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1.
松辽盆地变质核杂岩和伸展断陷的构造特征及成因 总被引：18，自引：3，他引：15
文中讨论了松辽盆地北部中央基底隆起变质核杂岩和徐家围子伸展断陷的构造特征、成因和演化 ,重点讨论了下列问题 :( 1)中央基底隆起变质核杂岩具有科迪勒拉变质核杂岩的许多特征 ;( 2 )识别出组成中央基底隆起变质核杂岩的多层次、低角度韧性拆离体系 ,它们是使中地壳的中深变质岩层抽拉至上地壳的主要原因 ;( 3)穹窿状火山岩台地于晚侏罗世 ( 145.7±6.2 )Ma形成 ,受顶部拆离断层控制的伸展断陷于早白垩世 ( 133～ 12 0Ma)形成 ,而邻近顶部拆离断层的糜棱岩年龄为 ( 12 6.7± 1.54)Ma。这表明变质核杂岩的形成始于晚侏罗世。早白垩世递进的伸展构造与变质核杂岩较深部的部分上拱至地表相伴生 ,推测该变质核杂岩的上拱和剥露、火山岩台地和伸展断陷盆地的形成可能是由伊泽奈奇和亚洲板块陆陆碰撞后的地幔拆沉作用、地幔的岩浆底侵作用以及伸展垮塌作用联合造成的。 相似文献
2.
滇黔桂地区晚古生代浅水碳酸盐岩台地与深水硅泥质盆地共存的古地理格局,是在加里东期褶皱基底上发生裂陷及差异沉降而发展起来的。广西宜州—柳州一带既是晚古生代上扬子碳酸盐岩地台南缘1条重要的沉积相分界线,也是晚古生代桂中和桂北地层分区、古生代—中生代雪峰山南段构造体系和桂中坳陷构造体系的分界线。文中通过对宜山—柳州一带晚古生代地层的区域对比和成因分析,恢复了桂中宜山—柳州地区晚古生代沉积盆地的演化历史。狭长型宜州裂陷槽盆地西起丹池断裂,向东经龙头、北牙、宜州延伸至柳州。自中泥盆世开始,首先在东西两端开始裂陷下沉,至早石炭世发展成型。受北侧来自江南隆起带陆源碎屑物质充填影响,其表现为南北不对称并在早石炭世晚期被填平。在宜州裂陷槽内发育多处早石炭世沉积型碳酸锰矿,含矿地层分布、地层序列及其沉积背景明显与裂陷槽演化有关。它们既是盆地演化历史的见证,也体现了桂中地区裂陷海槽的特色,值得在后续锰矿成因研究中予以重视。 相似文献
3.
Evolution of Yizhou aulacogen in Guangxi during Late Paleozoic and distribution of manganese deposits in Early Carboniferous 
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下载免费PDF全文 The palaeogeographic configuration of the shallow water carbonate platform and deep water siliceous basin formed in the Yunnan-Guizhou-Guangxi region during the Late Paleozoic,which developed on the rifting of fold basement and differential subsidence during the Caledonian period. Yizhou-Liuzhou in Guangxi is an important sedimentary boundary in the southern Upper Yangtze carbonate platform. It is also the stratigraphic boundary of Late Paleozoic between middle and northern Guangxi,and it is the tectonic boundary between the southern Xuefengshan and central Guangxi depression during Paleozoic and Mesozoic. In this paper,the evolution of sedimentary basin located at Yishan-Liuzhou region during the Late Paleozoic is reconstructed through the regional stratigraphic correlation and genetic analysis.The elongate Yizhou rifting belt develops from the Nandan-Hechi fault from the west,and extends along Longtou,Beiya,Yizhou,and to Liuzhou. The rifting started at the eastern and western ends of the narrow rifting belt during the Middle Devonian and it developed into the rifting basin during the Early Carboniferous. Due to massive terrestrial siliciclastic filling derived from the Jiangnan Uplift to north,the rifting basin presented the asymmetrical feature and it was eventually filled up at late Early Carboniferous. Many magnesium deposits of Early Carboniferous are found in the rifting basin of Yizhou. The distribution of ore-bearing strata,the depositional succession and sedimentary environment are obviously related with the evolution of rifting basin. They are the evidences of basin evolution,implying the characteristics of rifting aulacogen in central Guangxi,which should be paid more attention in the manganese ore genesis study. 相似文献
4.
William R. Page Floyd Gray Alexander Iriondo Daniel Miggins Robert B. Blodgett Florian Maldonado Robert J. Miller 《Journal of South American Earth Sciences》2010,29(3):557-571
Geologic mapping in the northern Sierra Los Ajos reveals new stratigraphic and structural data relevant to deciphering the Mesozoic–Cenozoic tectonic evolution of the range. The northern Sierra Los Ajos is cored by Proterozoic, Cambrian, Devonian, Mississippian, and Pennsylvanian strata, equivalent respectively to the Pinal Schist, Bolsa Quartzite and Abrigo Limestone, Martin Formation, Escabrosa Limestone, and Horquilla Limestone. The Proterozoic–Paleozoic sequence is mantled by Upper Cretaceous rocks partly equivalent to the Fort Crittenden and Salero Formations in Arizona, and the Cabullona Group in Sonora, Mexico.Absence of the Upper Jurassic–Lower Cretaceous Bisbee Group below the Upper Cretaceous rocks and above the Proterozoic–Paleozoic rocks indicates that the Sierra Los Ajos was part of the Cananea high, a topographic highland during the Late Jurassic and Early Cretaceous. Deposition of Upper Cretaceous rocks directly on Paleozoic and Proterozoic rocks indicates that the Sierra Los Ajos area had subsided as part of the Laramide Cabullona basin during Late Cretaceous time. Basal beds of the Upper Cretaceous sequence are clast-supported conglomerate composed locally of basement (Paleozoic) clasts. The conglomerate represents erosion of Paleozoic basement in the Sierra Los Ajos area coincident with development of the Cabullona basin.The present-day Sierra Los Ajos reaches elevations of greater than 2600 m, and was uplifted during Tertiary basin-and-range extension. Upper Cretaceous rocks are exposed at higher elevations in the northern Sierra Los Ajos and represent an uplifted part of the inverted Cabullona basin. Tertiary uplift of the Sierra Los Ajos was largely accommodated by vertical movement along the north-to-northwest-striking Sierra Los Ajos fault zone flanking the west side of the range. This fault zone structurally controls the configuration of the headwaters of the San Pedro River basin, an important bi-national water resource in the US-Mexico border region. 相似文献
5.
The Cotiella Nappe includes one of the most important Mesozoic basins of the southern Pyrenees, which was subsequently inverted during the Tertiary compression. The Late Cretaceous Cotiella Basin is here interpreted as the western sector of the Cretaceous Cotiella-Bóixols basin (100 km wide), located in the central part of the southern Pyrenees. The present-day complex structure of the Cotiella Nappe is the result of the inversion process, linked to the emplacement of basement thrust sheets of the Axial zone. In its western sector, the Cotiella Nappe consists of several superimposed thrust sheets, with complex geometry, becoming simpler towards the east, with a single thrust surface and smaller displacements. The Cotiella-Bóixols basin underwent strong subsidence during the Early Cretaceous at its eastern sector, and its depocentre migrated westward during the Late Cretaceous. The reconstruction of the sedimentary basin to the pre-compressional stage shows that during the Mesozoic the Cotiella-Bóixols basin was located to the south of a basement high, which later became the Pyrenean Axial Zone. From a balanced cross section, it can be inferred that the Cotiella, north-verging extensional system was connected with the north-Pyrenean rift by means of a 10-km deep horizontal detachment. The compressional Tertiary detachment within the upper crust was shallower than the extensional detachment, and individualised four basement thrust sheets, which form the Axial Zone antiform. 相似文献
6.
青藏高原东北缘酒泉盆地的演化特征与宽台山-黑山断裂的性质 总被引：7，自引：0，他引：7
宽台山-黑山断裂位于酒泉盆地的北侧，向西与阿尔金走滑断裂相交，其北部为花海-金塔盆地。对酒泉地区白垩纪沉积盆地的研究和对比发现，虽然当时盆地多为断陷盆地，均受东西向伸展构造控制，但宽台山-黑山断裂两侧的盆地具有不同的基底性质和沉积岩石学特征。酒泉盆地、昌马盆地和北祁连褶皱带内的白垩系具有相同的早古生代褶皱基底，并发育有热水喷流沉积和玄武岩夹层，北祁连北缘断裂在白垩纪时尚未开始活动；花海-金塔盆地为前长城系深变质基底，盆地内不发育热水喷流沉积。宽台山-黑山断裂是青藏高原东北缘重要的岩石圈剪切断裂，控制了其南北两侧白垩纪盆地的沉积-构造演化。 相似文献
7.
华北克拉通东部早白垩世伸展盆地的发育过程及其对克拉通的破坏 总被引：1，自引：0，他引：1
在晚侏罗世华北克拉通东部破坏之初出现了区域性隆起,全区缺失上侏罗统沉积。在早白垩世早期,出现了区域性的伸展活动,断陷盆地形成,克拉通南、北缘伸展活动最强,北部燕山构造带以出现变质核杂岩为特征,南部出现宽裂谷型盆地。早白垩世中期华北克拉通东部普遍出现了火山活动与岩浆侵入。早白垩世晚期克拉通上以出现窄裂谷型盆地为特征,沿北北东走向的郯庐断裂带断陷活动最强。这些断陷盆地的演化过程揭示,经历地表抬升后,克拉通破坏之初的岩石圈热而弱,从而形成变质核杂岩或宽裂谷型盆地。这期间的破坏强度在空间上具有不均匀分布的特征,受控于早期岩石圈地幔的结构。经过早白垩世中期的大量岩浆活动之后,早白垩世晚期克拉通岩石圈温度降低、强度变大,从而利用早期大型断裂构造形成窄裂谷型盆地。这现象支持华北克拉通东部晚中生代的岩石圈减薄是以逐渐拆沉机制为主。 相似文献
8.
黑龙江东部中-新生代盆地演化 总被引：9，自引：2，他引：7
黑龙江省东部中-新生代盆地基底由佳木斯地块和完达山地体复合而成.佳木斯地块以加里东期变质岩及花岗岩为主,东缘发育晚古生代和早中生代大陆边缘沉积.完达山地体在中-晚侏罗世就位在佳木斯地块东缘,并在早白垩世早期逆冲到佳木斯地块之上,形成具有前陆盆地性质的大三江盆地.大三江盆地在早白垩世晚期遭受逆冲、走滑构造改造.敦密断裂以北的诸多盆地均属大三江盆地改造后的残余盆地.这些残余盆地和完达山地体之下可能存在隐伏的晚古生代和早中生代大陆边缘沉积.三江盆地东部是古近纪断陷的主要发育区,可能存在一与佳依地堑平行的深断陷.隐伏的大陆边缘沉积和断陷是值得重视的油气勘探领域. 相似文献
9.
山东鲁西地块断裂构造分布型式与中生代沉积—岩浆—构造演化序列 总被引：7，自引：0，他引：7
鲁西地块的断裂构造有两类不同分布型式:一类呈放射状分布, 由陡倾、基底右行韧性剪切带和盖层内复杂力学性质的断裂组成; 另一类呈环绕地块基底核部同心环状分布, 由3个主要盖层伸展拆离带组成, 主滑脱面分别位于古生界盖层与基底间的不整合面、石炭系与奥陶系之间的平行不整合面和中新生代断陷-沉积岩系与新生代火山-沉积物之间的断层。中生代构造变形样式可以分为3个层次:印支期褶皱-逆冲推覆构造、燕山中期NNE轴向的隔槽式箱状褶皱和燕山晚期NW、NNE向共轭正断-走滑断裂。相应地鲁西地块经历了3个成盆期, 即早-中侏罗世、早白垩世和晚白垩世, 这些中生代盆地在空间上的叠置导致了地块内部复杂的盆-山耦合关系。鲁西地块中生代有两个岩浆活动集中时期, 即早侏罗世(约190Ma)和早白垩世(132~110Ma)。综合沉积记录、岩浆活动和构造变形过程, 将鲁西地块中生代构造演化历史划分为6个阶段:晚三叠世挤压变形, 早、中侏罗世弱伸展作用, 中、晚侏罗世挤压变形与地壳增厚作用, 早白垩世大陆裂谷与地壳伸展作用, 早白垩世末期挤压变形与盆地反转事件和晚白垩世区域隆升。这些构造演化阶段和构造事件对研究和理解中生代构造体制和深部岩石圈动力学转换过程具有重要意义。 相似文献
10.
The inversion of the Middle Proterozoic Belt sedimentary basin during Late Cretaceous thrusting in Montana produced a large eastwardly-convex salient, the southern boundary of which is a 200 km-long oblique to lateral ramp subtended by a detachment between the Belt rocks and Archean basement. A 10 km-long lateral ramp segment exposes the upper levels of the detachment where hanging wall Belt rocks have moved out over the Paleozoic and Mesozoic section. The hanging wall structure consists of a train of high amplitude, faulted, asymmetrical detachment folds. Initial west-east shortening produced layer parallel shortening fabrics and dominantly strike slip faulting followed by symmetrical detachment folding. “Lock-up” of movement on the detachment surface produced regional simple shear and caused the detachment folds to become asymmetrical and faulted. Folding of the detachment surface after lock-up modified the easternmost detachment folds further into a southeast-verging, overturned fold pair with a ramp-related fault along the base of the stretched mutual limb. 相似文献
11.
通过详细的野外观测结合地质填图资料,在聂荣变质杂岩及邻区厘定大规模逆冲推覆构造,不同时代的逆冲岩席自北—北东向南—南西逆冲推覆于上白垩统红层及下伏岩石地层之上,形成大量逆冲断层、滑脱构造、飞来峰、构造窗和褶皱构造。逆冲推覆构造运动导致侏罗纪蛇绿混杂岩、石炭系—二叠系构造层、古生界浅变质岩、变质基底之间发生拆离滑脱,在聂荣变质杂岩内部形成韧性剪切带和高角度斜冲断层。在唐古拉山口南侧形成北西—南东向土门-托纠-杂色右旋走滑断裂,走滑断裂末端转换为近东西向逆冲推覆构造。聂荣变质杂岩顶部逆冲推覆叠加滑覆,导致侏罗系混杂堆积和古生界沉积盖层向南西—西向运移86~110km,在那曲-巴尔达-班戈北形成近东西向长透镜状懂错蛇绿混杂岩逆冲岩席,沿缓倾斜断层发育向西倾斜的构造片理、摩擦镜面和近东西走向的矿物线理。裂变径迹测年表明,聂荣变质杂岩及邻区逆冲推覆及构造隆升时代主要为早白垩世晚期—晚白垩世早期(111±5~91±5Ma)、晚白垩世晚期(89±6~69±5Ma)、古新世晚期—始新世早期(55±4~44±2Ma),估算构造隆升视速率为0.10~0.69mm/a,部分断层逆冲推覆及构造隆升延续至古近纪晚期。综合各类观测资料,建立不同时期构造模式,探讨聂荣变质杂岩及邻区逆冲推覆构造演化过程及形成机理。 相似文献
12.
This paper presents the results of high-resolution reflection seismic surveys carried out between 1989 and 1996 along rivers and canals in northern Belgium. The seismic data penetrate down to 900 m in the sedimentary cover or to the Paleozoic basement. The reflection response of the acoustic basement provides clear indications with regard to the top of the Paleozoic: crystalline basement and Lower Paleozoic metasediments and volcanics of the London-Brabant Massif and NE-dipping Devonian and Carboniferous strata. The subhorizontal Mesozoic and Cenozoic sedimentary cover comprises 20 unconformity-bound seismic units: 5 in the Cretaceous and 15 in the Cenozoic. Based on borehole information, these units are correlated with lithostratigraphically defined formations or groups. Some of the unit-bounding unconformities are of regional importance. They are attributed i) to eustatic sea-level changes causing regional flooding during the Late Cretaceous or incision of deep valleys during the Late Oligocene and Late Miocene, ii) to regional tectonic tilting between Late Eocene and Early Oligocene, or iii) to a combination of eustasy and tectonics causing valley incisions during the Lutetian. Faults of the Roer Valley Graben have offset different stratigraphic levels by sometimes considerable amounts (up to 230 m in the Oligocene to Quaternary succession). Although the main tectonic phase took place during the Miocene, the activity has varied considerably through time, and also from fault to fault. Most faults seem to have a 10 to 30-m displacement since the Late Pliocene. 相似文献
13.
胶莱盆地及其邻区白垩纪－古新世沉积构造演化历史及其区域动力学意义 总被引：15，自引：2，他引：13
基于野外和钻孔测井资料分析、火山岩同位素年代学分析 (40Ar-39Ar and SHRIMP U-Pb)、地震剖面的构造解释、断层运动学的野外分析结果,综合研究了胶莱盆地及其邻区白垩纪－古新世沉积构造演化历史。岩性地层分析表明,胶莱断陷盆地由三套地层单元所充填：早白垩世莱阳群和青山群、晚白垩世－古新世王氏群。青山群火山岩的同位素年代学测试结果给出了该火山岩的喷发时代在120～105 Ma。地震剖面的构造解译结果揭示胶莱盆地伸展构造受到深部两个拆离构造系统控制：一个发育于盆地南部地区,拆离断面位于深部8~10 km,向南缓倾于苏鲁造山带之下;另一个拆离系统由一系列北倾的犁式断层组成、分布于宽阔的胶莱盆地北部地区,主拆离面向北倾。这两个拆离系统分别形成于早白垩世莱阳群和晚白垩世-古新世王氏群沉积阶段。通过对不同地层单元断层滑动矢量的野外测量和古构造应力场反演,以及地层时代和同位素年代学测试结果的制约,建立了白垩纪－古新世构造应力场演替的年代序列。结果表明,胶莱盆地在白垩纪-古新世之间经历了伸展－挤压应力体制的交替演化。早白垩世伸展作用经历了两个不同的阶段：早期NW-SE向伸展和晚期近W-E向伸展。在早白垩世末期至晚白垩世初期,盆地遭受NW-SE向挤压,导致了胶莱盆地的缩短变形和郯庐断裂带的左旋走滑活动。晚白垩世－古新世时期,构造应力场转变为N-S向伸展,直到古新世末期,构造应力场转换为NE－SW向挤压。胶莱盆地和沂沭裂谷系白垩纪－古新世沉积构造演化历史对华北地区岩石圈减薄过程的动力学背景提供了重要的构造地质学制约。笔者推断,早白垩世两期引张应力作用是分别对华北地区增厚地壳或岩石圈的重力垮塌和岩石圈拆沉的响应,而早白垩世末期NW-SE向挤压记录了古太平洋板块与亚洲陆缘俯冲碰撞产生的远程效应。晚白垩世-古新世的引张伸展作用完全不同于早白垩世伸展构造,它指示了沿NNE向郯庐断裂带的右旋走滑活动及其拉分作用,在动力学上受到青藏地区块体的陆－陆碰撞产生的远程效应和古太平洋板块向亚洲大陆俯冲作用的联合应力场控制。 相似文献
14.
Stratigraphic reconstruction of the Strzelecki Group outcrops in west Gippsland: new data on the present-day thickness and amount of erosion 总被引：1，自引：0，他引：1
The Lower Cretaceous Strzelecki Group forms the basement to the eastern part of the Gippsland Basin, but is exposed in the west and forms spectacular outcrops, especially along the coastal area between San Remo and Inverloch. The coastal area is highly faulted and lacks stratigraphic markers so matching sections in different fault blocks based only on lithology has not been possible. A combination of mapping, detailed logging, vitrinite reflectance measurements and palynology were used to determine the present-day thickness of the coastal sections and the amount of erosion that occurred during the Late Cretaceous. A total thickness of about 1500 m is inferred between Harmers Haven and Inverloch but because of the amount of faulting and probable repeated sections, the true thickness of Strzelecki Group exposed in the coastal outcrops is only about 300 m. Based on palynology and vitrinite reflectance results, the reconstructed Strzelecki Group stratigraphy has been subdivided into three distinct ‘bio-blocks’, with an eroded section estimated to range from 1.5 km (0.3–2.6 km at ±95% confidence limits) to 2.7 km (2.2–3.1 km at ±95% confidence limits). 相似文献
15.
广东梅县地区位于政和—大埔断裂南段之莲花山断裂带中。通过开展1:5万野外地质调查及室内研究表明,广东梅县地区存在晚中生代伸展构造体系,该体系主要由剥离断层和2个不同层次的剥离层组成,结合火山岩、侵入岩、沉积地层接触关系及高精度测年数据,讨论了该体系的形成时限,认为其形成和主导作用时期在晚侏罗世—早白垩世早期(160 ~135 Ma),最大伸展期在145 Ma左右; 前人认为莲花山断裂为早古生代俯冲带,但研究表明,其构造属性为晚侏罗世形成的剥离断层。因此,政和—大埔断裂一带很可能也存在晚中生代的伸展构造体系,说明华南主要构造形迹奠定于中生代,这为华南主要热液金属矿床区域成矿规律研究提供了新的参考模型。 相似文献
16.
辽西医巫闾山地区瓦子峪变质核杂岩的厘定 总被引：9，自引：0，他引：9
以前未被发现的辽西医巫闾山地区瓦子峪变质核杂岩主要由一条向西倾的低角度正断层———瓦子峪拆离断层组成 ,它将由早白垩世沉积岩和火山岩组成的上盘与糜棱岩化和未变形的下盘分开。瓦子峪拆离断层 (以前称之为孙家湾—稍户营子断裂 )位于变质核杂岩的西侧 ,倾角 10～ 4 0°,构造标志指示向北西方向 (约 2 90°)剪切。与早白垩世地壳伸展相伴生的下盘糜棱岩剪切方向也是北西向 ,这与瓦子峪拆离断层运动相关。已经发表的和未发表的锆石U Pb年龄、40 Ar/3 9Ar热年代学和上盘阜新盆地中生物地层的时代研究表明 ,地壳伸展和变质核杂岩形成时代为早白垩世 (约 12 7～ 116Ma)。我们未发现以前文献报道的医巫闾山是一对称的变质核杂岩的任何证据。瓦子峪变质核杂岩以及WNW侧的拆离断层的厘定会加深我们对华北克拉通早白垩世伸展作用的理解和认识 ,下一步的研究重点包括野外构造研究以确定拆离断层和下盘糜棱岩的空间展布 ,进一步采集样品以研究变质核杂岩的地质 /热年代学和变质核杂岩范围内的岩体成因。我们认为瓦子峪变质核杂岩的形成是太平洋板块边界重组、早白垩世岩浆作用致使地壳升温 ,从而导致经造山作用而加厚的地壳垮塌的结果。 相似文献
17.
林寺山组是胶莱盆地莱阳群底部重要的地层单元之一.准确限定其沉积时代与物源性质对于客观重建华北陆块东部晚中生代大地构造格局以及周缘造山带/前寒武纪变质基底晚中生代的折返过程具有重要的制约作用.以莱阳盆地蛇窝泊地区莱阳群林寺山组细砾岩为研究对象,对其开展了野外地质调查、岩相学观察、锆石U-Pb测年与锆石稀土元素分析等综合研究,并获得了如下初步认识.（1）林寺山组细砾岩中最小一组碎屑锆石加权平均年龄分别为129±1 Ma与127±5 Ma,结合区域上不整合于莱阳群之上青山群火山岩锆石谐和年龄为119±1 Ma,推测蛇窝泊地区林寺山组沉积时代介于127~119 Ma.（2）蛇窝泊地区林寺山组细砾岩的碎屑锆石年龄变化于2 858~126 Ma之间,并以新太古代晚期与白垩纪早期碎屑锆石为主.前古元古代的碎屑锆石主要来源于胶北前寒武纪变质岩,表明胶北太古宙-古元古代变质岩至少在白垩纪早期已折返至近地表.（3）160~120 Ma岩浆型碎屑锆石主要来源于胶东同时代的中酸性侵入体,暗示在白垩纪早期至少部分160~120 Ma中酸性侵入体已抬升至地表.（4）林寺山组发育少量的二叠纪（280 Ma）和印支期（213 Ma）变质锆石,表明胶东地区可能存在二叠纪约280 Ma区域变质-变形事件,同时暗示早白垩世苏鲁超高压变质岩已经折返到地表. 相似文献
18.
大兴安岭北部上古生界极低级变质温度——来自碳质物拉曼光谱的证据 总被引：3，自引：0，他引：3
使用Renishaw System-1000型激光拉曼光谱仪, 研究了大兴安岭北部上古生界泥质岩石碳质物的拉曼光谱特征及其对形成温度的表征, 探讨了拉曼光谱参数与镜质体反射率(Ro)的关系。研究表明:研究区上古生界泥质岩石碳质物不具有石墨的拉曼光谱谱带吸收峰, 揭示了地层的变质程度未达到低绿片岩相。利用此次经过完善建立的拉曼光谱地质温度计, 对大兴安岭北部上古生界泥质岩石变质温度的估算结果主要为270~320℃, 表明研究区上古生界遭受了极低级变质作用, 变质程度属近变质带。依据碳质物拉曼光谱参数与镜质体反射率的相互关系, 估算研究区有机质成熟度的Ro值主要分布为3.03%~4.23%, 与实测Ro值吻合, 表明有机质演化处于过成熟阶段, 泥质岩石具有生烃的能力, 部分层位可能具有形成油气资源的潜力。 相似文献
19.
中国南方中生代经历了中国大陆最终主体拼合的陆缘及其之后的陆内构造演化。晚古生代末期,在秦岭—大别山微板块与扬子板块之间存在向西张口的洋盆,即勉略古洋盆。中三叠世末期开始,扬子板块相对于华北板块发生自南东向北西的斜向俯冲碰撞作用,扬子北缘晚三叠世至中侏罗世发育陆缘前陆褶皱逆冲带与前陆盆地系统。晚侏罗世至早白垩世,中国东部的大地构造背景发生了重要的构造转变,中、上扬子地区处于三面围限会聚的大地构造背景。在这种大地构造格局下,中、上扬子地区晚侏罗世至早白垩世发育陆内联合、复合构造与具前渊沉降的克拉通内盆地系统。自中侏罗世末期开始,扬子北缘前陆带与雪峰山—幕阜山褶皱逆冲带经历了自东向西的会聚变形过程及盆地的自东向西的迁移过程和收缩过程。扬子北缘相对华北板块的斜向俯冲导致在中扬子北缘的深俯冲及超高压变质岩的形成。俯冲之后以郯庐断裂—襄广断裂围限的大别山超高压变质地块在晚侏罗世向南强逆冲,致使扬子北缘晚三叠世至中侏罗世前陆盆地被掩覆和改造。 相似文献