STABLE ISOTOPIC SYSTEMATICS OF THE BUSHVELD COMPLEX .2. CONSTRAINTS ON HYDROTHERMAL PROCESSES IN LAYERED INTRUSIONS

Fluid-rock interactions play a significant role in modifying the mineralogy, chemical composition, isotopic ratios, and physical properties of the Earth's crust. Although epizonal hydrothermal systems are well understood, relatively little is known about the nature and significance of large-scale fluid flow at crustal depths greater than about 10 km and temperatures greater than 400°C. The Bushveld hydrothermal system provides a well constrained example of large-scale fluid flow that occurred at crustal depths ranging to at least 15 km and temperatures ranging to at least 700°C. This paper reports oxygen, hydrogen, and carbon isotopic data for hydrothermally altered samples from the Bushveld Complex and its contact aureole. -from Authors