First report on Guanshan Biota(Cambrian Stage 4) at the stratotype area of Wulongqing Formation in Malong County,Eastern Yunnan,China     

Feiyang Chen  Zhifei Zhang  Marissa J.Betts  Zhiliang Zhang  Fan Liu 《地学前缘(英文版)》2019,10(4):1459-1476

Exceptionally preserved fossils,such as those from Cambrian Burgess Shale-type fossil-Lagerstatten are critical because of their unique contributions to knowledge of the phylogenetic radiation and palaeoecological expansion of metazoans during the Cambrian explosion.Critically,these deposits provide information that is usually unobtainable from shelly and skeletonized fossils alone.The Guanshan Biota(Cambrian Series 2,Stage 4)in the Yunnan Province of South China,has produced abundant and diverse,exquisitely preserved fossils that often retain soft tissues and organs.To date,most fossils from the Guanshan Biota have been collected from localities such as Gaoloufang and Gangtoucun,which have become inaccessible due to new urban expansions and constructions of residential buildings.Here we present the first report of soft bodied fossils from a new section at Kanfuqing,close to the Wulongqing village in Malong County,approximately 3 km east of the Wulongqing Formation stratotype section.Fossils retain soft morphology,and include brachiopods with delicate marginal setae,priapulids with well-preserved sclerites and vetulicolians with entire sections of body.In addition,this fauna includes rare occurrences of trilobites preserved with soft tissues replicated as pyrite pseudomorphs after weathering.This discovery represents an important palaeogeographical extension of soft-bodied fossils of the Guanshan fauna to the east of the Xiaojiang Fault(related to Tsinning tectonic movements ca.700 Ma).The fauna from the new Kanfuqing section is similar to that reported from the Wulongqing Formation west of the Xiaojiang Fault,and thus has significant implications for early Cambrian palaeogeography,faunal successions and palaeoenvironments of eastern Yunnan.  相似文献   

陕南镇巴筇竹寺期的海绵骨针化石     

郑亚娟  李勇  郭俊锋 《地球科学与环境学报》2012,(2):24-30

在陕南镇巴下寒武统西蒿坪段和水井沱组下段的碳酸盐地层中含有大量保存完好、类型多样的海绵骨针化石。基于形态描述法,对海绵骨针化石进行了详细的形态描述及产地与层位判断。结果表明:根据与其共生的小壳化石和三叶虫等生物地层学资料,发现这些海绵骨针化石属于筇竹寺期;该区海绵骨针类型不仅包含有形态规则的二轴四射骨针、三轴六射骨针、三轴五射骨针,而且还有形态不规则的四轴四射骨针、五轴五射骨针、尖头星状骨针、二歧分叉式骨针等;其中的四轴四射骨针、五轴五射骨针、五刺尖头星状骨针、二歧分叉二射式骨针为本次发现的新类型,极大地丰富了海绵骨针的类型。陕南镇巴筇竹寺期海绵骨针化石的数量以及分异度快速增加,充分说明海绵动物在陕南地区寒武纪早期开始大量繁盛并且迅速演化。  相似文献   

云南曲靖地区下寒武统筇竹寺组页岩气成藏地质条件及有利区预测   总被引：1，自引：0，他引：1  

张聪  包书景  石砥石  胡琳  苑坤 《海相油气地质》2017,22(1)

基于野外地质调查、岩心观测、地球化学分析、含气量现场解吸等技术手段,深入分析了云南曲靖地区下寒武统筇竹寺组页岩气形成与富集条件。研究认为该区筇竹寺组沉积期为浅水陆棚环境,黑色泥页岩厚度237~363 m,成熟度较高,平均R_o为3.06%,TOC多数大于2.0%;页岩中石英含量平均为53.18%,碳酸盐矿物含量平均为18.82%,储集空间以泥页岩微裂缝、粒间孔、粒内孔和有机孔为主;区域具有较好的页岩气勘探潜力。根据多口钻井现场解吸气量较低的特征,推断保存条件是曲靖地区页岩气富集的关键,马龙为页岩气勘探远景区。  相似文献   

细粒浊积岩特征、分布及发育机制:以川北唐家河剖面寒武系郭家坝组为例^*     

龚峤林  李飞  苏成鹏  曾楷  唐浩  谭秀成 《古地理学报》2018,20(3):349-364

细粒浊积岩是一类较为特殊的浊积岩类型,与可用鲍马序列解释的完整经典浊积岩相比,其颗粒粒径明显偏细,小于63μm的颗粒含量超过50%。通过对四川盆地北部唐家河剖面寒武系第二统郭家坝组上部地层的系统研究发现,Stow细粒浊积岩序列发育广泛。该序列下部(T0-T3)主要为极细砂、粉砂与泥质纹层互层,发育微弱冲刷构造和泄水构造等软沉积物变形构造;中部(T4-T6)为泥质层段夹断续粉砂质纹层;上部(T7-T8)转变为均质泥岩段,生物扰动构造发育,整体序列具有正粒序特征。浊积岩序列中碎屑颗粒主要为石英、岩屑和云母,长石少见,杂基含量高;粒度频率分布曲线(直方图)显示颗粒分选性比传统浊积岩好,且自下而上各砂质纹层内颗粒粒径变细;概率值累计曲线表现为“一段式”和“上凸的折线式”2种,且悬浮组分占据了绝大优势;C-M图以平行于“C=M”基线为特征,但受碎屑颗粒粒级偏小的影响,投点整体沿C=M基线向左下偏移,显示该序列具有浊流递变悬浮沉积的特点。结合筇竹寺阶(第二统)沉积背景,认为靠近研究区西北侧的摩天岭古陆为浊积岩发育的主要物源区,台内地形的遮挡为细粒浊积岩的发育提供了良好的地形条件,悬浮搬运和阵发性环境事件(如风暴、洪水等)搬运为细粒沉积物主要的搬运机制。以唐家河剖面为代表的寒武系郭家坝组细粒浊积岩的广泛发育,对于认识四川盆地北缘古地理格局和非常规油气勘探具有重要意义。  相似文献   

河南鲁山寒武系第二统辛集组风暴沉积及其相关的遗迹化石^*     

白万备  齐永安  郭英海  王敏  庆国帅 《古地理学报》2018,20(3):365-376

河南鲁山寒武系第二统辛集组为一套风暴作用影响下的含磷和海绿石的碎屑岩沉积,主要由中厚层石英砂岩及极薄层泥岩与砂岩互层组成。遗迹化石发育在交错层理砂岩以及极薄层泥岩与薄层砂岩互层的层面上。Skolithos sp. 属于风暴衰减期的Skolithos遗迹相机会种(r-选择)遗迹化石,它们以短小的垂直居住潜穴及低遗迹分异度和丰度为特征。Palaeophycus tubularis,P. striatus,Taenidum sp.,Gordia marina,Planolites montanus,P. beverleyensis等属于风暴间歇期的Cruziana遗迹相均衡种(K-选择)遗迹化石,以水平进食、觅食潜穴为主,遗迹分异度和丰度中等。早寒武世风暴衰减期,频繁的风暴事件不利于研究区机会种遗迹化石的保存,同时风暴间歇期持续时间短、风暴停息期不发育,造成均衡类生物殖居窗口期短暂,亦不利于对沉积底质的连续殖居。这种特殊的风暴沉积以及早寒武世造迹生物较差的掘穴能力,导致研究区遗迹化石种类及数量远不及寒武纪以后的风暴沉积。  相似文献   

塔里木盆地寒武系原油微量元素特征及意义          下载免费PDF全文

秦欢  杨涛  潘文庆  陈永权  张宝收 《高校地质学报》2018,24(6):822

塔里木盆地是中国最大的内陆含油气盆地,有关盆地内主力烃源岩层位时代目前仍存在一定争议。油-油对比能够 发现原油间的亲缘关系,明确不同类型原油地球化学特征,是解决这一问题的有效手段。中深1井及中深1C井发现的中寒 武统阿瓦塔格组、下寒武统肖尔布拉克组原油可以作为重要的端元油类型参与油-油对比。本文通过对比两种寒武系原油 及盆地内多种轻质原油微量元素组成,发现根据多种过渡金属元素比值进行聚类分析可将盆地内轻质原油分为I类和II类, Cr/V,Ni/Mn,Ni/Mo比值是原油分类的良好指标。I类原油较II类原油具有较低的Cr/V比及较高的Ni/Mn与Ni/Mo比,表明 其烃源岩沉积环境相对还原。本次分类结果与前人有机地球化学研究相符,表明无机地球化学指标可作为原油分类的重要 参考,具有较大的应用潜力。  相似文献   

塔东北库鲁克塔格地区中上寒武统白云岩类型与孔隙演化^*   总被引：1，自引：1，他引：0       下载免费PDF全文

钱一雄  陈代钊  尤东华  卿海若  何治亮  董少峰  马玉春  焦存礼  田蜜 《古地理学报》2012,14(4):461-476

对塔东北库鲁克塔格隆起的乌孜里塔格剖面中上寒武统白云岩的岩石学、成岩作用、裂隙—孔隙发育与充填等特征研究认为：可划分为有序度逐渐增加的粉晶白云岩、粉细晶白云岩、中细晶白云岩和中粗晶白云岩及晶洞中的中粗晶、巨晶和鞍形白云石等4种类型;分别对应于早期准同生—浅埋、中浅埋藏、中等埋藏和构造断裂—热液（热卤水）作用4期的成岩阶段;其中,沿走滑断裂—裂隙带、呈不规则的“侵入体” 具有斑点状、条纹—条带、雁行状—斑马、角砾状和不规则状结构的中粗晶、粗晶、巨晶（部分为鞍形）白云岩（石）,一般不发光或呈昏暗的暗红色,具有与加拿大西部盆地典型的热液白云岩相似的特征;中上寒武统白云岩存在4～5期构造裂隙和3期以上的充填作用;热液白云岩中以晶间孔、晶间溶孔（洞）、裂隙及沿裂隙的扩溶孔洞为主,主要有二世代的白云石和方解石和少量沥青、石英、微量硬石膏和重晶石等多期充填作用。与西加盆地寒武系部分或全部交代充填缝洞及角砾构造、受来自落基山造山带的晚白垩世至古近系拉腊米（Laramide）构造的被排驱的热液流体交代形成的典型热液白云岩稍有不同,海西晚期（晚二叠世）及燕山—喜马拉雅期（晚白垩世—第四纪）沿挤压—走滑断裂排驱的地层热卤水循环—扩散与交代作用可能是本区热液白云岩的主要成因,储集空间主要由中、晚期构造断裂—裂隙（溶蚀）所致,但不排除成岩早期埋藏或晚期大气水作用对其影响。  相似文献   

Geochemical characterization and methane adsorption capacity of overmature organic-rich Lower Cambrian shales in northeast Guizhou region,southwest China     

《Marine and Petroleum Geology》2017

  相似文献   

Spatiotemporal variability of ocean chemistry in the early Cambrian,South China     

JIN ChengSheng  LI Chao  PENG XingFang  CUI Hao  SHI Wei  ZHANG ZiHu  LUO GenMing & XIE ShuCheng 《中国科学:地球科学(英文版)》2014,57(4):579-591

Following the Ediacaran metazoan radiation, the “Cambrian Explosion” set up the major framework of todays’ animal phyla as well as modern marine ecosystem. Here, we present a preliminary investigation on the temporal and spatial (from shallow to deep waters) variations of the early Cambrian ocean chemistry in South China through analyzing a Fe-S-C systematic dataset integrated from literature. Our investigation indicates that the early Cambrian deep ocean in South China was still anoxic and Fe²⁺-enriched (i.e., ferruginous) although its surface was oxic, and in between a metastable euxinic (anoxic and sulfidic) water zone may have dynamically developed in anoxic shelf waters with an increasing weathering sulfate supply. Furthermore, accompanying marine transgression and regression cycles in the early Cambrian, such a “sandwich” structure in ocean redox chemistry demonstrates five evolutional stages, which can be well correlated to the spatiotemporal patterns of fossil records in South China. The good correlation between metazoan fossil occurrences and water chemistry in South China suggests that early animals possibly possessed ability to inhabit anoxic but generally not euxinic environments as free H₂S was fatal to most eukaryotes. This view can well explain why those small shell fauna and sponges disappeared from shelf to slope areas where sulfidic Ni-Mo-rich shales were widely deposited. Thus, we conclude that the spatiotemporal variations of ocean chemistry and its biological effects probably played a key role in the phased animal radiations and “extinctions” in the early Cambrian.  相似文献   

SCIENCE CHINA Earth Sciences SUBJECT INDEX TO VOLUME 57(2014)     

《中国科学:地球科学(英文版)》2014,(12)

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