科研之友
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摘要
The Salt Range, Pakistan is the surface expression of an evaporite detachment over which the Potwar Plateau fold-thrust belt has moved. Whilst previous publications regarding this region have focused on the petroleum prospectivity, deformation, and large-scale processes, this paper characterises the Salt Range detachment at the meso-(10 cm to 10s of metres) and micro-scale (cm to mu m) and examines correlations to the macro-scale (105 of metres to kms). Two detailed scaled cross sections are analysed alongside structural measurements to characterise the detachment at the mesa-scale with optical analysis of microstructures that formed during deformation characterising the micro-scale. Both ductile and brittle features observed in cross section indicate composite deformation processes acting simultaneously; this contrasts with models of salt detachments behaving homogeneously. Microstructural analysis indicates processes of grain boundary migration and crystal lattice distortions. The microstructurally revealed competition between intra-crystalline deformation and recrystallization at shallow depths and low temperatures links passes up-scale to mesoscale evaporite mylonites and progressively in the weaker units, whereas more brittle processes operate in the stronger lithologies in this near-unique outcrop of a the emergent toe of a major salt-bearing detachment fault.
- 出版日期2015-12-1
