Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids
Seventy‐two new Rb‐Sr whole‐rock analyses are reported for Haag Nunataks, Mount Woollard, the Whitmore Mountains, the Pirrit and Nash hills, and Pagano Nunatak. For Haag Nunataks, three isochrons for gneisses and later aplogranite and microgranite sheets establish the age of crustal formation as 100...
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American Geophysical Union
1987
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ftnerc:oai:nora.nerc.ac.uk:522874 2023-05-15T13:41:43+02:00 Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids Millar, I.L. Pankhurst, R.J. McKenzie, Garry D. 1987 http://nora.nerc.ac.uk/id/eprint/522874/ https://doi.org/10.1029/GM040p0151 unknown American Geophysical Union Millar, I.L.; Pankhurst, R.J. 1987 Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids. In: McKenzie, Garry D., (ed.) Gondwana Six: Structure, Tectonics, and Geophysics. Washington, D.C., American Geophysical Union, 151-160. (Geophysical Monograph, 40). Earth Sciences Publication - Book Section PeerReviewed 1987 ftnerc https://doi.org/10.1029/GM040p0151 2023-02-04T19:48:04Z Seventy‐two new Rb‐Sr whole‐rock analyses are reported for Haag Nunataks, Mount Woollard, the Whitmore Mountains, the Pirrit and Nash hills, and Pagano Nunatak. For Haag Nunataks, three isochrons for gneisses and later aplogranite and microgranite sheets establish the age of crustal formation as 1000–1100 Ma. No other basement rocks of this age are known from the Antarctic Peninsula or Ellsworth Land. Results from the migmatite‐pegmatite complex at Mount Woollard are inconclusive but do not suggest that this represents Precambrian crystalline basement. Provisional results for the Whitmore Mountains granites are compatible with crystallization of all components within error of a 182±5 Ma isochron for fine‐grained microgranite, but variation in initial 87Sr/86Sr from 0.707 for porphyritic granites to 0.722 for the microgranite rule out simple crystal fractionation models which require a common parental magma. The granites of the Ellsworth‐Thiel mountains ridge are well dated as Middle Jurassic by the new data: Pirrit Hills 173±3 Ma, Nash Hills 175±8 Ma, and Pagano Nunatak 175±8 Ma. Initial 87Sr/86Sr ratios of 0.707, 0.712, and 0.716, respectively, confirm that these are intracratonic S‐type granites with a large crustal component involved in magma generation. The dolerite of Lewis Nunatak is shown by its Rb, Sr, and 87Sr/86Sr composition to be a member of the Jurassic Ferrar Supergroup. Book Part Antarc* Antarctic Antarctic Peninsula Natural Environment Research Council: NERC Open Research Archive Antarctic The Antarctic Antarctic Peninsula Transantarctic Mountains Nash ENVELOPE(-62.350,-62.350,-74.233,-74.233) Ellsworth Land ENVELOPE(-85.000,-85.000,-75.000,-75.000) Haag ENVELOPE(-79.000,-79.000,-77.667,-77.667) Whitmore Mountains ENVELOPE(-104.000,-104.000,-82.500,-82.500) Thiel Mountains ENVELOPE(-91.000,-91.000,-85.250,-85.250) Haag Nunataks ENVELOPE(-78.400,-78.400,-77.000,-77.000) Pirrit Hills ENVELOPE(-85.350,-85.350,-81.283,-81.283) Nash Hills ENVELOPE(-89.383,-89.383,-81.883,-81.883) Mount Woollard ENVELOPE(-96.717,-96.717,-80.550,-80.550) Pagano Nunatak ENVELOPE(-87.667,-87.667,-83.767,-83.767) Lewis Nunatak ENVELOPE(-88.083,-88.083,-85.667,-85.667) 151 160 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Millar, I.L. Pankhurst, R.J. Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids |
topic_facet |
Earth Sciences |
description |
Seventy‐two new Rb‐Sr whole‐rock analyses are reported for Haag Nunataks, Mount Woollard, the Whitmore Mountains, the Pirrit and Nash hills, and Pagano Nunatak. For Haag Nunataks, three isochrons for gneisses and later aplogranite and microgranite sheets establish the age of crustal formation as 1000–1100 Ma. No other basement rocks of this age are known from the Antarctic Peninsula or Ellsworth Land. Results from the migmatite‐pegmatite complex at Mount Woollard are inconclusive but do not suggest that this represents Precambrian crystalline basement. Provisional results for the Whitmore Mountains granites are compatible with crystallization of all components within error of a 182±5 Ma isochron for fine‐grained microgranite, but variation in initial 87Sr/86Sr from 0.707 for porphyritic granites to 0.722 for the microgranite rule out simple crystal fractionation models which require a common parental magma. The granites of the Ellsworth‐Thiel mountains ridge are well dated as Middle Jurassic by the new data: Pirrit Hills 173±3 Ma, Nash Hills 175±8 Ma, and Pagano Nunatak 175±8 Ma. Initial 87Sr/86Sr ratios of 0.707, 0.712, and 0.716, respectively, confirm that these are intracratonic S‐type granites with a large crustal component involved in magma generation. The dolerite of Lewis Nunatak is shown by its Rb, Sr, and 87Sr/86Sr composition to be a member of the Jurassic Ferrar Supergroup. |
author2 |
McKenzie, Garry D. |
format |
Book Part |
author |
Millar, I.L. Pankhurst, R.J. |
author_facet |
Millar, I.L. Pankhurst, R.J. |
author_sort |
Millar, I.L. |
title |
Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids |
title_short |
Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids |
title_full |
Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids |
title_fullStr |
Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids |
title_full_unstemmed |
Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids |
title_sort |
rb-sr geochronology of the region between the antarctic peninsula and the transantarctic mountains: haag nunataks and mesozoic granitoids |
publisher |
American Geophysical Union |
publishDate |
1987 |
url |
http://nora.nerc.ac.uk/id/eprint/522874/ https://doi.org/10.1029/GM040p0151 |
long_lat |
ENVELOPE(-62.350,-62.350,-74.233,-74.233) ENVELOPE(-85.000,-85.000,-75.000,-75.000) ENVELOPE(-79.000,-79.000,-77.667,-77.667) ENVELOPE(-104.000,-104.000,-82.500,-82.500) ENVELOPE(-91.000,-91.000,-85.250,-85.250) ENVELOPE(-78.400,-78.400,-77.000,-77.000) ENVELOPE(-85.350,-85.350,-81.283,-81.283) ENVELOPE(-89.383,-89.383,-81.883,-81.883) ENVELOPE(-96.717,-96.717,-80.550,-80.550) ENVELOPE(-87.667,-87.667,-83.767,-83.767) ENVELOPE(-88.083,-88.083,-85.667,-85.667) |
geographic |
Antarctic The Antarctic Antarctic Peninsula Transantarctic Mountains Nash Ellsworth Land Haag Whitmore Mountains Thiel Mountains Haag Nunataks Pirrit Hills Nash Hills Mount Woollard Pagano Nunatak Lewis Nunatak |
geographic_facet |
Antarctic The Antarctic Antarctic Peninsula Transantarctic Mountains Nash Ellsworth Land Haag Whitmore Mountains Thiel Mountains Haag Nunataks Pirrit Hills Nash Hills Mount Woollard Pagano Nunatak Lewis Nunatak |
genre |
Antarc* Antarctic Antarctic Peninsula |
genre_facet |
Antarc* Antarctic Antarctic Peninsula |
op_relation |
Millar, I.L.; Pankhurst, R.J. 1987 Rb-Sr Geochronology of the Region Between The Antarctic Peninsula and The Transantarctic Mountains: Haag Nunataks and Mesozoic Granitoids. In: McKenzie, Garry D., (ed.) Gondwana Six: Structure, Tectonics, and Geophysics. Washington, D.C., American Geophysical Union, 151-160. (Geophysical Monograph, 40). |
op_doi |
https://doi.org/10.1029/GM040p0151 |
container_start_page |
151 |
op_container_end_page |
160 |
_version_ |
1766154555467235328 |