Titanium mobilization by hydrocarbon fluids related to sill intrusion in a sedimentary sequence, Scotland

An occurrence of vein-hosted bitumen in Carboniferous rocks, central Scotland, exhibits unusual enrichments in titanium, zirconium and chromium, detected by electron microprobe. These elements occur as mineral inclusions of titanium and titanium-iron oxides. A close association between titanium-rich tuffs and a quartz dolerite sill suggests that metals were leached from igneous rocks by a hydrocarbon-rich fluid generated by the heat of the intrusion into organic-rich shales. This occurrence supports other evidence for widespread titanium mobility under low-temperature conditions. Inclusions of nickel arsenide may reflect regionally important mineralization, including former ore deposits, related to sills and dykes. As sills are extensively intruded into petroleum-prospective basins offshore, they may have a significant influence upon sediment geochemistry. (C) 2003 Elsevier B.V. All rights reserved.