西藏南部晚白垩世-古新世大洋红层的分布与时代   总被引：11，自引：2，他引：9  

万晓樵  李国彪  司家亮 《地学前缘》2005,12(2):31-37

特提斯—喜马拉雅北沉积亚带沉积有一套大洋红色岩层,由东往西在羊卓雍错、江孜、萨迦、萨嘎、札达一带断续出露,并与宗卓组上部地层相关。这套海相红层,根据岩性特征和浮游有孔虫可以直接进行区域对比。其时代在江孜地区为Santonian晚期—Campanian中期,包括Dicarinella asymetrica, Globotruncanitaelevata,Globotruncana ventricosa 和Globotruncanita calcarata 浮游有孔虫带;在萨迦地区限于Campanian期,鉴定有Globotruncanita elevata, Globotruncana ventricosa 和G. linneiana等具时代意义的浮游有孔虫;在萨嘎—吉隆地区为Maastrichtian期,识别出Gansserina gansseri 和Abthomphalus mayaroensis 浮游有孔虫带;在札达地区为古新世早期,以Glibigerina eugubina G. fringa化石带为代表。海相红层在西藏南部由东往西其时代逐渐变新,主要沉积时代分布在Santonian晚期—古新世早期。其总体时间跨度较大,大约长达20Ma。而事件在各个地点的延续时间有限,基本在3~8 Ma之内。根据对海相红层和沉积基质中浮游有孔虫的研究,该沉积带宗卓组的顶界时代已超出白垩纪,进入了古新世。  相似文献   

拉萨地体南缘错布拉果花岗岩体锆石U-Pb年龄、地球化学特征及成岩动力学背景     

李成志  杨文光  朱利东  杨珍  吝利民  张洪亮 《矿物岩石》2019,(2):45-57

本次研究文对拉萨地体南缘错布拉果岩体进行了两件锆石U-Pb年代学和全岩地球化学分析,揭示了错布拉果花岗岩类型、岩浆源区与演化,并讨论了区域成岩动力学背景。分析结果显示,错布拉果岩体二长花岗岩LA-ICP-MS锆石U-Pb定年结果为61 Ma^59 Ma,与区域上冈底斯南缘岩浆弧为同一时期。在地球化学组成上,错布拉果花岗岩w(SiO2)70.09%~72.64%,具有高w(Al2O3)14.40%~15.99%,低w(TiO2)0.08%~0.24%,w(MgO)(0.41%~0.76%),w(Fe2O3T)6.82%~29.9%,w(P2O5)0.07%~0.12%和w(CaO)1.06%~1.75%的特征;属于高钾钙碱性-钾玄岩系列。错布拉果花岗岩轻稀土元素(LREE)含量介于133.69×10^-6~226.64×10^-6之间,重稀土元素(HREE)含量介于17.36×10^-6~32.11×10^-6之间,LREE/HREE介于5.05~7.83之间,富集轻稀土(LREE)和Rb,K,U等大离子亲石元素(LILE),亏损P,Nb,Ta等高场强元素(HFSE),具有弧型岩浆岩的地球化学组成。另外,错布拉果花岗岩体的铝饱和指数(A/CNK=1.06~1.11)属于弱过铝质的Ⅰ型花岗岩。综合分析表明,错布拉果花岗岩是在印度-亚洲板块碰撞的开始,俯冲下插的新特提斯洋板块由于重力作用造成与大陆板块脱离,引起软流圈上涌,导致岩石圈地幔下地壳底部发生部分熔融从而形成母岩浆,最终在侵位与成岩后期主要经历分离结晶作用。  相似文献   

Slope sediments of a Paleocene ramp-to-basin transition in NE Egypt     

C. Scheibner  J. Kuss  A. M. Marzouk 《International Journal of Earth Sciences》2000,88(4):708-724

Received: 9 November 1998 / Accepted: 6 October 1999  相似文献   

The Paleocene–Eocene transition in the marginal northeastern Tethys (Kazakhstan and Uzbekistan)     

M.-P. Bolle  A. Pardo  K.-U. Hinrichs  T. Adatte  K. Von Salis  S. Burns  G. Keller  N. Muzylev 《International Journal of Earth Sciences》2000,89(2):390-414

We studied two sections that accumulated during the Paleocene–Eocene transition in shelf waters in the northeastern Tethys. Stable carbon isotopic compositions of marine and terrestrial biomarkers are consistent with a ¹³C depletion in the oceanic and atmospheric carbon dioxide pools during the Late Paleocene Thermal Maximum (LPTM; Subzone P5b). The 2–3‰ negative δ ¹³C excursion in planktic foraminifera coincides with minimum δ ¹⁸O values, an incursion of transient subtropical planktic foraminiferal fauna, and the occurrence of an organic-rich sapropelite unit in Uzbekistan, which accumulated at the onset of a transgressive event. Biomarker distributions and hydrogen indices indicate that marine algae and bacteria were the major organic matter sources. During the Late Paleocene (Subzones P4 and P5a), the marginal northeastern Tethys experienced a temperate to warm climate with wet and arid seasons. Most likely, warm and humid climate initiated during the LPTM (Subzone P5b) and subsequently extended during the Eocene (Zone P6) onto adjacent land areas of the marginal northeastern Tethys. Received: 18 May 1999 / Accepted: 2 February 2000  相似文献   

Karsts polyphasés, faciès marins et continentaux dans le Paléocène de la partie orientale des Pyrénées fran?aises     

Pierre-Jean Combes  Bernard Peybernès  Marie-José Fondecave-Wallez 《Eclogae Geologicae Helvetiae》2004,97(2):155-174

In the Eastern part of French Pyrenees, the Cucugnan area (Southern Corbières) corresponded during the early/Mid-Paleocene (Danian/Selandian) to a narrow transitional zone between the sea to the South (Pyrenean Paleocene Trough) and the continent (fluvio-palustrine and lacustrine Vitrollian deposits) to the North. To the South, in the North-Pyrenean Zone, the polygenic marine breccias and the associated Dano-Selandian Globigerinid-bearing hemipelagites have been preserved within successive paleokarsts superimposed onto the carbonate substratum (ante-Albian). Four paleosurfaces are recognized, principally filled by marine internal sediments with proximal and distal facies. To the North, in the Sub-Pyrenean Zone, a continental foreland basin is characterized by four formations of variegated Microcodium-bearing marls and channelized conglomerates, separated by erosional paleosurfaces underlining well-marked unconformities. An event correlation (chronodiagrams) between the marine realm to the South and the continental realm to the North is proposed, using the successive paleosurfaces and the lithological sequences (same number within the two realms). Our paleogeographic reconstruction shows, to the North, the Lake of Cucugnan and, to the South, a calcareous mountainous zone broken by the juxtaposition of deep paleocanyons (eroded in a continental context) later converted into rias submitted to marine oscillations. Several palinspastic transects are reconstructed: they show the polyphase control of the Frontal North-Pyrenean Overthrust on the Paleocene sedimentation and the importance of the successive intra-Vitrollian compressions/ transpressions (phase fini-crétacée auct.) inducing, within the two juxtaposed realms, emersions, erosions and karstic features which give a very contrasted paleogeography during a period characterized by plate convergence and creation of steep topographies.Manuscrit reçu le 25 septembre 2003 Révision acceptée le 4 mai 2004  相似文献   

Reappraisal of early Paleogene CCD curves: foraminiferal assemblages and stable carbon isotopes across the carbonate facies of Perth Abyssal Plain     

Haidi J. L. Hancock  Gerald R. Dickens  Ellen Thomas  Kevin L. Blake 《International Journal of Earth Sciences》2007,96(5):925-946

Bulk carbonate content, planktic and benthic foraminiferal assemblages, stable isotope compositions of bulk carbonate and Nuttallides truempyi (benthic foraminifera), and non-carbonate mineralogy were examined across ∼30 m of carbonate-rich Paleogene sediment at Deep Sea Drilling Project (DSDP) Site 259, on Perth Abyssal Plain off Western Australia. Carbonate content, mostly reflecting nannofossil abundance, ranges from 3 to 80% and generally exceeds 50% between 35 and 57 mbsf. A clay-rich horizon with a carbonate content of about 37% occurs between 55.17 and 55.37 mbsf. The carbonate-rich interval spans planktic foraminiferal zones P4c to P6b (∼57–52 Ma), with the clay-rich horizon near the base of our Zone P5 (upper)—P6b. Throughout the studied interval, benthic species dominate foraminiferal assemblages, with scarce planktic foraminifera usually of poor preservation and limited species diversity. A prominent Benthic Foraminiferal Extinction Event (BFEE) occurs across the clay-rich horizon, with an influx of large Acarinina immediately above. The δ¹³C records of bulk carbonate and N. truempyi exhibit trends similar to those observed in upper Paleocene–lower Eocene (∼57–52 Ma) sediment from other locations. Two successive decreases in bulk carbonate and N. truempyi δ¹³C of 0.5 and 1.0‰ characterize the interval at and immediately above the BFEE. Despite major changes in carbonate content, foraminiferal assemblages and carbon isotopes, the mineralogy of the non-carbonate fraction consistently comprises expanding clay, heulandite (zeolite), quartz, feldspar (sodic or calcic), minor mica, and pyrolusite (MnO₂). The uniformity of this mineral assemblage suggests that Site 259 received similar non-carbonate sediment before, during and after pelagic carbonate deposition. The carbonate plug at Site 259 probably represents a drop in the CCD from ∼57 to 52–51 Ma, as also recognized at other locations.  相似文献   

R?les respectifs des tectoniques fini-crétacée et éocène dans la partie orientale de la cha?ne des Pyrénées. Le ?Garumnien? de Cucugnan et ses relations avec le Chevauchement Frontal Nord-Pyrénéen (Corbières méridionales, France)     

Michel Bilotte  Joseph Canerot 《Eclogae Geologicae Helvetiae》2006,99(1):17-27

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The Paleocene and Eocene in the Russian part of West Eurasia     

M. A. Akhmets’ev  V. N. Beniamovski 《Stratigraphy and Geological Correlation》2006,14(1):49-72

Biostratigraphic charts of marine Paleocene and Eocene in the European and West Siberian parts of Russia include the unified zonations of nannoplankton, planktonic and benthic foraminifers, dinocysts, radiolarians, diatoms, and palynomorphs of higher plants. These regional zonations summarize comprehensive data on the Lower Paleogene, which have been obtained by paleontologists and biostratigraphers in the last century. In the content and resolution degree, they represent a solid basis for geological and paleogeographic consideration and characterize the time succession of diverse biotic and abiotic events. On the other hand, the depicted biotic events have been controlled by successive tectonic, paleogeographic, and paleoclimatic events, because organisms determining contents of biostratigraphic zones changed not only in the course of evolution, but also in response to transformation of surroundings. As elements of general communication systems, epicontinental seas of the Paleogene have been interconnected via straits and seaways, which promoted interchange of water masses and biotas belonging to the Tethys, Atlantic or Arctic oceans, and inner seas. Size and configuration of the seas and seaways changed under influence of tectonic processes and eustatic events of epeirogenic or regional origin. Widening, narrowing, and cessation of communication ways have been responsible for different-scale changes in sedimentation and biotic environments. New materials on the Paleogene in a vast territory of Russian sector of West Eurasia offer an opportunity to revise somewhat the dynamics of climatic changes in the Northern Hemisphere during the Early Cenozoic, which characterize the terminal phase of transition from the warm to cold biosphere of the Earth.  相似文献   

Cretaceous and Tertiary of the Iullemmeden Basin in Nigeria (West Africa)     

C.A. Kogbe 《Cretaceous Research》1981,2(2):129-186

The Iullemmeden Basin (Mali-Niger-Benin-Nigeria) of tectono-epeirogenic origin was invaded several times by epicontinental transgressions during the Cretaceous and Paleocene.Three major subdivisions are recognized in the Nigerian section of the basin (the “Sokoto Basin”): (1) the lower, continental beds (= Continental Intercalaire) of Late Jurassic to Early Cretaceous age, (2) intermediate marine and brackish water deposits and (3) “Continental T Terminal” of upper Eocene-Miocene age.The geology of the Iullemmeden Basin is reviewed and updated. The relationships between the “Continental Intercalaire” of francophone authors and the Illo and Gundumi Formations are analysed and the type sections of the latter described. It is suggested that the Illo and Gundumi Formations are lateral equivalents.Detailed information on the formations of the Maastrichtian Rima Group is presented. It is concluded that there is no age difference of consequence between the Paleocene Dange, Kalambaina and Gamba Formations.The epicontinental transgressions are interpreted as coming from the north-east, east of the Hoggar massif during the Cenomanian and Turonian and west of the Hoggar during the Maastrichtian and Paleocene. The Sokoto Paleocene molluscan fauna is considered to be terminal Paleocene to Eocene and somewhat younger than the Ewekoro association of coastal Nigeria.A new interpretation of the Continental Terminal is presented. The structural history of the Sokoto Basin is reviewed and partly re-interpreted in the light of new field evidence.  相似文献   

塔西南坳陷中新生代蒸发岩沉积初探          下载免费PDF全文

桑洪  曹养同  朱礼春  张华  张亮  姚佛军  曾昌民  焦鹏程  姜红  梁华 《古地理学报》2014,16(4):473-482

通过资料搜集、蒸发岩野外露头地质调查、石盐岩沉积特征分析及盐类矿物学研究,对塔里木盆地塔西南坳陷中新生代蒸发岩的分布、层位、盐类矿物组合、成因进行了初步探讨。塔西南坳陷石盐岩沉积呈透镜体状,主要沿西昆仑山前分布,常含有褐红色、灰绿色泥砾,泥砾岩性与吐依洛克组下段岩性一致,推测应为吐依洛克组沉积晚期海退期成盐,其层位应归属于吐依洛克组上段。石盐岩透镜体在横向分布上不连续,反映了当时塔西南坳陷内部可能存在多个古盐湖次级凹地,其在干旱气候条件下经浓缩蒸发成盐。蒸发岩矿物除石盐、石膏外,还见有杂卤石、钙芒硝等,其中杂卤石可能为后期富钾卤水交代原生石膏的产物,而乌泊1井石盐表面大量的次生钙芒硝可能为盐湖后期石盐析出阶段含钙地下水缓慢持续补给盐湖的产物。  相似文献