Paul Dennis edited geology3.tex  over 8 years ago

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Dirtlow Rake (GR) is a major WSW-ENE trending strike slip fault lying just to the south of Castleton. The width of the exposed fault is greater than 10m and it has been extensively worked over a greater than 10km length for Pb (galena) and Zn (sphalerite). Hydrothermal calcite occurs as large syntaxial and elongate, sparry crystals. The growth form often exhibits dog-tooth terminations indicative of growth into a void. for the top of the platformevidence for high pore fluid pressures during the period of faulting with the development of mode I fractures and in places a pervasive mesoscale fracture network. Fracture dimensions range from sub-mm to fault widths of several metres. Fracture and fault vein fill at all the locations is dominated by white, sparry calcite often showing a syntaxial growth pattern with varying degrees of complexity as a result of repeated episodes of movement, brecciation and renewed hydrothermal mineral growth.