McPhee formation
The McPhee formation is the final formation of the Talga Talga subgroup belonging to the Warrawoona Group in Western Australia ( Pilbara Kraton ). With an age of around 3480 million years BP , the predominantly ultramafic formation comes from the Paleo-Archean . It lies on the border between Isuum and Vaalbarum .
etymology
The McPhee Formation was named after the McPhee Creek , a small river that drains over the De Gray River to the north coast of Western Australia. The river name, in turn, honors the Australian surveyor Robert McPhee , who prospected in the Pilbara region in the 1880s .
Occurrence
The McPhee Formation can be found in the following greenstone belts of the East Pilbara Terrane :
stratigraphy
The McPhee Formation, which is very variable in terms of its thickness (usually 50 to 200 meters, but can reach 750 meters and more), follows with a mighty chert layer ( Big Chert ) concordantly on the Upper Extrusives of the North Star Basalt . The formation consists mainly of ultramafic rocks and basalts , with ribbon ores , pelite and acidic volcanic plastics as a subordinate feature. The ultramafic rocks are now available as talc - chlorite- shale or as carbonated talc-shale due to the regional metamorphosis . The McPhee Formation is discordantly overlaid by the Mount Ada basalt of the Coongan Subgroup . It correlates with the Dresser formation .
Deposits
The McPhee Formation shows base metal enrichments , multiple gold occurrences in the Marble Bar greenstone belt, and massive sulfides in the Warralong greenstone belt.
Individual evidence
- ^ Van Kranendonk, MJ: Geology of the Coongan . In: 1: 100000 sheet 2856 . v 1st Geological Survey of Western Australia, 2010, p. 67 .