Tectonics of Precambrian basement along the Pacific margin of Antarctica and relation to western North America

Conference · Mon Feb 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6138517

Goodge, J W; Hansen, V L ^[1]; Walker, N W ^[2]

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1. Southern Methodist Univ., Dallas, TX (United States). Dept. of Geological Sciences
2. Univ. of Texas, Austin, TX (United States). Dept. of Geological Sciences

High-grade metamorphic rocks of the Precambrian Nimrod Group (NG) constitute one of few cratonal basement exposures in the Transantarctic Mountains. These rocks represent an outlier of the East Antarctic craton, evolved as part of Gondwana and pre-Gondwana (Rodinia) supercontinents. Despite pervasive, high-strain ductile deformation at T [>=] 650 C, they preserve petrologic and geochronologic evidence of an earlier history. Sm-Nd model ages from several NG lithologies, including that of a [approximately]1.7 Ga orthogneiss, range from about 2.7--2.9 Ga; these ages reflect both sedimentary and magmatic derivation from Archean crust. Individual detrital zircon U-Pb ages (about 1.7--2.6 Ga) from NG quartzites indicate clastic input from Archean to Paleoproterozoic source terrains. The Sm-Nd and U-Pb ages are reminiscent of both the Yavapai-Mazatzal (1.6--1.8 Ga) and Wyoming (> 2.5 Ga) provinces in western North America. U-Pb ages from syn-tectonic metaigneous and pelitic NG tectonites indicate that this basement complex was re-worked by the major ductile deformation in latest neoproterozoic to Early Cambrian time. Supracrustal assemblages that lie outboard of the Nimrod craton include Neoproterozoic graywacke, impure carbonate, and minor mafic volcanics (Beardmore Group), and Cambrian to Lower Ordovician carbonate and siliciclastic rocks (Byrd Group). Neoproterozoic ([approximately]750 Ma) rifting along the proto-Pacific margin of East Antarctica is reflected by deposition of Beardmore turbidites and coeval mafic magmatism. Latest Neoproterozoic to early Paleozoic orogenesis occurred along a left-oblique convergent plate margin of East Antarctica is reflected by deposition of Beardmore turbidites and coeval mafic magmatism.

• OSTI ID: 6138517
• Report Number(s): CONF-9303212-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:1; Conference: 27. annual Geological Society of America (GSA) South-Central Section meeting, Fort Worth, TX (United States), 15-16 Mar 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ANTARCTICA
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
ISOTOPE DATING
NORTH AMERICA
BASEMENT ROCK
CAMBRIAN PERIOD
CARBONATE ROCKS
COMPARATIVE EVALUATIONS
DEFORMATION
GRAYWACKE
LEAD ISOTOPES
METAMORPHIC ROCKS
NEODYMIUM ISOTOPES
PETROGENESIS
PLATE TECTONICS
PRECAMBRIAN ERA
SAMARIUM ISOTOPES
URANIUM ISOTOPES
ZIRCON
ACTINIDE ISOTOPES
AGE ESTIMATION
ANTARCTIC REGIONS
CRYOSPHERE
EVALUATION
GEOLOGIC AGES
GEOLOGY
ISOTOPES
MINERALS
PALEOZOIC ERA
PETROLOGY
POLAR REGIONS
RARE EARTH ISOTOPES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SILICATE MINERALS
TECTONICS
580000* - Geosciences