Geology of the Paringa River, South Westland

Waters, Jeffrey Carl.

In the Paringa River area in South Westland a part of the eugeosynclinal suite has been intensely deformed and metamorphosed to quartzofeldspathic schists, amphibolites, metacherts and pegmatites under upper garnet zone to medium grade oligoclase zone P-T conditions. The quartzofeldspathic schists contain plagioclase An20-30 co-existing with albite in the garnet zone and more calcic plagioclase in the oligocalse zone. Muscovite and biotite are ubiquitous. The amphibolites contain ferroan pargasitic hornblende and plagioclase An21-30, with accessory garnet, epidote, calcite, sphene, rutile and opaques. Several different metachert horizons were studied including; quartz-spessartine chert, piemontite chert and epidosite. In the headwaters of Swindle Creek a pegmatite which was inferred to have formed by partial melting intrudes quartzofeldspathic schist parallel to the foliation.
Uplift of the alpine schists caused by the collision of the Pacific and. Indian plates occurs over a 10-15km wide zone between the Main Divide and the Alpine Fault. The uplift in the schists is taken up by movement along weaknesses in the schist (usually phyllosilicatico-rich segregations} and by transposition of early phase folds.
An example of a basic alkali dyke swarm was located in a tributary of Lamprophyre Creek. Float samples of dykes from the swarm were also studied. The dyke swarm in the Paringa River is composed of camptonites, spessartites and vogesites; all show some alteration by late stage alkali rich fluids.
Intrusions of carbonate breccia and carbonate veins were located in Gorgy Creek and may be related to the late stage fluids which have altered the lamprophyres. The alteration of the schist, by these fluids may be described as fenitization if this is the case

89 leaves : ill.(some col.), maps ; 30 cm.

1983Waters

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