About 33 genus 47 species corals were discovered in the so-called "Xiala Formation(Ft)" in north of Oma Village, G(e)rz(e) County, Tibet. These newly-discovered corals indicate that the so-called Xiala Ft is the Late Jurassic Oxfordian-Kimmeridaian instead of the Early Permian in age. Therefore, the Xiala Ft is revised to be the Tukari Ft. Sabozhibule Ft is also suggested to be established and represents the strata below the Tukari Ft. Thus the Upper Jurassic in west part of the Bangong Co-Nujiang stratigraphic zone is suggested tobe divided into Sabozhibule Ft, Tukari Ft and Shamuluo Ft ascendingly. The present discovery of the Tukari Ft in the Oma area indicates that the Late Jurassic carbonate sediments spread widely and are much developed in the west part of the Bangong Co-Nujiang stratigraphic zone. Therefore, the Bangong Co-Nujiang stratigraphic zone did not suffer so strong and rapid compressional movement during the Late Jurassic as previous thoughts. The revision of the Xiala Ft to be the Tukari Ft also indicates that there wasn't the tectonic mélange phenomenon of the Permian limestone intermixed into the Jurassic Mugagangri Group. The Tukari Ft possesses good potential for petroleum-producing and storage for its considerable thickness and characteristic carbonate platform facies. Therefore, it should be pay due attentions to the petroleum prospects and evaluations of the Late Jurassic carbonate sediments in the Bangong Co-Nujiang stratigraphic zone and its north and south neighboring regions.%西藏改则物玛地区发现了约33属47种及未定种的晚侏罗世珊瑚化石.珊瑚化石指示其所在的地层并非是原来认为的早二叠世下拉组,而是晚侏罗世牛津期-基末里期的吐卡日组.基于对改则物玛北剖面的研究,在吐卡日组之下新建了晚侏罗世萨泼直不勒组.进而将斑公湖一怒江地层区西段的上体罗统自下而上划分为萨波直不勒组、吐卡日组和沙木罗组.改则县物玛乡北部吐卡日组的发现证明吐卡日组在班公湖-怒江地层区西部有着更广泛的分布.将"下拉组"修订为吐卡日组也表明班公湖-怒江地层区改则地区物玛段并不存在二叠系灰岩与体罗系木嘎岗日岩群碎屑岩的构造混杂现象.吐卡日组以浅海碳酸盐台地相的生物礁亚相、鲕粒滩亚相为特征,厚度也十分可观,指示其具有良好的生油和储油潜力,班公湖-怒江地层区西段及南北两侧的碳酸盐岩相上侏罗统的油气前景评价工作应予以重视.
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