Diagenesis, palaeoclimate and tectono-sedimentary influences on clay mineralogy and stable isotopes from Upper Cretaceous marine successions of the Basque-Cantabrian Basin (N Spain)     

lvaro Jimnez Berrocoso  Maria Cruz Zuluaga  Javier Elorza 《Cretaceous Research》2008,29(3):386-404

Clay mineralogy and whole-rock stable isotopes (δ¹⁸O and δ¹³C) of Upper Cretaceous marly sediments on the Basque-Cantabrian Basin have been integrated to determine the main effects of diagenesis, palaeoclimate and tectono-sedimentary factors in sections belonging to deep- (Barrika) and platform-marine (Isla de Castro, Villamartín and Olazagutía) settings.The mean values for the clay assemblages and δ¹⁸O exhibit notable differences among the sections, partially explainable by the influence of diagenesis. The Barrika sediments, with more diagenetically advanced illite-smectite (I-S) mixed-layer (R1, 70% illite), authigenic chlorite, and low δ¹⁸O (−4.05‰ PDB), experienced higher diagenetic grade than Isla de Castro and Olazagutía, which have R0 I-S (20% illite) and heavier δ¹⁸O. Villamartín was also affected by higher diagenesis than Isla de Castro and Olazagutía, given the occurrence of R1 I-S (60% illite) and low δ¹⁸O (−4.11‰ PDB). However, the absence of other clays in Villamartín (e.g. authigenic chlorite) is indicative of less diagenetic grade than Barrika. These results show the useful integration of clay mineralogy and stable isotopes to detect different diagenetic grades in distinct marine successions of the same basin.Despite being influenced by diagenesis, the clay mineralogy partially preserves its inherited signature. This allows detection of major contents of I-S and mica, and minor kaolinite, interpreted as indicative of warm palaeoclimatic conditions. High kaolinite content in Villamartín and absence of kaolinite in Isla de Castro, though, are considered to be a product of neither diagenesis nor palaeoclimatic influences. Instead, tectono-sedimentary causes, related to unsuitable conditions for clay formation and transport from the local source areas, contributed to original clay differences. The inferred effects of diagenesis, palaeoclimate and tectono-sedimentary factors make this work important to show the potentially great variety of controls on the clay mineralogy of marine sections, which are often uncritically treated in studies concerning the Late Cretaceous.  相似文献   

Belemnites from the lower middle Cenomanian of Hoppenstedt, northern Germany: significance and integrated correlation     

Markus Wilmsen  Michel Rabe 《Cretaceous Research》2008,29(5-6):936

The belemnite species Praeactinocamax primus (Arkhangelsky, 1912) and Belemnocamax boweri Crick, 1910 are described from the Cenomanian of the abandoned limestone quarry section of Hoppenstedt (Sachsen-Anhalt, northern Germany). They co-occur in the upper part of a prominent tripartite bioclastic limestone bed associated with the ammonite Acanthoceras rhotomagense, indicating the primus Event of the lower middle Cenomanian A. rhotomagense ammonite Zone. An integrated stratigraphical calibration including carbon stable isotope correlation to southern England suggests that the belemnite event horizon at Hoppenstedt occupies exactly the same chronostratigraphical position as elsewhere, highlighting the strictly isochronous character of the primus Event across northwestern Europe. Furthermore, stratigraphical gaps in the Hoppenstedt succession are evaluated.  相似文献   

冀北—辽西早白垩世沉积有机质特征与古气候环境演变     

李洪涛  宋之光  邹艳荣  王成善  季强 《地质学报》2008,82(1):72-76

本文对冀北—辽西地区早白垩世沉积盆地富有机质沉积岩进行了初步有机地球化学分析研究。结果显示,冀北—辽西沉积盆沉积有机质特征在时间和空间上存在很大差异,代表白垩系早期沉积的滦平盆地大北沟组有机质丰度低,这不仅显示其所代表的沉积相带不利于有机质的聚集,也反映了当时生物不够繁盛;大店子组时期沉积相带发生了变化,有机质类型随着发生了变化,丰度有所增高,但总体上显示环境条件不利于生物的发育和繁盛。到了桥头组和义县组沉积岩有机质丰度大幅升高,表明生物界非常繁盛,古气候环境有利于有机质的大量生成和堆积,总体上反映了温湿的气候条件;但同时也存在较为频繁或交替性寒冷气候波动,具体的古气候环境状态尚需进一步深入研究。  相似文献   

藏南白垩系黑-红层沉积岩有机质组成分布特征   总被引：1，自引：0，他引：1  

傅培刚  宋之光  胡修棉  王成善 《地质学报》2008,82(1):85-91

对藏南江孜县床得剖面白垩系黑层和红层沉积岩进行的有机地球化学研究表明,黑层有机碳含量高于红层5～10倍,红层和黑层饱和烃主峰碳数分别为nC25和nC23;黑层和红层沉积有机质的母质来源都以水生植物和菌藻类等低等生物为主,陆源有机质的输入非常有限;但饱和烃的分布和主峰碳数的差异可能反映了有机母源物质在种群方面的差异,而这种差异可能主要是水体温度存在差异造成的,即红层发育时期水体温度可能高于黑层沉积时期.而在高温度条件下,水生生物和陆生植物的生长发育受到限制,造成原始有机质产率和有机质沉积保存量低可能是红层沉积岩形成的主要原因.  相似文献   

中国甘肃省酒泉地区公婆泉盆地早白垩世恐龙化石   总被引：2，自引：0，他引：2  

尤海鲁  罗哲西 《地质学报》2008,82(1):139-144

中国甘肃省酒泉地区公婆泉盆地下白垩统新民堡群的恐龙化石主要由1992年中日丝绸之路恐龙考察计划和1997~2000年中美马鬃山恐龙考察计划发掘和研究。先后发现的恐龙包括兽脚类、蜥脚类、禽龙类和新角龙类等。这一新的公婆泉恐龙组合的主要特征是同时包含了在晚白垩世占主导地位的几类恐龙的基干分子,如戈壁巨龙(Gobititan)是巨龙型类的基干分子,马鬃龙(Equijubus)是鸭嘴龙型类的基干分子,而古角龙(Archaeoceratops)和黎明角龙(Auroraceratops)是新角龙类的基干分子。公婆泉恐龙组合的另一特征是其某些成员的体型较大,如似鸟龙类和镰刀龙类恐龙是同期同类中最大的。比较研究发现,公婆泉盆地新民堡群的恐龙和辽西热河群的恐龙关系密切,但前者的整体来说要比后者进步。考虑到公婆泉盆地新民堡群的时代(Albian)较辽西热河群(Hauterivian晚期-Aptian早期)晚,公婆泉恐龙组合似应代表中国北方早白垩纪鹦鹉嘴龙恐龙动物群进化过程中较进步的一个阶段。  相似文献   

蒙古塔木察格坳陷白垩系震积岩特征及其地质意义   总被引：5，自引：1，他引：4  

王化爱  钟建华  陈鑫  高玉飞 《地质学报》2008,82(8):1088-1094

通过岩芯观察,结合构造背景研究,在蒙古塔木察格坳陷白垩纪地层中识别出震积岩。震积岩的主要标志有微同沉积断裂、同沉积塑性变形构造、液化脉、震积枕状及伴生构造等。通过对塔219 井、塔1943 井等岩芯的系统观察,建立了蒙古塔木察格坳陷白垩系震积岩的垂向序列。震积岩的垂向序列自下而上依次为砂岩脉（砂火山）层段、水塑性褶皱变形层段、斧式构造层段、滑塌构造层段、阶梯状微断层和震裂缝层段、准原地沉积湖泊津浪丘状层理和内碎屑角砾岩层段、异地沉积震浊积岩层段,对应于地震由强变弱的一个变化过程。震积岩的发现具有重要的研究意义,有助于分析盆地边界断裂的强烈活动时期。  相似文献   

Drawing the line: the history of the Jurassic—Cretaceous boundary     

John C.W. Cope 《Proceedings of the Geologists' Association. Geologists' Association》2008,119(1):105-117

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Biofacies analysis of Upper Cretaceous deposits in the Ust-Yenisei region: Implications of palynomorphs     

N. K. Lebedeva 《Stratigraphy and Geological Correlation》2008,16(2):182-197

The results of palynomorph biofacies analysis in the Upper Cretaceous deposits of the Ust-Yenisei region are presented. The established facies confinement and indicative features of separate palynomorph groups are used, along with identified dinocyst morphotypes and taxa, in paleogeographic reconstructions. Seven palynomorph associations characterizing continental, coastal-marine, shallow-and deep-water facies are distinguished based on quantitative proportions between morphological groupings and individual taxa. As boundaries between distinguishable biostratigraphic and facies subdivisions do not coincide, dinocysts were likely insignificantly dependent in distribution on facies in the West Siberian epicontinental basin at least. On the other hand, distribution trends of particular dinocyst morphotypes and other microphytofossils are correlative with transgressive-regressive cycles and can be used for reconstruction of paleoenvironments.  相似文献   

First U–Pb SHRIMP age of the Hauterivian stage, Neuquén Basin, Argentina     

M. Beatriz Aguirre-Urreta  Pablo J. Pazos  Darío G. Lazo  C. Mark Fanning  Vanesa D. Litvak   《Journal of South American Earth Sciences》2008,26(1):91-99

A high-resolution ion-microprobe (SHRIMP) U–Pb zircon age from a tuff layer intercalated in the ammonoid bearing sedimentary succession of the Neuquén Basin in Argentina provides a robust geochronologic date to add to the absolute ages and to improve the relative chronology of the Early Cretaceous Hauterivian stage. The tuff layer appears interbedded between shales of the upper member (Agua de la Mula) of the Agrio Formation within the Spitidiscus riccardii ammonoid zone (base of the Late Hauterivian) yielding a date of 132.5 ± 1.3 Ma. This date confirms and supports an accurate correlation between the ammonoid biostratigraphy of the Neuquén Basin with the Western Mediterranean Province of the Tethys during the Early Cretaceous and matches with the most recently published time scale. It also casts doubts on the validity of K–Ar ages on glauconite-grains recently reported from the Lower Cretaceous of the Vocontian Basin of France.  相似文献   

云南罗平中三叠世安尼期生物群的发现及其意义   总被引：15，自引：0，他引：15  

张启跃  周长勇  吕涛  谢韬  楼雄英  刘伟  孙媛媛  江新胜 《地质论评》2008,54(4):523-526

本文介绍了云南罗平地区新发现的罗平生物群的产出层位、生物面貌、保存特征、古地理位置及其研究意义。该生物群产于关岭组二段薄层泥晶灰岩中,地层对比和化石鉴定表明其时代为中三叠世安尼期,以鱼类为主,伴生有爬行类、两栖类（？）、棘皮动物、节肢动物（甲壳类、昆虫等）、双壳类、腹足类以及植物化石;化石保存完好,分布广泛,埋藏方式独特。罗平生物群无论在丰度、分异度及化石保存上都极为罕见和独特,对研究埋藏学、古生态学、古地理以及三叠纪海洋生物尤其是海生爬行类都具有极为重要的意义。  相似文献