Copper enrichments in the Kimberley formation in Gale crater, Mars: Evidence for a Cu deposit at the source

Research areas:
Year:
2019
Keywords:
Copper deposit, Gale crater, Kimberley, ChemCam, Hydrothermal alteration
Authors:
  • Valérie Payré
  • Cécile Fabre
  • Violaine Sautter
  • Agnès Cousin
  • Nicolas Mangold
  • Laetitia Le Deit
  • Olivier Forni
  • Walter Goetz
  • Roger C. Wiens
  • Olivier Gasnault
  • Pierre-Yves Meslin
  • Jérémie Lasue
  • William Rapin
  • Ben Clark
  • Marion Nachon
  • Nina L. Lanza
  • Sylvestre Maurice
Journal:
Icarus
Volume:
321
Pages:
736 - 751
ISSN:
0019-1035
Abstract:
Copper quantification with laser induced breakdown spectroscopy (LIBS) using a univariate calibration model enables the ChemCam instrument onboard the Curiosity rover to measure unusually elevated Cu concentrations in potassic sandstones and Mn-oxide-bearing fracture fills in the Kimberley region of Gale crater, Mars. Mostly, the copper phases occurring in sedimentary bedrock are associated with detrital silicates, including feldspars, pyroxenes and K-phyllosilicates, likely coming from a potassic igneous source near the northern crater rim, while those present in the fractures are likely adsorbed on the surface of manganese oxides. These two different mineralogical associations imply at least two distinct processes: Cu enrichment in bedrock at the source, likely during crystallization of the igneous silicates, and adsorption of Cu on Mn-oxides precipitated from groundwater that encountered oxidizing conditions within fractures in the bedrock. The potassic sediments enriched in copper may be evidence of a porphyry copper deposit or an impact-induced hydrothermal deposit in the source region.