红河活动断裂带在南海西北部的反映

红河断裂带是一条走滑的活动断裂带，它控制着南海西北部的构造活动，也控制着莺歌海盆地的形成和演化。根据南海西北部中穿过莺歌海盆地的地震剖面和历史资料进行解释，结果表明，莺歌海盆地的形成可分3个阶段：自50MaB．P．开始，沿红河断裂带的左旋错动和在印支地块的顺时针旋转的应力作用下，形成了莺歌海盆地的雏形；24MaB．P．之后在左旋压扭应力场作用下，形成了盆地西北部的反转构造；5MaB．P．之后发生了右旋错动，盆地内快速沉降，发育巨厚沉积层。根据盆地内最老和最新的沉积中心之间的距离，推测沿红河断裂带的左旋位错约200km。该断裂带发展到现代，其活动性大为减弱，曾发生10次小于5级地震。     

莺歌海盆地反转构造变形特征及其动力学演化

莺歌海盆地位于印支半岛与南海北部大陆边缘交接区,复杂的地质构造背景使其形成演化的动力学机制成为国内外研究的焦点。综合新的区域资料,对影响莺歌海盆地发育的区域构造演化特征进行了系统分析,认为新生代以来印度板块与欧亚板块的碰撞造成印支板块的逃逸构造,以及印支板块的顺时针旋转,红河断裂带新生代的变形机制,直接或间接地控制了莺歌海盆地的形成与演化。在此背景条件下,莺歌海盆地新生代以来的构造演化经历了3个阶段,即左旋走滑-伸展裂陷阶段、地壳韧性伸展-热沉降阶段和加速沉降阶段。     

红河断裂带的新生代变形机制及莺歌海盆地的实验证据

红河断裂带是印藏碰撞过程中，印支地块被顺时针旋转挤出的走滑变形带。莺歌海盆地发育于红河断裂带海上延伸带上。根据莺歌海盆地和相邻的NE向琼东南盆地在晚中新世前(5．5Ma B．P．)独立的构造发育和差异的沉降特点，认为红河断裂不可能穿越莺琼盆地界限向北东延伸，而越东断裂和中建南断裂很可能是红河断裂的延续。莺歌海盆地成盆机制的物理模拟结合红河断裂带陆上的变形特征、年代学证据与青藏高原隆升过程的研究，参考莺歌海盆地模拟过程中不同应力场下沉降中心的长轴方向，我们推断红河断裂带新生代的演化大致分4个阶段：(1)50-38Ma B．P．期间的缓慢平移运动；(2)38—25MaB．P．期间的快速左行走滑运动；(3)25—5Ma B．P．期间的左行走滑逐渐停止阶段；(4)5Ma B．P．后的右行走滑阶段。     

南海北部莺歌海盆地成因机制:与渭河盆地构造对比分析的启示

南海北部莺歌海盆地为新生代沉积盆地,地处欧亚板块、太平洋板块和印度-澳大利亚板块交汇处,构造位置独特,复杂的地质构造现象使其形成演化的动力学机制成为国内外研究的热点。同一类型盆地具有相似的构造、沉降、沉积演化历史与成因机制。莺歌海盆地与渭河盆地均位于多板块交汇处,存在长期相对快速沉积、沉降及构造演化迁移等典型走滑型盆地特征。在明确渭河盆地成因机制的基础上,对比两盆地构造、沉降及沉积演化历史,结合莺歌海盆地特殊的构造位置及南海扩张的构造背景,分析得出:莺歌海盆地形成演化和印度-澳大利亚板块与青藏板块碰撞、印支板块逃逸及自身旋转、华南板块向东挤出及太平洋板块俯冲关系密切,受多板块构造活动影响较大,新生代以来先后依次经历左旋走滑、伸展—热沉降—右旋走滑、伸展三大成盆演化期。另外,与渭河盆地相比,莺歌海盆地发育有高温、高压及泥底辟等特殊地质现象,主要受控于热沉降阶段,与渐新世以来(33~15Ma)南海扩张事件具有重要关系。     

莺歌海盆地形成与演化的动力学机制

莺歌海盆地位于印支半岛与南海北部大陆边缘交接区,复杂的地质构造背景使其形成演化的动力学机制成为国内外的研究焦点。从区域动力学演化的角度,系统分析了影响莺歌海盆地发育的印支地块构造演化特征,认为莺歌海盆地构造演化主要受印支半岛早期的逃逸挤出构造和晚期的挤压-伸展构造系统影响(或控制),在此动力学驱动机制下,莺歌海盆地新生代以来的构造演化经历了3个阶段,即左旋走滑-伸展裂陷阶段、中下地壳韧性伸展-热沉降阶段和加速沉降阶段。     

印度-欧亚板块碰撞期间红河断裂带活动性的数值模拟研究

红河断裂带是一巨型走滑断裂带,在印度板块与欧亚板块碰撞过程中成为印支地块和华南地块之间相互运动的主位移带。通过有限差分数值模拟试验,结果表明,在碰撞期间,红河断裂带首先经历了左旋走滑运动,红河断裂带中央部分的左旋偏移量最大,达到约325km,印支地块向南东挤出,在5Ma BP后表现为右旋走滑,说明沿红河断裂带的剪切运动是红河断裂带西端与印度-欧亚碰撞边界之间距离的函数,随时间而减小并控制了印支地块与华南地块之间的相对运动。     

莺-琼盆地基底控制断裂样式的模拟探讨

莺歌海盆地与琼东南盆地(即莺一琼盆地)是南海西北部2个重要的含油气盆地。莺歌海盆地走向NW,发育在红河断裂带上;琼东南盆地走向NE,与莺歌海盆地近直角相交。根据物理模拟实验,认为莺歌海盆地的演化受到了NW与近S-N向基底断裂的控制,在印支地块顺时针挤出应力场下发育和演化;而琼东南盆地则受到NE向基底断裂的控制,在SSE向伸展应力场控制下发育,NW与NE向构造带相互影响,造成了琼东南盆地北侧边界断裂走向近E—W,向南呈台阶式下掉,南侧边界断裂走向NE,莺琼过渡区隆凹格局复杂。由于莺歌海盆地NW向构造活动早于琼东南盆地NE向裂陷作用,从而导致NW向构造控制地位的形成,NW向断裂和构造表现为对NE向断裂和构造的阻截。     

莺歌海盆地构造演化动力学机制探讨

莺歌海盆地是在印支地块与华南地块缝合线上发展起来的新生代沉积盆地,其奇特的地质现象与复杂的动力学背景是国内外学者研究的热点。关于其形成机制,目前主要有四种观点:"中国东部裂陷式"观点、"左旋走滑"观点、"右旋走滑"观点、"先左旋后右旋"观点。通过对该盆地区域地质背景、盆地构造几何学、运动学及沉积学综合分析,认为莺歌海盆地形成演化受印-藏碰撞、太平洋板块俯冲以及地幔上涌的影响,主要经历了古新世—早渐新世左旋拉分、晚渐新世—中新世热沉降、上新世—第四纪右旋拉分三个阶段。     

莺歌海盆地新构造运动与超压体系喷溢油气成藏作用

莺歌海盆地是在岩石圈伸展减薄和红河断裂带南段的右旋扭动联合作用下形成的一个以伸展为主的转换—伸展盆地。受该应力场作用,盆地新构造运动活跃,主要表现包括中新统末、上新统与第四纪之间及层系内部的不整合,盆地的沉降,沉积中心的迁移,断裂活动,底辟带的发育与分布,泥火山和地震等。新构造运动不但控制了盆地的形成演化、沉降—沉积中心的迁移和底辟构造带发育以及它们的雁行排列特征,同时还控制了盆地油气的成藏和分布。莺歌海盆地是一个强超压盆地,新构造时期断裂的多期活动及其控制的多期底辟活动不但形成超压体系(包括油气)快速垂向运移的通道,同时决定了莺歌海超压盆地油气田的快速幕式充注成藏规律。成熟的烃类以溶解状态储存在超压体系中,当超压体系孔隙流体压力大于封闭盖层破坏压力时封闭盖层就产生水压破裂,超压体系便沿着活动断裂和底辟带等通道发生喷溢活动,油气向上或侧向往过渡带和常压带运移聚集成藏,随着压力的下降,断裂重新闭合形成新的封闭层。这一喷溢过程以幕式活动形式周而复始,在超压盆地的过渡带和常压带中形成大的油气藏。     

华北板块东部中生代构造变形与盆地格局

华北板块东部印支和燕山期构造演化差异、盆地分布格局变迁及其空间叠合关系是中国东部构造变化的结果。中生代期间，郯庐断裂带应对应依兰—舒兰断裂带，它们与兰考—聊城—盐山—台安—大洼—敦化—密山断裂带呈共轭关系。两断裂带将华北板块东部分割为多个三角块体，三角块体的构造演化与陆内壳下拆沉和壳内挤出逃逸构造有关，并控制了华北东部燕山期高原隆升及岩石圈减薄、郯庐左行走滑机制及其两侧反对称盆地格局和挤压与伸展型盆地共存的现象。     

Structural differences between the western and eastern Qiongdongnan Basin: evidence of Indochina block extrusion and South China Sea seafloor spreading

Located at the intersection between a NW-trending slip system and NE-trending rift system in the northern South China Sea, the Qiongdongnan Basin provides key clues for us to understand the proposed extrusion of the Indochina Block along with Red River Fault Zone and extensional margins. In this paper we for the first time systematically reveal the striking structural differences between the western and eastern sector of the Qiongdongnan Basin. Influenced by the NW-trending slip faults, the western Qiongdongnan Basin developed E–W-trending faults, and was subsequently inverted at 30–21 Ma. The eastern sector was dominated by faults with NE orientation before 30 Ma, and thereafter with various orientations from NE, to EW and NW during the period 30–21 Ma; rifting display composite symmetric graben instead of the composite half graben or asymmetric graben in the west. The deep and thermal structures in turn are invoked to account for such deformation differences. The lithosphere of the eastern Qiongdongnan Basin is very hot and thinned because of mantle upwelling and heating, composite symmetric grabens formed and the faults varied with the basal plate boundary. However, the Southern and Northern Uplift area and middle of the central depression is located on normal lithosphere and formed half grabens or simple grabens. The lithosphere in the western sector is transitional from very hot to normal. Eventually, the Paleogene tectonic development of the Qiongdongnan Basin may be summarized into three stages with dominating influences, the retreat of the West Pacific subduction zone (44–36 Ma), slow Indochina block extrusion together with slab-pull of the Proto-South China Sea (36–30 Ma), rapid Indochina block extrusion together with the South China Sea seafloor spreading (30–21 Ma).     

华南沿海B／M界线附近的群发地质事件

在距今0.7Ma的B/M古地磁极性界线附近,华南沿海发生了一系列地质事件,其中包括火山喷发、断裂、褶皱、不整合、侵蚀、玻璃陨石撒落及气候突变事件。这种突发性的事件群是受地球星体运动统一控制的,并具有某种周期性,可与中国北方和其他大陆对比。文中提出了新灾变论的观点。     

The flexural margin,the foredeep,and the orogenic margin of a northern Cordilleran foreland basin: Cretaceous tectonostratigraphy and detrital zircon provenance,northwestern Canada

Reconstructions of the Albian to Campanian foreland basin adjacent to the northern Canadian Cordillera are based on outcrop and well log correlations, seismic interpretation, and reconnaissance-level detrital zircon analysis. The succession is subdivided into two tectonostratigraphic units. First is an Albian tectonostratigraphic unit that was deposited on the flexural margin of a foreland basin. At the base is a shallow marine sandstone interval that was deposited during transgressive reworking of sediment from cratonic sources east of the basin that resulted in a dominant 2000–1800 Ma detrital zircon age fraction. Subsequent deposition in a west-facing muddy ramp setting was followed by east-to-west shoreface progradation into the basin.Near the Albian–Cenomanian boundary, regional uplift and exhumation resulted in an angular unconformity at the base of the Cenomanian–Campanian tectonostratigraphic unit. Renewed subsidence in the Cenomanian resulted in deposition of organic-rich, radioactive, black mudstone of the Slater River Formation in a foredeep setting. Cenomanian–Turonian time saw west-to-east progradation of a shoreface-shelf system from the orogenic margin of the foreland basin over the foredeep deposits. Detrital zircon age peaks of approximately 1300 Ma, 1000 Ma, and 400 Ma from a Turonian sample are consistent with recycling of Mississippian and older strata from the Cordillera west of the study area, and show that the orogen-attached depositional system delivered sediment from the orogen to the foreland basin. A near syndepositional detrital zircon age of ca. 93 Ma overlaps with known granitoid ages from the Cordillera. After the shelf system prograded across the study area, subsequent pulses of subsidence and uplift resulted in dramatic thickness variations across an older structural belt, the Keele Tectonic Zone, from the Turonian to the Campanian.The succession of depositional systems in the study area from flexural margin to foredeep to orogenic margin is attributed to coupled foreland propagation of the front of the Cordilleran orogen and the foreland basin. Propagation of crustal thickening and deformation toward the foreland is a typical feature of orogens and so the distal to proximal evolution of the foreland basin should also be considered as typical.     

中国大陆阶梯地貌的基本特征

本文通过中国大陆山顶面高程等值线图和大河河床高程等值线图来研究和讨论中国大陆阶梯地貌的基本特征。大致沿大兴安岭—太行山—雪峰山和昆仑山—阿尔金山—祁连山—龙门山—玉龙山—喜马拉雅山存在两条明显的山顶面高程等值线和大河河床高程等值线梯度带。它们是重要的构造地貌界线,将我国大陆分成三级由西向东逐级降低的地貌阶块。中国大陆阶梯地貌于晚期喜马拉雅运动中初具雏形。在新构造运动中,特别是发生于1.4—1.2MaB.P.的构造运动以来,使其得到进一步加强和发展。现今中国的地貌格局,主要是近100万年期间新构造运动造成的。     

Structural evolution of the Orange Basin gravity-driven system,offshore Namibia

The Orange Basin records the development of the Late Jurassic to present day volcanic-rifted passive margin of Namibia. Regional extension is recorded by a Late Jurassic to Lower Cretaceous Syn-rift Megasequence, which is separated from a Cretaceous to present day post-rift Megasequence by the Late Hauterivian (ca. 130 Ma) break-up unconformity. The Late Cretaceous Post-rift evolution of the basin is characterized by episodic gravitational collapse of the margin. Gravitational collapse is recorded as a series of shale-detached gravity slide systems, consisting of an up-dip extensional domain that is linked to a down-dip zone of contraction domain along a thin basal detachment of Turonian age. The extensional domain is characterized by basinward-dipping listric faults that sole into the basal detachment. The contractional domain consists of landward-dipping listric faults and strongly asymmetric basinward-verging thrust-related folds. Growth stratal patterns suggest that the gravitational collapse of the margin was short-lived, spanning from the Coniacian (ca. 90 Ma) to the Santonian (ca. 83 Ma). Structural restorations of the main gravity-driven system show a lack of balance between up-dip extension (24 km) and down-dip shortening (16 km). Gravity sliding in the Namibian margin is interpreted to have occurred as a series of episodic short-lived gravity sliding between the Cenomanian (ca. 100 Ma) and the Campanian (ca. 80 Ma). Gravity sliding and spreading are interpreted to be the result of episodic cratonic uplift combined with differential thermal subsidence. Sliding may have also been favoured by the presence of an efficient detachment layer in Turonian source rocks.     

南海及其周缘地区全新世海平面遗迹的构造含义

通过对海南岛海岸带野外考察,在文昌市铜鼓岭石头公园观察到高程为30m的海平面遗迹,在东方市黄流镇观察到高程为25~35m的海平面遗迹,在三亚市鹿回头观察到高程为2.5m的海平面遗迹。综合研究前人在该区关于海平面变化的研究成果,得出如下几点初步认识:(1)南海及其周缘地区中全新世以来海平面呈下降趋势,海平面最高位置出现在7000a左右、高于现代海平面3m左右的位置;(2)南海中全新世以来海平面遗迹所揭示的古海平面高程的差异性是古海平面本身持续下降和该区地壳差异性垂直运动共同作用的结果;(3)南海及其周缘地区中全新世期间中央海盆及其西缘的珠江口、红河、湄公河和昭披耶河4个河流三角洲地区为构造沉降区,而南海周缘的台湾岛、雷州半岛、印支半岛、南马来半岛、爪哇岛和苏拉威西岛6个地区为构造抬升区,抬升幅度最大的地方在台湾岛。