Journal Article

Fracture development and diagenesis of Torridon Group Applecross Formation, near An Teallach, NW Scotland; millennia of brittle deformation resilience?

Laubach, Steve E, Hargrove, P, Olson, J. E, Eichhubl, P, Ellis, Magdalena A

2012

نظرة عامة

The Late Proterozoic Torridon Group Applecross Formation in the foreland of the Moine Thrust Belt, NW Scotland, contains deformation bands, three fracture sets (from oldest to youngest A, B, and L) defined by orientation, crosscutting relations, and progressively less quartz cement in younger sets, and joints. Set A crosscuts deformation bands and strikes north-south. Set B has trimodal orientation defining three linked subsets that formed concurrently. Set L strike ranges from NE-SW to ENE-WSW, in parent crack-wing crack arrays that formed progressively; these are more abundant near small-displacement, oblique-slip faults that offset the overlying Cambrian Eriboll Formation and the Moine Thrust Belt. Applecross sandstones have low fracture abundance, possibly a consequence of low elastic moduli (Young's modulus 2.3-17.0 GPa, most values <6.9 GPa) and moderate to high subcritical crack index (45-78), resulting from compacted soft lithic grains and clay-mineral cements. Low abundance contradicts models that postulate persistent incipient failure by subsurface fracture. The fracture sequence resembles that found in the overlying Cambrian Eriboll Formation quartzarenites, implying that no widespread late Proterozoic fracture sets exist in this part of the Applecross Formation, an uneventful record for a rock profoundly resistant to brittle deformation.

• الناشر: Geological Society of London,The Geological Society of London,Geological Society,Geological Society Publishing House
• موضوع: An Teallach / Applecross Formation / Apples / arenite / brittle deformation / Cambrian / Cement / clastic rocks / Crystalline rocks / Deformation / Diagenesis / Earth sciences / Earth, ocean, space / elastic constants / Eriboll Formation / Europe / Exact sciences and technology / faults / Field study / fractures / Fruits / Geology / Great Britain / Igneous and metamorphic rocks petrology, volcanic processes, magmas / Mechanical properties / Moine thrust zone / Neoproterozoic / oblique-slip faults / orientation / Paleozoic / Plate tectonics / Precambrian / Proterozoic / Quartz / quartz arenite / Rocks / sandstone / Scotland / sedimentary rocks / stiffness / Stone / structural analysis / Structural geology / style / subcritical crack index / Torridon Group / Torridonian / United Kingdom / upper Precambrian / Western Europe / Young's modulus