河南汝阳地区-巨型蜥脚类恐龙股骨化石的发现及其地层学意义     

吕君昌 徐莉贾松海  张兴辽季强 《地质通报》2006,25(11):1299-1302

报道了首次在河南省汝阳县发现的大型蜥脚类恐龙股骨化石。从股骨近端的大小来判断，该股骨的实际长度可能超过2m，应属于巨型蜥脚类恐龙的股骨无疑。虽然化石破碎，种属的归属存在一定的困难，但是它的发现无论从晰脚类恐龙的分布、演化还是从地层学上都具有重要意义。该恐龙股骨化石的发现，将该地区原认为属于古近系蟒川组的时代向前推至早白垩世晚期或晚白垩世早期，同时其下伏地层陈宅沟组也应划归白垩纪时期的沉积。  相似文献   

黔中隆起及其周缘地区“下组合”油气地质特征   总被引：8，自引：1，他引：8  

周明辉  梁秋原 《海相油气地质》2006,11(2):17-24

黔中隆起及其周缘地区包括滇黔北部坳陷、黔中隆起、滇东隆起、黔西南坳陷、黔南坳陷和武陵坳陷等六个一级构造单元。“下组合”包括震旦系、寒武系、奥陶系和志留系,具有丰富的油气资源和较好的油气成藏条件。两套区域性海相烃源岩,包括下寒武统牛蹄塘组碳质页岩和上奥陶统五峰组—下志留统龙马溪组石灰岩和碳质页岩,Ro值普遍在2%以上,主体处于高成熟晚期—过成熟早期。上震旦统陡山沱组发育地区性黑色页岩和碳质灰岩等烃源岩。主力储层包括上震旦统灯影组、中—上寒武统、下奥陶统桐梓组—红花园组及下志留统石牛栏组。区域盖层发育于下寒武统下部和下志留统下部,皆以泥质岩为主。各区块海相“下组合”纵向生储盖组合发育情况有所差异,黔中隆起区和黔南坳陷有两套组合,滇黔北部坳陷则有四套组合。以下寒武统牛蹄塘组为烃源岩、上震旦统灯影组白云岩为储层、下寒武统泥岩为盖层的生储盖组合,是黔中隆起及其周缘地区“下组合”勘探的主要目的层系。  相似文献   

贵州紫云扁平剖面早二叠世非筵有孔虫动物群   总被引：2，自引：0，他引：2  

董宝清刘家润  施贵军 《地层学杂志》2007,31(4):317-324,I0007

贵州紫云扁平剖面紫松阶上部一罗甸阶非筵有孔虫动物群由25属82种（含相似种、亚种而不含未定种）构成，其中7属（Cribrogenerina、Nodosaria、Glomospira、Tetrataxis、Palaeotextularia、Climacammina及Globival-vulina）的物种分异度最高，合计占总种数的71％；该动物群自紫松期开始发育，在隆林期类群构成发生显著变化并繁盛至罗甸早期，在罗甸中晚期明显衰落。研究剖面由下至上可划分为Cr拍rogPnP-nncelebrata-C．hemispaera间隔带、Glomospira-Nodosaria富集带（又可进而分为Geinitzina postcarbonica-Globivalvulina cyprica间隔亚带、Climacammina elegantula延限亚带）、Lasiodiscus-Eotuberitina间隔带。  相似文献   

藏北色哇地区索布查组、曲色组岩石地层、层序地层、生物地层特征及三叠系与侏罗系界线     

王永胜  郑春子 《地层学杂志》2007,31(4):377-384

对藏北羌塘盆地南缘色哇地区的三叠纪与侏罗纪地层进行研究,在下侏罗统曲色组之下发现了一套以灰岩为主的地层,建立了索布查组,该组下部产晚三叠世腕足类、双壳类、六射珊瑚,上部产早侏罗世菊石,因此确定索布查组地质时代为晚三叠世—早侏罗世。三叠系-侏罗系界线应在索布查组之内,三叠系与侏罗系可能为整合接触。  相似文献   

Early Pleistocene climate changes in the central Mediterranean region as inferred from integrated pollen and planktonic foraminiferal stable isotope analyses     

Sébastien Joannin  Frédéric Quillévéré  Christophe Lécuyer  François Martineau 《Quaternary Research》2007,67(2):264-274

Vegetation inherited from a Pliocene subtropical climate evolved through obliquity oscillations and global cooling leading to modern conditions. An integrated, highly time-resolved record of pollen and stable isotopes (δ¹⁸O and δ¹³C of Globigerina bulloides) was obtained to understand vegetation responses to Early Pleistocene climate changes. Continental and marine responses are compared in the Central Mediterranean region with a particular consideration of environmental changes during anoxic events.Pollen data illustrate vegetation dynamics as follows: [1] development of mesothermic elements (warm and humid conditions); [2] expansion of mid- and high-altitude elements (cooler but still humid conditions); and [3] strengthening of steppe and herb elements (cooler and dry conditions). These successions correlate with precession. δ¹⁸O variations recorded by Globigerina bulloides define two cycles (MIS 43-40) related to obliquity. At northern low- to mid-latitudes, the pollen signal records temperature and wetness changes related to precession even during global climate changes induced by obliquity. This may result in unexpected increasing wetness during glacial periods, which has to be considered specific to the Central and Eastern Mediterranean region. Lastly, an analysis of anoxic events reveals that enhanced runoff is indicated by increasing frequency of the riparian trees Liquidambar and Zelkova.  相似文献   

Excess in precipitation as a cause for settlement decline along the Israeli coastal plain during the third millennium BC     

Avraham Faust  Yosef Ashkenazy 《Quaternary Research》2007,68(1):37-44

Although the relations between climate and settlement are not straightforward, there is a general agreement that arid conditions are less favorable for human settlement in the semiarid Near East than humid conditions. Here we show that humid conditions resulted in the abandonment of settlements along the Israeli coastal plain. We first present archaeological evidence for a drastic decline in settlement along the Israeli coast during most of the third millennium BC (Early Bronze Age II-III). Then, based on archaeological and climatic evidence, we link this decline to an environmental change occurring at that time. We propose that increased precipitation intensified the already existing drainage problems and resulted in flooding, which led to the transformation of arable land into marshes and to the spread of diseases, gradually causing settlement decline and abandonment.  相似文献   

塔里木板块东北部柳园粗面玄武岩带：软流圈地幔减压熔融的产物   总被引：4，自引：6，他引：4  

姜常义  夏明哲余旭 逯东霞魏巍  叶书锋 《岩石学报》2007,23(7):1765-1778

在塔里木东北部,甘肃省西部敦煌市柳园镇南侧,有一条近东西向展布的粗面玄武岩带,长度约150km,宽度达10km,厚度为1900m。这条粗面石玄武岩带属下二叠统哲斯群,岩浆喷发方式以裂隙式溢流为主,枕状构造特别发育。在玄武岩层间夹有很薄的酸性凝灰岩和沉凝灰岩层,属典型的双峰式火山岩组合。按照岩石化学组成的 TAS 分类命名,主要岩石类型为玄武岩、夏威夷岩和橄榄粗安岩。主要造岩矿物为钠长石(Ab 91～100)和普通辉石。普通辉石斑晶、钠长石斑晶和部分基质中的钠长石具有中空结构,并被层状硅酸盐微晶充填。这些岩石基本属碱性玄武岩系列和过渡型系列,大部分属演化的岩浆。演化程度较低的样品具有轻稀土元素亏损型配分曲线,微量元素地球化学具有 MORB 亲和性,ε_(Nd)(t)= 10.14～10.89。玄武质岩浆与陆壳物质之间有较轻的同化混染作用。普通辉石、铁钛氧化物的分离结晶作用是岩浆演化的主要机制。玄武质岩浆源区属于软流圈地幔,部分熔融发生于尖晶石稳定域,是软流圈地幔减压(上涌)熔融的产物。  相似文献   

The sauropod diversity of the La Amarga Formation (Barremian), Neuquén (Argentina)     

Sebastin Apesteguía 《Gondwana Research》2007,12(4):533-546

A study of the abundant and undescribed isolated and associated bones and teeth from the La Amarga Formation (Barremian of Neuquén, Argentina) permitted the recognition of additional clades of sauropod dinosaurs: basal titanosauriforms, both basal and derived titanosaurs, and rebbachisauroid diplodocoids, which are now added to the already known dicraeosaurids and a recently published basal diplodocoid. These forms substantially increase the knowledge on the Early Cretaceous sauropod diversity in Gondwana.  相似文献   

Early cretaceous granitoids and their implications for the collapse of the Dabie orogen, eastern China: SHRIMP zircon U–Pb dating and geochemistry     

Haijin Xu  Changqian Ma  Kai Ye   《Chemical Geology》2007,240(3-4):238-259

Two stages of early Cretaceous post-orogenic granitoids are recognized in the Dabie orogen, eastern China, which recorded processes of extensional collapse of the orogen. The early stage granitoids ( 132 Ma) are foliated hornblende quartz monzonites and porphyritic monzogranites. They are of high-K calc-alkaline series and metaluminous to weakly peraluminous, with high K₂O and low MgO contents (Mg^# values: 32.0–46.0), they contain high Sr, low Y and heavy rare earth elements (HREE), and have high Sr/Y and (La/Yb)_N ratios, without clear negative Eu, Sr and Ti anomalies. The early stage deformed granitoids have adakitic geochemical compositions and are equilibrated with residues rich in garnet and poor in anorthite-rich plagioclase, and thus indicate the existence of an over-thickened (> 50 km) crustal root beneath the orogen at  132 Ma. The later stage granitoids ( 128 Ma) are undeformed fine-grained monzogranites, fine-grained K-feldspar granites and coarse-grained K-feldspar granite-porphyry. They belong to a peraluminous and high-K calc-alkaline to shoshonite series, and display a flat HREE pattern and have strong negative Eu, Sr and Ti anomalies, with low Sr/Y and (La/Yb)_N ratios. The late stage granitoids are equilibrated with residues rich in anorthite-rich plagioclase, hornblende, ilmenite/titanite and poor in garnet, indicating that the crust of the Dabie orogen became thinner (< 35 km) at  128 Ma. SHRIMP zircon U–Pb ages and changing compositional trends for these two stages of granitoids indicate that the over-thickened crust formed by the Triassic continental subduction/collision under the Dabie orogen remained until the early Cretaceous, and collapsed quickly in a few million years during the early Cretaceous.  相似文献   

我国早期的地震科学研究概述     

张俊玲  钟心  张惠芳 《高原地震》2007,19(4):1-9

我国早期的现代地震学研究，曾孕育于现代地质学中。用现代科学观点，最早调查研究现场大地震的年代，可追溯到1913年云南峨山7级地震考察。地震台站监测工作，是从1923年地质调查所派李善邦先生前去日本东京学习测震，并于1930年在北京西山郊区建造鹫峰地震观测台开始。最早的地震目录是1913年由上海黄司铎编的“法文中国地震表”。1921年翁文灏先生发表的“甘肃地震考”，首次将史料中的地震情形描述与罗西一福来氏烈度表加以对照，来确定地震烈度，从而提供了更详细、确切的“甘肃地震表”。1922年翁文灏在布鲁塞尔国际地质大会上宣读的“中国地质构造对于产生地震的影响”论文，曾引起与会者极大兴趣与关注，是最早论述我国地震地质和地震区域划分的文献。  相似文献