Nature, distribution and relationships of the mineralization at Woodlawn, New South Wales

Abstract

The Woodlawn Deposit comprises an outcropping, composite body consisting of one large and several smaller lenses of polymetallic massive sulphides with an associated zone of copper mineralization, and several separate non‐outcropping bodies of massive sulphides occurring downdip in the same stratigraphic sequence.

Most data relate to the outcropping body. They indicate that the main massive sulphides lens in that body is a stratigraphic unit which changes laterally to a thicker sequence of mineralized volcanics to the south and west, and apparently lenses out completely in other directions. The distribution of metal values within and adjacent to the massive sulphides lens is discussed.

A concept of the Woodlawn mineralization is developed: of a central, thick volcanic pile, comprising mainly felsic fragmentals and welded or foliated tuffs containing widespread traces of base metals, flanked by sequences of fine‐grained volcanics, volcanic‐derived sediments and shales. The massive sulphides lenses extend out from the central volcanic pile and are interbedded with the sedimentary sequence.

The massive sulphides appear to be chemical sediments deposited by mineralizing fluids travelling along the sea floor. The copper mineralization appears to result from mineralizing fluids intruding along and across bedding beneath or adjacent to the massive sulphides.