Conference proceeding
Heavy metal enrichments in the Kimberley bedrocks; evidence of an ore deposit at the source?
American Geophysical Union Fall Meeting, Vol.2017
American Geophysical Union 2017 fall meeting
12/2017
Abstract
Three years ago, the Curiosity rover reached a sedimentary formation called Kimberley that is compositionally very different from previous and subsequent analyses. These sandstones contain elevated amounts of K (sub 2) O with an average of 2.1 wt.% according to ChemCam instrument, explained by the occurrence of potassic minerals: a sandstone named Windjana has been analyzed by CheMin instrument, showing large amounts of sanidine. Mafic minerals (augite, pigeonite, magnetite) and minor phases including F-apatites and sulfides have also been identified. ChemCam analyzed several points where micas may have been sampled. All these minerals are thought to be detrital having originated from igneous sources like potassic and mafic rocks in the northern rim. High Zn and Cu contents (up to 2000 ppm and 1010 ppm, respectively) have been measured in these K-bedrocks. The ChemCam instrument allows the analysis of materials with depth: a LIBS point is ablated by 30-150 laser-shots, measuring the composition of the first micrometers. These depth profiles show evidences of the occurrence of a Cu-phase within K-spars. In a potassic sandstone containing up to 1010 ppm of Cu and 250 ppm of Ge according to ChemCam and APXS analysis respectively, a Cu-phase is potentially hosted in clays or micas. These high values would be related to local hydrothermalism at the igneous source region of the Kimberley detrital minerals. These observations and the occurrence of 800 ppm of Cu in a porphyric alkali feldspar within a trachyandesite, suggest that these Cu enrichments may be due to a porphyry copper deposit at the source region of the potassic minerals. Another hypothesis is the presence of an ore deposit related to an impact-induced hydrothermalism. Hence, circulation of high temperature fluids would have happened at the magmatic source region of the Kimberley minerals, favoring the formation of a metallic deposit.
Details
- Title: Subtitle
- Heavy metal enrichments in the Kimberley bedrocks; evidence of an ore deposit at the source?
- Creators
- Valerie Payre - Université de LorraineCecile FabreViolaine SautterNicolas MangoldAgnes CousinLaetitia Le DeitWalter GoetzOlivier ForniOlivier GasnaultRoger C. WiensSylvestre Maurice
- Resource Type
- Conference proceeding
- Publication Details
- American Geophysical Union Fall Meeting, Vol.2017
- Conference
- American Geophysical Union 2017 fall meeting
- Publisher
- American Geophysical Union
- Alternative title
- AGU 2017 fall meeting
- Language
- English
- Date published
- 12/2017
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984318344902771
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