摘要
详细的生物地层学调查研究,揭示了四川广元上寺二叠系—三叠系界线上,古生代海生无脊椎动物大规模的绝灭,还检测到铱和微量元素的地球化学异常(Ir达2±0.5ppb)、碳和氧同位素(δ^(13)C和δ^(18)O)的剧烈变动、沉积相的显著变化(盆地相—潮间带)。(图4、5、6)这些证据表明二叠纪末期有地外事件发生,而地外事件又诱发了地内事件,包括构造上升、海水退却、火山喷发、古气候变化以及伴随的动物群大规模绝灭。古生代动物群的大规模绝灭和中生代动物群渡过萧条期才茁壮成长的迟滞、新生过程,说明了古生代与中生代间的地质事件是巨大的、深刻的,传统的二叠系—三叠系界线是一条全球灾变线。
The detailed biostratigraphical reasearch has revealed a mass extinction of Palaeozoic marine invetebrate faunas at the Permian-Triassic boundary of Shangsi,Guangyuan county,Sichuan province.All of the non-fusulinid Foraminifer and Radiolaria(Spumellinid)disaappear near the boundary.About 75%of the families of Goniatitids and some Ceratitids and 98%of the spcies of Ammonoids are eliminited.Conodonts are dropped off in diversity and abundance,but a few of Neogondolellids(Neogondolella subcarinata,N.changxingensis)survied into the Mesozoic.The course of regeneration became so slow that the Mesozoic faunas flourished only after a period of depression(Fig.4).The mass extinction implies the occurrence of certain of catastrophic events which have been confirmed by the discovery of abnomalies Ir(2±0.5 ppb)and geochimical abnomalies of the trace elements in the Permian-Triassic clay,the great change in the Carbon and Oxygen isotopes and the volcanic tuff with in montmorilloniteillite clay formed by the process of dehaline and ion exchange,near the boundary(Fig.5,6).these evidences support the occurrence of an extraterrestrial event,the bombarment of a planet or comet,by which other terristrial events such as crustal uplift,the regional regression,the volcanic explosion,the notable palaeoclimatic and the coincided mass extinction of the faunas is induced at the end of the permian.According to the rate and the extant,the events between Palaeozoic and Mesozoic eras are more striking than those happening between systems and the traditional Permiam-Triassic boundary marks a catastrophic event in the region.
作者
李子舜
詹立培
朱秀芳
张景华
金若谷
刘桂芳
盛怀斌
沈桂梅
戴进业
黄恒铨
谢隆春
严正
Li Zishun;Zhan Lipei;Zhu Xiufang;Zhang Jinghua;Jin Ruogu;Liu Guifang;Sheng Huaibien;Shen Guimei;Dai Jinye;Huang Hengquan;Xie Longchun;Yan Zheng(Institute of Geology,CAGS;Petroleum Geological Bureau of South-Wcst China,Ministry of Geology anl Mineral Resoutces;Institute of Geology,National Bureau of Seismology)
出处
《地质学报》
1986年第1期1-17,115-117,123,共21页
Acta Geologica Sinica
