胶东诸城晚白垩世恐龙骨骼化石地球化学及埋藏学研究  

Geochemistry and Taphonomy of Late Cretaceous Dinosaur Bonebeds in Zhucheng,Eastern Shandong,China

作　　者：旷红伟[1] 许克民[2] 柳永清[1] 董超[3] 彭楠[1] 王克柏 陈树清 张艳霞 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]山东省地质调查院,济南250000 [3]油气资源与勘探技术教育部重点实验室(长江大学),长江大学地球物理与石油资源学院,湖北荆州434023 [4]诸城市恐龙文化研究中心,山东诸城262200

出　　处：《地质论评》2013年第6期1001-1023,共23页Geological Review

基　　金：国家自然科学基金面上项目(编号41272021);国家自然科学基金重点项目(编号90914003);中国地质科学院地质研究所基本业务费项目(编号J1106);中国地质调查局项目(编号12120113096500;1212011120105)的成果

摘　　要：胶东诸城发育了世界罕见的晚白垩世中晚期恐龙化石集群埋藏点,主要分布在诸城市东南的库沟、恐龙涧、西见屯和臧家庄。本文通过薄片鉴定、电子探针、常量、微量和稀土元素分析等方法技术,系统研究了诸城恐龙骨骼化石微观特征与地球化学特征,分析了恐龙骨骼埋藏成岩过程,厘定4个化石集群埋藏层的相对层位关系和骨骼沉积物来源方向,探讨了恐龙死亡的可能原因。研究表明,研究区恐龙骨骼化石主要矿物成分为磷灰石和方解石,也零星含有Fe、Mn、BaSO4及SiO2等矿物成分;骨骼化石和围岩主量、微量与稀土元素分析显示,CaO、P2O5、F、REE、Y、Sr和Ba、U高值且远高于围岩,其中CaO、P2O5、F、Sr和Ba的高值是由于原始骨骼组成中这些元素背景含量高,而REE、Y及U的异常高值是成岩过程中吸附作用所致;骨骼中Rb、Th、Nb、SiO2、Al2O3、TiO2、Zr、Hf含量低于围岩是由于它们属于亲沉积碎屑元素,都来自母岩的风化产物;骨骼化石中稀土元素表现为轻稀土富集型,稀土配分模式与上地壳相似,并具有Eu轻微正异常和Ce负异常特点;研究认为,骨骼与围岩较高的Sr、Ba含量及稀土元素异常系源于干旱气候与氧化环境的浅埋藏成岩作用;依据不同化石点骨骼中磷灰石矿物与方解石矿物组成的对比、骨骼与围岩主量元素分子风化率指数及REE、HREE、LREE与(La/Yb)N、(Ce/Yb)N和(La/Sm)N、δEu、δCe等参数的对比,研究区4个集群埋藏的恐龙化石层相对层位关系由下至上分别厘定为库沟、西见屯、恐龙涧与臧家庄;骨骼围岩沉积物源主要来自下伏青山群火山岩与莱阳群沉积岩的剥蚀产物;研究区上白垩统红土崖组下部不到100m厚的地层中恐龙化石异地集群埋藏层的多次出现表明,集群埋藏不是一个简单孤立事件,恐龙的死亡也可能受制于干旱气候的影响,特别是环境背景的Sr和Ba等元素有可能是�Kugou, Konglongjian, Xijiantun and Zangjiazhuang of Zhucheng, Eastern Shandong, China are famous for the world-class dinosaur bone beds of the early Late Cretaceous. Based on analyses by thin section and Electronic Probe Mieroanalyzer （EPMA） and the analyses of Major element, rare-earth element （ REE ） and trace element, the paper systemically studies the micro structure and geochemical characteristics of dinosaur bones, analyzes the taphonomy and diagenetic process of dinosaur bones, clarifies the interrelationships of the four bone beds stratigraphically and the resource provenance direction of dinosaur bones and discusses the possible facts causing the death of the dinosaurs. Apatite and calcite are the main mineral composition of dinosaur bones in study areas, with a small amount of odd Fe, Mn, BaSO4 and SiO2, etc. Analysis the principle and Major element, REE and trace element of the dinosaur bones and the host matrix shows that the values of CaO, P205, F, REE, Y, Sr, Ba and U in the former are much higher than in the latter. The high value of CaO, P2O5, F, Sr and Ba in dinosaur bones may have been resulted from a high background value in life; whereas the abnormal high values of REE, Y and U may have been caused by postmodern absorption during the diagenetic process. Since Rb, Th, Nb, SiO2, A12O3 , TiO2 , Zr and Hf belong to sedimentophile clastics elements from the weathering products of parent rocks, they occupy less in dinosaur bones than the host rock. REE of dinosaur bones belong to the enriching type of light rare earth element （LREE）, similar to that of the upper crust, with a slight positive anomaly of Eu and a passive anomaly of Ce. Our study suggests that shallow burying diageneses under a draught climate and oxide environment may have caused the high content of Sr, Ba and REE such as Eu and Ce in dinosaur bones and the host rock. Based on comparisons between apatite and calcite, rock, and the correlation of many elements, such molecular weathering ratios between dinosaur bones and the

关 键 词：胶东诸城 晚白垩世 恐龙 骨骼化石 地球化学 埋藏学 

分 类 号：Q915[天文地球—古生物学与地层学]