Geology of the Moke Creek area

Author:

Barber, Anton Joshua William.

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Abstract:

The schist basement in Moke Creek area is part of the Haast Schist Group, which represents the early Jurassic tectonic collision between the Caples, Torlesse and Aspiring Terranes. The schists within the Moke Creek area are predominately quartzofeldspathic, with subordinate greenschist and rare metachert. The quartzofeldspathic schists (greyschists) represent metamorphosed greywacke and argillite protoliths. Differing greyschist types are geochemically indistinguishable from each other; with major differences being attributed to varying amounts of disseminated graphite and the organization of leucocratic and phyllosilicate rich layers. Greenschist bands were geochemically shown to represent metamorphosed basaltic rock, of both MORB and within-plate affinities. The immediate host rocks of the Moke Creek massive sulphide deposit are compositionally similar to quartzofeldspathic schists, rather than metabasalts, as previously assumed. The Turnbull et al. (in press) textural zone classification was more useful in subdividing the schists than the Bishop classification. Using the Turnbull et al. classification, the schists were subdivided into TZIIB, TZIII and TZIV. With the exception of the TZIII-IV isotect, textural boundaries represent faulted contacts. The TZIIB schist has a Caples affinity, whereas the TZIII-IV schist is of Torlesse/Aspiring affinity. The boundaries between Caples and Torlesse schists were also faulted. Late Tertiary reverse movement on the Moonlight Fault has strongly influenced the structure within the area. Schist foliation steepens dramatically towards the fault, with overturned foliation immediately adjacent to it. Reverse faulting has also infaulted the Oligocene Bobs Cove Beds, imposing a considerable overburden pressure on them. Estimates on burial using vitrinite reflectance and petrography, range from ~2500-3500 meters.

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vi, 113 leaves : ill. (some col.), maps (some folded) ; 30 cm.

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OU geology Identifier:

2000Barber

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Location (WKT, WGS84):

POLYGON ((168.65766260775672 -44.944648796535638,168.655335491342782 -44.970997774719919,168.61580386492281 -44.970198648825253,168.588968521445167 -44.983215714677037,168.559152619566163 -44.982534272017233,168.563756069586873 -44.940318036821431,168.65766260775672 -44.944648796535638))

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http://download.otagogeology.org.nz/temp/Abstracts/2000Barber.pdf

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Citation

Barber, Anton Joshua William., “Geology of the Moke Creek area ,” Otago Geology Theses, accessed March 9, 2021, http://theses.otagogeology.org.nz/items/show/359.

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