The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lu...The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lunpola Basin.The medial condyle of the distal trochlea of the humerus specimen from Lunbori gradually contracts from medially to laterally.The margin of the medial surface of the medial condyle is not prominent,the well-developed medial epicondyle strongly extends posteriorly,and is divided from the articular facet of the medial condyle by a groove;all of which are characteristic for the Rhinocerotidae.The medial condyle is wide at the bottom and narrow at the top.The medial collateral ligament fossa is relatively shallow,and the medial collateral ligament tubercle is very weak.The medial part of the upper margin of the medial condyle smoothly connects to the bony surface above,but there is no clear boundary between them.All of these characteristics are identical with those of Plesiaceratherium.These comparisons imply that the Lunbori specimen is closest to Plesiaceratherium gracile in the Shanwang Fauna from Linqu,Shandong Province,in size and morphology.Thus,its age is suggested to be the late Early Miocene(Shanwangian Age),about 18-16 Ma.Discovery of the rhinocerotid fossil suggests that the upper part of the Dingqing Formation deposited in the Neogene.While adjusting to paleo-temperatures of the Early Miocene,a paleo-ecosystem reconstruction indicates that the paleo-elevation was close to 3000 m in the Lunpola Basin during this time.展开更多
探讨西藏伦坡拉盆地北缘古近系牛堡组的油气成藏。通过分析伦坡拉盆地油气地质条件,综合含油气系统的研究方法,研究成藏过程和机理。伦坡拉盆地北缘中深层牛堡组的主要烃源为牛二段,属自生自储型油气藏,烃源岩在牛三段沉积末期即开始生...探讨西藏伦坡拉盆地北缘古近系牛堡组的油气成藏。通过分析伦坡拉盆地油气地质条件,综合含油气系统的研究方法,研究成藏过程和机理。伦坡拉盆地北缘中深层牛堡组的主要烃源为牛二段,属自生自储型油气藏,烃源岩在牛三段沉积末期即开始生烃,大量生烃期为丁青湖组沉积期。伦坡拉盆地北缘的油气成藏过程可以归纳为3个阶段：1渐新世（34~23 Ma B.P.）,古油藏的形成;2渐新世末-中晚中新世（23~13 Ma B.P.）,古油藏的调整;3晚中新世（13 Ma B.P.）至今,古油藏的进一步调整和破坏。青藏高原其他古近纪形成的类似沉积充填盆地也具有相似的油藏形成与破坏过程。展开更多
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q09)the National Basic Research Program of China (2012CB821906)the National Natural Science Foundation of China (40730210)
文摘The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lunpola Basin.The medial condyle of the distal trochlea of the humerus specimen from Lunbori gradually contracts from medially to laterally.The margin of the medial surface of the medial condyle is not prominent,the well-developed medial epicondyle strongly extends posteriorly,and is divided from the articular facet of the medial condyle by a groove;all of which are characteristic for the Rhinocerotidae.The medial condyle is wide at the bottom and narrow at the top.The medial collateral ligament fossa is relatively shallow,and the medial collateral ligament tubercle is very weak.The medial part of the upper margin of the medial condyle smoothly connects to the bony surface above,but there is no clear boundary between them.All of these characteristics are identical with those of Plesiaceratherium.These comparisons imply that the Lunbori specimen is closest to Plesiaceratherium gracile in the Shanwang Fauna from Linqu,Shandong Province,in size and morphology.Thus,its age is suggested to be the late Early Miocene(Shanwangian Age),about 18-16 Ma.Discovery of the rhinocerotid fossil suggests that the upper part of the Dingqing Formation deposited in the Neogene.While adjusting to paleo-temperatures of the Early Miocene,a paleo-ecosystem reconstruction indicates that the paleo-elevation was close to 3000 m in the Lunpola Basin during this time.
文摘探讨西藏伦坡拉盆地北缘古近系牛堡组的油气成藏。通过分析伦坡拉盆地油气地质条件,综合含油气系统的研究方法,研究成藏过程和机理。伦坡拉盆地北缘中深层牛堡组的主要烃源为牛二段,属自生自储型油气藏,烃源岩在牛三段沉积末期即开始生烃,大量生烃期为丁青湖组沉积期。伦坡拉盆地北缘的油气成藏过程可以归纳为3个阶段：1渐新世（34~23 Ma B.P.）,古油藏的形成;2渐新世末-中晚中新世（23~13 Ma B.P.）,古油藏的调整;3晚中新世（13 Ma B.P.）至今,古油藏的进一步调整和破坏。青藏高原其他古近纪形成的类似沉积充填盆地也具有相似的油藏形成与破坏过程。
