An Essay on Devonian Stratigraphy and Sedimentary Environment of Hunan Province , Southern China

Author: Chung-Hung Hu

Abstract：

Devonian deposits of the Hunan province furnish record of remarkably rhythmic transgression and regression of shallow sea. Two rhythmic sedimentary cycles are recognizable during the early Middle Devonian to the late Upper Devonian period. The first sedimentary cycle is named Tiaomachien cycle, which contains Tiamachien transgression and Chetzechiao regression, and the second is Shetienchiao cycle contains Shetienchiao transgression and Hsikuangshan regression. During the advance of the sea pread over of the entire area, it leaves record of its existance in deposits of conglomerate, sandstone, purplish shale, yellowish sandy shale, argillaceous lime stone, lump limestone sequence or sandstone, shales, shaly limestone, banded limestone, and lump limestone sequence. During the retreat of the sea, it remains record of ero-sional surface to form an unconformity or disconformity between the next sedimentary cycle.
Study of the whole body of deposits, taking account of characters observed both horizontally and vertically, lead inescapably to the conclusion that during the Devonian period the trangression of the seas inward from northern Kwangton and Kwangsi provinces to northern Hunan and the regression seas outward from northern Hunan to northern Kwangton and Kwangsi. The depositional area is a shallow sea showing an embayment structure. The embayment lies mainly from south-central to north central areas of Hunan. According to the result of lithologic analysis of the deposits, it suggests that on the west side of the embayment occupies possibly an high land or mountains, and the north and east sides are low land, might stand just above the sea level.

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