Hi Midnight, Based on this scholarly article you have reproduced...

Hi Midnight,

Based on this scholarly article you have reproduced the conditions for mineralisation at Serra Leste seem particularly restrictive (narrow) in regard to the pH and oxygen fugacity which existed at the time of deposit formation plus the source of the Pd-Pt remains contentious as to whether it has been scavenged from nearby ultramafic sequences or along with the gold came from the dioritic intrusion directly or even from the carbonaceous meta-siltstone. The article is by no means categorical on the source of the metals. Do we have any evidence here of a carbonaceous siltstone in contact with our diorite which could have provided the necessary chemical barrier which is theorised about in the article. It seems like more than intermediate intrusion alone is needed to form another Serra Leste according to the article you posted.Esh

"The solubility of Au and PGE as Cl-complexes are of the same order of magnitude and drop rapidly with pH increase or ƒO2 decrease (Mountain and Wood 1988). The carbonaceous metasiltstone possibly acted as a chemical barrier, triggering focused deposition of precious metals through a rapid decrease of oxidation conditions of the hydrothermal fluid. This process was possibly coupled with carbonate dissolution of dolomitic marble that triggered open-space-filling processes, developed an external jasperoid envelope around the orebodies and caused a pH increase.