Multiple Influences of Paleogeography, Sequence Stratigraphy, and Fold Structure on Coalbed Methane Accumulation in the Lopingian (Late Permian) of Junlian Coalfield, SW China

Figure 2

Photographs of the lithology of the Lopingian coal-bearing system in the southern Sichuan area: (a) gray conglomerate, meandering river channel retention sediment, Xunsi section, Junlian; (b) conglomerate-bearing fine sandstone, flattened mud gravel with biaxially aligned tectonics, matrix-supported, average rounded, and poorly sorted, borehole YSL1, 610.5 m in depth, lower member of the Longtan Formation; (c) conglomerate-bearing fine sandstone, flattened mud gravel with biaxially aligned tectonics, matrix-supported, poorly rounded, and poorly sorted, storm event disturbance structure, borehole YSL1, 582.5 m in depth, upper member of Longtan Formation; (d) lenticular bedding sandstone, borehole Z105, 581.56 m in depth, Junlian; (e) lenticular bedding sandstone with well-developed bioturbation structure, borehole YSL152, 581.5 m in depth; (f) tidal bedding-trough-shaped cross-bedded sandstone with well-developed bioturbation structure, borehole YSL152, 582.5 m in depth, Junlian; (g) rhodolitic mudstone with oolitic tectonics, borehole YSL152, 607.5 m in depth, upper member of Longtan Formation; (h) muddy limestone, Xuyong; (i) dark mudstone with marine faunal fossils, borehole YSL1, 610.5 m in depth, upper member of Longtan Formation; (j) dark mudstone with biogenic subduction development, borehole YSL152, 581.7 m in depth, upper member of the Longtan Formation; (k) dark mudstone with Lepidodendron fossils, borehole Z105, 609.3 m in depth, upper member of the Longtan Formation; (l) primary-fractured structural coal with pyrite layer-filled fissures, borehole YSL37, Muai, Junlian; (m) primary-fractured structural coal, borehole YSL37, Muai, Junlian; (n) calcite cement in coal, borehole YSL1, 608.7 m in depth, Muai, Junlian; (o) Bauxitic mudstone, developing pyrite crystals, bottom of Longtan Formation. 10 cm diameter core in borehole YSL1, 5 cm diameter in other cores, geological hammer length about 30 cm.

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