摘要:
青藏高原南部乌郁盆地是欧亚与印度板块碰撞以来冈底斯山隆升最具代表性的盆地之一,也是青藏高原南部较大的新生代残留盆地之一。沉积盆地中保存着完整的渐新世—早更新世连续沉积记录,自下而上由古新世—始新世林子宗群(典中组、年波组和帕那组)、渐新世—中新世日贡拉组、中新世芒乡组、来庆组、上新世—早更新世乌郁群(乌郁组、达孜组),总厚度大于4180m。林子宗群为一套中—酸性钙碱性火山岩系,夹紫红色砂岩、砾岩及粉砂岩。日贡拉组主要为紫红色砂岩、砾岩,夹少量火山熔岩及酸性火山凝灰岩,为一套山间盆地沉积。芒乡组为灰色、深灰色泥岩、砂岩,夹煤和油页岩,为湖泊相—前三角洲相—沼泽相。来庆组为一套褐色安山岩、火山碎屑岩。乌郁组是一套碎屑岩,颜色呈灰色、灰褐色,夹煤及油页岩,为山间盆地辫状河—湖泊—沼泽沉积。达孜组是一套黄褐色砾岩、砂砾岩、砂岩,夹少量泥岩,发育铁质结核,为辫状河沉积。沉积相分析表明具有明显的古新世—始新世林子宗群(典中组、年波组和帕那组)、渐新世—中新世日贡拉组—芒乡组、中新世来庆组—上新世乌郁组、上新世—早更新世达孜组四个阶段式隆升—剥蚀过程。从芒乡组的潮湿炎热的气候转变为乌郁组的干燥凉爽,显然与青藏高原隆升密切相关。乌郁盆地渐新世—早更新世沉积相分析对于研究青藏高原隆升和油气等能源均具有重要意义。
Abstract:
The Wuyu Basin, southern Tibetan Plateau is one of presental basin of India-Eurasia collision, a continuous sedimentary record throughout Oligocene to Miocene was discovered in the Wuyu Basin and considered as the most integrated Oligo-Miocene record within the Tibetan plateau, observed so far. The sedimentary include the Paleo-Eocene Linzizong Group (include the Dianzhong Formation, Nianbo Fm. and Pala Fm.) and the Oligo-Miocene Rigongla Fm., the Miocene Mangxiang Fm., the Miocene Laiqin Fm., the Pliocene Wuyu Fm., the Plio-Pleistocene Dazi Fm., with a total thickness of 4180m.The Linzizong Gr. composed chiefly of intermediate-acid lava, its middle part intercalated with brownish grey clastic sediment. The Oligo-Miocene Rigongla Fm., is the sediment of intermountain basin, consists mainly of reddish brown sandstone and conglomerate, intercalated with lava. The Miocene Mangxiang Fm. is the sediment from fluvial facies to lacustrine facies, swamp, chiefly grey, dark grey sandstone, siltstone, and mudstone, with coal and oil shale. The Miocene Laiqin Fm. is brown lava and pyroclastic flow sediment. The Pliocene Wuyu Fm. is grey, brown grey sandstone, siltstone, and mudstone, with coal and oil shale, which is fluvial-lacustrine-swamp facies. The Plio-Pleistocene Dazi Fm. is conglomerate, intercalated with grey mudstone. The Mangxiang Fm., suggesting the significant shifting of sediment provenance, the stable trending of tectonic movement, and the wet and torridity aridity of paleoclimate condition. The Oligo-Miocene paleoclimate and tectonic evolution of the Wuyu Basin has displayed its significance for understanding the early uplift of the Tibetan Plateau.
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