陕西紫阳志留系温洛克统莫企森弓笔石(Cyrtograptus murchisoni)及地层意义  

New Material of Wenlock Graptolite Cyrtograptus murchisoni from Ziyang County,Shaanxi Province,China and Its Stratigraphic Significance

作　　者：王健[1,2] 王欣 李银华[3] WANG Jian;WANG Xin;LI Yinhua(Xi'an Center of Geological Survey,CGS,Xi'an 710054,Shaanxi,China;Field Observation Site on Strata type Section for the Bottom of Wenlock in Ziyang,Shaanxi,Ministry of Natural Resources,Xi'an 710054,Shaanxi,China;Shaanxi Nature Museum,Xi'an 710061,Shaanxi,China)

机构地区：[1]中国地质调查局西安地质调查中心,陕西西安710054 [2]自然资源部中志留统底界层型剖面-陕西紫阳野外科学观测基地,陕西西安710054 [3]陕西自然博物馆,陕西西安710061

出　　处：《西北地质》2022年第4期175-182,共8页Northwestern Geology

基　　金：中国地质调查局项目“陕西安康地区地质遗迹调查(DD20190078)”;“西北地区自然资源动态监测与风险评估(DD20211393)”;中国科学院南京地质与古生物研究所国家重点实验室开放基金“扬子板块北缘志留系温洛克统底界生物地层学研究(213121)”联合资助。

摘　　要：在紫阳芭蕉口-A剖面上发现了多个完整的莫企森弓笔石(Cyrtograptus murchisoni)。笔者对其始部、主枝、一级幼枝、二级幼枝、胞管等特征进行了描述和数据统计,并与国内外相似的弓笔石类群进行了详细得对比。该种弓笔石是志留系重要的带化石,同时它的首现是国际温洛克统底界的标志;该种化石的特点是笔石主枝粗壮,幼枝发育,常见二级胞管幼枝,始部有旋圈,胞管形态鸟喙状,口刺较短。对该种化石的深入研究为中国和国际温洛克统底界的对比和弓笔石演化研究提供了重要依据。Several well-preserved,complete specimens of Cyrtograptus murchisoni Caruthers,1867 are discovered in the Bajiaokou-A section in Ziyang County,southern Shaanxi Province.In this paper,we describe these specimens,especially the characteristics of the proximal end,main stipe,the primary cladium,secondary cladium and theca,by a comparison with those specimens from elsewhere in the world.The species is characterized by its thick main stipe and cladia.The secondary cladia are common,with spiral circles in the proximal end,bird beak-shaped theca with short apertural spines.The first occurrence of the index species indicate precisely the base boundary of the Wenlock Series of Silurian in China.

关 键 词：Cyrtograptus murchisoni 中志留统 温洛克统 陕西紫阳地区 

分 类 号：P52[天文地球—古生物学与地层学]