PUBLICATIONS. Geochemistry, Geophysics, Geosystems

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1 PUBLICATIONS RESEARCH ARTICLE Key Points: Negative Sr isotope excursions in Miocene Mediterranean marine sediments Sr isotope excursions primarily correspond to sea level fall or basin uplift Groundwater effects on river and basin water geochemistry are likely important Supporting Information: Readme Sr_Master_dataonly_FINALrevised Correspondence to: T. F. Schildgen, Citation: Schildgen, T. F., D. Cosentino, G. Frijia, F. Castorina, F. O. Dudas, A. Iadanza, G. Sampalmieri, P. Cipollari, A. Caruso, S. A. Bowring, and M. R. Strecker (2014), Sea level and climate forcing of the Sr isotope composition of late Miocene Mediterranean marine basins, Geochem. Geophys. Geosyst., 15, , doi:. Received 10 MAR 2014 Accepted 2 JUL 2014 Accepted article online 8 JUL 2014 Published online 24 JUL 2014 Sea level and climate forcing of the Sr isotope composition of late Miocene Mediterranean marine basins T. F. Schildgen 1, D. Cosentino 2,3, G. Frijia 1, F. Castorina 3,4,F. O. Dudas 5, A. Iadanza 2, G. Sampalmieri 2, P. Cipollari 2,3, A. Caruso 6, S. A. Bowring 5, and M. R. Strecker 1 1 Institut f ur Erd- und Umweltwissenschaften and DFG-Leibniz Center for Surface Processes and Climate Studies, University of Potsdam, Potsdam, Germany, 2 Dipartimento di Scienze, Universita degli Studi Roma Tre, Rome, Italy, 3 Instituto di Geologia Ambientale e Geoingegneria-CNR, Rome, Italy, 4 Dipartimento di Scienze della Terra, Universita degli Studi La Sapienza, Rome, Italy, 5 Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA, 6 Dipartimento di Scienze della Terra e del Mare, Universita degli Studi di Palermo, Palermo, Italy Abstract Sr isotope records from marginal marine basins track the mixing between seawater and local continental runoff, potentially recording the effects of sea level, tectonic, and climate forcing in marine fossils and sediments. Our 110 new 87 Sr/ 86 Sr analyses on oyster and foraminifera samples from six late Miocene stratigraphic sections in southern Turkey, Crete, and Sicily show that 87 Sr/ 86 Sr fell below global seawater values in the basins several million years before the Messinian Salinity Crisis, coinciding with tectonic uplift and basin shallowing. 87 Sr/ 86 Sr from more centrally located basins (away from the Mediterranean coast) drop below global seawater values only during the Messinian Salinity Crisis. In addition to this general trend, 55 new 87 Sr/ 86 Sr analyses from the astronomically tuned Lower Evaporites in the central Apennines (Italy) allow us to explore the effect of glacio-eustatic sea level and precipitation changes on 87 Sr/ 86 Sr. Most variation in our data can be explained by changes in sea level, with greatest negative excursions from global seawater values occurring during relative sea level lowstands, which generally coincided with arid conditions in the Mediterranean realm. We suggest that this greater sensitivity to lowered sea level compared with higher runoff could relate to the inverse relationship between Sr concentration and river discharge. Variations in the residence time of groundwater within the karst terrain of the circum-mediterranean region during arid and wet phases may help to explain the single (robust) occurrence of a negative excursion during a sea level highstand, but this explanation remains speculative without more detailed paleoclimatic data for the region. 1. Introduction The Sr isotopic composition of seawater has changed over time in response to varying geochemical inputs from weathered continental crust, and has therefore been used to make inferences concerning continental weathering and the climatic evolution of the Earth [e.g., Burke et al., 1982; DePaolo and Ingram, 1985; Palmer and Elderfield, 1985; Chaudhuri and Clauer, 1986; Hess et al., 1986; Veizer, 1989; Richter et al., 1992; Blum and Erel, 1997]. Because the global oceans have a relatively fast mixing time of 1500 years [Broecker and Peng, 1982] and the residence time of Sr is several million years [e.g., Veizer, 1989], the major ocean bodies tend to have a fairly uniform Sr isotope composition [e.g., Burke et al., 1982; DePaolo and Ingram, 1985]. In marginal marine basins, however, 87 Sr/ 86 Sr values can differ from global seawater values due to local mixing with large amounts of continental water and/or hydrothermal fluids. For example, in the San Francisco Bay estuary, late Pleistocene 87 Sr/ 86 Sr values similar to global seawater values were measured in foraminiferal tests from isotope stage 5.5 (a relative sea level highstand), while short-term differences from global seawater values were explained by increased continental runoff during relative sea level lowstands [Ingram and Sloan, 1992]. On longer time scales, low 87 Sr/ 86 Sr values in Miocene marine basins adjacent to the uplifting Alps, Apennines, and Sicilian Maghrebides were attributed to a high influx of Sr from low 87 Sr/ 86 Sr (Mesozoic) carbonates in the hinterland coupled with restricted exchange of water with the global oceans [Keogh and Butler, 1999; Kocsis et al., 2008]. Such results imply that Sr isotopes in marginal basins could be sensitive to past changes in continental runoff, erosion, and/or sea level changes, and thus can potentially be used to infer local palaeogeographic evolution and past changes in hydrological budgets. SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2964

2 The late Miocene sedimentary record of the Mediterranean Basin provides one of the best examples of how water chemistry and volume respond to tectonic and climatic forcing. Today, the 87 Sr/ 86 Sr values of the Rh^one [ , Albarède and Michard, 1987] and the Nile [ , Brass, 1976], which together contribute a majority of the riverine influx to the Mediterranean, are much lower than the global seawater average of [DePaolo and Ingram, 1985; Hess et al., 1986]. Mediterranean water today nonetheless matches global seawater values, because the Sr concentration of continental runoff is typically more than an order of magnitude lower than that of seawater [e.g., Palmer and Edmond, 1989]. However, several of the Mediterranean s marginal basins record 87 Sr/ 86 Sr values that fell below the contemporaneous global seawater values starting at 8 9 Ma, while more central basins (farther from the margins of the Mediterranean, i.e., in Sicily, Crete, and Cyprus) continued to track global seawater [e.g., Flecker and Ellam, 2006]. Such records have been interpreted to reflect the importance of low 87 Sr/ 86 Sr continental runoff in subbasins along the Mediterranean s margins with restricted connections to the larger water body [Flecker and Ellam, 2006; Topper et al., 2011]. The entire Mediterranean water body was later influenced by low 87 Sr/ 86 Sr runoff when water exchange with the Atlantic Ocean became highly restricted during the Messinian Salinity Crisis [Hs uetal., 1972], from [Manzi et al., 2013] (previously constrained to Ma [Krijgsman et al., 1999a]) to Ma [Van Couvering et al., 2000]. Because the sedimentary succession during the Messinian Salinity Crisis has been astronomically tuned, uncertainty in the timing of individual events is estimated at Ma, except where noted otherwise (see discussion in Cosentino et al. [2013]). During that time, substantial decreases in 87 Sr/ 86 Sr occurred in both marginal and central basins [e.g., McCulloch and De Dekker, 1989; M uller et al., 1990; M uller and Mueller, 1991; Keogh and Butler, 1999; Matano et al., 2005; Flecker and Ellam, 2006; Lugli et al., 2007]. As a consequence of the restricted exchange of water with the Atlantic and high evaporation, the salinity of Mediterranean water increased, resulting in the deposition of the Lower Evaporites at the start of the Messinian Salinity Crisis [Hs u etal., 1972]. Mediterranean sea level likely fluctuated by less than 200 m during Lower Evaporite deposition, based on continuous deposition of gypsum in the Mediterranean s marginal basins [Krijgsman et al., 1999a; Roveri et al., 2008], particularly without associated halite [Krijgsman and Meijer, 2008]. This observation is consistent with only m of estimated eustatic sea level lowering during the late Messinian glacial phases [Kastens, 1992; Shackleton et al., 1995]. Nonetheless, Lugli et al. [2010] and Dela Pierre et al. [2011] interpreted variations in the evaporite stacking pattern and facies to indicate a shallowing upward trend starting at Ma (i.e., sixth evaporite cycle within the Lower Evaporites). Increased isolation of the Mediterranean from the Atlantic, coupled with a km scale fall in Mediterranean sea level, occurred during a short interval between and Ma [Cosentino et al., 2013], which has been interpreted to result from obliquity-forced, glacio-eustatic sea level fall being superimposed on the long-term trend of tectonic restriction [Krijgsman et al., 1999a; Rouchy and Caruso, 2006; Hilgen et al., 2007; Cosentino et al., 2013]. Subsequent wetter conditions created a brackish to fresh Lago Mare water body, and the deposition of the Upper Evaporites from to Ma [Krijgsman et al., 1999a; Hilgen et al., 2007; Manzi et al., 2009; Cosentino et al., 2013], which have yielded the lowest 87 Sr/ 86 Sr values in the Mediterranean basin (e.g., as low as from M uller and Mueller [1991] and from Matano et al. [2005] relative to NBS ). Reflooding of the Mediterranean with Atlantic water at the start of the Pliocene (5.332 Ma), possibly as a result of dynamic subsidence of the Gibraltar Arc due to subduction of the Gibraltar slab [Govers, 2009], brought the 87 Sr/ 86 Sr value of the Mediterranean back within uncertainty of global seawater values [e.g., McKenzie et al., 1988; M uller and Mueller, 1991; M uller, 1993; Fortuin et al., 1995; Castorina and Vaiani, 2009; Cipollari et al., 2013b]. Although the importance of restricted exchange with the open ocean and low 87 Sr/ 86 Sr runoff from the Mediterranean s margins in producing these changes in water geochemistry is understood generally, few studies have attempted to quantify the amount of precipitation, evaporation, and the degree of basin restriction required to reproduce the changes in the Mediterranean s late Miocene Sr isotope and salinity record. Using a nondimensional steady state model, Flecker et al. [2002] and Flecker and Ellam [2006] inferred that sea level changes (as they impact basin isolation and water exchange) controlled most of the variations in 87 Sr/ 86 Sr. Topper et al. [2011] later used a box model with time-dependent equations to highlight the importance of elevated river discharge to partially isolated marginal basins to explain the low observed 87 Sr/ 86 Sr values. They then inferred that changes in riverine input likely controlled changes in 87 Sr/ 86 Sr prior to the MSC. In a further step, Topper et al. [2014] investigated the potential for precessionally SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2965

3 driven changes in runoff to explain 87 Sr/ 86 Sr variations in the Lower Evaporites of the northern Apennines. Although they found that the large variations in 87 Sr/ 86 Sr linked to runoff should occur across a wide range of parameter space, they did not include concurrent glacio-eustatic changes in sea level (including its effect on basin isolation) in their modeling. To better differentiate the relative roles of fluctuations in sea level and continental runoff on the Sr isotopic composition of Mediterranean subbasins during the late Miocene and to explore the potential use of Sr isotope records as climate/sea level proxies, we present Sr isotope data derived from marine fossils and gypsum spanning two different time scales. First, we report 110 new 87 Sr/ 86 Sr measurements on 56 oyster and foraminifera samples from late Miocene marine sections spanning several million years in southern Turkey, Crete, and Sicily. We combine high-resolution sampling, multiple analyses from individual horizons, and trace element data to examine the evolution of 87 Sr/ 86 Sr in areas experiencing different degrees of tectonic activity. Second, our 55 new Sr measurements from the astronomically tuned Lower Evaporites in the central Apennines (Italy) allow us to test the role of runoff versus glacio-eustatic sea level forcing on Sr isotope composition over several hundreds of thousands of years in a single location. By combining our different time scales of observations, we gain insights into both long and short-term controls on the Sr isotope composition of marine basins. 2. Paleogeography and Tectonic Activity of the Miocene Mediterranean Basin During the Oligocene, the Mediterranean-Paratethys realm covered a broad region with connections to both the Indian and Atlantic oceans [Popov, 1993; R ogl, 1998]. The connection between the eastern Mediterranean and the Indian Ocean became severely restricted in early Miocene time (19 Ma), when mammal and shallow marine fauna indicate the existence of a landbridge [Popov, 1993; R ogl, 1998; Harzhauser et al., 2002, 2007], although a gateway appears to have persisted until between 13 and 11 Ma based on continued marine sediment deposition in eastern Turkey [Gelati, 1975; H using et al., 2009]. At the Mediterranean s western connection with the Atlantic, the Betic corridor through Spain [Wijermars, 1988; Garces et al., 1998; Betzler et al., 2006; Martın et al., 2009] and the Rifian corridor through Morocco [Krijgsman et al., 1999b; Ivanovic et al., 2013] were progressively restricted and then closed during the late Miocene as a result of tectonic uplift and sedimentation, leading to the onset of the Messinian Salinity Crisis [e.g., Hs u etal., 1972; Krijgsman et al., 1999a; Ryan, 2009]. At approximately the same time, tectonic activity was locally generating relief in the Mediterranean region. In the central Mediterranean, as a consequence of the convergence between the African and Eurasian plates, Miocene uplift defined the postcollisional evolution of the Alps, the Apennines, and the Sicilian Maghrebides, as parts of the peri-mediterranean Neogene fold-and-thrust belt [Boccaletti et al., 1990; Bigi et al., 1989; Butler et al., 1992; Lentini et al., 1994; Catalano et al., 1996]. Late Miocene uplift of the southern margin of Central Anatolia (Central Taurides), most likely related to slab break-off [Cosentino et al., 2012b; Schildgen et al., 2012a, 2012b] and plate convergence [Schildgen et al., 2014], led to gradual uplift and shallowing of marine basins, including the Sarıalan [Schildgen et al., 2012b] and Başyayla [Cosentino et al., 2012b] areas (Figure 1). Tauride uplift coincided with the delivery of coarse sediment to the Adana Basin, which borders the mountains to the south [Radeff, 2014]. Within the Tyrrhenian Sea, episodes of rapid extension and basin deepening between 9 and 5 Ma first affected the western margin, then shifted eastward through the Pliocene [Kastens et al., 1988; Bigi et al., 1989; Mascle and Rehault, 1990; Rosenbaum and Lister, 2004]. In Italy, the central Apennines were composed of an eastward migrating thrust-belt and associated foredeep, with pronounced phases of tectonic activity during the late Tortonian, early Messinian, and latest Messinian-early Pliocene [Patacca et al., 1990, 2008; Cipollari and Cosentino, 1995; Cipollari et al., 1999; Cosentino et al., 2010; Cosentino and Cipollari, 2012]. More limited topographic relief and tectonic activity characterized other regions that are included in our study. In Crete, areas exposed above sea level were characterized by low relief, with greater relief developing only after the onset of Pliocene uplift [Meulenkamp et al., 1994; Zachariasse et al., 2008]. In Cyprus, limited evidence for topography above sea level occurs until the late Pliocene to Pleistocene, when collision of the Eratosthenes continental fragment with southern Cyprus initiated regional uplift [Robertson et al., 1995; Stow et al., 1995; Robertson and Woodcock, 1986; Harrison et al., 2004; Kinnaird et al., 2011; McCay and Robertson, 2012]. SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2966

4 Figure 1. Map of the Mediterranean region showing the locations of stratigraphic sections from which Sr isotopic data for the late Miocene-Pliocene period have been reported. Sections from which we report new 87 Sr/ 86 Sr data are shown with orange circles, and other locations are indicated with yellow circles. Star marks position of Ain el Beida section in Morocco from which d 18 O data are available [van der Laan et al., 2005]. 3. Paleoclimate of the Late Miocene Mediterranean Basin The Mediterranean region experienced several notable climate shifts during the late Miocene. Based on fossil amphibian and reptile assemblages, the period from 8 to 5.3 Ma was characterized by persistently wet conditions and fluvial-lacustrine environments in SW Europe, while precipitation in central and eastern Europe was reduced to about half of its present-day value [B ohme et al., 2008], coinciding with the expansion of steppe biomes in eastern Europe [Velichko et al., 2005]. In northeast Africa, carbon isotopes and paleobotanical data indicate that C4 biomass gradually increased between 11 and 5 Ma, coupled with a reduction in grass pollen [Bonnefille, 2010; Feakins et al., 2013]. The replacement of grasslands by shrublands indicates increasingly arid conditions, with an exception of high amounts of grass pollen in core samples that span from 7.5 to 6.5 Ma, when conditions appear to have been much wetter than the modern [Feakins, 2013]. Similarly, farther west, pollen data indicate a humid climate with woodlands in the Niger basin from 7.5 to 7 Ma [Morley, 2000]. In north central Africa, evidence for high lake levels in the Lake Chad basin and a drainage system leading toward the Mediterranean led Griffin [2002, 2006] to suggest particularly wet conditions during the Messinian. A model of the late Miocene hydrologic budget for the Mediterranean is broadly consistent with these paleoclimate records, finding precipitation to be similar to the present day over much of the region, but with higher precipitation over north Africa, and particularly over the Chad Basin [Gladstone et al., 2007]. Finer details superimposed on these general climate trends have been derived from astronomically tuned marine sedimentary sections. Variations in d 18 O and d 13 C related to glacio-eustatic cycles during the late Miocene are dominantly controlled by 41 kyr obliquity cycles [Hodell et al., 1994; Shackleton et al., 1995; Vidal et al., 2002; van der Laan et al., 2005, 2012], with the Mediterranean experiencing cool, dry conditions during glacial phases, and warm, humid interglacials [van der Laan et al., 2012]. The strongest drawdown of the Mediterranean, which led to the precipitation of halite, has been chronologically linked to the last Messinian glacial event [TG12, Cosentino et al., 2013]. Earlier, less precise constraints had linked it to two glacial intervals: TG12 and TG14 [Krijgsman et al., 1999a; Rouchy and Caruso, 2006; Hilgen et al., 2007]. Fluid inclusion homogenization temperatures from the Messinian halite support this interpretation, as the halite precipitated from marine water with mean sea-surface temperatures of C, which are cooler than the C temperatures at the same locations in the present Mediterranean water body [Speranza et al., 2013]. Additional variations in late Miocene Mediterranean climate, particularly with respect to humidity, are associated with kyr precessional cycles. During the Messinian Salinity Crisis, a drier climate and deposition of evaporites occurred during precessional maxima (insolation minima), while more humid conditions, higher sea-surface temperature, and deposition of organic-rich shales/sapropels occurred during precessional minima (insolation maxima) [Hilgen et al., 1995; Hilgen and Krijgsman, 1999; Krijgsman et al., 1999a, 2001; Sierro et al., 2001; Hilgen et al., 2007; Lugli et al., 2007, 2010; Krijgsman and Meijer, 2008; Cosentino et al., 2013]. Equivalent changes have been noted in Morocco, where arid and humid conditions were linked respectively to SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2967

5 Figure 2. Stratigraphic logs illustrating 87 Sr/ 86 Sr sample positions and identified bioevents (circled letters) for sections in southern Turkey, Crete, and Sicily. Red numbers indicate age constraints from the bioevents. MES: Messinian Erosional Surface. Panasos and Sarıalan section logs modified from Schildgen et al. [2012b]; Olukpınar section log modified from Cipollari et al. [2013a]; Başyayla section log modified from Cosentino et al. [2012b]; Adana-1 section log modified from Faranda et al. [2013]; Gibliscemi section log modified from Sprovieri et al. [2003]. Biostratigraphic age constraints are as follows: (a) deposition of Tripoli like marls (6.7 Ma from Pissori section in Cyprus, Krijgsman et al., 2002]; (b) first common occurrence of Amaurolithus delicatus (7.24 Ma) [Frydas, 2004]; (c) presence of Discoaster hamatus and lack of Minilytha convallis ( Ma) [Faranda et al., 2008]; (d) disappearance of Siphonina reticulata (<7.17 Ma) [Schildgen et al., 2012b]; (e) acme of Sphaeroidinellopsis spp. (7.8 Ma) [Schildgen et al., 2012b]; (f) occurrence of Sphaeroidinellopsis spp. (<7.92 Ma) [Schildgen et al., 2012b]; (g) occurrence of Globigerinoides extremus (<8.35 Ma) [Schildgen et al., 2012b]; (h) cooccurrence of G. extremus and Catapsidrax parvulus, and reverse polarity ( Ma) [Cosentino et al., 2012b]; (i) first common occurrence of Reticulofenestra pseudoumbilicus (13.1 Ma) [Cipollari et al., 2013a]; (j) MNN5b/MNN6a boundary (13.6 Ma) [Cipollari et al., 2013a]; (k) first common occurrence of Helicosphaera walberdorfensis (14.4 Ma) [Cipollari et al., 2013a); (n) cooccurrence of Neogloboquadrina atlantica and sinistrally coiled N. acostaensis ( Ma) [Faranda et al., 2013]; (o) first common occurrence of Amaurolithus delicatus (7.221 Ma) [Faranda et al., 2013]. SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2968

6 precessional maxima and minima [van der Laan et al., 2012]. Maximum rainfall and runoff during the late Miocene in Spain [Sierro et al., 1993], the central Apennines [Cosentino et al., 2012a], and Crete [Schenau et al., 1999] were also associated with precessional minima. Because total insolation is related to eccentricity plus obliquity (tilt) minus precession (i.e., E1T-P or ETP), the most arid conditions and strongest glacial phases resulted when obliquity minima coincided with precessional maxima, i.e., at ETP minima. 4. Sampled Sections and Age Assignments Our sampled stratigraphic sections include the Başyayla, Sarıalan, Olukpınar, and Adana-1 sections in southern Turkey, the Panasos section in Crete, the Gibliscemi section in Sicily, and the Maiella composite section in central Italy (Figure 1). The quality of age control (as described below) varies among the different sections, which is taken into account in our interpretations. Figure 3. Stratigraphic log illustrating facies variations and sampling positions from the Maiella composite section, central Apennines, Italy Southern Turkey: Olukpınar, Adana-1, Başyayla, and Sarıalan Sections From the Olukpınar section (Figure 2), we analyzed 1 aliquot each ( planktonic foraminifera tests) from five sampled horizons. Nannofossil assemblages constrain the age of the full section to between 15.6 and 12.5 Ma [MNN5a to MNN6b, Cipollari et al., 2013a], while three additional nannofossil bioevents allow us to constrain the ages of our Sr isotope samples to between 14.4 and 12.5 Ma (Figure 2). We found no evidence for important gaps in sedimentation, so we assumed a constant sediment accumulation rate between bioevents to assign individual ages to the samples. At the time of deposition, the region was characterized by a platform-to-basin system [Cipollari et al., 2013a], with basement lithologies in surrounding highlands consisting primarily of Mesozoic carbonates and ophiolitic rocks. We combined foraminifera from several consecutive stratigraphic horizons SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2969

7 (spanning 3 m) in the Adana-1 section [Figure 2, described in detail by Faranda et al., 2013] for Sr isotope analysis due to the low yields of foraminifera extracted from individual horizons [likely due to relatively shallow-water, stressed conditions, Faranda et al., 2013]. We analyzed one composite sample interval from the lower (sample ADA1 2345), middle (sample ADA1 679), and upper (sample ADA ) parts of the section, and three oysters from one horizon collected at the top of the section. Based on nannofossil assemblages, the basal portion of the section is between 7.2 and 6.8 Ma, and the middle interval is between 6.65 and 6.43 Ma. A combination of planktonic foraminifera, ostracod, and nannofossil assemblages constrains the whole section to the early Messinian [Faranda et al., 2013], hence we assign an age of 6.4 Ma to the uppermost part. Continental runoff entering the Adana Basin would have drained southward from the Central Taurides, where Tortonian to Aquitanian marine and terrestrial sedimentary rocks blanket Paleozoic to Mesozoic metamorphic, carbonate, ophiolitic, and clastic basement rocks [Ulu, 2002; Faranda et al., 2013]. From the Başyayla section (Figure 2), we analyzed 3 7 aliquots of foraminifera or loose oyster shells for each of six samples. The age of the samples is between 8.35 and 8.10 Ma, based on a combination of magnetostratigraphy and biostratigraphy [Cosentino et al., 2012b]. Based on a lack of evidence for unconformities in the section, we assume a constant sediment-accumulation rate for the period between 8.35 and 8.10 Ma to assign ages to individual samples. The sampled marls and overlying limestones onlap Triassic to Cretaceous neritic limestones that overthrust an ophiolitic melange, Jurassic to Cretaceous limestones, and Triassic tuffites, spilites, and basalt. The predominantly Mesozoic carbonates locally form a high ridge that defines the drainage-basin boundary. From the Sarıalan section (Figure 2), we analyzed between 1 and 3 aliquots (loose oyster shells or foraminifera) each from 18 samples. Ages range from 8.2 Ma at the base to 6.7 Ma at the top, based on zircon U- Pb dating of a volcanic ash and analyses of the planktonic foraminifera assemblages [Schildgen et al., 2012b]. Because we found no evidence for pronounced unconformities in the section, we assumed a constant sediment accumulation rate between dated strata to assign ages to samples. Benthic foraminifera indicate a range of paleodepths from littoral inner shelf (10 m depth) to circalittoral (> m depth) [Schildgen et al., 2012b]. The sampled sedimentary rocks onlap a high ridge of Triassic to Cretaceous neritic limestones to the west, and lie within a narrow N-S-oriented valley bordered by similar rocks to the east Crete: Panasos Section We collected oysters and large benthic foraminifera from the southern Iraklion Basin (the Messara Basin) in south-central Crete. Near the town of Panasos, the well-exposed marine sedimentary rocks were deposited from 10 to 5.5 Ma (Figure 2). Calcite overgrowths on foraminifera throughout much of the section prevented detailed sampling; nonetheless, we measured 2 4 aliquots of foraminifera or loose oyster shells for each of the three collected samples Sicily: Gibliscemi Section To compare our results from marginal basins in southern Turkey to a more central basin, and to test the consistency of results from two different laboratories, we analyzed 20 samples (1 3 aliquots each) collected in 2005 and 2006 from the Gibliscemi section in Sicily. The sequence is one of the stratigraphic segments of the Gibliscemi composite record calibrated by Hilgen et al. [1995]. The samples span the interval from to Ma within the astronomically tuned section proposed by Sprovieri et al. [2003] Maiella Section, Central Apennines, Italy We collected samples from the Lower Evaporites of the Maiella composite section, which spans gypsum quarries from the Trovigliano and Colle di Votta areas, NW of the Maiella Mountains in the central Apennines. The facies and natural radioactivity (NRD) from gamma ray logs of the gypsum deposits of the area were used by Sampalmieri et al. [2008, 2010] to distinguish different lithofacies within each evaporite cycle (e.g., gypsum and sapropel layers). We collected 36 samples from various gypsum facies, 14 samples from massive carbonate and microbial carbonate, and five samples from gypsum/carbonate laminites (Figure 3). To constrain the age of the individual gypsum beds, we use the astronomical tuning from Cosentino et al. [2013], which uses the published NRD measurements and the gypsum facies to define the number of cycles within the section, and matches the center of each evaporite cycle with a peak in the precessional curve [e.g., Krijgsman et al., 2001]. Although others have suggested the occurrence of up to 17 precession- SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2970

8 modulated sedimentary cycles within the Lower Evaporites [e.g., Krijgsman et al., 2001; Hilgen et al., 2007; Krijgsman and Meijer, 2008], the identification of 20 cycles in the Maiella section could be related to (1) the high-resolution gamma ray scans from Sampalmieri et al. [2008, 2010] that were used to identify sapropels between gypsum layers, and (2) the more tectonically stable position of the Maiella section at the time of deposition, with less erosion of the top of the section during the formation of the Messinian Erosional Surface (MES). This tuning scheme places the center of the first gypsum bed at Ma [e.g., Krijgsman et al., 1999a]. An alternative tuning scheme suggested by Manzi et al. [2013] was based on reinterpretations of mixed polarity signals from sedimentary units below the Lower Evaporites in Vena del Gesso (northern Apennines) and recognition of a transitional gypsum layer below what was originally considered to be the first evaporite bed in the Sorbas Basin (Spain), where paleomagnetic stratigraphy had also been done on units underlying the Lower Evaporites. That revised tuning scheme places the center of the first gypsum bed at Ma and shifts the start of the Messinian Salinity Crisis to Ma, hence, earlier than the 5.96 Ma timing suggested by Krijgsman et al. [1999a]. For completeness, we tested both tuning schemes: the first assuming the center of the first gypsum layer in the Maiella section is Ma and the second assuming it is Ma. Uncertainty exists concerning the time span for gypsum deposition, which leads to uncertainty in the temporal spacing of samples within a bed. Because the center of each gypsum bed is linked to a peak in precession, greatest uncertainty lies in the ages assigned to samples near the lower and upper boundaries of the gypsum beds. A range of durations for the deposition of a gypsum bed from 10 to 14 kyr yielded results that are nearly indistinguishable when plotted (e.g., as in Figure 5), as only a few samples were collected from the edges of the gypsum beds. Hence, we proceeded assuming a 12 kyr duration for the deposition of each gypsum bed. 5. Sample Preparation and Analysis 5.1. Oyster and Foraminifera Samples We prepared oyster samples by first cutting and polishing the shells, then washing for 15 min at 50 Cinan ultrasonic bath in five alternating steps of milliq water and methanol. Under a microscope, portions of the shells with preserved foliated layering and no evidence of recrystallization or borings were microdrilled to depths of less than 0.1 mm. Some samples from the matrix were also drilled for comparison with the shells. Half of the drilled material was used for trace element analyses and the remaining was processed for 87 Sr/ 86 Sr measurements. Foraminifera were separated from encasing marls by disaggregation in a H 2 O 2 5% vol solution, wet sieving to retain the >63 lm fraction, and hand-picking under a microscope to ensure no visual evidence of calcite overgrowth. Planktonic foraminifera samples were placed through a Frantz magnetic separator, which helped remove tests with iron oxide discoloration. Microscopic and SEM inspection of the larger benthic foraminifera tests helped to eliminate ones that showed obvious discoloration or filled chambers. Sample aliquots of planktonic foraminifera included up to 100 tests, while aliquots of benthic foraminifera ranged from 1 to 15 tests. Subsequent steps in preparation followed procedures modified from Gao et al. [1996] and Bailey et al. [2000]. Samples were washed 3 times in an ultrasonic bath for 15 min with 1 ml of 0.2 M ammonium acetate to replace all Sr that is not structurally bound in carbonate with ammonium. The samples were then rinsed 3 times for 15 min in an ultrasonic bath with 1 ml of ultrapure water to remove excess ammonium and some fraction of clay contaminants. To test if cleaning procedures have a significant effect on Sr results, we crushed a second set of foraminifera tests from the Başyayla section prior to the ammonium acetate treatment and also added three additional ultrasound washing steps of 15 min with 1 ml of 1:1 mixture of methanol and ultrapure water, according to procedures in McArthur et al. [2006]. After cleaning, the samples were reacted for 5 min in 1 ml of acetic acid (samples in the first batch were reacted in 1.4 M acetic acid, while those of the second batch were reacted in 0.5 M acetic acid), centrifuged for 5 min, and the acetic acid solution was pipetted into Teflon beakers. This solution was dried down with 1 ml of concentrated HNO 3. The resulting sample cake was dissolved in 0.5 ml of 3.5 M HNO 3 and processed through ion exchange columns containing 50 ml of Eichrom SrSpec resin. The Sr fraction was dried down with H 3 PO 4 and then loaded onto degassed Re filaments with a TaCl 5 -H 3 PO 4 mixture. Mass SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2971

9 spectrometric analyses were completed on an IsotopX IsoProbe-T at the Massachusetts Institute of Technology, using a three sequence, dynamic multicollector analysis routine with target beam intensity of 88 Sr 5 3V. All analyses were fractionation corrected using 86 Sr/ 88 Sr A minimum of 60 ratios was collected for each sample, providing 2r uncertainties of less than 30 ppm for 87 Sr/ 86 Sr. Total procedural blanks ranged from 60 to 150 pg Sr, most of which derives from the SrSpec resin. The long-term average of NIST-987 standard analyses at MIT is (2r, n > 100 over the period ). All 87 Sr/ 86 Sr data (supporting information Table S1) have been adjusted to a value of for NIST-987 to enable comparison with the LOWESS curve [McArthur et al., 2001] Gypsum and Carbonate Samples Gypsum and carbonate samples collected from the Maiella composite section were prepared and analyzed at IGAG-CNR, Rome La Sapienza Italy. About 30 mg of carbonate was quickly dissolved using 2.0 N ultrapure HCl. The insoluble residue was separated by centrifugation, and the solution was loaded onto standard Bio-Rad AG50-X8 cation exchange resin. Sr was collected in 2.0 N HCl and evaporated to dryness. For gypsum samples, 30 mg of sample extracted from single gypsum crystals was mixed with 300 mg of ultrapure Na 2 CO 3 and treated with 40 ml of bidistilled water for 12 h at 70 C to induce metasomatic transfer of Sr from Ca(Sr)SO 4 to Ca(Sr)CO 3. The latter was then dissolved with 2.0 N ultrapure HCl. Sr was separated in a 3 ml AG50 W-X8 resin column for the gypsum and carbonate samples. Sr isotopic analyses were performed using a Finnigan Mat 262 RPQ multicollector mass spectrometer with Re double filaments in static mode. Sr analyses were normalized to 86 Sr/ 88 Sr The Sr analytical blank was 1 ng. Internal precision ( within-run precision) of a single analytical result is given as two standard deviations (2r) and is obtained as a mean of more than 200 ratios collected on each carbonate and gypsum sample with a stable bean of 2.5 V. In the period during which mass-spectrometric analyses were performed, 37 measurements of SRM 987 (NIST-987) gave a mean of All 87 Sr/ 86 Sr data (supporting information Table S1) have been adjusted to a value of for NIST-987 so that they are comparable to the LOWESS curve [McArthur et al., 2001]. Gypsum samples from Italy reported by Lugli et al. [2007] and Matano et al. [2005] were also processed and measured for 87 Sr/ 86 Sr at the IGAG-CNR La Sapienza laboratory using the procedure described here. Repeated measurements of the Sr isotope ratio of modern Mediterranean water yielded a 87 Sr/ 86 Sr value of (2r, n 5 5). 6. Sr Isotope and Trace Element Results In supporting information Table S1, we report all 87 Sr/ 86 Sr measurements and trace element data for individual analyses. Similar 87 Sr/ 86 Sr values throughout the sampled section and for individual stratigraphic levels argue against diagenetic alteration, which may otherwise lead to nonsystematic changes in the isotopic composition [e.g., McArthur, 1994; McArthur et al., 2004, 2006; Steuber et al., 2005; Frijia and Parente, 2008; Brand et al., 2012]. We also consider that diagenesis generally leads to decreased concentrations of Sr (denoted [Sr] ) and increased [Mn] and [Fe] [e.g., Brand and Veizer, 1980; Veizer, 1983; Al-Aasm and Veizer, 1986]. Although different thresholds have been proposed, we follow the suggestion of Jones et al. [1994] to consider [Fe] > 150 ppm and [Mn] > 50 ppm as indicative of diagenesis in oysters. We excluded some aliquots suspected to be diagenetically altered based on these guidelines. In some cases, we also excluded aliquots when trace element concentrations were still within these threshold limits, but the 87 Sr/ 86 Sr value was much different from other aliquots of the same sample. We furthermore eliminated aliquots when we found petrographic evidence of possible alteration. With the remaining aliquots measured from the same stratigraphic horizon, we calculated a weighted mean 87 Sr/ 86 Sr value (supporting information Table S1). Throughout, we use the McArthur et al. [2001] LOWESS model values, as updated (LOWESS V4B 08 04; McArthur, personal communication, 2010), as the reference value for global seawater Sr composition Olukpınar, Adana-1, Başyayla, and Sarıalan Sections (Southern Turkey) From the Olukpınar section, the five samples yield 87 Sr/ 86 Sr values that are comparable to the contemporaneous global seawater values (Figure 4), suggesting that this area was fully connected to the Mediterranean and larger ocean bodies during the Serravallian. The foraminifera samples from the Adana-1 section yield 87 Sr/ 86 Sr values within uncertainty of contemporaneous global seawater values (supporting information Table S1 and Figure 4). The high [Fe] (>400 ppm) SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2972

10 Figure 4. Compilation of 87 Sr/ 86 Sr data from (a) this work, and (b) this work plus previously published data from subbasins of the Mediterranean. All new and previously published data have been standardized to NBS Note break in x axis. Gray shaded region shows global seawater Sr isotopic values from McArthur et al. [2001, Look-Up Table Version 4: 08/04]. Locations of sections are shown in Figure 1. New data presented here (Gibliscemi, Olukpınar, Başyayla, Sarıalan, Adana-1, Maiella, and Panasos sections), shown with colorfilled circles. For samples with multiple analyzed aliquots, only the mean 87 Sr/ 86 Sr is plotted. Low uncertainties (often smaller than the symbol size) from data published here are the result of calculating weighted mean uncertainties from multiple aliquots (see supporting information Table S1). Most reported errors for individual analyses fall in the range of to Sources for previously published data (circles with white fill) are as follows: Tyrrhenian: Castorina and Vaiani [2009, Site 132], M uller and Mueller [1991, Site 654A], M uller et al. [1990, Site 654A], McKenzie et al. [1990, Site 653A]. Sicily: Sprovieri et al. [2003, Gibliscemi], McKenzie et al. [1988, C. Rossello], M uller and Mueller [1991, Eraclea]. S. Turkey: Cipollari et al. [2013b, Avadan]. Cyprus: McCulloch and De Deckker [1989, Site 376], M uller and Mueller [1991, Site 376], Flecker and Ellam [2006, Pissouri]. Balearic: M uller and Mueller [1991, Site 372], McCulloch and De Deckker [1989, Site 372]. Spain: Fortuin et al. [1995, Vera], M uller [1993, Vera]. Italy: Lugli et al. [2007, Vena del Gesso], Montanari et al. [1997, Sardella] with ages from Channell et al. [1990]. Crete: Flecker et al. [2002, Gavdos], McCulloch and De Deckker [1989, Site 129A]. and [Mn] (>100 ppm) for the oysters sampled from a stratigraphic horizon in the uppermost part of the section are suggestive of alteration, so we exclude them from Figure 4. In the Başyayla section, multiple replicate analyses of benthic foraminifera yield similar mean values from at the base of the section to at the top (supporting information Table S1). The subset of foraminifera samples that was treated with the more rigorous cleaning procedure (including methanol rinse) yielded results that were within analytical uncertainty of samples from the first set, suggesting that both of our cleaning procedures were effective at removing clay particles and labile Sr. All the oysters fall beyond trace element limits suspected to be indicative of diagenesis, except for sample SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2973

11 Figure Sr/ 86 Sr variations in gypsum beds from the Maiella composite section (based on two different astronomical tuning schemes compared to the total insolation (ETP) curve i.e., the normalized sum of eccentricity, tilt, and negative precession, using the Laskar et al. [1993] solution, and d 18 O records from the Ain el Beida section in NW Morocco [van der Laan et al., 2005]. Note that no data are from the sapropel layers (light gray shaded regions on right side of figure) between the gypsum beds. Correlations between negative excursions in 87 Sr/ 86 Sr and insolation minima are indicated with dashed lines; blue lines show the correlations using tuning scheme A (from Cosentino et al. [2014]), and red lines show the correlations from tuning scheme B (from Manzi et al. [2013]). The few correlations between negative excursions in 87 Sr/ 86 Sr and insolation maxima are indicated with dotted lines. TG labels on d 18 O peaks indicate numbered glacial intervals within the Gilbert magnetozone, just below the Thvera event (Thvera-Gilbert 5 TG) [Shackleton et al., 1995]. EK02 TS3.3, which we excluded. Trace element values of the remaining oyster samples contrast strongly with the trace element analysis of the matrix, which yields much higher [Fe], [Mg], and [Sr] (supporting information Table S1), further indicating that the shell material was not homogenized with the matrix through diagenesis [e.g., Brand et al., 2012]. The different types of foraminifera yielded similar 87 Sr/ 86 Sr values as the oysters, suggesting that the original Sr isotopic values are preserved, as it is unlikely that diagenesis would affect different components in the same way. Despite the internally consistent results and lack of clear evidence for diagenesis (except for the one noted sample), all samples plot well below the global seawater values between 8.3 and 8.1 Ma (Figure 4). In the Sarıalan section, 87 Sr/ 86 Sr measured on foraminifera and oysters decrease slightly from a maximum of near the base to at the top of the section, despite global seawater values increasing over the same time period (Figure 4). Furthermore, [Fe] and [Mg] for all oysters fall below the limits indicative of diagenesis [Jones et al., 1994], except for SAR 15.3 and SAR16.1, which were excluded from mean 87 Sr/ 86 Sr calculations. Within individual stratigraphic horizons, Sr ratios generally agree within analytical uncertainty. Oyster ANT-08.2 was excluded from mean calculations, because its 87 Sr/ 86 Sr value differed substantially from the other oyster sampled from the same horizon, and because the value was similar to that measured for the matrix (ANT-08.2M) Panasos Section (Crete, Greece) For the two samples collected from the Panasos section in oyster-rich horizons, 87 Sr/ 86 Sr values are consistent within analytical uncertainty, but nonetheless, we excluded some aliquots from calculations of a mean SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2974

12 87 Sr/ 86 Sr when [Fe] or [Mg] was slightly high, or the [Sr] was slightly low. The two aliquots of benthic foraminifera from a single horizon (single sample) yielded similar 87 Sr/ 86 Sr. Sr isotope ratios from each of the three samples overlap with global seawater values (supporting information Table S1 and Figure 4) Gibliscemi Section (Sicily, Italy) Our Sr isotopic results for the Gibliscemi section in Sicily track the global seawater curve throughout the period from 9.3 to 8.4 Ma (Figure 4 and supporting information Table S1) and they overlap within analytical uncertainty of the previous results published by Sprovieri et al. [2003]. The results from Sprovieri et al. [2003] show that the marine basin in Sicily continued to track the global seawater curve until at least 7.5 Ma (Figure 4) Maiella Composite Section (Italy) The 87 Sr/ 86 Sr values of the gypsum and carbonate samples from the Lower Evaporites in the Maiella composite section vary from to with average 2r uncertainties of (supporting information Table S1). Large variations in 87 Sr/ 86 Sr characterize almost all the multimeasured gypsum beds (supporting information Table S1). The variability is characterized by 87 Sr/ 86 Sr values that are either within uncertainty of the global seawater values, or below them (Figure 4). The lowest values in the data set are from the first two gypsum beds. Interestingly, the first two gypsum beds are the only ones that are characterized by giant selenite crystals (Figure 3), which tend to grow under low levels of supersaturation [Lugli et al., 2010], implying less evaporation and/or more riverine input at the time. As a whole, our samples show a wider range of values compared to results reported from other Lower Evaporite sections around the Mediterranean Basin (Figure 5) [M uller and Mueller, 1991; Keogh and Butler, 1999; Playaetal., 2000; Matano et al., 2005; Lugli et al., 2007, 2010]. Also, although Lugli et al. [2007, 2010] found that 87 Sr/ 86 Sr values returned to global seawater values only in the branching or banded selenite facies within the northern Apennines, our results show a wide range of values for that facies (both overlapping with and much lower than global seawater values), and also that other facies yield global seawater values. Moreover, unlike Lugli et al. [2007], who only found a return to global ocean values in the upper part of the Lower Evaporite sections (from cycle six onward), we see a return to global ocean values (or near them) throughout the section (Figure 5). 7. Discussion 7.1. Late Miocene Sr Isotope Records in Mediterranean Subbasins At 8 9 Ma, 87 Sr/ 86 Sr in several marginal marine basins of the Mediterranean started to fall below global seawater values (Figure 4b and associated references). Although the various marginal subbasins show different histories relative to the global seawater curve, the excursions in each basin tend to be much more gradual and smaller (e.g., by over 2 myr) than those during the MSC (e.g., up to over a few kyr) (Figure 4b). One exception is the Ahmetler section in southern Turkey [Flecker and Ellam, 1999], which shows large variations in 87 Sr/ 86 Sr almost equivalent to those during the MSC. However, the low sample density, lack of replicate analyses, and limited age constraints may make for a less reliable data set compared to the others. Overall, our results are consistent with earlier interpretations [e.g., Flecker and Ellam, 2006] of a partial isolation of marginal subbasins prior to the MSC, while the central Mediterranean basins (e.g., sampled in the Gibliscemi section in Sicily and Panasos section in Crete) maintained ample exchange with global seawater. Increased erosion of low 87 Sr/ 86 Sr rocks in tectonically active source areas and its influence on riverine geochemistry has been suggested to help explain local variations in 87 Sr/ 86 Sr [e.g., Montanari et al., 1997]. For example, 87 Sr/ 86 Sr values from the Sardella section in the northern Apennines (Italy) start to fall below the global seawater curve at 9 Ma[Montanari et al., 1997], corresponding to a major phase of uplift/exhumation of low 87 Sr/ 86 Sr rocks in the Apennines during the Tortonian [Patacca et al., 1990, 2008; Cipollari and Cosentino, 1995], and then return to open ocean values at Ma. Differential uplift was used to explain the differences between the neighboring Vera and Sorbas basins in Spain, as the former tracks global seawater values during the Pliocene [Fortuin et al., 1995; M uller, 1993], and the uplifted Sorbas basin does not [McCulloch and De Dekker, 1989]. 87 Sr/ 86 Sr from both the Sarıalan and Başyayla areas start to fall below global seawater values prior to when they were uplifted above sea level [Cosentino et al., 2012b; Schildgen SCHILDGEN ET AL. VC American Geophysical Union. All Rights Reserved. 2975