Siderophile elements from the Eyreville drill cores of the Chesapeake Bay impact structure do not constrain the nature of the projectile

2010 ◽  
Author(s):  
S. Goderis ◽  
J. Hertogen ◽  
F. Vanhaecke ◽  
Ph. Claeys
Keyword(s):  
Chesapeake Bay ◽  
Impact Structure ◽  
Siderophile Elements ◽  
Drill Cores

scholarly journals Melt in the impact breccias from the Eyreville drill cores, Chesapeake Bay impact structure, USA

2011 ◽  
Vol 46 (3) ◽  
pp. 396-430 ◽  
Author(s):  
Katerina BARTOSOVA ◽  
Lutz HECHT ◽  
Christian KOEBERL ◽  
Eugen LIBOWITZKY ◽  
Wolf Uwe REIMOLD
Keyword(s):  
Chesapeake Bay ◽  
Impact Structure ◽  
The Impact ◽  
Drill Cores

The ICDP-USGS Deep Drilling Project in the Chesapeake Bay impact structure: Results from the Eyreville Core Holes

2009 ◽  
Author(s):  
Gregory S. Gohn ◽  
Christian Koeberl ◽  
Kenneth G. Miller ◽  
Wolf Uwe Reimold
Keyword(s):  
Chesapeake Bay ◽  
Impact Structure ◽  
Deep Drilling ◽  
Drilling Project

Genesis of the mafic granophyre of the Vredefort impact structure (South Africa): Implications of new geochemical and Se and Re-Os isotope data

2021 ◽  
Author(s):  
Wolf Uwe Reimold ◽  
Toni Schulz ◽  
Stephan König ◽  
Christian Koeberl ◽  
Natalia Hauser ◽  
...  
Keyword(s):  
South Africa ◽  
Country Rock ◽  
Order Estimate ◽  
Impact Structure ◽  
Impact Melt ◽  
Highly Siderophile Elements ◽  
Isotope Data ◽  
Rock Types ◽  
Siderophile Elements ◽  
Os Isotope

ABSTRACT This contribution is concerned with the debated origin of the impact melt rock in the central uplift of the world’s largest confirmed impact structure—Vredefort (South Africa). New major- and trace-element abundances, including those of selected highly siderophile elements (HSEs), Re-Os isotope data, as well as the first Se isotope and Se-Te elemental systematics are presented for the felsic and mafic varieties of Vredefort impact melt rock known as “Vredefort Granophyre.” In addition to the long-recognized “normal” (i.e., felsic, >66 wt% SiO2) granophyre variety, a more mafic (<66 wt% SiO2) impact melt variety from Vredefort has been discussed for several years. The hypothesis that the mafic granophyre was formed from felsic granophyre through admixture (assimilation) of a mafic country rock component that then was melted and assimilated into the superheated impact melt has been pursued here by analysis of the two granophyre varieties, of the Dominion Group lava (actually metalava), and of epidiorite mafic country rock types. Chemical compositions, including high-precision isotope dilution–derived concentrations of selected highly siderophile elements (Re, Os, Ir, Pt, Se, Te), and Re-Os and Se isotope data support this hypothesis. A first-order estimate, based on these data, suggests that some mafic granophyre may have resulted from a significant admixture (assimilation) of epidiorite to felsic granophyre. This is in accordance with the findings of an earlier investigation using conventional isotope (Sr-Nd-Pb) data. Moreover, these outcomes are in contrast to a two-stage emplacement model for Vredefort Granophyre, whereby a mafic phase of impact melt, derived by differentiation of a crater-filling impact melt sheet, would have been emplaced into earlier-deposited felsic granophyre. Instead, all chemical and isotopic evidence so far favors formation of mafic granophyre by local assimilation of mafic country rock—most likely epidiorite—by a single intrusive impact melt phase, which is represented by the regionally homogeneous felsic granophyre.

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