The Uplift of the Longmenshan Thrust Belt and Subsidence of the West Sichuan Foreland Basin

Based on fission track dating of apatite, and measurement of vitrinite reflectance of rock samples from the Longmenshan (Longmen Mountain)area and the West Sichuan foreland basin and computer modelling it is concluded that (l)the Songpan-Garze fold belt has uplifted at least by 3-4 km with an uplift rate of no less than 0.3-0.4 mm/a since 10 Ma B.P.; (2) the Longmenshan thrust nappe belt has uplifted at least by 5-6 km with an uplift rate of more than 0.5- 0.6 mm /a since 10 Ma B.P.; (3) the Longmenshan detachment belt has uplifted by 1 - 2 km at a rate of 0.016-0.032 mm/a since 60 Ma B.P.; (4) the West Sichuan foreland basin has uplifted by 1.7-3 km at a rate of 0.028-0.05 mm/a since 60 Ma B.P.; (5) the uplift rate of the area on the west side of the Beichuan-Yingxiu-Xiaoguanzi fault for the last 10 Ma is 40 times as much as that on its east side; (6) the uplifting of the the Songpan - Garze fold belt and the subsidence of the West Sichuan foreland basin 60 Ma ago exhibit a mirro-image correlation, i.e. the rapid uplifting of the the Songpan-Garze fold belt was corresponding to the rapid subsidence of the basin;the Songpan-Garze fold belt has uplifted at a much greater rate than the West Sichuan foeland basin in the last 60 Ma;and (7) the palaeogeothermal gradient was 25℃ /km in the West Sichuan foreland basin.

Thermal Evolution of Plutons and Uplift Process of the Yanshan Orogenic Belt

Abstract: Thermochronological dating was used to study the thermal evolution of the Mesozoic plutons and uplift history of the Yanshan orogenic belt. The results show that the cooling history of the plutons is complicated, corresponding to the inhomogeneous uplift process of the Yanshan orogenic belt. The Panshan granite cooled fast during 226.48–204.95 Ma at a rate of 10.22°C/Ma after its emplacement at a depth of about 10 km, and its fast uplift occurred in about 96–35 Ma at an average rate of 0.115 mm/a. The Wulingshan pluton cooled fast during 132–127.23 Ma at a rate of 94.34°C/Ma, and its rapid uplift occurred in 86–45 Ma at an average rate of 0.186 mm/a. The Yunmengshan granite cooled fast during 143–120.99 Ma at a rate of 19.51°C/Ma, and its rapid uplift occurred in 106–103.95 Ma and 20–0.0 Ma at a rate of 1.06 mm/a and 0.15 mm/a respectively. The Sihetang granite-gneiss uplifted rapidly since 13 Ma at an average rate of 0.256 mm/a. The Badaling granite uplifted rapidly since 6 Ma at an average rate of 0.556 mm/a. The Cenozoic uplift of the Yanshan Mountains can be well correlated to the rifting process of the surrounding basins.

East central Uplift Belt of Junggar Basin

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长江中下游成矿带南陵—宣城矿集区中生代构造—岩浆—成矿特征及其地质意义

安徽南陵—宣城矿集区是长江中下游成矿带中一个新确立的矿集区,近年来找矿勘查工作取得重要进展。笔者等在广泛收集以往区域地质调查以及最新地球物理探测和矿床地质勘查成果的基础上,系统总结了矿集区地质构造、岩浆岩和铜多金属矿床的地质和地球化学特征,探讨了中生代时期区域构造作用与岩浆作用和成矿作用的相互关系。研究认为,南陵—宣城矿集区构造上为一个受深大断裂控制的中生代—新生代陆相凹陷—断陷火山—沉积盆地,盆地之上叠置古生代地层构成的NE向指状展布的复背斜/逆冲推覆体,盆地基底地层组成和构造特征与盆地之上叠置的复背斜/逆冲推覆体基本一致,且两者均发育相同时代和特征的侵入岩及相关铜多金属矿床。南陵—宣城矿集区构造—岩浆—成矿特征总体上与长江中下游成矿带其他地区基本一致,反映自中生代以来受古太平洋板块向欧亚板块之下俯冲作用的控制,经历了强烈的陆内变形改造以及相应的多期次NW—SE向挤压作用和拉张作用。南陵—宣城矿集区构造—岩浆—成矿特征同时又具有其独特性,表现在其地质构造格架、侵入岩和矿床特征与长江中下游成矿带其他火山—沉积盆地明显不同,反映其在区域构造空间以及地壳基底结构和组成上的差异,同时揭示南陵—宣城矿集区是长江中下游成矿带跨构造单元复合系统的典型代表。

青藏高原隆升对中国疆域自然环境的影响:破解“胡焕庸线”的思考

中国疆域广大,人口、土地、耕地和发展程度很不均衡。1935年,知名学者胡焕庸据此提出了著名的“胡焕庸线”。利用这条北东-南西走向直线,将中国大陆划分为东西两个部分。该线的东、西两侧差异悬殊。究其缘由,制约因素多元,而近地表的自然环境和地球内部物质与能量的交换起着重要作用。研究与探索表明:印度次大陆与欧亚大陆两陆-陆板块的碰撞-挤压驱使高原南缘喜马拉雅造山带的突起是根本原因。喜马拉雅造山带的突起阻隔了印度洋南来温湿气流的北进,并形成了西风带,造成了中国西北地域的干旱和荒漠化。在力系作用下,壳、幔物质重新分异、调整,地壳短缩增厚、高原整体抬升不仅导致东、西两部降水量、气温、人口、耕地与生态环境的显著改变,且地球物理场发生了强烈变异与分布不均。西部发展的关键在于水,水进则人进,人进则文化进,文化进则科技进,科技进则发展快,西部人民生活与生存环境不断优化,社会则更安宁。东部不断强化开辟与利用地下空间,西部期盼“红旗河”西部调水工程实施,维护生态环境,兴建亿亩现代化耕地、牧场与绿洲。中国东部与西部共同发展与建设十分重要,饭碗要永远端在自己手中。

塔里木盆地东北缘吐格尔明背斜和阳北断裂带构造分析

吐格尔明背斜和阳北断裂位于塔里木盆地北缘,南天山山前库车褶皱冲断带的东段,两者均为基底卷入型构造。阳北断裂是一个反转构造,其变形历史可以追溯到侏罗纪—白垩纪的正断层;新生代构造反转,发生了多期冲断变形加速期,分别发生于白垩纪末—古近纪初、古近纪末—新近纪初、中新世早期、上新世和第四纪。吐格尔明背斜构造带是阳北断裂中新世早期及以后的冲断作用派生出来的一个次级基底卷入型构造变形带。它由吐格尔明背斜及其南、北两条呈背冲关系的逆冲断层组成。背斜核部元古宇变质岩出露地表;中、新生界直接不整合于变质岩之上,缺失全部古生界,说明研究区可能属于一个长期存在的古生代古隆起。

蚌埠—淮北地区电性结构及地质意义

通过安徽蚌埠—淮北地区开展大地电磁剖面探测,结合重磁异常,获得了该区深部电性结构及主要地层展布和断裂性质的信息,尤其是徐宿弧形构造形态和深部含煤系地层发育情况。结果表明:①上古生界主要分布在徐宿弧形构造地表高阻推覆体之下,具有低阻、低密度的物性特征,连续性较好,认为推覆构造下煤矿勘查潜力大。②剖面上断层早期以逆断层为主,使得局部下古生界及元古宇覆于上古生界之上,后期以正断层为主,控制新生界沉积。③徐宿弧形构造海拔-4 km以浅表现为“高、低”双层电性结构,主冲断层面由F 5、F 6断裂组成;其地表高阻推覆体前缘西北至萧县,南至固镇县北,在闸河地区被广泛剥蚀。上述成果为该区基础地质研究和找矿勘查提供了重要地球物理信息。

渤海湾盆地惠民凹陷中央隆起带张扭性断裂演化的构造物理模拟研究

惠民凹陷位于渤海湾盆地济阳坳陷西部,新生代时期经历了南北向伸展,形成了典型的“北断南超”半地堑结构。平面上,惠民凹陷中央隆起带发育了NE至近EW向的张扭断裂体系;垂向上,中央隆起带断裂体系从深部到浅部呈现出由雁列式分段到逐渐连接贯通的特征。目前对惠民凹陷中央隆起带断裂体系的结构特征有了较好的刻画,但是对于该断裂体系形成的运动学过程及其控制因素仍然停留在描述阶段。文章设计了一组张扭构造物理模拟实验,以探究惠民中央隆起带断裂构造演化过程及其控制因素。实验再现了惠民凹陷中央隆起带断裂体系在平面上由早期孤立分段、侧向传播、最终贯通的三个阶段;在剖面上也很好对应了中央隆起带沿走向由共轭断裂系向阶梯式断裂的结构转变特征。基于粒子成像测速(PIV)的应变分析,文章构建了三阶段的应变—断层距离统计图,揭示了各分段断裂由早期无连接,经历侧向生长,从软连接到硬连接的构造演化过程。研究证实在南北向区域伸展作用下,盆地基底NEE向先存断裂的活化是惠民凹陷中央隆起带张扭构造形成的根本原因。文章利用砂箱构造物理模拟实验揭示了惠民凹陷中央隆起带断裂发育的机制,可为类似的张扭性断陷盆地的断裂演化与油气成藏研究提供有益的启示。

断陷盆地陡坡带新近系目标圈闭优势运移路径与汇聚能力分析:以渤海海域庙西北凸起东侧陡坡带为例

断陷盆地新近系的成藏规模与深层油气汇聚及立体输导体系息息相关,断陷盆地新近系源外目标圈闭油气充注的差异性是新近系目标研究中需要重点关注的问题。以渤海海域庙西北凸起东侧陡坡带为例,分析了陡坡带油气汇聚体系组成要素,通过断层输导能力评价划分了优势充注段,进而在断层充注段控制下开展了油气运移模拟。研究表明:(1)陡坡带汇聚体系由深层聚烃砂体、边界大断层、浅层晚期断层3个部分组成。(2)汇聚体系中3个部分的各自优势汇烃要素相互作用组成主要运移路径,最终体现在与目标圈闭搭接的断层充注段上;庙西北凸起东侧主干运移断层中段为强充注区,北段为中等充注区;次级运移断层中4,6,8号断层发育强充注段,1,2,11号断层发育中等充注段。(3)构造层运移模拟发现庙西北凸起东侧陡坡带中段发育油气聚集区,东侧发育2条主要运移路线,同时南侧发育1条主要运移路线;3号典型砂体发育4个汇聚区,其中汇聚区C为汇聚能力最强区域。研究成果可为目标区井位部署提供参考,技术方法可为油气汇聚成藏分析提供技术支持。

The Geology, Fluid Inclusions, and O-S Isotopes of the Mibei Gold Deposit, Hunan Province, Southern China

The Mibei gold deposit,located in the southwestern part of the Xuefengshan uplift zone,the middle section of the Jiangnan orogenic belt in southern China,has estimated gold resources of approximately seven tons.This deposit is primarily a quartz vein-type gold deposit,with ore bodies occurring mainly within Neoproterozoic metasediments.The main metallic minerals in the ore are pyrite,chalcopyrite,and arsenopyrite.In this study,the petrography and microthermometry of ore-forming fluid inclusions,oxygen isotopes of gold-bearing quartz,and sulfur isotopes of goldbearing sulfides and arsenopyrite were analyzed.Three types of fluid inclusions were identified:type Ⅰa three-phase inclusions comprising vapor and two phases of liquids(V_(CO_(2))+L_(CO_(2))+L_(H2O)),type Ⅰb two-phase liquids(L_(CO_(2))+L_(H2O)),typeⅡ two-phase vapor-rich inclusions(V/V+L> 50%),and type Ⅲ pure liquid inclusions.Type Ⅰ inclusions were heated uniformly to the liquid phase,type Ⅱ inclusions were heated uniformly to the gas phase,and type Ⅲ inclusions were heated without change.In general,the temperature range of homogenization to liquid phase of fluid inclusions in the Mibei gold deposit is 204-227℃.The salinity of the inclusion ranges from 4.6 to 12.2 wt% NaCl equiv.The δ~(18)O_(SMOW) of gold-bearing quartz varies from 16.9‰ to 17.5‰.The δ~(18)O_(H2O) of gold-bearing quartz are varied from 6.5‰ to 7.5‰.The δ~(34)S values of gold-bearing pyrite range from 1.7‰ to 6.8‰.The δ~(34)S values of gold-bearing arsenopy rite range from 5.6%o to 5.9‰.Theδ~(34)S values of pyrite from wall rocks slate range from 6.4‰ to 11.6‰.This evidence implies that the ore-forming fluids of the Mibei gold deposit originated from magmatic-hydrothermal processes,mixing with minor S from the surrounding metasediments.Combined with the evolution of the Jiangnan orogenic belt,due to the magmatic and tectonic activities of the Xuefengshan uplift during the Caledonian period,the fault seal mechanism controlled the ore-forming process.Overall,the Mibei gold deposit is more akin to a magmatic-hydrothermal gold deposit.

渤海湾盆地辽东-渤东凸起构造带地质结构与形成演化

为了明确渤海湾盆地辽东-渤东凸起构造带的形成演化过程与油气的关系,结合研究区最新三维地震数据,详细分析了辽东-渤东凸起构造带的地质结构特征和隆升时间,对比了构造变形特征,确定了隆升时间的差异性,在此基础上建立了辽东-渤东凸起构造带的形成演化模式。研究认为,渤东低凸起受控于伸展断层,辽东凸起受控于早期伸展断层和晚期走滑断层,构造带内除辽东断层以外,各主干断层均在孔店组—沙四段沉积期开始活动,峰值期出现在沙三段和东营组沉积期,馆陶组沉积后断层活动变弱。辽东-渤东凸起构造带从南向北逐渐抬升:渤东低凸起在沙四段沉积末期抬升,辽东凸起南段在沙三段沉积末期抬升,辽东凸起北段在东三段沉积末期抬升。构造演化分为孔店组-沙四段沉积期、沙三段沉积期、沙一二段沉积期、东三段沉积期、东营组沉积末期和现今等6个阶段。构造演化与油气运聚成藏密切相关,辽东-渤东凸起构造带的形成时间早于周缘生烃凹陷主要生、排烃期,有利于油气在凸起带附近聚集。渤东低凸起由伸展断层控制,油气主要在凸起区聚集成藏;辽东凸起由伸展断层与走滑断层共同控制,油气主要在斜坡区聚集成藏。

松南中央隆起带聚热机制及对青山口组地热资源开采影响

通过岩心热物性测试、地热井生产数据分析,结合数值模拟技术对松南中央隆起带青山口组聚热机制、地热井温度恢复规律等方面开展研究,对比不同构造部位、不同埋深的地热储层及生产井的共性与差异,笔者总结了盆地型地热资源聚热机制及其对生产井的影响规律。结果表明:青山口组中部温度在45~165℃之间,凸起部位温度明显高于凹陷部位,温度最大相差达100℃;同时地热井开采模拟显示,持续开采30 a凸起部位较凹陷部位井的流体温度降低更为缓慢,降幅相差约7℃。综合地质结构、断裂系统、构造格局分析,认为凹凸相间的构造格局是松南中央隆起带青山口组储层主要聚热机制,并且在相似条件下,构造凸起部位在地热井开采过程中,温度降低幅度较构造凹陷部位缓慢,可持续开采的时间更久。

Three-Phase Uplift of the Qinghai-Tibet Plateau During the Cenozoic Period: Igneous Petrology Constraints

In northern Qinghai\|Tibet plateau there are developed Cenozoic volcanic rocks. They constitute a trachybasalt\|shoshonite\|latite\|trachydacite assemblage. According to the forming ages, three Cenozoic volcanic rock lithozones can be distinguished in the northern part of the plateau. Cenozoic volcanic rocks and muscovite/two\|mica granites forming the three belts in pairs represent the northern and southern margins of the plateau in different periods. In fact, the tectonic setting of the northern part of the Qinghai\|Tibet plateau is significantly different from that of the southern part—Himalayas. The southern part has experienced subduction and continent\|continent collision. There are developed the Cenozoic S\|type granites (muscovite/two\|mica granites) there. But the northern part is characterized by Cenozoic basaltic magmatism which obviously comes from the upper mantle. Slight doming of the upper mantle is recognized underneath the northern part of the plateau, which is the result of resistance of the Tarim plate to the north direction\|sense movement of the Tibetan plate. And at the same time, the uplift machanism shows that the formation of the Qinghai\|Tibet plateau involved three orogenic stages (35-23 Ma, 23-10 Ma and <2 Ma) of uplift in the vertical direction and extension in the horizontal direction with the Gangdise\|Qiangtang orogenic belt as its core.

THE PATTERN OF GENERAL ATMOSPHERIC CIRCULATION IN EASTERN ASIA BEFORE THE UPLIFT OF THE TIBETAN PLATEAU

The global climatic change study is a hot point today.As the pattern of the general circulation of the atmosphere is the key factor for climate,the reconstruction of the pattern of the past general circulation of the atmosphere has become important part of the global climatic change study.The paleowind belts are the comprising part of the past general circulation of the atmosphere and also the records of the circulation,therefore,their reconstruction will be helpful to the reconstruction of the general circulation of the atmosphere.In present years,the pattern of the general circulation of the atmosphere has attracted great concern from scientists.For example,Zhang Linyuan and Liu Dongsheng, based on the existence and inexistence of the Tibetan Plateau and paleogeography,divide the evolution of the general circulation of the atmosphere in eastern asia into two stages:the planetary wind stage before the uplift of the plateau and the monsoon stage after the uplift of the plateau which is subdivided into ancient monsoon and modern monsoon stages.While Dong Guangrong et al., Jiang Xinsheng et al. and Cooke et al, based on the latitudinal distribution of the Cretaceous and Tertiary deserts and the generation of arid climate,suggest that there was a subtropical high pressure zone across the eastern asia and was a planetary wind system,but have not found any direct record of the circulation.It is true that before the Early Tertiary,not only organism, but also inorganism,i.e.,biogeography and lithogeography, show strong zonal distribution.It can only indicate that zonal climate was evident at that time.Of course, as the climate is the result of the influences on the ground by zones of the circulation,it is reasonable to deduce the existence of zonal circulation,i.e. the the existence of the planetary wind system,from the zonal climate.But it would be much better if direct record of planetary wind system were found.Prevailing winds are the main geological agent for a desert which must leave deep stamps on the desert.The stamps on modern desert are reflected by dune migrating directions and on paleodesert by foreset dip directions..It is the most direct geological record for reconstructing paleowind belts and has been extensively used to reconstruct paleowind belts,paleogeography,paleoclimate and even to check the paleolatitude determined by paleomagnetism (for example, Opdyke and Runcorn, 1960; Creer, 1958; Pook, 1962; Bigarella and Salamuni,1961).

Evolution of Mesozoic Volcanic Basins and Red Basins in the Gan-Hang Tectonic-Volcanic Metallogenic Belt

This paper mainly proposes six major regional geological events in the active continental-margin mantle uplift zone and discusses the oscillation nature of the evolution of Mesozoic volcanic basins and red basins, origin of erosion in the late stage of red basins and mechanism of volcanism.

Silurian hydrocarbon exploration breakthrough and its implications in the Shajingzi structural belt of Tarim Basin,NW China

The Silurian hydrocarbon exploration in the northwest Tarim Basin had long been fruitless, till Well XSD1 drilled in 2018 in the Shajingzi structural belt, northwest Tarim Basin tapped industrial gas flow from the Silurian for the first time. The reservoir-forming model and resource extent need to be made clear urgently. Based on the comprehensive research of drilling,formation testing, geochemical data, and sedimentary and accumulation history, in combination with field surveys, experiments, structure interpretation and reconstruction of structure evolution, it is found that:(1) The northwest Tarim Basin had widespread tidal deltaic deposits in the Silurian period, which contain good reservoir-cap combinations;(2) the Shajingzi fault and associated faults connected the Cambrian-Ordovician source rocks in the Awati sag, and controlled the formation of Silurian structural traps, hence, the traps turned up along the structural belt in an orderly pattern and came together into contiguous tracts;(3) the Silurian petroleum in Shajingzi structural belt was dominated by gas, and the major accumulation period was the Himalayan period when the traps fixed in shape;(4) the Silurian gas resources in the Shajingzi belt were estimated at around 2.018×10^(11)m^(3), and Silurian gas resources of the northwest Tarim Basin were estimated at 2.03×10^(12)m^(3), implying huge exploration potential, so this area will become a major area for reserve and production increase from clastic strata in the basin;(5) with the Shajingzi fault of large scale and long active time connecting deep source rock layers, multiple formations in Lower Paleozoic of Shajingzi structural belt may have breakthroughs in hydrocarbon exploration.

Tectonic Evolution of the Himalayan Collision Belt

This paper discusses the tectonic divisions of the Himalayan collision belt anddeals with the tectonic evolution of the collision belt in the context of crustal accretion in thefront of the collision belt, deep diapirism and thermal-uplift extension and deep material flow-ing of the lithosphere-backflowing. Finally it proposes a model of the tectonic evolution-progressive intracontinental deformation model-of the Himalayan belt.

松辽盆地北部古中央隆起带基底岩石弹性参数测试及特征分析

古中央隆起带基底上覆地层缺失断陷期沉积地层,基岩暴露地表时间长,风化壳普遍发育。基底岩性复杂,主要发育花岗岩、浅变质沉积岩及浅变质火山岩3大类岩石;基底主要发育花岗岩、变质岩储层,不同类型储层的裂缝发育程度不同。钻井揭示:花岗岩的脆性大,易形成裂缝,花岗岩储层物性最好,属于孔隙—裂缝型储层;基底花岗岩风化壳储层非均质性强,储层物性较差,以裂缝为主。目前有关基底花岗岩和变质岩的岩石物理弹性参数特征的实验室研究较少。为此,采用超声频段和地震频段弹性参数测试方法,系统分析了围压及孔隙压力对岩石纵、横波速度的影响,研究了不同孔隙度和饱和状态下岩石弹性参数与微裂缝密度及孔隙纵横比的关系;应用弹性参数交会分析,明确了基底风化壳储层及裂缝敏感参数,建立了符合基底孔隙—裂缝型储层特征的岩石物理模型,获得以下成果和认识:(1)对松辽盆地北部古中央隆起带基底33块岩性样品,采用超声频段和地震频段实验测试,测得的标准铝块的超声频段纵波速度(6430 m/s)与参考值(6400 m/s)基本相同,相对误差为0.5%,精度较高。(2)随着围压增加,在水饱和和气饱和状态下纵、横波速度均增大,且横波速度变化不大。随着孔压增加,在水饱和和气饱和状态下纵、横波速度均呈降低趋势,且在气饱和状态下纵波速度的变化量大于水饱和状态,在水饱和和气饱和状态下横波速度的下降趋势相似。(3)不同压力的超声频段和地震频段速度差异表明微裂隙是影响频散绝对变化量的主要因素,随着压力增加,微裂隙逐渐闭合,孔隙间的流体流动效应减弱,喷射效应降低。(4)地震频段和超声频段储层敏感参数优选结果相同,即v_(P)/v_(S)(纵横波速度比)、ν(泊松比)、λ(拉梅系数)、λ/μ(拉梅系数/剪切模量)、λ_(ρ)(拉梅系数×密度)等参数对流体最敏感,可作为识别基底风化壳的储层敏感参数。(5)在裂缝密度为3条/m、裂缝倾角为50°的条件下建立了饱和度—孔隙度解释图板,在含水饱和度为50%、裂缝倾角为50°的条件下建立了裂缝密度—孔隙度解释图板,为风化壳孔隙—裂缝型储层预测奠定了理论基础。

川东高陡构造带震旦系灯影组丘滩相气藏预测

在川东高陡构造带内,构造复杂、地震资料差,寻找震旦系灯影组油气富集带具有重大挑战。为此,运用构造形迹分析构造期次,环状构造结合地震相特征预测藻丘滩;丘滩相特征结合构造形迹期次分析WT1井失利原因;综合丘滩相与构造的叠合关系以预测开江地区灯影组油气富集带。结果表明:①开江地区的NE构造主体为川东高陡构造带在燕山中晚期挤压形成,喜山期强烈改造定型。②EW向低幅度构造为大巴山于晚燕山期弱挤压形成。③SN向构造形成于喜马拉雅晚期,动力来自龙门山南段挤压。④燕山中晚期的NE构造与裂解气富集晚期匹配。发育大量的环状构造,为藻丘滩刚性地质体形成,为古岩性圈闭,与原油成藏期匹配。⑤环状构造+NE向构造是油气富集带。综合构造形迹与地震相预测了多个油气目标:七里南背斜内的七3环是最有利目标,藻丘滩地震相最为明显,且叠加NE向构造;铁1环是现实的目标;里1环是潜在的目标区。环状构造在开江地区大量存在,具有较好的油气勘探远景。

渤海湾盆地中部428构造带近S-N向走滑断裂的形成时期及其在中生代期间的调节转换作用

渤海湾盆地中部428构造带自印支期以来经历了多期次构造运动叠加改造过程,区域内发育了大量的近S-N向与近EW向褶皱、断层构造,并控制了潜山的形成。然而目前对428构造带的研究仅局限于探索区域内潜山构造成因及其油气圈闭特性,对区域内的断裂系统,尤其是发育的大量近S-N向断裂的形成时期及其后期演化过程中所起到的调控作用尚不明确。鉴于此,为明确其形成时期、探索其对区域构造格局演化模式所产生的影响,基于前人的研究成果,以石臼坨凸起东侧428构造带为主要研究对象,通过对该区域典型的地震剖面进行精确解析,对其展开了系统性的研究。研究结果表明:(1) 428构造带与石臼坨凸起东侧连接处存在一条近S-N向走滑断裂;(2)该走滑断裂的形成最早可追溯至印支期。根据古生界褶皱和薄底构造的分布特征可知,该走滑断裂最初为近E-W向逆冲推覆断裂的侧向断坡;(3)近S-N向走滑断裂阻挡了燕山期NWW向的逆冲推覆作用,从而控制古生界和中生界大量协调褶皱的发育。而近E-W向断裂表现为压扭性质,控制了中生界雁列式褶皱的形成。基于以上认识,认为该近S-N向走滑断裂在印支-燕山期均起到了重要的调控作用,是一个重要的调节转换带。