ResearchOnline@JCU This file is part of the following reference: Quentin de Gromard, R. (2011) The Paleozoic tectonometamorphic evolution of the Charters Towers Province, North Queensland, Australia. PhD thesis, James Cook University. Access to this file is available from: http://eprints.jcu.edu.au/22000 The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact ResearchOnline@jcu.edu.au and quote http://eprints.jcu.edu.au/22000
- SECTION B - THE SIGNIFICANCE OF E-W STRUCTURAL TRENDS FOR THE ALICE SPRINGS OROGENY IN THE CHARTERS TOWERS PROVINCE, NORTH QUEENSLAND
138 o E 12 o S 150 o E 12 o S Hodgkinson-Broken River Orogen Georgetown Block Greenvale Province Charters Towers Province Townsville Arunta Block Alice Springs Orogeny 450-300 Ma Amadeus Basin Alice Springs Petermann Orogeny ~ 600-520 Ma Musgrave Block Harts Range ~ 470 Ma Mt Isa Block DIO Adria Downs 1 510.0 +/- 2.8 Ma GSQ Maneroo 1 472.9 +/- 2.7 Ma AMX Toobrac 1 469.4 +/- 7.7 Ma AAE Towerhill 1 385.0 +/- 4.6 Ma PPC Carlow 1 483.6 +/- 5.9 Ma Anakie Province Thomson Orogen New England Orogen Gawler Craton Curnamona Craton Sydney Adelaide Delamerian Orogen 40 o S 138 o E Melbourne 40 o S 150 o E Lachlan Orogen 500 km Hobart Figure 1: Map of the eastern two thirds of Australia showing the Phanerozoic Tasman Orogenic System against the Precambrian craton of Australia to the west along a boundary (the thick line) that ~ marks the Tasman Line. Thin lines are aeromagnetic trends and the open circles show the location of dated samples discussed in text within the Harts Range and the Thomson Orogen. 28
Arunta Block Mt Isa Block 1670-1500 Ma Georgetown Block Greenvale Province Charters Towers Province Anakie Inlier ~500 Ma Petermann Orogen ~600-520 Ma Musgrave Block Alice Springs Orogen 450-300 Ma New England Orogen 310-210 Ma Grenville Orogen 1300-1000 Ma Gawler Craton >1540 Ma Lachlan Orogen 450-340 Ma Delamerian Orogen 520-490 Ma Figure 2: Aeromagnetic map of Australia (Milligan & Franklin, 2004; Magnetic Anomaly Map of Australia (fourth Ed.), 1:5 000 000, Geoscience Australia, Canberra.) showing major truncational trends associated with successively developed orogens. Note the truncation of relics of PreCambrian N-S grain in the Mount Isa Block by the 500 to 300 Ma W-E trends from central Australia to the East coast. 29
Balcooma145 E Metavolcanics 144 30'E Georgetown Block 145 30'E 146 E ± 146 30'E Broken River Province Greenvale Province 19 S 19 S Townsville lt Fau r e v Clarke Ri 19 30'S 19 30'S Burdekin Basin Charters Towers Province Ravenswood Batholith Reedy Springs Batholith 20 S Charters Towers 20 S Fig.4b Lolworth Batholith 0 12.5 25 50 Km Cape River metamorphics 144 30'E Fault Alex Hill Shear Zone Sedimentary Rocks Fig.4a Thalanga Seventy Mile Range Group 145 E 145 30'E Granitoids 146 E 146 30'E Metamorphic Rocks Silurian - Devonian Cambro - Ordovician Metavolcanics LateDev-EarlyCarb Silurian Neoproterozoic - Cambrian Ordovician - Devonian Ordovician - Devonian Paleoproterozoic - Mesoproterozoic Figure 3. The Townsville Hinterland showing the eastern Georgetown block, the Greenvale, the Broken River and Charters Towers Provinces, the distribution of granitoids and metamorphic rocks and the location of the Balcooma Metamorphics. Rectangles show location of Figs. 4a and 4b. 30
20 17'0"S 145 42'0"E 145 43'0"E 145 44'0"E 145 45'0"E 20 18'0"S 77 78 79 83 80 81 84 85 87 88 86 29 30 89 31 21 27 26 25 15 14 13 12 5 6 7 8 9 10 2 Flinders Highway ± 4 20 19'0"S 0 0.5 1 km 20 17'0"S 20 18'0"S 50 76 88 87 85 65 80 65 81 86 70 89 86 75 80 56 75 89 80 81 86 79 70 76 85 73 Flinders Highway ± 57 20 19'0"S 0 0.5 1 km 145 42'0"E 145 43'0"E 145 44'0"E 145 45'0"E 73 4 Sample number Main foliation Quaternary Alluvium Late Cambrian - Early Ordovician Shovel Creek complex Fault Creek Late Tertiary - Quaternary Campaspe Formation Mid ordovician Mt Glengalder granite Cambrian - Ordovician Trooper Creek Formation Mt Windsor volcanics Puddler Creek Formation Figure 4a: Location of the samples (numbers are prefixed by rq in text) used for FIA measurements (top) and main foliation trends (bottom) from within the porphyroblastic portion of the Puddler Creek Formation in the Thalanga region. Location is shown on Fig. 3. 31
146 o 14'30"E 146 o 15'00"E 20 o 03'00"S 53 58 rq92 rq91 ± 0 250 500 m 20 o 03'30"S 20 o 04'00"S 75 66 rq51 64 rq50 rq49 rq47 87 rq101 65 76 53 86 86 75 54 rq100 rq99 rq97 34 rq96 rq94 31 rq93 rq96 75 Creek Sample number Main foliation Silurian - Devonian Millchester Creek Tonalite Cambrian - Ordovician Buchland Hill Diorite Neoproterozoic - Cambrian Calc - Silicate Charters Towers Quartzite and Marble Metamorphics Cordierite Schist Figure 4b: Location of the samples used for FIA measurements within the Charters Towers Metamorphics in the Charters Towers region and the main foliation trends. Location is shown on Fig. 3. 32
(a) 120 (b) 120 rq79 rq79 (c) 150 (d) 150 Figure 5: Photomicrographs and line diagrams showing examples of inclusion trails preserved within cordierite pseudomorphs. The porpyroblasts have been totally pinitized. Those in sample rq79 only preserved a single anticlockwise asymmetry while in sample, inclusion trails from core to rim both show anticlockwise asymmetry. Vertical thin section. Single barbed arrow show strike and way up. Plane polarized light. Continues on next page 33
(e) 60 (f) 60 rq10 rq10 (g) 30 (h) 30 rq30 0.5mm rq30 0.5mm Figure 5: Photomicrographs and line diagrams showing examples of inclusion trails preserved within cordierite pseudomorphs. The porphyroblasts have been totally pinitized. Inclusion trails from core to rim both showing clockwise asymmetry. Vertical thin sections. Single barbed arrows show strike and way up. Plane polarized light. 34
(a) 30 (b) 30 rq21 rq21 (c) 0 (d) 0 rq13 0.5mm rq13 0.5mm Figure 6: Photomicrographs and line diagrams showing inclusion trails preserved within cordierite pseudomorphs. The porphyroblasts have been totally replaced by coarse grain chlorite and white mica. Both porphyroblasts in sample rq21 and rq13 only preserve a single clockwise asymmetry. Vertical thin sections. Single barbed arrow shows strike and way up. Plane polarized light. 35
(a) 60 (b) 60 rq21 rq21 (c) 0 (d) 0 rq77 0.5mm rq77 0.5mm (e) 90 (f) 90 rq77 rq77 Figure 7: Photomicrographs and line diagrams showing inclusion trails preserved within andalusite pseudomorphs. The porphyroblasts have been partially to totally replaced by a fine grain white mica aggregate. The porphyroblast in sample rq21 only preserves a single clockwise asymmetry while in sample rq77 inclusion trails differ from core to rim. Vertical thin sections. Single barbed arrow shows strike and way up. Plane polarized light. 36
(a) 90 (b) 90 (c) 120 (d) 120 Rim FIA @125 o +/- 5 Continues on next page 37
Rim FIA @125 o +/- 5 (e) 130 (f) 130 Core FIA @135 o +/- 5 (g) 140 (h) 140 (i) 150 (j) 150 Figure 8: FIA measurement technique shown on pseudomorphs after cordierite for sample. The FIA for both core and rim is located where the inclusion trails asymmetry switch occurs from clockwise to anticlockwise. Vertical thin sections. Single barbed arrow shows strike and way up. Plane polarized light. 38
sample cordierite andalusite single FIA core median rim single FIA core rim rq002 145 105 rq004 130 105 rq005 165 130 rq006 135 105 rq007 85 rq008 135 125 rq009 105 55 rq010 145 135 65 rq012b 135 rq012c 125 rq013a 85 85 rq013b 135 105 rq014 85 rq015 85 125 rq021 105 105 rq025 130 rq026 35 rq027 105 65 rq029 125 rq030 85 105 rq031 120 rq057 125 rq062 125 rq063 95 rq074 125 rq077 55 30 rq078 55 30 rq079 85 rq080 90 rq081 35 rq083 65 30 rq084 60 30 rq085 60 30 rq086 65 rq087 145 rq088 125 rq089 125 Table 1. List of FIA measurements for cordierite and andalusite porphyroblasts from rocks of the Puddler Creek Formation in the Thalanga region. Single FIA represents only one stage of porphyroblast growth from the one sample. Multiple porphyroblasts growth produces multiple FIAs within one sample recorded within the core, median and rim of the porphyroblasts. 39
Total FIA N 15 10 5 a) N = 56 Andalusite FIA N 40 Cordierite FIA N 20 20 10 b) N = 10 c) N = 46 Figure 9: Equal-area rose diagrams showing the FIA trends measured in andalusite and cordierite porphyroblasts from within rocks from the Puddler Creek Formation (Thalanga region). a) FIA trends measured from both andalusite and cordierite porphyroblasts, b) FIA trends measured from andalusite porphyroblasts and c) FIA trends measured from cordierite porphyroblasts. 40
sample cordierite single FIA core rim rq047 145 65 rq049 60 rq050 135 rq051 135 95 rq091 90 rq092 45 rq093 115 105 rq094 140 rq096 140 45 rq097 150 70 rq099 135 rq100 105 rq101 150 60 Table 2. List of FIA measurements for cordierite porphyroblasts from rocks of the Charters Towers Metamorphics in the Charters Towers region. Single FIA represents only one stage of porphyroblast growth from the one sample. Multiple porphyroblasts growth produces multiple FIAs within one sample recorded within the core, median and rim of the porphyroblasts. 41