Ar/Ar THERMOCHRONOLOGY OF A FOSSIL LL CHONDRITE FROM MOROKWENG CRATER, SOUTH AFRICA
نویسندگان
چکیده
SOUTH AFRICA. F. Jourdan, W. Maier, M. A. G. Andreoli and I. McDonald. Western Australian Argon Isotope Facility, Applied Geology & JdL-CMS, Curtin University of Technology, GPO Box U1987, Perth WA 6845, Australia ([email protected]). Centre for Exploration Targeting, 35 Stirling Highway Crawley WA 6009, Australia. South African Nuclear Energy Corporation, PO Box 582, Pretoria 0001, South Africa. School of Geosciences, University of the Witwatersrand, Wits 2050, South Africa. School of Earth, Ocean & Planetary Sciences, Cardiff University, Cardiff CF10 3YE, UK.
منابع مشابه
A deep drillcore from the Morokweng impact structure, South Africa: petrography, geochemistry, and constraints on the crater size
The Morokweng impact structure in South Africa was formed 145 Ma ago, at the time of the minor mass extinction that marks the Jurassic^Cretaceous boundary. Previous size estimates for the Morokweng impact structure ranged between 70 and 340 km, and those workers favoring a very large size speculated on the role that the Morokweng impact might have played in relation to this mass extinction. Con...
متن کاملComparison of the osmium and chromium isotopic methods for the detection of meteoritic components in impactites: Examples from the Morokweng and Vredefort impact structures, South Africa
Breccias and melt rocks found at possible meteorite impact structures on Earth may contain a minor extraterrestrial component. In the absence of evidence of shockmetamorphic effects in such rocks, the unambiguous detection of an extraterrestrial component can be of diagnostic value regarding the impact origin of a geologic structure. Previously the concentrations of siderophile elements, mainly...
متن کاملEvidence for a second L chondrite impact in the Late Eocene: Preliminary results from the Wanapitei crater, Canada
Introduction: The Wanapitei impact structure (46°45 ́N; 80°45 ́W) is located 40 km NE of the city of Sudbury, Ontario, Canada. The 7 to 8 km in diameter crater is not exposed and lies completely within Lake Wanapitei [1]. The Wanapitei impact melt rocks contains about 1% of an extraterrestrial component and, based on Ni/Ir, Ni/Cr and Co/Cr ratios an L or LL chondrite projectile is advocated [2, 3...
متن کاملMagnetic and gravity model of the Morokweng impact structure
The geophysical characteristics of the 145-Ma-old Morokweng impact structure in South Africa have been studied by modeling combined gravity and magnetic data along a 100-km cross section. Rock physical properties to guide the modeling were measured on samples from three drill cores in the central part of the structure. Based on the resultant model, the current crater diameter is estimated at 65...
متن کاملAr-ar Impact Ages of Shocked Ll Chondrites
Introduction: Due to the relatively low closure temperature of feldspar, Ar-Ar ages of shocked meteorites typically record the age of an impact, not the formation age. Ar-Ar dating of lunar rocks has shown an increase in the impact rate around 3.9Ga [1], and many eucrites [2] and H chondrites [3] give similar ages, but with a larger spread than in the lunar case. Although only a small number of...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2009