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Oil‐source correlation studies have demonstrated that the crude oils in the Ordos Basin were mainly derived from organic‐rich lacustrine mudstones of the Yanchang Formation. The sedimentology, petrology and organic geochemistry of these mudstones have been studied intensively, but their trace and rare earth element (REE) characteristics have received little attention. In this paper, we present trace and rare earth element data of the Upper Triassic Yanchang Formation mudstones in the southern Ordos Basin to constrain the palaeoenvironment, provenance and depositional setting. Our results show that the REE and trace element concentrations of the Yanchang Formation mudstones are higher than those of the upper continental crust (UCC). The Sr contents and Sr/Ba and Y/Ho ratios of these mudstones indicate the absence of a marine transgression during the sedimentation of the Upper Triassic mudstones. The depositional environment of the Upper Triassic mudstones was slightly oxic as evidenced by the values of Eu/Eu*, Ce/Ce*, Ceanom, δU, U/Th, V/Cr and Ni/Co. The UCC‐normalized distribution pattern of REEs, spider diagrams, the ratios of related elements, the bivariate diagrams of Th/Sc–Zr/Sc and La/Th–Hf and the ternary plots of La–Th–Sc and Th–Sc–Zr/10 signify that the provenances of the Chang9–7 mudstones were mainly derived from a continental island arc, whereas the provenances of the Chang6–3 mudstones were mainly derived from a mixture of continental island arc and active continental margin, and the latter contain less recycled materials. Combined with the previous studies of detrital zircon dating and petrography of the Yanchang Formation sandstones in the southern Ordos basin, we propose that the Qinling orogenic belt served as one of the primary source regions occurring between the Chang7 and Chang6 periods, corresponding to the initial uplift of the west Qinling Mountains due to the collision between the Yangtze and North China blocks. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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宁南盆地咸化湖相清水营组沉积记录,是研究青藏高原东北缘地区晚古近纪气候变化及其驱动机制的绝佳选择。以宁南盆地古近系清水营组为研究对象,通过野外地质调查、样品采集、石膏主量元素和锶同位素的测试,分析沉积地层记录的化学风化和古气候的变化;并通过与全球气候变化和青藏高原隆升过程的对比分析,研究青藏高原东北缘宁南盆地气候变化的驱动机制。结果表明:宁南盆地清水营组石膏中Al2O3/SiO2、Al2O3/Ti2O、K2O/Na2O和87Sr/86Sr等指标可以很好地反映晚古近纪气候变化,在38~36 Ma、34.5~33 Ma、32~31 Ma、30~27 Ma、26~23 Ma这5个时期,化学风化减弱,气候干旱化;在36~34.5 Ma、33~32 Ma、31~30 Ma、27~26 Ma这4个时期,化学风化增强,气候湿润化。晚古近纪38~26 Ma,青藏高原东北缘宁南盆地古气候变化主要受到全球气候变化的驱动;但在26~23 Ma之间,宁南盆地古气候变化受到了青藏高原隆升的重要影响。 相似文献
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The petrography and geochemistry (major, trace, and rare earth elements) of clastic sedimentary rocks from the Paleogene Dainan Formation (E2 d) in the North Jiangsu Basin, eastern China, are investigated to trace their provenance and to constrain their tectonic setting. The studied samples are characterized by LREE enrichment, flat HREE, and negative Eu anomaly similar to the upper continental crust composed chiefly of felsic components in the source area. Petrographic observation indicates that the sandstones contain predominant metamorphic and sedimentary clasts that were derived from peripheral recycled orogen and intrabasinal materials. The trace element ratios (Co/Th, La/Sc, La/Th, and Th/U) and the La-Th-Sc ternary plot further confirm that the sandstones are derived from granitic gneiss sources from recycled orogen and the intrabasinal mixed sedimentary provenance. The granitic gneiss source rocks may have derived from the Proterozoic granitic gneiss denuded in the eastern Dabie-Sulu orogen; and the intrabasinal provenance may come from the underlying strata during the Late Paleocene Wubao movement. The chemical index of alteration (CIA) and A-CN-K plot show that these source rocks may have experienced weak to medium chemical weathering. Analysis on tectonic setting of the source area suggests an active continental margin, which is intimate with tectonic feature of the Dabie-sulu orogen and the Yangtze block. In summary, we suggest that the North Jiangsu Basin is an ideal site for the study of the coupling between the uplift of the orogen and the subsidence of the foreland basin. 相似文献
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《Journal of Asian Earth Sciences》2011,40(6):740-759
Cenozoic sedimentary deposits in central-southern Ningxia province, NW China are an important record of Tertiary tectonic events along the evolving Qinghai–Tibetan Plateau’s northeast margin. Shortly after the onset of the Indo-Eurasia collision to the south, a thrust belt and adjoining foreland basin began to form during 40–30 Ma. The Eocene Sikouzi Formation developed in a distal setting to this basin, in normal fault-bound basins that may have formed in a forebulge setting. Subsequent deposition of the Oligocene Qingshuiying Formation occurred during a phase of apparently less intense tectonism and the previous underfilled foreland basin became overfilled. During the Early Miocene, contractional deformation was mainly distributed to the west of the Liupan Shan. This resulted in deformation of the Qingshuiying Formation as indicated by an unconformity with the overlying Miocene Hongliugou Formation. The unconformity occurs proximal to the Haiyuan Fault suggesting that the Haiyuan Fault may have begun movement in the Early Miocene. In the Late Miocene, thrusting occurred west of the southern Helan Shan and an unconformity developed between the Hongliugou and Qingshuiying Formations proximal to the the Cha-Gu Fault. Relationships between the Miocene stratigraphy and major faults in the region imply that during the Late Miocene the deformation front of the Qinghai–Tibetan Plateau had migrated to the Cha-Gu Fault along the western Ordos Margin, and the Xiang Shan was uplifted. Central-southern Ningxia was then incorporated into the northeast propagating thrust wedge. The driving force for NE propagation of the thrust wedge was most likely pronounced uplift of the northeastern plateau at the same time. Analysis of the sedimentary record coupled with consideration of the topographic evolution of the region suggests that the evolving fold-and-thrust belt experienced both forward-breaking fold-and-thrust belt development, and out-of-sequence fault displacements as the thrust wedge evolved and the foreland basin became compartmentalised. The documented sedimentary facies and structural relationship also place constraints on the Miocene-Recent evolution of the Yellow River and its tributaries. 相似文献
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Babu K 《Journal of Earth System Science》2017,126(3):45
The Trichinopoly Group (later redesignated as Garudamangalam) has unconformable relationship with underlying Uttatur Group and is divided into lower Kulakanattam Formation and upper Anaipadi Formation. These calcareous sandstones are analysed major, trace and rare earth elements (REEs) to find out CIA, CIW, provenance and tectonic setting. The silica content of fossiliferous calcareous sandstone show wide variation ranging from 12.93 to 42.56%. Alumina content ranged from 3.49 to 8.47%. Higher values of Fe2O3 (2.29–22.02%) and low MgO content (0.75–2.44%) are observed in the Garudamangalam Formation. CaO (23.53–45.90) is high in these sandstones due to the presence of calcite as cementing material. Major element geochemistry of clastic rocks (Al2O3 vs. Na2O) plot and trace elemental ratio (Th/U) reveal the moderate to intense weathering of the source rocks. The Cr/Zr ratio of clastic rocks reveal with an average of 1.74 suggesting of felsic provenance. In clastic rocks, high ratios of \(\sum \)LREE/\(\sum \)HREE, La/Sc, Th/Sc, Th/Co, La/Co and low ratios of Cr/Zr, and positive Eu anomaly ranges from (Eu/Eu* = 1.87–5.30) reveal felsic nature of the source rocks. 相似文献
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试论宁夏地区始新统寺口子组沉积的构造背景 总被引：9，自引：0，他引：9
做为新生代宁夏境内的第一套沉积,始新统寺口子组具有其特殊的意义,但一直没有得到满意的解释。从寺口子组的沉积规模以及较为剧烈的沉积相变化来看,寺口子组的沉积来的很突然。通过沉积相以及构造分析表明寺口子组是走廊南山前陆盆地中前隆位置靠前陆盆地一侧的沉积。该盆地是30～40Ma之间走廊南山逆冲隆起的前陆盆地,盆地的前隆沉积单元位于鄂尔多斯西缘及香山等地区,隆后沉积单元位于鄂尔多斯西缘以东,由于挠曲作用在该前隆上产生了许多倾向造山带的正断层,这些正断层控制了寺口子组的分布．基本上是一种近源的快速堆积,形成一系列围绕前隆的冲积扇或洪积扇沉积,物源为鄂尔多斯西缘隆起等地区。 相似文献
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为探讨下扬子地区下寒武统幕府山组底部富有机质黑色岩系的物源属性及源区构造背景特征,在南京幕府山剖面幕府山组底部系统的采集样品,并对其进行地球化学测试与分析。Th/Sc?Zr/Sc图解表明幕府山组黑色岩系未曾经历沉积再循环;通过分析主量元素比值特征、稀土元素（REE）配分模式、δEu、（La/Yb）N及La/Th?Hf和La/Yb?∑REE判别图解,认为幕府山组黑色岩系源岩主要是花岗岩和富含长英质矿物的沉积岩等上地壳长英质岩石,存在基性岩的混入。从物源属性、地质年代关系、华南大陆构造演化历程等多方面考虑,源岩中花岗岩成分主要为新元古时期岩浆活动形成的岩浆岩,物源区为江南古陆（江南造山带）。通过分析K2O+Na2O?SiO2、K2O/Na2O?SiO2/Al2O3、La?Th?Sc、Th?Co?Zr/10和Th?Sc?Zr/10图解,认为幕府山组黑色岩系源区构造背景为被动大陆边缘。 相似文献
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青藏高原东北部隆升：来自宁夏同心小洪沟剖面的证据 总被引：3，自引：0，他引：3
青藏高原边界地区的研究,尤其是砾石研究,对探讨青藏高原的隆升过程及隆升机制具有重要意义。本文选取青藏高原东北部香山山前小洪沟剖面,对出露的新生界各层位的砾石进行统计。统计结果显示,该剖面寺口子组上段、红柳沟组下段、红柳沟组上段、第四系以及现今河床出露的砾石成分主要为砂岩和石英砂岩,这与香山地区岩性相符合;砾石主要呈次圆状和次棱角状;长短轴比主要为1至2之间,为近圆状;砾石主要集中在中砾和小砾类别;分选好至中等好。砾石粒径分布显示出向细粒成分偏的特征,主要呈尖峰正态分布。这些特征表明各层位砾石相似的搬运过程,为中距离山前河流冲积砾石。沉积分析表明该砾石与气候振荡无必然联系,为构造隆升的产物。砾石沉积年龄由邻区磁性地层定年结果来限定。砾石特征结合邻区沉积分析表明香山地区在寺口子组沉积时（始新世）沉积之前已具有相当大的高程;至清水营组沉积时（渐新世）,该山体被剥蚀剥蚀夷平;到红柳沟组沉积时（中新世早、中期）,香山经历了再次的隆升;至干河沟组沉积时（中新世晚期到上新世）,构造趋于稳定;到更新世时,再次出现隆升事件。始新世香山山体可能与晚白垩世至新生代早期的构造事件有关,中新世的隆升时间可以作为印－藏碰撞效应到达香山地区的时限,显示青藏高原东北边界新生代的变形隆升时间较前人研究结果早,且存在多期隆升。 相似文献
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鄂尔多斯盆地东胜地区直罗组砂岩的地球化学特征与物源分析 总被引：4，自引：0，他引：4
沉积岩物源分析对揭示盆地砂体展布、物质组成、储集层性质及砂岩型铀矿床铀源等科学问题具有重要的意义。对取自鄂尔多斯盆地东北部8个钻井中的中侏罗统直罗组砂岩进行了详细的岩石学和地球化学研究,试图鉴别岩石的源区和形成的构造环境。研究表明,砂岩以中粗粒杂砂岩为主,其w(SiO2)值及w(Al2O3)/w(SiO2)值中等到较高,w(K2O)值相对较高,Fe2O3、MgO、TiO2含量较低,暗示碎屑物质的富长英质、贫镁铁质特征。Nb、Ta、Ti、P等不活动元素的强烈亏损和K、Rb、Sr、Ba等LILE的富集,共同指示源区具有明显的俯冲带的特征;而w(TFe2O3+MgO)-w(TiO2)、w(TFe2O3+MgO)-w(Al2O3)/w(SiO2)、w(Th)-w(Sc)-w(Zr)/10、w(Th)-w(Co)-w(Zr)/10等判别特征则表明砂岩源区岩石可能形成于大陆弧-活动大陆边缘环境。而且,在球粒陨石标准化分配模式中,LREE强烈富集,HREE无明显分异、有着较平坦的曲线,Eu无异常或表现为弱的正、负异常;在PAAS标准化曲线中,轻重稀土均无明显分异,仅Eu表现为明显正异常。本区直罗组砂岩与华北北缘显生宙闪长岩-花岗闪长岩有着很强的亲缘性。 相似文献
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盐源盆地始新世丽江组沉积时期发育了一套具大型高角度交错层理的红色砂岩,其确切成因对于厘定青藏高原东缘古近纪古地理格局、恢复东亚新生代干旱带与古气候演化过程具有重要意义。文中通过对盐源盆地始新统丽江组红色砂岩的沉积特征进行系统分析,证明该套砂岩的岩性、粒度分布、石英颗粒表面特征与沉积构造等明显不同于水成沉积,而与典型风成沙丘相应特征完全一致,表明其为风成沙丘沉积。结合古近纪研究区的古气候条件、大气环流样式与大地构造背景,笔者进一步推断盐源盆地始新世风成沙丘可能沉积于中国古近纪干旱带内的沙漠环境。根据目前相关研究资料,确认青藏高原东缘存在一个厚度稳定的古近纪风成沙丘富集带。 相似文献
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Geochemistry and Provenance of Maastrichtian Clastic Rocks in the Dikmendede Formation of Orhaniye in Kazan-Ankara-Turkey Region 总被引：1，自引：0，他引：1
An integrated petrographic and geochemical study of the sandstones of the Maastrichtian-aged in the Orhaniye (Kazan-Ankara-Turkey) was carried out to obtain more information on their provenance, sedimentological history and tectonic setting. Depending on their matrix and mineralogical content, the Maastrichtian sandstones are identified as lithic arenite/wacke. The Dikmendede sandstones derived from types of provenances, the recycled orogen and recycled transitional. The chemical characteristics of the Dikmendede sandstones, i.e., fairly uniform compositions, high Th/U ratios (>3.0), negative Eu anomalies (Eu/Eu* 0.72–0.99) and Th/Sc ratios (mostly less than 1.0), favor the OUC (old upper continental crust) provenance for the Dikmendede sandstones. The SiO2/Al2O3, Th/Sc (mostly <1.0) and La/Sc (<4.0) ratios are; however, slightly lower than typical OUC, and these ratios may suggest a minor contribution of young arc-derived material. The rare earth element (REE) pattern, and La/Sc versus Th/Co plot suggests that these sediments were mainly derived from felsic source rocks. The Dikmendede sandstones have high Cr (123–294 ppm) and Ni (52–212 ppm) concentrations, Cr/Ni ratio of 1.93, and a medium correlation coefficient between Cr and Ni and corresponding medium to high correlation of both (Cr and Ni, respectively) elements with Co. These relationships indicate a significant contribution of detritus from ophiolitic rocks. As rare earth element data are available for the Dikmendede sandstones, the Eu/Eu* is compared with LaN/YbN. Samples plot in the area of overlapping between continental collision, strike-slip and continental arc basins. The predominantly felsic composition of the Dikmendede sandstones is supported by the REE plots, which show enriched light REE, negative Eu anomaly and flat or uniform heavy REE. The Dikmendede sandstones have compositions similar to those of the average upper continental crust and post-Archean Australian shales. This feature indicates that the sediments were derived mainly from the upper continental crust. The Dikmendede sandstones have chemical index of alteration (CIA) values of 28–49, with an average of 40 indicating a low degree of chemical weathering in the source area. The compositional immaturity of the analyzed sandstone samples is typical of subduction-related environments, and their SiO2/Al2O3 and K2O/Na2O ratios and Co, Sc, Th and Zr contents reflect their oceanic and continental-arc settings. The Dikmendede sandstones were developed as flysch deposits derived from mixed provenance in a collision belt. 相似文献
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Tertiary sandstones collected from southwest Sarawak, Malaysia, were analyzed to decipher their provenance, weathering, and tectonic setting. The studied sandstones have a sublitharenite composition and are dominantly composed quartz with little mica and feldspar, and a small amount of volcanic fragments. These sandstones were generally derived from quartz-rich recycled orogenic sources. They have relatively high SiO2 content with low Na2O, CaO, MnO, and MgO contents. Values of Chemical Index of Alteration (CIA) of these rock samples vary from 71 to 93, with an average of 81, implying intense chemical alteration during weathering. A felsic igneous source is suggested by a low concentration of TiO2 compared to CIA, enrichment of Light Rare Earth Elements, depletion of Heavy Rare Earth Elements, and negative Eu anomalies. A felsic origin is further supported by a Eu/Eu* range of 0.65–0.85 and high Th/Sc, La/Sc, La/Co, and Th/Co ratios. This work presents the first reported geochemical data of Tertiary sandstones of the Sarawak Basin. These data led us to conclude that the sandstones were dislodged from recycled orogenic sources and deposited in a slowly subsiding rifted basin in a passive continental tectonic setting. 相似文献
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松辽盆地钱家店地区姚家组砂岩矿物、地球化学成分与源区岩石性质和沉积构造环境密切相关。岩相学观察和矿物化学分析表明,所研究的岩石主要碎屑矿物由石英、岩屑和长石组成,含少量的黄铁矿、炭屑和重矿物等矿物。地球化学特征上,这些岩石普遍具有高SiO2含量(68.4%~79.61%)、相对高的K2O/Na2O比值(1.83~2.03)和较低的Fe2O3T+MgO含量(1.48%~4.22%),稀土元素标准化配分曲线呈现轻稀土富集,重稀土平坦和弱Eu、Ce负异常特征。较低的CIA(57~63)和PIA(60~71)指数、A-CN-K以及AK-C-N分布模式还说明源区经历了相对较弱的风化作用。Zr/Sc和Th/Sc比值共同表明姚家组的碎屑组成不具备沉积再旋回的特征,说明其为近源沉积,具有较差的分选性。砂岩物源区组成判别图研究表明,姚家组砂岩的物源区主要出露长英质岩浆岩。砂岩形成构造环境判别图解及特征指数分析表明,姚家组主要形成于被动大陆边缘沉积环境。 相似文献
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采用电感耦合等离子体质谱(ICP-MS)方法对兰坪盆地古近系104件细碎屑岩样品进行了稀土元素及微量元素分析,结果显示∑LEE含量较高,轻稀土含量较富集、重稀土含量较亏损,显示出明显的"右倾"型配分模式。根据稀土元素和微量元素特征、w(Zr)-w(Th)、La-Th-Sc、Th-Sc-Zr/10等多种沉积构造背景判别图解及多种交叉分析方法,对兰坪盆地古近系细碎屑源岩构造背景进行了详细研究。利用La/Th-Hf和La/Yb-∑REE判别图解对兰坪盆地古近系源岩属性进行了分析,结果表明:兰坪盆地古近系碎屑源岩主要以上地壳长英质岩石为主,并混有少量基性岩,反映其物源区构造背景为早期为大陆岛弧构造背景,至晚期逐渐过渡为被动大陆边缘构造背景。 相似文献
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北大巴山地区斑鸠关组砂岩地球化学特征对物源和构造环境的限定 总被引：1，自引：0，他引：1
北大巴山是南秦岭造山带的重要组成部分,保留较完整的地层记录。长期以来,斑鸠关组被认为形成于相对稳定的构造环境。本文通过对斑鸠关组砂岩的沉积序列和地球化学分析,详细分析其物源区和形成构造环境。沉积学特征表明,斑鸠关组砂岩主要为一套深水沉积的细砂岩、粉砂岩和泥岩组合序列,形成于海底扇。砂岩中交错层理恢复的古流向表明,其物源主要来自于北侧。地球化学分析表明,斑鸠关组砂岩SiO_2为61.54%～84.35%,主要为成熟度较低的岩屑砂屑岩。稀土元素标准化配分曲线呈现轻稀土富集、重稀土平坦和Eu负异常的特征。砂岩的风化蚀变指数为51～67,Th/U比值为3.36～7.02,表明砂岩物源区经历了较弱的风化作用。Zr/Sc和Th/Sc比值指示斑鸠关组砂岩没有经历沉积再旋回,为近源沉积。砂岩物源区组成判别图表明,斑鸠关组物源主要为长英质岩石。砂岩源区构造环境判别图以及特征指数表明,斑鸠关组源区形成于大陆岛弧和被动大陆边缘环境。综合区域资料,表明斑鸠关组形成于大陆岛弧相关环境,非大陆裂谷。 相似文献
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The Bengal Basin originated during the collision of India with Eurasia and Burma. The provenance analysis of the Chittagong Tripura Fold Belt (CTFB), which is the folded eastern flank of the Bengal Basin as well as the Neogene belt of the Indo-Burman Ranges (IBR) is key to better understand the possible sources of sediment input from the complex interplay of the Indian, Eurasian and Burma plates. We report new whole rock geochemical and detrital zircon U–Pb data from the upper Neogene sandstones of Tipam-Dupi Tila formations (Pliocene to Plio-Plestocene succession) from the CTFB. Detrital zircon U–Pb age spectra show three predominant peaks at <200 Ma, 480–650, ∼800–1000 Ma. The geochemical discriminations and elemental ratios of Eu/Eu* (∼0.70), La/Sc (∼16.13), La/Co (∼15.76), Th/Sc (∼2.95), La/Th (∼5.67), Th/Co (∼2.87), Cr/Th (∼4.63) as well as Chondrite-normalized REE patterns with flat HREE, LREE enrichment, and negative Eu anomalies for the Tipam and Dupi Tila formations are suggestive of a dominantly felsic source area experiencing moderate to intensive chemical weathering (Chemical index of alteration, CIA - 57 to 81) and have a recycled provenance orogen related to active continental or passive margin settings. Integrated geochemical and zircon U–Pb studies reveal that the main sediment input might have been from the Himalayan orogen with significant arc-derived detritus, possibly from the Gangdese arc as well as from the Burma magmatic arc. 相似文献