INDOSINIAN YENSHANIAN TECTONIC EVOLUTION OF XIKUANGSHAN, HUNAN AND ITS SIGNIFI-CANCE FOR OIL AND GAS PROSPECTING

This paper deals with the folds and faults of different directions,the minor-structures,especially incipient en echelon tension fissures filling with veins that are widely developed.It is shown that four horizontal compressive tectonic stress fields of different directions successively exerted on this district during the period from Indosinian to Yenshanian.This discovery is important and it provides clues and evidents for studying the tectonic evolution during this period in Southern China.According to the characteristics of structural deformation that were caused by different tectonic stress fields,it is inferred that there are possible favorable structural traps in the oil and gas-bearing rocks ranging from Upper Palaeozoic to Lower Triassic in Mid-Hunan area.We hope this result will throw some light on prospecting in this district.