滇东南奥陶纪三叶虫的地层记录  

STRATIGRAPHICAL RECORD OF ORDOVICIAN TRILOBITES IN SOUTHEASTERN YUNNAN

作　　者：罗惠麟 周志毅[2] 胡世学 詹冬琴 卢玉喜 

机构地区：[1]云南省地质科学研究院,昆明650051 [2]中国科学院南京地质古生物研究所,南京210008

出　　处：《古生物学报》2014年第1期33-51,共19页Acta Palaeontologica Sinica

基　　金：国家自然科学基金(41221001;41290260;41172034)资助

摘　　要：滇东南位于奥陶纪扬子区的西南边缘,濒临古陆,水体较浅,沉积物中陆源碎屑丰富,而且因地壳升降运动幅度相对较大,导致了巨大的地层沉积厚度,仅含三叶虫地层就厚达385—2 080m,是我国奥陶纪三叶虫研究的空白地区。文中首次记述该地区下奥陶统下木都底组(下特马豆克阶)、独树柯组(上特马豆克阶)、闪片山组(特马豆克阶顶部—弗洛阶底部)、下奥陶统(弗洛阶)—中奥陶统上部(达瑞威尔阶下部)老寨组和中奥陶统顶部(达瑞威尔阶上部)—上奥陶统底部(桑比阶底部)冷水沟组的三叶虫序列,并系统描述了有关三叶虫,共计10科,15属,18种。其中特马豆克阶—达瑞威尔阶下部的三叶虫与鄂西和黔北所产最为相似,与川南及渝南一带同期分子也有关联,而达瑞威尔阶上部—桑比阶底部的分子则与黔北十字铺组动物群并无差异,代表当时滇黔隆起边缘的浅水动物群。对Mansuy(1920)描述的越南北部下奥陶统下部Dong Son组的三叶虫作了厘定,但由于有关材料保存太差、种级单元的鉴定特征模棱两可,目前暂无法得以在区内沿用。Faunal evidence suggests that southeastern Yunnan formed part of the Ordovician Yangtze Region （Chang, 1965; Lu etal., 1976; Lai etaZ., 1982; Wang et al. , 1996; Zhou et al., 2001, 2008）. Located to the east of Mengzi and Qiubei, the north of Vietnam and the northeast of the Honghe Fault （Text-fig. 1） between 103°--106° E and 22°20′--24°20′ N, the area contains extensive exposures of thick Ordovician shallow-sea clastics and terregenous carbonates, indicating a marginal setting close with lands. The trilobite-bearing beds vary in thickness from 385 m to 2 080 m in the area, but almost no trilobites have been described before. For the first time, this paper depicts the stratigraphic succession of trilobite faunas （Text-fig. 2） from southeastern Yunnan with systematic descripion of 18 species assigned to 15 genera and 10 families from 10 horizons respective of the Early Ordovician Xiamududi Formation （early Tremadocian）, Dush- uke Formation （late Tremadocian）, Shanpianshan Formation （latest Tremadocian--earliest Floian）, the Early--Middle Ordovician Laozhai Formation （Floian--early Darriwilian）, and the Middle--Late Ordovician Lengshuigou Formation （late Darriwil- ian--earliest Sandbian）. Trilobites are mostly poorly preserved, but share a large number of species with the Tremado- cian--early Darriwilian sequence of western Hubei, northern Guizhou, southern Sichuan and southern Chongqing, except for Sthenarocalymene sp. , the genus of which being erected in the upper- most Darriwilian from the Oslo region of Norway by Siveter （1977） is recorded in the Yangtze Re- gion for the first time. Whereas, during the late Darriwilian--earliest Sandbian, trilobites dwelled in southeastern Yunnan are indistinguished from those of northern Guizhou （as described from the Shihtzupu Formation, see Zhou et al. , 1984）, and may have formed a single shallow water fauna distributed along the marginal area of the then unified Dianqian （Yunnan-Guizhou） Uplift. The Ordovician stratig

关 键 词：地层纪录 奥陶纪三叶虫 滇东南 

分 类 号：Q915[天文地球—古生物学与地层学]