Bulletin, 16(1): Pe-Piper, G., Triantafyllidis, S., and Piper, D. J.W. 28. Geochemical identification of clastic sediment provenance from known sources of similar geology: the Cretaceous Scotian Basin, Canada. Journal of Sedimentary research, 78(9): Pe-Piper, G., Tsikouras, B., Piper, D. J. W., and Triantaphyllidis, S. 29. Chemical fingerprinting of detrital minerals in the Upper Jurassic-Lower Cretaceous sandstones, Scotian Basin. Geological Survey of Canada, Open File, 6288, pp. 151.Pe-Piper, G., Piper, D. J.W., and Triantafyllidis, S Detrital monazite geochronology, Upper Jurassic Lower Cretaceous of the Scotian Basin: significance for tracking first-cycle sources. Geological Society, London, Special Publications, 386(1): Piper, D.J.W., Pe-Piper, G., Hundert, T., and Venugopal, D.K. 27. The Lower Cretaceous Chaswood Formation in southern New Brunswick: provenance and tectonics. Canadian Journal of Earth Sciences, 44: Piper, D.J.W., Hundert, T., Pe-Piper, G. and Okwese, A.C. 29. The roles of pedogenesis and diagenesis in clay mineral assemblages: Lower Cretaceous fluvial mudrocks, Nova Scotia, Canada. Sedimentary Geology, 213(1): Piper, D.J.W., Bowman, S.J., Pe-Piper, G., and MacRae, R.A. 211.The ups and downs of Guysborough County - the mid Cretaceous Naskapi Member in the Scotian Basin: eustacy or tectonics? Atlantic Geology, 47:

33 Piper, D.J.W., Pe-Piper, G., Tubrett, M., Triantafyllidis, S., and Strathdee, G Detrital zircon geochronology and polycyclicic sediment sources, Cretaceous Scotian Basin, southeastern Canada. Canadian Journal of Earth Sciences, 49: Purcell, L.P., Rashid, M.A., and Hardy, I.A Geochemical characteristics of sedimentary rocks in Scotian Basin. American Association of Petroleum Geologists Bulletin, 63: Reynolds, P. H., Pe-Piper, G., and Piper, D. J.W. 21. Sediment sources and dispersion as revealed by single-grain 4 Ar/ 39 Ar ages of detrital muscovite from Carboniferous and Cretaceous rocks in mainland Nova Scotia. Canadian Journal of Earth Sciences, 47(7): Reynolds, P. H., Pe-Piper, G., and Piper, D. J.W Detrital muscovite geochronology and the Cretaceous tectonics of the inner Scotian Shelf, southeastern Canada. Canadian Journal of Earth Sciences, 49(12): Stea, R. R. and Pullan, S. E. 21. Hidden Cretaceous basins in Nova Scotia. Canadian Journal of Earth Sciences, 38(9): Tsikouras, B., Pe-Piper, G., Piper, D.J.W. and Schaffer, M Varietal heavy mineral analysis of sediment provenance, Lower Cretaceous Scotian Basin, eastern Canada. Sedimentary Geology, 237: Turner, P Continental Red Beds. Elsevier, Amsterdam, 562 pp. Wade, J.A., and MacLean, B.C Aspects of the geology of the Scotian Basin from recent seismic and well data. Chapter 5. In Geology of the continental margin off eastern Canada. Edited by M.J. Keen and G.L.Williams. Geological Survey of Canada, Ottawa, Ont., Geology of Canada, no. 2, p Weston, J. F., MacRae, R. A., Ascoli, P., Cooper, M. K. E., Fensome, R. A., Shaw, D., and Williams, G. L A revised biostratigraphic and well-log sequence-stratigraphic framework for the Scotian Margin, offshore eastern Canada. Canadian Journal of Earth Sciences, 49 (12):

34 Williams, G.L Dinoflagellate and spore stratigraphy of the Mesozoic-Cenozoic, offshore eastern Canada; Geological Survey of Canada, Paper 74-3, 2: Withjack, M. O., Schlische, R. W., and Baum, M. S. 29. Extensional development of the Fundy rift basin, southeastern Canada. Geological Journal, 44(6): Zhang, Y., Pe-Piper, G., and Piper, D. J. W Sediment geochemistry as a provenance indicator: unravelling the cryptic signatures of polycyclic sources, climate change, tectonism and volcanism. Sedimentology, 61:

35 Figure Captions Fig.1. (A) Map of the Scotian Margin showing depth to Mesozoic Cenozoic basement (modified after Williams and Grant 1998; Wade and MacLean 199), major structural features, and the location of the studied wells. (B) Stratigraphic summary of the Scotian Basin (modified from OETR 211). Red box highlights the stratigraphic interval of this study. (C) Location of studied wells and correlation transects (Figs. 2-7). Fig. 2. Correlation of Panuke B-9, Cree E-35 and Cohasset L-97 wells. The correlation datum is the top of the Missisauga Formation. Formation and Member picks in columns to left of logs are from the previous literature; particularly from Weston et al. (212) and where not available, from MacLean and Wade (1993), based in part on biostratigraphy studies (Table 1). Coloured blocks overlying the wireline logs are dominant lithologies interpreted from washed cuttings samples. Sidewall core interpretation based on descriptions found in well history reports available from the Canada Nova Scotia Offshore Petroleum Board. Allostratigraphic surfaces A- top of the Upper Missisauga Formation, B- base of the shales of the Naskapi Member, C- Intra-Aptian MFS, and D-top of the Naskapi Member. Fig. 3. Correlation of Cree E-35, Glenelg J-48 and Whycocomagh N-9 wells. Legend as in Fig. 2. Interpretation of depositional environment based on wireling log response, lithostratigraphy, biostratigraphy and key sequence surfaces. Fig. 4. Correlation of Glenelg J-48, Eagle D-21 and South Griffin J-13 wells. Legend as in Fig. 2. Fig. 5. Correlation of Sable Island C-67, Penobscot L-3 and Dover A-43 wells. Legend as in Fig. 2. Fig. 6. Correlation of Penobscot L-3, West Esperanto B-78 and Hesper I-52 wells. Legend as in Fig. 2. Fig. 7. Correlation of COST G-2, Naskapi N-3 and Cree E-35 wells. Legend as in Fig

36 Fig. 8. Summary of markers used in the correlation of the Naskapi Member using gamma ray logs of the studied wells. Coloured block overlying the gamma ray log represents dark and varicoloured shales that are based on observations from the washed cuttings. Fig. 9. Modal abundance of detrital heavy minerals plotted against the stratigraphic column for conventional core of the Naskapi Member in the Sable Island C-67 well and basal Cree Member in the North Banquereau I-13 well. Lithofacies from Gould et al. (212). Comparison with heavy minerals sourced by the Sable River from Tsikouras et al. (211) Fig. 1. Representative lithic clasts of the Sable Island C-67 and North Banquereau I-13 wells. A) and B) chloritized volcanic ash with surrounding quartz grains; C) trachyte composed mainly of albite laths is slightly altered to chlorite; D) silty shale; E) rhyolite composed of quartz, albite, muscovite and chlorite is engulfed by calcite and quartz cements; F) granite comprising partly dissolved K-feldspar, quartz and muscovite; and G) albite-chlorite schist, plastically deformed and partly engulfed by Fe-calcite cement.. Fig. 11. Chemical variation in tourmaline of Sable Island C-67 and North Banquereau I-13 wells, based on Al-Mg-Fe 2+ showing definition of types. Tourmaline type fields are from Pe-Piper et al. (29), modified after Henry and Guidotti (1985). Comparative bar charts of types from Tsikouras et al. (211) for the central Scotian Basin (Upper Missisauga and Cree average) and Dutuc et al. (217) for the SW Scotian Basin. Fig. 12. A) Al t a.f.u. vs K a.f.u. variation in muscovite. MET= metamorphic; IGN= igneous fields from Meguma Terrane after Reynolds et al. (21). Fig. 13. Chemical variation in spinel in wells of the Scotian Basin (above) and for potential source rocks (below) from Pe-Piper et al. (29). Fields after Pearce et al. (2). Fig. 14. Variation in geochemistry of mudstones from samples of the Scotian Basin. The plots show unnormalized element variation. A. Zr with Cr; B. Ti/Al 2 O 3 with Cr/Al 2 O 3 ; C.Zr with Ta; and D. Ce with 36

37 P 2 O 5. Naskapi Member field is shown in pink, the Meguma sourced field is shown in blue, the Newfoundland sourced field is in yellow and the Sable River sourced field is in green. Fig. 15. Summary of horizons with volcanic detritus near the base of the Cree Member in wells studied here and from Bowman et al. (212). Datum is at the top of the Naskapi Member to allow easier comparison of the Cree Member. Lithostratigraphic columns from MacLean and Wade (1993) and Weston et al. (212) to show where the top of the Naskapi Member has been redefined. Fig. 16. Key sedimentological interpretation from conventional core at North Banquereau I-13 well Cree Member. Fig. 17. Cartoon showing proposed diversion of the Sable River northwards towards the Orphan Basin. 1. Diversion of the Sable River to the south-west through Fundy Basin due to Meguma uplift into western Shelburne Subbasin and Georges Bank Basin (Piper et al. 211); and 2. Diversion to the east into the Orphan Basin or diversion to the west into the Western Canada Sedimentary Basin through what now is the St. Lawrence River valley (this study). 9 Supplementary data Figure showing proposed correlation of all wells in this study 37

38 A N Quebec Newfoundland 2 Maine G u l f o f 2 2 M a i n e Georges Bank COST G-2 m MOHAWK B-93 2 Georges Basin New Brunswick. B a y o f F u n d y 3 km Nova Scotia m P.E.I. m Shelburne SB 4 m 2 m S c o t i a n S h e l f 4 km 8 km 12 km Orpheus Graben Canso Ridge ARGO F-38 W. ESPERANTO B-78 HESPER I-52, P-52 SABLE ISLAND C-67 DAUNTLESS D-35 N. TRIUMPH G-43 DOVER A-43 S. GRIFFIN J-13 PENOBSCOT L-3 N. BANQUEREAU COHASSET L-97 PRIMROSE A-41 PANUKE B-9 EAGLE D-21 CHEBUCTO K-9 SAMBRO I-29 CREE E-35 ALMA F-67 GLENELG J-48 NASKAPI N-3 WENONAH J-75 GLOOSCAP C-63 WHYCOCOMAGH N-9 EVANGELINE H-98 MOHICAN I- Sabl e SB Scot ian Basin Cobequid- Chedabucto fault zone 5 m G r a n d Laurentian SB B a n k s EMERILLON C-56 km Studied wells Volcanic centres B Investigated Interval Age (Ma) Cretaceous 15 2 Early Late Jurassic Early Middle Coniacian Turonian Cenomanian Albian Aptian sandstone MOH- AWK Marmora Petrel Naskapi MIC MAC Baccaro MOHICAN ABENAKI Sable Cree Barremian Upper Hauterivian OMarker Valanginian MISSISAUGA Middle Berriasian Tithonian Kimmeridgian Oxfordian Callovian Bathonian Bajocian Aalenian Toarcian Pliensbachian Sinemurian Hettangian LOGAN CANYON DAWSON CANYON Lower North Mountain Basalt shale hiatus Scatarie IROQUOIS VERRILL CANYON oil, gas reservoirs carbonate Shortland Shale salt C QC km ME Georges Bank NB NS Scot ian Basi n Chavez et al. Figure 1

39 CREE MB N 195 MD (m) 235 Biostrat. Mb Cree E-35 gamma acoustic 5 25 Sidewall core 25 Scot ian Basi n SW 24 Apt-Alb bound. MD (m) 2 Mb Core Panuke B-9 gamma 5 acoustic 25 Sidewall core Georges Bank 2 MD (m) 25 Cohasset L-97 Biostrat. Mb Core gamma 5 acoustic 25 Markers SE Lithology Dark shale Green shale Red shale Sandstone packages Limestone Sandy dolomite based on colour based on log response Sidewall core Dark shale Red shale Green shale Sandstone Limestone Sandy dolomite Boundary lines Correlation lines A-D Allostratigraphic markers datum 26 NASKAPI MB TYPE SECTION?? UPPER MB NASKAPI MB Apt-Alb bound. Intra-Aptian MFS NASKAPI MB Apt-Barr unconf. UPPER MB Figure 2?? D C B A

40 CREE MB N Interpretations 23 NW 235 Biostrat. Mb Core Cree E-35 gamma 5 acoustic MLD (m) 325?Alb-Apt bound. MFS Biostrat. Mb Core Glenelg J-48 gamma 5 acoustic Georges Bank Scot ian Basi n Low delta plain to shoreface deposits (log signature irregular: serratedblocky) sequence boundary Shallow marine deposits (log signature upward coarsening) Apt-Alb bound.?? NASKAPI MB TYPE SECTION Intra-Apt. MFS NASKAPI MB MD (m) NASKAPI MB CREE MB Whycocomagh N-9 Fm Mb Core gamma 5 acoustic 25 Markers D C SE transgressive surface Delta plain or delta front deposits (log signature mainly serrated) 26 storm-dominated prodelta/delta front deposits (log signature mainly serrated) Apt-Barr unconf. 29 B A Figure 3

41 3 35 CREE MB 27 3 N SW MLD (m) ?Alb-Apt bound. MFS Biostrat. Mb Core Intra-Apt. MFS NASKAPI MB Glenelg J-48 gamma 5 acousti MD (m) Fm Mb Core NASKAPI MB Eagle D-21 gamma 5 acoustic 25 Georges Bank28 MLD (m) Intra-Apt MFS. Biostrat. Apt-Alb bound. NASKAPI MB Mb CREE MB Core S. Griffin J-13 gamma 5 Scot ian Basi n acoustic 25 Markers D C NE Apt-Barr unconf Apt-Barr unconf. dark shales B A 36 Figure 4

42 255 N SW Sable Island C-67 Fm Mb Core gamma 5 acoustic 25 2 Georges Bank 17 Scot ian Basi n 265 MD (m) 175 Fm Mb Core Dover A-43 gamma 5 acoustic 25 Markers NE CREE MB Penobscot L-3 Fm Mb Core gamma 5 acoustic CREE MB NASKAPI MB LOGAN CANYON FM CREE MB LOGAN CANYON FM NASKAPI MB LOGAN CANYON FM NASKAPI MB siderite mudstone D? C? 195 B? 225 A 29 MISSISAUGA FM UPPER MB 2 MISSI. FM UPPER MB 23 Figure 5

43 SW LOGAN CANYON FM CREE MB Penobscot L-3 Fm Mb Core NASKAPI MB MISSISAUGA FM UPPER MB gamma 5 acous MD (m) W. Esperanto B-78 Biostrat. Mb Core Top Mis. Fm. Intra-Aptian MFS Apt-Alb bound. UPPER MB NASKAPI MB CREE MB gamma 5 acoustic 25 siderite mudstone MFS N Georges Bank Volcanic unit Interpretations MD (m) 265 Shallow marine deposits 27 Shallow marine deposits Fm Mb Core CREE MB LOGAN CANYON FM NASKAPI MB MISSISAUGA FM UPPER MB 1 Scot ian Basi n Hesper I-52 gamma 5 Basalt flow acous 25 Markers D C B A NE 23 Figure 6

44 N 23 SW 95 MD (m) Fm Mb Core CREE MB COST G-2 Gamma (GR) 5 2 qz sands Sonic (DT) 18 Georges Bank 12 MD (m) 125 Shoreface to river mouth (log signature irregular: serrated-blocky) Fm Mb Core CREE MB Naskapi N-3 gamma 5 qz sands Scot ian Basi n acoustic Low delta plain to shoreface deposits (irregular: serratedblocky) 24 Biostrat. Mb Core Apt-Alb bound. Cree E-35 gamma 5 acoustic 25 Markers D NE MISSISAUGA FM LOGAN CANYON FM UPPER MB NASKAPI MB deltaic river mouth to shoreface deposit MISSISAUGA FM LOGAN CANYON FM UPPER MB NASKAPI MB Delta plain or delta front deposits (log 26 signature mainly serrated) NASKAPI MB?? C B A 15 Figure 7

45 Georges Bank Basin SW Scotian Basin central Scotian Basin outboard wells Cree E-35 5 Panuke B-9 5 Cohasset L-97 5 Whycocomagh N-9 5 COST G-2 5 Naskapi N-3 Eagle D-21 5 S. Griffin J-13 5 Sable Island C-67 5 Penobscot L-3 NE Scotian Basin inboard wells Glenelg J-48 5 Limestone unit 5 Dover A-43 5 W. Esperanto B-78 Hesper I Cree Member m D locally erosional Intra-Aptian MFS C Naskapi Member B A datum Upper Missisauga Formation Erosional Unconformity in inboard wells Figure 8

46 North Banquereau I-13 litofacies (Gould et al., 212) CREE MB Sable River supply to the Scotian Basin (Tsikouras et al., 211) Cree Member Alma Peskowesk Sable Island C-67 Upper Missisauga Glenelg N. Triumph Dauntless Middle-Lower Missisauga Thebaud Venture Figure 9

47 Altered volcanic ash A chl Trachyte C B Kfs qz Silty shale zrn D zrn qz ab+chl qz qz chl sd+chl 5µm ab Kfs I Rhyolite 25µm I Granite F E kln chl+tio2 I µm 5µm I Schist G cal qz+ab qz ms qz ca l Fe- kln ab qz ms + chl Kfs ms qz 5 µm qz C qz C µm chl I µm Figure 1

48 Scotian Basin- tourmaline Al Al Al Al n= 34 n= 65 n= 58 Type Type Fe Type-3 Mg Type Type-4 Type Type Type-4 Type Fe % Type-2 Sable Island C-67 Mg Fe North Banquereau I-13 n=34 n= Type-2 Meguma sourced SW Scotian Basin Dutuc et al. (217) MgFe C H C H 2+ C= core H= heavy mineral Type 3 - meta-ultramafic Type 1 - granite Type-2 I C I C I H I H I H Tourmaline types Type 4 - metapelite & metapsammite Type 2 - metapelite or calc-silicate Mg Figure 11

49 Scotian Basin- muscovite Al (a.f.u.) MET IGN K (a.f.u.) Al (a.f.u.) Sable Island C-67 n= 11 N. Banquereau I-13 n= K (a.f.u.) C H C H C= core H= heavy mineral I C I C I C I C I C I H I H I H Figure 12

50 Scotian Basin- chromite 1. BONINITE ISLAND-ARC THOLEIITE 1. BONINITE ISLAND-ARC THOLEIITE Cr/(Cr+Al).5 MORB Cr/(Cr+Al).5 MORB n= 48 n= 27 N. Banquereau I-13 Sable Island C BONINITE TiO 2 (wt%) Newfoundland Appalachians Quebec Appalachiansl ISLAND-ARC THOLEIITE Boninitictype Chromite TiO 2 (wt%) C C I H C C I H C H I H C H I H C= core; H= heavy mineral Cr/(Cr + Al) TiO (wt %) 2 MORB Al-spinel Cr-spinel Chromite Figure 13

51 4 A 6 B 5 Newfoundland Zr (ppm) Zr (ppm) Cr (ppm) C Ta (ppm) Figure 14-4 (*1 ) Ti/Al 2O 3 Ce (ppm) Meguma Terrane D -4 Cr/Al 2 O 3 (*1 ) Sable River Cree Mbr Peskowesk A-99 Panuke-Cohasset Alma K-85 Glenelg-Sable I. Thebaud-Chebucto Naskapi Mbr Panuke - Sable I. Hesper I-52 N. Banq. I-13 Thebaud C-74 Roseway Fm Mohican I- Iroquois Fm Mohican I- Abenaki Fm Mohican I- Mohican Fm Mohican I- Missisauga Fm Naskapi N P2O 5 (wt. %)

52 5 Fm Mb Core Sable Island C Fm Mb Core 19 5 N. Banquereau I Biostrat. Mb Core 5 Biostrat. Mb Core MD (m) Panuke B-9 MD (m) CREE MB CREE MB CREE MB 25 CREE MB MLD (m) 29 Biostrat. Mb Core Glenelg N-49 MLD (m) 3 Biostrat. Mb Core Peskowesk A-99 Glenelg J CREE MB Cree Member LOGAN CANYON FM UPPER MB NASKAPI MB NASKAPI MB 225 Intra-Aptian MFS Naskapi Member Top Missisauga Intra-Apt. MFS 32 NASKAPI MB 33 NASKAPI MB NASKAPI MB 315 LOGAN CANYON FM NASKAPI MB 265 Top Naskapi LOGAN CANYON FM 3 32?Alb-Apt bound. MFS Lithology Dark shale Green shale Red shale 35 Apt-Barr unconf. 335 Sandstone packages Limestone Sandy dolomite Gamma ray (API units) volcanic clasts in thin section >3 345 MISSI. FM U. MB Figure 15

53 North Banquereau I-13 Early Cretaceous Epoch Logan Canyon Fm Cree Mb Fm - Mb lithofacies alternating river mouth turbidite (9), tidal flat deposits (5) and estuarine channels (4) prodeltaic mudstone with siltstone & sandstone beds marine shales Samples Evidence in this study Volcanic input trachyte altered pumice altered pumice Heavy mineral variation increasing chromite, tourmaline & abundant zircon increasing titania Overall mudstone geochemistry* higher Ti/Al 2 O 3 & Nb than Naskapi Mb Interpretations erosion of volcanic rocks supplied abundant volcanic detritus to the lower Cree Mb gradual increase in sand sea level falls with forced regression Aptian-Albian MFS Figure 16

54 Hu mb er f au l t Mesozoic basin Jurassic ocean Permo-Carb. basin Lower Paleozoic basin Appalachian orogen Mesoproterozoic er LO NG bl Sa Option 2 in this study. 2 Gulf of St Lawrence New Brunswick Option 1 in this study Orphan Knoll RA NG E Grenville Province Québec Orphan Basin ch ala ia n s p Ap Newfoundland Cabot Strait Flemish Pass 1 Proposed in the literature (Piper et al., 211) e Meguma Terran Grand Banks Nova Scotia Scotian Basin Georges Bank COST G-2 Central Atlantic Ocean 2 km Figure 17