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Abstract: The Kela-2 gas field, located in the Kuqa Depression of Tarim Basin, is the most productive gas field in China, based on per unit surface acreage. The gas trap is a subsurface anticline formed along an E–W trending thrust belt in front of the southern Tianshan Mountains. The gas pay zones are located in fine-grained sandstones of a fan delta front facies in the Lower Cretaceous Bashijiqik Formation (Klbs), and Eogene evaporitic rocks serve as regional cap rocks. The gases were derived primarily from over-mature Jurassic coal measures. Peak gas generation and final shaping of the Kela-2 structure occurred relatively late, in the late Himalayan orogeny (5–0Ma). Thrust faulting appears to have played a significant role in the hydrocarbon generation, migration, accumulation and preservation in this foreland basin. Detailed delineation of the Kela-2 gas field indicates that high-quality regional cap rocks are essential for the formation of the super-rich, abnormally pressured, giant gas fields, while buried anticlines under the overthrust zone are the favorable gas habitat. Late gas accumulation is considered to be decisive for the conservation of the giant gas fields. [Copyright &y& Elsevier]

In northeastern China, Cenozoic ‘reverse faults’ can be found in most basins. It was proposed that these faults were the products of inversion tectonics during a Cenozoic regional compressional event. This explanation is inconsistent with regional structures that are dominated by normal faults on seismic profile. As a typical example, the Rongxintun fault in northeastern Liaohe basin is systemically analyzed on the basis of deformation style, sedimentary character, and systemic mapping using seismic data. We conclude that the Rongxintun fault was related to right-lateral strike slipping of the Yannan main fault during the late Paleogene when the Dongying deposition occurred, and it was a secondary right-lateral/reverse fault (P Plane Fault) of the Yannan strike-slip fault system. The fold was a fault related fold formed as a result of movement along the Rongxintun fault. According to this analysis of the Rongxintun fault, we conclude that the Cenozoic ‘reverse fault’ in northeastern China was a secondary right-lateral/reverse fault of a strike-slip fault system and did not represent a compressional event. This kind of mechanism of ‘reverse faulting’ is consistent with the fact that there was large-scale strike-slip faulting in northeastern China during the Cenozoic. [Copyright &y& Elsevier]