Structural Controls on Shallow Cenozoic Fluid Flow in the Otago Schist, New Zealand

Figure 5

Geochemistry and mineralogy of hydrothermal carbonate veins. (a) Scan of a thin section of a hydrothermal carbonate vein from the altered greyschist showing a distinct alteration zone with cross-cutting segmented quartz veins. Ternary diagram of magnesite-calcite-siderite, showing the compositions of the carbonate veins. The carbonate vein shows a compositional variation between calcite and ankerite. (b) Element map (Ca, Fe, and K) of the carbonate vein and alteration zone (location in (a)) showing a network of thin calcite veins defining the alteration zone. (c) Close-up element map of the white box in (b), showing a carbonate vein containing ankerite, siderite, and calcite.

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