内蒙古阿鲁科尔沁旗陶海营子剖面林西组地球化学特征及其对物源-构造背景的制约          下载免费PDF全文

甄甄  陈树旺  郑月娟  张健  李永飞  苏飞  黄欣  公繁浩 《中国地质》2018,45(5):1011-1022

大兴安岭中南段上二叠统林西组发育厚层的暗色泥页岩,是区域上重要的上古生界生烃层系之一。阿鲁科尔沁旗陶海营子剖面是林西组的典型剖面之一,本文以该剖面为研究对象,对取自该剖面林西组的10件砂、泥岩样品进行主量元素、微量元素和稀土元素测试分析。剖面样品元素分析和物源判别函数（F₁-F₂）、Ni-TiO₂、La/Th-Hf图解判别结果表明,陶海营子剖面林西组沉积物来源多样,主要来源于上地壳长英质火成物源区和石英岩沉积物源区,还有少量来自中、基性岩火成物源区。剖面样品微量元素PAAS（后太古庙澳大利亚页岩）标准化蛛网图、稀土元素球粒陨石标准化配分模式图、K₂O/Na₂O-SiO₂、Zr/Th、TiO₂-（TFe₂O₃+MgO）图解、物源构造背景判别函数（F₁-F₂）''的分析判别和剖面样品与不同构造环境砂岩地球化学参数对比结果表明,陶海营子剖面林西组物源构造背景具有被动大陆边缘、活动大陆边缘和大陆岛弧特征,构造背景较复杂。综合分析可知,陶海营子剖面林西组物源主要为被动大陆边缘背景下的火成岩、石英质沉积岩,以及活动大陆边缘和大陆岛弧背景下的火成岩。结合前人相关研究成果,推测兴蒙造山带内伸展作用背景下的晚石炭世-二叠纪岩浆型被动陆缘沉积建造和与俯冲背景有关的古生代弧岩浆岩应该是陶海营子剖面林西组的主要物源。  相似文献   

柳河盆地中生代充填特征与盆地演化     

曲鹏展  程日辉  宋立斌  沈艳杰  许中杰 《世界地质》2018,37(1):185-198

柳河盆地中生代地层发育有中侏罗统侯家屯组,下白垩统果松组、鹰嘴砬子组、林子头组、下桦皮甸子组和亨通山组。主要岩石类型为碎屑岩、火山碎屑沉积岩、火山碎屑岩和熔岩,沉积相为扇三角洲-湖泊相。根据岩性变化和岩相组合,将下白垩统划分为13个三级层序和8种充填类型。根据盆地构造和层序特征,划分为5个构造发育阶段,分别是中侏罗世初始凹陷阶段、晚侏罗世抬升剥蚀阶段和早白垩世的3个火山喷发-沉降阶段。柳河盆地是一个受走滑张扭-走滑压扭机制控制的走滑伸展盆地。  相似文献   

榆树林油田扶杨油层沉积岩地球化学特征及地质意义     

施秋华  袁亚娟  夏斌  林舸 《地质学报》2018,92(1):154-169

三肇凹陷榆树林油田扶杨油层中泥岩、粉砂岩和砂岩样品主量元素和微量元素地球化学分析表明,多数主量元素含量中等,与全球平均大陆上地壳(UCC)相比,Fe_2O_3、MgO、CaO、Na_2O含量较低,而TiO_2、Al_2O_3、K_2O、MnO含量均略高;样品中的相容元素(V、Cr、Co、Ni等)含量均低于澳大利亚后太古宙页岩(PAAS)和UCC;稀土元素总量为102×10~(-6)~276×10~(-6),平均为188×10~(-6),与PAAS表现出相似的球粒陨石标准化曲线,显示了相似的物源和构造背景。元素间的相关性分析显示大部分元素与SiO_2负相关而与Al_2O_3正相关,说明大部分元素受到黏土矿物吸附作用的影响,石英与长石矿物对这些元素表现出一定的稀释效应。根据主元素物源判别方程图和Th-Hf-Co图投影及La/Hf、(Gd/Yb)N值,扶杨油层物源主要来自后太古宙长英质火山岩,可能卷入了部分再循环沉积岩。通过一系列的构造背景判别图解分析,表明扶杨油层沉积时以大陆岛弧环境为主。在对油层组进行了纵向古气候分析后,认为FI油层组沉积时处于一个构造活动强、干旱的环境中,所形成的沉积岩储层物性更好,是油气勘探开发的重点层位。  相似文献   

Spatial and temporal geochemical variability in lacustrine sedimentation in the East African Rift System: Evidence from the Kenya Rift and regional analyses     

《Sedimentology》2018,65(5):1697-1730

Many previous studies on lacustrine basins in the East African Rift System have directed their attention to climatic controls on contemporary sedimentation or climate change as part of palaeoenvironmental reconstruction. In contrast, this research focuses on the impact of tectonism and volcanism on rift deposition and develops models that help to explain their roles and relative importance. The study focuses on the spatial and temporal variability in bulk sediment geochemistry from a diverse range of modern and ancient rift sediments through an analysis of 519 samples and 50 major and trace elements. The basins examined variously include, or have contained, wetlands and/or shallow to deep, fresh to hypersaline lakes. Substantial spatial variability is documented for Holocene to modern deposits in lakes Turkana, Baringo, Bogoria, Magadi and Malawi. Mio‐Pleistocene sediments in the Central Kenya Rift and Quaternary deposits of the southern Kenya Rift illustrate temporal variability. Tectonic and volcanic controls on geochemical variability are explained in terms of: (i) primary controlling factors (faulting, subsidence, uplift, volcanism, magma evolution and antecedent lithologies and landscapes); (ii) secondary controls (bedrock types, rift shoulder and axis elevations, accommodation space, meteoric and hydrothermal fluids and mantle CO ₂); and (iii) response factors (catchment area size, orographic rains, rain shadows, vegetation densities, erosion and weathering rates, and spring/runoff ratios). The models developed have, in turn, important implications for palaeoenvironmental interpretation in other depositional basins.  相似文献   

Using climate to relate water discharge and area in modern and ancient catchments     

《Sedimentology》2018,65(4):1378-1389

Models relating sediment supply to catchment properties are important in order to use the geological record to deduce landscape evolution and interplay between tectonics and climate. Water discharge (Q _w) is an important factor in the widely used ‘BQART ’ model, which relates sediment load to a set of measurable catchment parameters. Although many of the factors in this equation may be independently estimated with some degree of certainty in ancient systems, water discharge (Q _w) certainly cannot. An analysis of a world database of modern catchments with 1255 entries shows that the commonly applied equation relating catchment area (A ) to water discharge (Q _w = 0·075A^0·8) does not predict water discharge from catchment area well in many cases (R ² = 0·5 and an error spanning about three orders of magnitude). This is because the method does not incorporate the effect of arid and wet climate on river water discharge. The inclusion of climate data into such estimations is an opportunity to refine these estimates, because generalized estimates of palaeoclimate can often be deduced on the basis of sedimentological data such as palaeosol types, mineralogy and palaeohydraulics. This paper investigates how the relationship between catchment area and river discharge varies with four runoff categories (arid, semi‐arid, humid and wet), which are recognizable in the geological record, and modifies the coefficient and exponent of the above‐mentioned equation according to these classes. This modified model yields improved results in relating discharge to catchment area (R ² = 0·95 and error spanning one order of magnitude) when core, outcrop or regional palaeoclimate reconstruction data are available in non‐arid systems. Arid systems have an inherently variable water discharge, and catchment area is less important as a control due to downstream losses. The model here is sufficient for many geological applications and makes it possible to include variations in catchment humidity in mass‐flux estimates in ancient settings.  相似文献   

柴北缘达达肯乌拉山地区闪长岩锆石LA-ICP-MSU-Pb年龄、岩石地球化学特征及其构造意义   总被引：1，自引：0，他引：1  

刘永乐  刘智刚  张爱奎  何书跃  张大明  毛生元  李兴良  奎明娟 《矿床地质》2018,37(5):1079-1090

达达肯乌拉山位于柴达木盆地北缘中东部,区内发育闪长岩体,以小岩株形式产出。通过对达达肯乌拉山闪长岩岩石LA-ICP-MS锆石U-Pb定年和地球化学特征的研究,获得闪长岩体的年龄为(240.5±1.7) Ma,属早印支期。闪长岩体的w(K_2O)较高,为2.03%～2.30%,w(Na2O)含量较低,为3.2%～3.44%,为一套准铝质及弱过铝质高K、低Na的高钾钙碱性型I型花岗岩。岩石稀土元素总量为158.35×10~(-6)～200.41×10~(-6),球粒陨石标准化曲线向右倾斜,重稀土元素曲线呈水平状,轻稀土元素富集,但负铕异常不明显,岩浆分异程度不高。岩石的La/Ta(54.32～68.51)、Sm/Nd(0.18～0.19)及Rb/Sr(0.11～0.19)比值特征反映该岩体岩浆具有壳幔混合的特点。通过构造判别,反映达达肯乌拉山岩体可能形成于俯冲陆壳断离、幔源岩浆底侵的地球动力学背景,在中央造山带早中生代统一的板块碰撞与挤压构造体制下,以滩间山蛇绿岩带为基础,发生陆壳俯冲和断离作用,并诱发幔源岩浆的底侵和下地壳物质的部分熔融,沿火山机构侵位形成达达肯乌拉山岩体。  相似文献   

川滇黔邻区龙马溪组页岩气富集主控因素与勘探方向   总被引：2，自引：2，他引：0       下载免费PDF全文

汪正江  余谦  杨平  刘伟  杨菲  刘家洪  熊国庆  何江林  邓奇 《沉积与特提斯地质》2018,38(3):1-15

中国的页岩气资源评价必须立足于中国主要陆块的地质条件与构造演化特点之上,对于不同层系、不同地区的页岩气选区评价,也必须抓住关键因素。川滇黔邻区的五峰组-龙马溪组富有机质页岩发育,但保存条件较渝东南地区更为复杂。印支期以来,该区经历了多期次构造应力场转换,断裂、褶皱发育,因此,建立针对性的页岩气选区评价参数体系是该区页岩气勘探走出困局的当务之急。本文在分析该区已有页岩气钻井成效的基础上,立足于扬子海相层系页岩气勘探应是基于保存条件的"连续型甜点区"的选区评价基本思路,结合前人研究成果,系统梳理出一套评价指标体系。该体系涵盖5大因素(区域盖层、直接盖层、底板条件、页岩层自身条件、构造改造强度)、4个等级、17个选区评价参数。另外,根据已有相关钻井数据,总结提出了5个页岩气层评价表征参数(含气量、孔隙度、电阻率、氮气组分含量和压力系数)。根据该指标体系,对川滇黔邻区的主要构造单元进行了梳理分析,优选出5个有利区,提出了各有利区的首选可能突破点。本研究对复杂构造区页岩气有利区带优选具有一定的指导意义。  相似文献   

青海南山吾口侵入岩体锆石U-Pb年代学、地球化学特征及其地质意义          下载免费PDF全文

郝亚青  杨启安  石玉莲  李生虎 《沉积与特提斯地质》2018,38(4):13-23

本文对青海南山吾口正长花岗岩和花岗闪长岩进行了岩石学、岩石地球化学及年代学研究。首次测得吾口侵入岩体正长花岗岩的锆石206Pb/238U年龄为253. 8±3. 3Ma(MSWD=0. 96),形成时代为晚二叠世。岩石中Al_2O_3为(14. 13～16. 51)×10~(-2),K_2O为(1. 66～3. 59)×10~(-2),A/NK=1. 15～2. 35,A/CNK=0. 75～1. 03,TFe O/(TFe O+MgO)=0. 53～0. 81,岩石具偏铝质中-高钾钙碱性花岗岩特征;吾口岩体表现为富集大离子亲石元素Rb、K等,亏损高场强元素Nb、Ta、Ba等;轻重稀土分异较明显,具右倾特征,中等负Eu异常(δEu=0. 44～0. 68),具壳幔岩浆混合特征。吾口岩体代表了阿尼玛卿洋盆向北削减俯冲运动在青海南山构造带与西秦岭造山带和南祁连造山带的构造转换衔接部位的构造演化的地质记录。该侵入岩体形成时代及构造环境的确定,为研究印支早期青海南山构造演化及动力学机制提供重要依据。  相似文献   

断裂应力特征及其转折控油气规律研究——以南堡凹陷为例     

马强  德勒恰提&#;加娜塔依  陈亚军  马乐  于景维  祁利祺 《地质力学学报》2018,24(5):587-597

为了分析断裂对油气宏观分布规律的控制作用,寻找有勘探潜力的油气富集带,文中以地质力学理论为指导,对南堡凹陷断裂组合应力特征、断裂转折及成因进行解析,并结合砂体分布和古今构造应力场分布特征,对南堡凹陷东营组油气分布规律和有利勘探区带做了研究。结果表明:断裂转折部位对油气分布有着控制作用,东营组已探明的油气主要在帚状断裂系、入字形断裂系、交织式断裂系转折轴部高曲率附近呈环带状分布;断裂转折凹面一侧控油性明显,从宏观上来看,油气具有沿沉积相带由细到粗的构造脊高点以及弧形断裂转折凹面一侧的选择性运移的特征,断裂转折轴部高曲率高孔、高渗域与高孔、高渗砂体沉积相带的有利对置决定了油气的主流向;综合研究指出,南堡凹陷北堡构造带是今后优势勘探的首要区带,其次是南堡构造带和南堡4号蛤坨构造带南部。  相似文献   

Sequence stratigraphy of the Berriassian-Lower Aptian deposits of West Siberia     

S.V. Ershov 《Russian Geology and Geophysics》2018,59(7):891-904

The geological structure and conditions of formation of a Lower Cretaceous clinoform complex in West Siberia are examined based on sequence stratigraphy. The regional Berriasian-Hauterivian clinoforms are interpreted as third-order sequences, and their formation should be considered in terms of the Depositional Sequence III model. Productive beds of both shallow and deep marine as well as continental genesis formed mostly in a regressive basin and belong to the highstand systems tracts.  相似文献