Soft-Seditnent Recumbent Folding in a Slump-Generated Bed in Jharia Basin, Eastern India

Abstract

Paraconglomerates, with pebble- or boulder-sized phenoclasts of laminated clay in a matrix of medium grained massive. sandstone, occur toward the top of a turbidite sequence in the Talchir Formation at the N. W. corner of the Jharia Coal Basin in eastern India. The soft-sediment folds within the shale phenoclasts are dominantly recumbent. An analysis of the geometry of the structures suggests that a mass of sand with interlayered clay units was liquefied or fluidized. This in its turn generated a plastic mass flow in the course of which tenacious clay yielded slabs which were subsequently rotated and deformed. When the down-slope movement of the sand body had slowed down or had come to rest on the basin floor, the piled up mass of soft sediments was flattened under its own load and the contortions of the clay phenoclasts acquired their recumbent character.