Geology of the Letham Burn Wairaki Valley Area, Southland.


Campbell, HJ


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A detailed geologic map is presented of an area in the Wairaki Hills to the immediate east of the Takitimu Mountains (western Southland). The area involves rocks of the Takitimu Group, Productus Creek Group, Malakoff Hill Group and Cenozoic strata.
The exact position and nature of part of the Takitimu GroupMalakoff Hill Group Contact is established and the Productus Creek GroupMalakoff Hill Group contact is described and inferred to be an angular unconformity.
The Productus Creek Group is subdivided on a newly modified basis into four formations. The Elsdun Formation is redefined to incorporate the Weetwood Member which is interpreted on the basis of some new observations to be a lava flow, coeval with the Elsdun Formation.
A number of new occurrences of Productus Creek Group are described, including a large body here named the Pleasant Creek Formation, from which a trilobite was collected and is here described.
A large folded block of downfaulted Malakoff Hill Group is described and correlated with the Discaria Formation (Begg 1974), on the basis of general lithology and a tuff marker horizon. A lower Triassic plant fossil and a Daonella sp. fossil (Etalian Stage indicator fossil) are described from these rocks. On the basis of the relationship between Discaria rocks and a tuff marker horizon which can be traced through much of the Southland Syncline (Coombsl9SO, Watters 1951, Boles 1971, Begg 1974), an Etalian Stage is proposed for certain strata of the North Taringatura Hills and the Hokonui Hills.
Petrographic studies of Productus Creek Group and Malakoff Hill Group sandstones provide evidence that Takitimu Group rocks were metamorphosed to prehnite - pumpellyite facies assemblages, uplifted and eroded during early to middle Permian time and into Triassic time.
Strata of suspected Tertiary (possibly Cretaceous) age are mapped and described lithologically, and it is shown that some coarse sandstones contain pyroclastic detritus. .
Inferences are made with regard to environments of deposition, metamorphism and structure.

Thesis description:

133 leaves. Ill, photos. Maps (folded in pocket). 30 cm.


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Location (WKT, WGS84):

POLYGON ((167.892149226133654 -45.856918980420367,167.904984925198193 -45.725904754915206,167.905795527116169 -45.717009607397621,167.99622754501388 -45.722802637770492,167.98906770081868 -45.859435117016176,167.892149226133654 -45.856918980420367))




Campbell, HJ, “Geology of the Letham Burn Wairaki Valley Area, Southland.,” Otago Geology Theses, accessed May 22, 2024,

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