扬子西缘泛非造山与绵阳－长宁克拉通裂陷的沉积充填过程研究          下载免费PDF全文

汪正江  王启宇  杨菲  熊国庆  马龙  杜秋定  郑炳嵩 《沉积与特提斯地质》2022,42(3):350-367

四川盆地安岳震旦—寒武系特大型气田的发现,掀起了探索四川盆地深层油气勘探新领域的热潮。然而对于川西北深层原型盆地沉积充填过程及其动力学机制的认识尚处于探索阶段。本文通过对扬子西北缘及盆内典型钻井震旦—寒武纪地层序列的综合调查与区域对比研究,基于关键事件序列的系统厘定,重建了扬子西北缘及邻区新元古代—寒武纪原型盆地沉积充填格架;对比全球冈瓦纳大陆汇聚与泛非造山过程,系统厘定了泛非运动在扬子西缘的沉积－构造－岩浆作用记录,进一步明确了华南扬子克拉通为新元古代末期冈瓦纳大陆的一部分。同时,结合盆内最新深层钻井和二维地震资料解析,研究认为绵阳－长宁克拉通边缘裂陷的成生、发展、充填与折返隆升过程主要受控于扬子西缘的泛非期弧后伸展、弧陆碰撞及陆陆碰撞造山过程,研究提出绵阳－长宁克拉通边缘裂陷经历了如下6个演化阶段：①陡山沱早期克拉通边缘裂陷开启,表现为克拉通边缘的裂陷与快速沉降;②陡山沱晚期—灯影早期为克拉通裂陷的持续沉降与克拉通碳酸盐台地的补偿性生长,区域沉积分异明显;③灯影晚期为克拉通裂陷扩展、定型与碳酸盐台地的活化与重建;④麦地坪期为克拉通边缘的差异隆升与碳酸盐台地的风化剥蚀;⑤筇竹寺期为克拉通增生陆块边缘的构造活化与克拉通边缘的挤压挠曲沉降;⑥沧浪铺期为陆陆碰撞造山与克拉通边缘裂陷的快速充填。至沧浪铺末期,绵阳－长宁克拉通裂陷沉积充填结束,并快速折返隆升为天井山－川中古隆起。因此,本文对扬子西缘克拉通边缘裂陷的盆地动力学过程重塑,不仅为华南板块在冈瓦纳古大陆重建中的构造定位提供了新资料,亦将对探索川西北乃至四川盆地深层油气勘探新领域、新方向具有重要的启示意义。  相似文献   

钱塘江下切河谷SE4孔晚第四纪沉积环境与古气候演化^*          下载免费PDF全文

夏长发  张霞  林春明  黄舒雅  江凯禧  周学谦 《古地理学报》2022,24(3):433-448

综合钱塘江下切河谷SE4孔岩心观察和描述及粒度、孢粉、测年等分析数据,探讨了钱塘江下切河谷晚第四纪沉积环境和古气候演化,揭示了其气候变化机制下沉积响应的具体过程。研究表明SE4孔晚第四纪沉积物自下而上包括河床亚相、河漫滩亚相、古河口湾相、浅海亚相和现代河口湾相5套沉积。研究区晚第四纪以来古植被和古气候演化分为6个阶段:第一阶段植被类型为阔叶树为主的针阔混交林—草原,气候温和偏湿,沉积了河床和河漫滩亚相;第二阶段为落叶栎稍多的针阔混交林,气候温和湿润,沉积了古河口湾相和浅海亚相;第三阶段为针阔混交林,气候温暖湿润,浅海亚相沉积发育;第四至第六阶段植被类型经历了针阔混交林—草原、针阔混交林、针阔混交林—草原的交替,气候经历了温和偏干、温和偏湿、温和偏干的变化,现代河口湾相沉积发育。  相似文献   

四川盆地震旦系灯影组地层厘定与岩相古地理特征^*          下载免费PDF全文

赵文智  王小芳  王鑫  王坤  沈安江 《古地理学报》2022,24(5):852-870

埃迪卡拉(震旦)系是元古代第2次大氧化事件(NOE)后形成的具有良好生储盖条件的碳酸盐岩沉积组合,已在四川盆地获得原生气藏勘探重大突破,但德阳—安岳台内裂陷及周缘区灯影组划分对比尚不统一,制约了对台缘带丘滩体横向分布特征的认识。基于露头、钻井和地震资料,通过岩石学、电性和地球化学特征分析,开展了灯影组地层层序重新厘定,在此基础上对灯影组岩相古地理进行了重建,取得以下研究成果: (1)建立了宁强胡家坝灯影组典型剖面,明确了灯影组分段岩性组合特征,指出高石131X、中江2、蓬探1井原划分的灯二段应归属灯四段,台缘带灯四段具有三分性,特征明显,并构建了等时地层格架。 (2)明确了等时地层格架内丘滩体迁移规律,即德阳—安岳台内裂陷东段灯四段台缘丘滩体垂直相带展布方向呈由东向西进积、平行相带方向呈由南向北迁移特征,灯四下亚段丘滩体发育于南部的川中古隆起一带,灯四中亚段丘滩体发育于中部太和区块,灯四上亚段丘滩体则发育于北部的宁强区块。(3)根据灯四下、中、上亚段构造-岩相古地理特征,预测了德阳—安岳台内裂陷及周缘灯影组有利储集层展布,对指导天然气勘探具重要意义。川中古隆起、太和区块和宁强区块均位于震旦纪同一台缘带上,南部的川中古隆起已探明安岳万亿立方米大气田,中部的太和区块含气规模达万亿立方米的大气区已初步明朗,北部的宁强区块也具备形成万亿立方米大气区的有利条件。  相似文献   

攀枝花市地质灾害发育规律与防灾减灾对策研究     

马成兵  唐得胜  肖宇月  佘猛  郝雷 《中国地质调查》2022,9(4):37-44

针对四川省攀枝花市典型“干热河谷流域”地质灾害频繁成灾问题,在收集地质灾害资料收集的基础上,统计分析了不同类型地质灾害与地形地貌、岩土体类型等控灾因素的关系,系统分析了攀枝花市地质灾害发育分布规律,揭示了干热河谷区人类活动与地质灾害的密切关系,总结了区内昔格达组特殊易滑地层对区域地质灾害的影响特征。研究成果为区域工程和城镇规划建设过程中科学规避易滑地层等防灾减灾提出合理化建议,为地方政府防灾减灾及城乡建设规划提供参考依据。  相似文献   

Depositional model for lacustrine nearshore subaqueous fans in a rift basin: The Eocene Shahejie Formation,Dongying Sag,Bohai Bay Basin,China     

《Sedimentology》2018,65(6):2117-2148

The origin of the fourth member of the Eocene Shahejie Formation in the northern steep slopes of the Minfeng Sub‐sag, Dongying Sag, China, was investigated by integrating core studies and flume tank depositional simulations. A non‐channelized depositional model is proposed in this paper for nearshore subaqueous fans in steep fault‐controlled slopes of lacustrine rift basins. The deposits of nearshore subaqueous fans along the base of steep border‐fault slopes of rift basins are typically composed of deep‐water coarse‐grained sediment gravity‐flow deposits directly sourced from adjacent footwalls. Sedimentation processes of nearshore subaqueous fans respond to tectonic activities of boundary faults and to seasonal rainfall. During tectonically active stages, subaqueous debris flows triggered by episodic movements of border‐faults dominate the sedimentation. During tectonically quiescent stages, hyperpycnal flows generated by seasonal rainfall‐generated floods, normal discharges of mountain‐derived rivers and deep‐lacustrine suspension sedimentation are commonly present. The results of a series of flume tank depositional simulations show that the sediments deposited by subaqueous debris flows are wedge‐shaped and non‐channelized, whereas the sediments deposited by hyperpycnal flows generated by sporadic floods from seasonal rainfall are characterized by non‐channelized, coarse‐grained lobate depositional bodies which switch laterally because of compensation sedimentation of hyperpycanal flows. The hyperpycnal‐flow‐deposited non‐channelized lobate depositional bodies can be divided into a main body and lateral edges. The main body can be further subdivided into a proximal part, middle part and frontal part. Normal mountain‐derived river‐discharge‐deposited sediments are characterized by thin‐bedded, fine‐grained sandstones and siltstones with a limited distribution range. Normal mountain‐derived river‐discharge‐deposited sediments and deep‐lacustrine mudstones are commonly eroded in the area close to boundary faults. A nearshore subaqueous fan can be divided into three segments: inner fan, middle fan and outer fan. The inner fan is composed of debrites and the proximal part of the main body. The middle fan consists of the middle part of the main body and lateral edges, normal mountain‐derived river‐discharge‐deposited fine‐grained sediments and deep‐lacustrine mudstones. The outer fan comprises the frontal part of the main body, lateral edges, and deep‐lacustrine mudstones. Based on the non‐channelized depositional model for nearshore subaqueous fans, criteria for stratigraphic subdivision and correlation are discussed and applied.  相似文献   

华北克拉通五台地区2.2～2.1Ga花岗岩的成因与构造背景   总被引：6，自引：6，他引：0  

杜利林  杨崇辉  宋会侠  赵磊  路增龙  李伦  王涛  任留东 《岩石学报》2018,34(4):1154-1174

华北克拉通中部造山带内古元古代中期(2.2~2.0Ga)岩浆活动较为广泛,对探讨华北古元古代地质演化过程具有十分重要的意义。本文选择了五台地区古元古代大洼梁、王家会和莲花山花岗岩进行了地球化学、锆石U-Pb年代学和Hf同位素研究。大洼梁似斑状花岗岩SHRIMP锆石U-Pb年龄为2170±17Ma,王家会二长花岗质片麻岩LA-ICPMS锆石U-Pb年龄结果为2101±6Ma,3个莲花山花岗岩的LA-ICPMS锆石U-Pb年龄结果分别为2117±6Ma、2110±4Ma和2143±15Ma。大洼梁花岗岩高SiO_2、富K_2O+Na_2O,低CaO,稀土元素含量较高(Eu除外),Zr、Nb、Ga和Y等高场强元素含量也较高,而Sr含量极低;同时Ga/Al比值和Zr+Nb+Y+Ce总量高,全岩Zr饱和温度高达876～968℃。该花岗岩体具有A型花岗岩的特征。王家会花岗岩和莲花山花岗岩样品也具有高硅、富碱和低镁钙特征,稀土元素具有弱到较强烈的分异,Eu负异常明显。3个花岗岩岩体微量元素都具有较高的Nb和Y值,因此具有后碰撞到板内花岗岩特征。所有花岗岩样品中锆石的εHf(t)值均远低于同期亏损地幔值,同时单阶段和两阶段模式年龄为2.4～2.6Ga和2.45～2.75Ga,明显大于花岗岩的成岩时代。这些花岗岩与五台地区新太古代晚期TTG质片麻岩具有相似的锆石Hf模式年龄。因此,结合岩石学、地球化学和同位素特征,本文倾向于认为古元古代花岗岩为新太古代TTG质片麻岩在伸展条件下部分熔融形成的。综合资料发现,华北克拉通中部带内2.2～2.0Ga岩浆事件不同地区表现有分带性。2.2～2.1Ga岩浆活动代表较早的阶段,其中部分花岗质岩石具有A型花岗岩特征,与同期的基性岩形成双峰式组合,推断其与华北克拉通古元古代中期陆内裂谷有关。  相似文献   

博格达造山带东段芨芨台子地区晚石炭世双峰式火山岩地球化学特征及其地质意义   总被引：2，自引：1，他引：1       下载免费PDF全文

汪晓伟  徐学义  马中平陈隽璐朱小辉孙吉明崔方磊 《中国地质》2015,42(3):553-569

博格达造山带东段芨芨台子地区出露大量晚石炭世早期双峰式火山岩组合,岩石类型以亚碱性玄武岩为主,含有少量的流纹岩,属拉斑系列。其玄武岩富钠贫钾(Na2O/K2O=2.84~3.01),Ti O2含量为1.32%~1.43%,略高于N型大洋中脊玄武岩,高Al(Al2O3含量为19.81%~20.60%)、低Mg(Mg O含量为2.95%~3.25%,Mg#为32.33~34.50),表明其原始岩浆发生过明显的橄榄石和辉石的分离结晶作用。玄武岩具有近于平坦的稀土配分模式,轻微正Eu异常(δEu=1.02~1.10,平均为1.04),富集Rb、Ba、P等大离子亲石元素,亏损Nb、Ta、Th、Sr、Ti等高场强元素的特征;其微量元素Zr/Nb比值41.13~41.38,Zr/Y比值4.26~4.52(均大于4.00),Rb/Sr比值0.02~0.04(均小于0.05),Dy/Yb比值1.92~2.00,La/Nb比值2.42~2.49,Ba/Nb比值113.58~126.05,Ba/La比值47.02~50.62以及火山岩Zr-Nb、La/Yb-Dy/Yb和La/Nb-La/Ba等判别图解,表明玄武岩可能是亏损尖晶石相地幔橄榄岩向石榴石相地幔橄榄岩过渡相较高程度部分熔融的产物,且在其上升过程中受到一定程度的地壳物质混染,显示了板内玄武岩的地球化学特征,形成于陆内裂谷环境。流纹岩具有较高的Si O2(76.54%~77.74%)和全碱(Na2O+K2O=6.70%~7.70%)含量,以及较低的Ti O2(0.15%~0.16%)、Al2O3(10.70%~10.90%)和Mg O(0.17%~0.18%,Mg#为13.93~14.52)含量;显示右倾负斜率稀土配分模式,铕负异常明显(δEu为0.32~0.33),显著富集Rb、Th、U等大离子亲石元素,相对亏损Nb、Ta,强烈亏损Sr、Ti、P等高场强元素,指示流纹岩应来自于玄武岩浆上升过程中提供的热量对地壳物质重熔,源区有斜长石残留。芨芨台子地区双峰式火山岩的地球化学特征表明该套火山岩应形成于大陆裂谷环境,同时获得流纹岩锆石U-Pb年龄为(312±1)Ma,表明该套火山岩形成于晚石炭世早期。进一步的Rb-Sr地壳厚度网络图投影表明当时博格达地区地壳厚度为20.0~30.0 km,而且根据Zr-Zr/Y图解推断其地壳拉张速率介于2.0~5.0 cm/a,表明早石炭世早期开始的博格达初始裂谷在晚石炭世早期进一步快速拉张,发展到鼎盛阶段,也代表着博格达地区由碰撞挤压到伸展拉张这个地球动力学环境的重大转折,这一发现进一步证实了博格达造山带在石炭纪处于大陆裂谷演化的观点,为进一步理解博格达地区晚古生代构造格局及板块构造体制提供了重要的地质依据。  相似文献   

Chronology of Late Pleistocene environmental changes in the lower Mahi basin,western India     

Navin Juyal  Rachna Raj  Deepak M. Maurya  Laxman S. Chamyal  Ashok K. Singhvi 《第四纪科学杂志》2000,15(5):501-508

Sediments exposed in the lower Mahi basin at the southern fringe of the Thar Desert, Rajasthan, India, provide evidence of three distinct depositional environments, namely marine, aeolian and fluvial. These have been used to reconstruct Late Pleistocene environmental and tectonic history of the region. Infrared stimulated luminescence (IRSL) chronology of the fluvial and aeolian litho‐units provides evidence of two major fluvial aggradation phases in the region corresponding to Oxygen Isotopic Stages 5 and 3. The basal marine clay is inferred to represent the last interglacial stage and its present elevation at +20 m a.s.l. is attributed to post‐depositional tectonism. Comparison of fluvial records from other regions indicates interhemispherically documented wetter phases during Oxygen Isotope Stages 5 and 3. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

东亚夏季风区的低频振荡对长江中下游旱涝的影响   总被引：62，自引：19，他引：43  

琚建华  赵尔旭 《热带气象学报》2005,21(2):163-171

利用相关分析与合成分析的方法,讨论了东亚夏季风区的低频振荡及其与我国长江中下游地区旱涝的关系。研究发现,东亚强季风涌年,准30～60d振荡的影响显著,容易造成长江中下游多雨;东亚弱季风涌年,准30-60d振荡减弱,10-20d低频振荡为主要的振荡周期,容易造成长江中下游干旱。研究结果初步揭示了低频振荡对我国长江中下游地区旱涝的影响。研究表明,东亚夏季风中低频振荡传播规律对长江中下游地区降水的中长期预报有重要的指导意义。  相似文献   

ENGINEERING PERSPECTIVE FOR THE SEISMIC SITE RESPONSE OF ALLUVIAL VALLEYS     

M. RASSEM  A. GHOBARAH  A. C. HEIDEBRECHT 《地震工程与结构动力学》1997,26(4):477-493

The seismic site response of alluvial valleys with limited width is evaluated using three engineering models. The models are based on the one-dimensional, two-dimensional and the frame model approaches. The objective is to analyse the effects of the main parameters governing surface motions and provide engineering guidance for predicting them. The limitations on the use of the one-dimensional model in site response evaluation in valleys are pointed out. The frame model, which accounts for the limited width of valley, gives response results that are in good agreement with the two-dimensional model results. It is found that the effect of the two-dimensional amplification is significant over a distance from the valley edges beyond which the response may be adequately represented by one-dimensional analysis. The soil amplification varies depending on the soil type, site location relative to the valley and the dominant period and amplitude of input rock record. © 1997 by John Wiley & Sons, Ltd.  相似文献