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晚古生代末期至早中生代期间,上扬子西部边缘地区经历了峨眉山大火成岩省构造岩浆热事件和与古特提斯洋闭合相关的三江造山带形成事件,导致康滇古陆两侧形成了独特的盆山格局和沉积模式.由于目前人们对盐源盆地早三叠世青天堡组的物源与构造背景了解不多,故以盐源、盐塘剖面为代表,对青天堡组碎屑岩进行了砂岩组分、全岩地球化学和碎屑锆石年代学分析.结果显示,盐源盆地下三叠统青天堡组物源来自于近源搬运的火山岩,青天堡组与峨眉山大火成岩省的高钛玄武岩具有一致的元素组合配分模式,青天堡组锆石谐和加权平均年龄为261±16Ma,与峨眉山大火成岩省形成的地幔柱活动时期一致.上述结果表明早三叠世盐源盆地青天堡组物源为其东侧的峨眉山大火成岩省,扬子西部三江造山带可能并没有为盐源盆地提供物源,上扬子西南边缘地区早三叠世时期仍然为被动大陆边缘沉积.
During the late Paleozoic to early Mesozoic, the western margin of the upper Yangtze experienced structural tectono-magmatic events in the Emeishan large igneous province and the Sanjiang orogenic belt associated with the closure of the ancient Tethys Ocean, resulting in the formation of unique Basin-mountain pattern and sedimentary model.Because people do not know much about the provenance and tectonic setting of the Early Triassic Qingxhibao Formation in the Yanyuan Basin, the source rocks and salt ponds are the representatives of the Qingxhibao Formation clastic rocks Sandstone components, lithochemistry and detrital zircon zircon dating.The results show that the source of the Lower Triassic Qingxhibao Formation in the Yanyuan Basin comes from volcanic rocks transported by nearby sources, and from the Qingtianbao Formation and the Emeishan Igneous Province Titanic basalts have the same pattern of elemental assemblages, and the zircon ages of Qingtianbao Formation were 261 ± 16Ma, consistent with the period of mantle plume formed in the Emeishan large igneous province.The above results show that the Qingtianbao The source of the assemblage is the Emeishan Igneous Province on the east side of the Yangtze River. The Sanjiang orogenic belt in the western Yangtze may not provide a source for the Yanyuan Basin and the upper Triassic margin of the Upper Yangtze The period is still passive continental margin deposition.