紫阳动物群:华南一个早奥陶世斜坡相化石库  

Ziyang Fauna: A slope facies fossil lagerst?tte of Early Ordovician in South China

作　　者：王健 华洪[1] 王欣[2] 辜平阳[2] 陈锐明[2] 庄玉军[2] 何世平 李银华[3] Jian Wang;Hong Hua;Xin Wang;Pingyang Gu;Ruiming Chen;Yujun Zhuang;Shiping He;Yinhua Li(Shaanxi Key Laboratory of Early Life and Environments,State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China;Centre for Orogenic Belt Geology,China Geological Survey,Xi'an 710054,China)

机构地区：[1]西北大学地质学系早期生命与环境陕西省、重点实验室,大陆动力学国家重点实验室,西安710069 [2]中国地质调查局造山带地质研究中心,西安710054 [3]陕西自然博物馆,西安710061

出　　处：《科学通报》2019年第22期2342-2350,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(41890844,41672025,41621003);中国地质调查局项目(DD20160014,DD20190078);陕西省早期生命与环境重点实验室(西北大学)开放课题基金(19LELE04)资助

摘　　要：陕西省紫阳县洄水镇早奥陶世地层中发现了一个以完整保存的三叶虫化石为主,兼有笔石、腕足动物、节肢动物、遗迹化石等多个门类化石的特异埋藏生物群——紫阳动物群.经初步研究,该动物群中三叶虫化石主要有Seleneceme, Niobe, Nileus, Ampyx, Degamella, Borogothus, Geragnostus, Dividuagnostus等;笔石主要包括Tetragraptus和Paratemnograptus等;腕足动物则主要有Tritoechia和Lingulella等.这是一个以三叶虫占优势、处于较深水斜坡相的特殊埋藏动物群,其中三叶虫兼具有寒武纪Ibex动物群和奥陶纪Whiterock动物群的过渡特征.该动物群的发现和研究将为奥陶纪生物多样性大辐射提供重要化石证据,也为扬子西北缘斜坡相生物多样性辐射研究提供了新的化石材料."Great Ordovician Biodiversification Event"(GOBE) is one of the major biological innovation in Phanerozoic. Trilobite is one of the major taxa in Cambrian and Ordovician. In 1998, Adrain divided the global Ordovician trilobites into two groups, i.e. Ibex Fauna and Whiterock Fauna, and subsequently, the former was subdivided into Ibex Ⅰ and Ibex Ⅱ faunas in 2004. The Ordovician radiation of the trilobites was associated with temporal and spatial expansion of the Whiterock Fauna and contraction of the Ibex Fauna. Ibex Fauna is also known as the Cambrian Evolutionary Fauna, which originated at Cambrian, had high diversity and differentiation soon, decline rapidly in Early Ordovician, and went extinct in Late Ordovician. The Ibex Ⅰ Fauna raised and flourished only in the Early Tremadocian, while Ibex Ⅱ fauna declined after the Early Ordovician radiation. Whiterock Fauna is also called the Paleozoic Evolutionary Fauna, which appears in Early Ordovician and shows rapidly radiation and high diversification in Middle Ordovician, and then survived the Ordovician Mass Extinction, evolved into Silurian Fauna, some of them might develop and extend to Devonian, Carboniferous and Permian.In 2006, Zhiyi Zhou dubbed the Ordovician trilobite radiation in the South China Block, suggested that the time of onset and the environmental pattern of the Ordovician trilobite radiation may have varied geographically, and the major radiation was likely a long-sustained event that extended through about 25 Ma of the late Early-early Late Ordovician interval,coinciding with the worldwide expansion and domination of the Whiterock Fauna. So the taxa of Zhou’s Ibex Fauna were proportionally dominant over those of Whiterock Fauna.Ziyang fauna, an Early Ordovician fossil lagerst?tte is discovered and reported from Ziyang County, Shaanxi Province.It is Floian(the late Early Ordovician) in age based on the occurrences of Tetragraptus approximatus Nicholson. The fossiliferous rocks are blackish-grey mud limestone and calcareous mudstone of

关 键 词：早奥陶世 弗洛阶 紫阳动物群 三叶虫动物群 过渡相生物多样性 扬子区 陕西紫阳 

分 类 号：Q915[天文地球—古生物学与地层学]