PALEOZOIC SEQUENCE STRATIGRAPHY OF THE TARIM BASIN

摘要

In terms of Kalpin and Wushi outcrop characteristics, all of the boundaries between sequences are I-type ones. Main characteristics are as follows: ① angular unconformity between sequences; ② abrupt change in lithology; ③ abrupt change of rock facies; ④ presence of paleosol as much as 3-5 cm thick; ⑤ existence of high maturation basal conglomerate; ⑥ sandy conglomerate on the bottom of sequence, which occurs as lenses in the siltstone and mudstone and acts as channel fill deposits of incised valleys. Therefore, the Silurian, Devonian and Carboniferous have been divided into five, two and three sequences respectively in outcrop areas. The Silurian sequences are 40-155 m thick and composed of LST, TST and HST; Devonian sequences are 70-105 m thick and contain LST, TST and HST; Carboniferous sequences are 380-1200 m thick and mainly made up of LST and TST.