渤海湾盆地中北部沉降史分析及裂后期异常沉降分离

为了探究渤海湾盆地新生代沉降过程与西太平洋板块俯冲过程的对应关系,作者收集整理27口钻孔和1条地震地质 剖面数据,并运用回剥技术和应变速率反演方法,模拟出渤海湾盆地中北部裂陷期地壳应变速率变化,分离出裂后期异常 沉降。模拟获得裂陷期地壳应变速率曲线具有明显的三次大的波动,可指示三次构造沉降事件：裂陷Ⅰ幕（60~42 Ma）,对 应于渤海湾盆地孔店组-沙四段沉积过程,平均构造沉降速率为4.6 m/Ma;裂陷Ⅱ幕（42~36 Ma）,对应沙三段-沙二段沉 积过程,平均构造沉降速率为5.5~30.5 m/Ma;裂陷Ⅲ幕（36~24.6 Ma）,对应于沙一段-东营组沉积过程,平均构造沉降速 率为14.7~54.7 m/Ma。研究区内裂后期观测构造沉降与模拟的理论值存在明显的差异,即存在异常沉降。盆地北部异常沉 降值在100~200 m,中部渤海海域异常沉降值在500~700 m,裂后期异常沉降向海域增大。作者推测渤海湾盆地裂后异常沉 降主要是太平洋板块俯冲诱发的深部地幔物质流动导致向下拖拽力引起的。因此,渤海湾盆地中异常沉降可能是一种动力 沉降。     

珠江口盆地构造演化旋回及其新生代沉积环境变迁

目前对珠江口盆地中生代以来的演化过程及其与沉积环境演变的响应关系尚缺乏系统性认识.基于珠江口盆地中-新生代岩浆活动、断陷结构样式及其改造、典型构造变形样式、沉积中心的转换等特征的对比分析,将盆地中-新生代的构造演化划分为4个阶段、7个期次：（1）中侏罗世-晚白垩世早期（～170～90 Ma）为古太平洋板块俯冲主控的陆缘岩浆弧-弧前盆地演化阶段;（2）晚白垩世-始新世中期（～90～43 Ma）为太平洋板块俯冲后撤背景下弧后周缘前陆/造山后塌陷-主动裂谷演化阶段;（3）始新世中期-中中新世（～43～10 Ma）为华南挤出-古南海俯冲拖曳主导的被动陆缘演化阶段;（4）晚中新世以来（～10～0 Ma）为菲律宾板块NWW向仰冲主导的挤压张扭演化阶段.～90 Ma、～43 Ma、～10 Ma分别实现了由安第斯型俯冲向西太平洋型俯冲、由主动裂谷向被动陆缘伸展、由被动陆缘伸展向挤压张扭的转换.在此过程中,伴随着古南海和南海的发育-消亡,新生代裂陷期沉积环境由东向西、由南向北逐渐海侵,裂后期由南向北阶段性差异沉降,由陆架浅水向陆坡深水转换,这使得珠一/三、珠二、珠四坳陷的石油地质条件具有显著的分带差异性...     

珠江口盆地裂后阶段性差异沉降及其成因机制*

位于南海北部陆缘的珠江口盆地裂后沉降特征不同于陆内典型断陷盆地。研究表明,盆地裂后期发生了阶段性有序差异沉降,可分为4个阶段: (1)渐新世早期(~33.9~27.2 Ma),以盆地整体缓慢沉降,大规模海侵为主要特征;(2)渐新世晚期(~27.2~23.0 Ma),以邻近西北次海盆的珠四坳陷强烈沉降为主要特征,差异沉降控制了陆架坡折带的发育和该时期陆架浅水和陆坡深水沉积环境的分布;(3)中新世早—中期(~23.0~10.0 Ma),陆缘强烈沉降区向北扩展至珠二坳陷,尤其是白云凹陷,导致陆架坡折带向北跃迁,并奠定了现今陆架浅水和陆坡深水的沉积格局;(4)中新世晚期—现今(~10.0~0 Ma),陆缘构造沉降逐渐减弱,陆坡由沉积区转变为沉积过路区,沉积物得以大量进入西北次海盆。渐新世2期快速沉降的初始时间,分别对应于南海扩张脊的跃迁,陆缘裂后沉降随扩张脊向南跃迁而向北扩展,并伴有岩浆作用的早强晚弱特点,而沉降量的大小则与裂陷期地壳的薄化程度正相关,反映了陆缘岩石圈经历了早期挠曲回弹的均衡调整和扩张脊跃迁导致地幔物质有序向南撤离而沉降的演化过程。珠江口盆地裂后有序差异沉降控制了陆架坡折带的发育,进而控制了浅水与深水两大沉积体系的展布。     

Tectonic Evolution of the Wanan Basin,Southwestern South China Sea

Quantitative studies on the extension and subsidence of the Wanan Basin were carried out based on available seismic and borehole data together with regional geological data.Using balanced cross-section and backstripping techniques,we reconstructed the stratigraphic deposition and tectonic evolution histories of the basin.The basin formed from the Eocene and was generally in an extensional/transtensional state except for the Late Miocene local compressoin.The major basin extension ocurred in the Oligocene and Early Miocene(before ~16.3 Ma) and thereafter uniform stretch in a smaller rate.The northern and middle basin extended intensely earlier during 38.6–23.3 Ma,while the southern basin was mainly stretched during 23.3–16.3 Ma.The basin formation and development are related to alternating sinistral to dextral strike-slip motions along the Wanan Fault Zone.The dominant dynamics may be caused by the seafloor spreading of the South China Sea and the its peripheral plate interaction.The basin tectonic evolution is divided into five phases:initial rifting,main rifting,rift-drift transition,structural inversion,and thermal subsidence.     

中国大陆东部晚中生代构造活化及其演化过程

与中生代中期造山型构造活化不同．晚中生代期间,中国大陆东部的构造活化表现为规模宏大的断陷盆地系、变质核杂岩、花岗岩浆侵位、火山岩喷发以及沿大型走滑断层的转换伸展为特征的大陆裂陷作用。根据岩浆活动、盆地的充填记录,构造格架和盆地的沉降史分析,可以将裂陷作用划分为两个大的阶段,即由兴安岭群火山喷发为代表的第一阶段和以巴彦花群含煤、油碎屑岩系为代表的断陷盆地形成阶段。盆地沉降史回剥研究表明,裂陷作用第二阶段断陷盆地的发育受控于次一级的幕式构造作用过程。此外．对晚中生代裂陷作用的动力学背景的探讨需要阐明岩石圈的深部过程和构造应力场的反转这个两个重要的问题。     

黑龙江省三江盆地绥滨坳陷沉降史分析

三江盆地绥滨坳陷现有4口钻井的一维正、反演构造沉降模拟结果表明,绥滨坳陷显示出张裂盆地的特征,表现为120Ma之前张裂阶段和之后的裂后热沉降阶段。张裂阶段沉降速率大约为80.37m/Ma,沉降量达1300m,拉张因子大约为1.16。热沉降阶段的沉降速率降到了6.6m/Ma,沉降量也只有200m左右。     

Sequence Thickness and its Response to Episodic Tectonic Evolution in Paleogene Qikou Sag,Bohaiwan Basin

The sequence stratigraphy framework of Paleogene of Qikou Sag has been built in this paper. The evolution law of episodic subsidence in Qikou Sag has been expounded, with the analysis of the characteristic of sequence thickness, as well as the study of consedimental tectonic activity, subsidence history, paleogeomorphology and the coupling relationship among them. The faults controlling action was the dominant mechanism during rifting stage I , as the depression was the dominant mechanism during rifting stage III, which embodies a process from intense disparity fault depression to integral subsidence. Meanwhile, under the control of regional faulting and later stage depression, subsidence rate centers and paleogeomorphic concave centers are always corresponding to the sequence thickness centers, and the changes of subsidence centers and paleogeomorphology concave centers are consistent with the migration of thickness centers, which presents the restriction, coupling and response among them and clarifies the law that tectonic activity controls the basin fill by means of controlling the subsidence rate and paleogeomorphology from contributing factor angle. On this basis, the dynamic evolution of the composite pattern of structure-subsidence-deposition in the fault controlling actic region during the three rifting stages and their petroleum geological significance has been discussed.     

南海礼乐滩碳酸盐台地的发育及其新生代构造响应

为了探索碳酸盐台地在海盆演化过程中的作用,对南海南部礼乐滩区域碳酸盐台地的发育及其与新生代构造沉降特征的相关性进行研究.对多道地震数据的分析表明:在研究区广泛发育包括碳酸盐台地和生物礁在内的碳酸盐沉积,其发育时间主要集中在晚渐新世至早中新世期间,在中中新世后开始退积和淹没.通过对穿越礼乐滩区的两条NW-SE向测线NH973-2和DPS93-2的构造沉降反演,进行沉降量、沉降速率计算和构造分析.结果表明:沉降速率及沉降量随不同时期的构造活动而发生变化,可分为缓慢沉降期(古新世-早渐新世,张裂阶段)、隆升剥蚀期(晚渐新世-早中新世,漂移阶段)、加速沉降期(早中新世末期,后漂移阶段1)、强烈沉降期(中新世,后漂移阶段2)和稳定沉降期(晚中新世至今,后漂移阶段3)5个发育期.碳酸盐台地的发育期和南海海盆的漂移阶段相对应,构造沉降的分析表明该期间具有构造抬升作用,其与相对上升的海平面结合有利于碳酸盐沉积的发育.在南海扩张期间主地幔对流的控制下,南部陆缘区礼乐地块和礼乐滩盆地之间较大的地壳厚度差异会导致侧向上地温梯度的差异,从而形成礼乐滩盆地之下的次生对流.该次生对流控制了研究区在晚渐新世至早中新世期间的隆升剥蚀作用.      

Regional sandstone-type uranium mineralization rooted in Oligo–Miocene tectonic inversion in the Songliao Basin,NE China

The tectonic inversion of the Songliao Basin during the Oligo–Miocene may have played an important role in controlling the development of sandstone-type uranium deposits (SUDs). Here we investigate drill holes along a southeast to northwest section in this basin based on apatite fission-track (AFT) and zircon fission-track (ZFT) techniques. We present 50 data from 15 deep boreholes at different depths between 665 and 3956 m and different structural units including grabens and horsts formed in the Early Cretaceous beneath the basin. The results of the effective AFT ages are 100 ± 11 to 2.3 ± 0.4 Ma (P(x²) > 5%) and ZFT ages are 97.5–20.4 Ma (including binomial peak ages). These results reveal that the basin underwent two distinct stages of rapid cooling after Late Cretaceous. In the first stage, during the Late Cretaceous–Early Paleogene (~80–50 Ma), tectonic uplift occurred in all of the structural units including grabens and horsts, which was marked by an unconformity between the latest Cretaceous Mingshui and the Eocene Yi'an formations. In the second stage, during the Oligo–Miocene (~40–10 Ma), tectonic uplift occurred mainly in the grabens but not in the horsts, corresponding with a few sediments of the Neogene Da'an and Taikang formations. We propose that the folds and the thrust faults mostly characterize in the second stage indicating a major tectonic inversion in the basin. The shifting of the two stages was probably in response to differences in the subduction angles and directions of motion of the Paleo-Pacific Plate from the southeast. Combined with previous information, it was demonstrated that most of the U mineralization ages are younger than 40 Ma, with a peak in the Miocene or later (<20 Ma). We thus propose that the SUDs have been redistributed and redeposited locally in successive stages during and after the Oligo–Miocene tectonic inversion.     

桂北-桂东加里东期盆地构造沉降史分析

对造山带各地史阶段的沉积盆地进行构造沉降分析,进而探讨其地球动力学过程,是近年来盆地分析的前缘研究之一。本文采用回剥分析技术,分别编绘了桂北、桂东地区加里东期盆地沉降曲线,并进行了构造沉降史分析。结果表明,桂北、桂东加里东期盆地演化均经历了从拉张裂解到挤压闭合的完整过程。但与桂东大瑶山地区相比,桂北兴安地区在裂陷阶段的沉积速率和构造沉降速率明显偏低;热沉降阶段的持续时间偏长;裂陷阶段与前陆挠曲阶段的分界拐点偏晚;前陆挠曲阶段,由构造宁静期的缓慢沉降向构造活动期的快速沉降转化的分界拐点也偏晚。这些差别这一方面说明了两地区具有不同的构造背景,另一方面也反映了华夏板块由南东逐渐地向北西扬子板块靠拢,沉积盆地相应地向西北迁移的动力学过程。     

珠江口盆地深水区晚中新世以来构造沉降与似海底反射（BSR）分布的关系*

2007年中国在南海北部神狐海域通过钻探首次获得天然气水合物样品,证实了珠江口盆地深水区是水合物富集区。通过对珠江口盆地深水区构造沉降史的定量模拟研究,发现晚中新世以来区内构造沉降总体上具有由北向南、自西向东逐渐变快的演化趋势;从晚中新世到更新世,盆地深水区经历了构造沉降作用由弱到强的变化过程：晚中新世(11.6～5.3 Ma),平均构造沉降速率为67 m/Ma;上新世(5.3～1.8 Ma),平均构造沉降速率为68 m/Ma;至更新世(1.8～0 Ma),平均构造沉降速率为73 m/Ma。而造成这些变化的主因是发生在中中新世末-晚中新世末的东沙运动和发生在上新世-更新世早期的台湾运动。东沙运动（10～5 Ma）使盆地在升降过程中发生块断升降,隆起剥蚀,自东向西运动强度和构造变形逐渐减弱,使得盆地深水区持续稳定沉降;台湾运动（3 Ma）彻底改变了盆地深水区的构造格局,因重力均衡调整盆地深水区继续沉降,越往南沉降越大。将似海底反射（BSR）发育区与沉降速率平面图进行叠合分析,发现80％以上的BSR分布趋于构造沉降速率值主要在75～125 m/Ma之间、沉降速率变化迅速的隆坳接合带区域。     

Subsidence Analysis and Burial History of the Late Carboniferous to Early Jurassic Soutpansberg Basin, Limpopo Province, South Africa

The subsidence history of the Soutpansberg Basin was reconstructed by a tectonic subsidence analysis coupled with backstripping calculations based on data of newly interpreted sequence boundaries. Furthermore,burial and time plots were constructed in order to understand the burial and thermal history of the basin. Input data were based on facies,lithostratigraphic models and tectonic interpretations. The studied succession is up to 1000 m and is underlain by the Achaean Limpopo Mobile Belt. The subsidence within the basin supports the primary graben system which must have been centred within the present basins,and later became a region of faulting. The subsidence and burial history curves suggests two phases of rapid subsidence during the Early-Late Permian(300–230 Ma) and Middle Triassic(215–230 Ma). The areas of greater extension subsided more rapidly during these intervals. Two slow subsidence phases are observed during the Late Triassic(215–198 Ma) and Early Jurassic(198–100 Ma). These intervals represent the post-rift thermal subsidence and are interpreted as slow flexural subsidence. Based on these observations on the subsidence curves,it is possible to infer that the first stage of positive inflexion(300 Ma) is therefore recognised as the first stage of the Soutpansberg Basin formation.     

The Relationship between Tectonic Subsidence and BSR of Upper Neogene in the Deep-Water Area of the Northern Continental Slope, South China Sea

BSR (Bottom Simulating Reflector) occurs widely in the strata since the late Miocene in the deep-water area of the northern continental slope of South China Sea (SCS). It is an important seismic reference mark which identifies the gas hydrate and its distribution influenced by the tectonic movements. Single-point basin modeling was conducted using 473 points in the study area. To discuss the relationships between the tectonic subsidence and BSR, the volume and rate of tectonic subsidence in each geological time have been simulated. The results show that there are three tectonic accelerate subsidence processes in the study area since the late Miocene, especially since 1.8Ma the tectonic subsidence accelerates more apparently. Since the Late Miocene to Pleistocene, the rate of tectonic subsidence in deep-water underwent a transformation from weak to strong. The ratio of tectonic subsidence to the total subsidence was relatively high (65-70%). Through the superposition of the BSR developed areas and the contours of tectonic subsidence in this area, it was discovered that more than 80% of BSR tend to be distributed at the slope break or depression-uplift structural transfer zone and the average tectonic subsidence rate ranges from 70 m/Ma to 125 m/Ma.     

Tectono-thermal evolution of the Reed Bank Basin,Southern South China Sea

The Reed Bank Basin in the southern margin of the South China Sea is considered to be a Cenozoic rifted basin. Tectono-thermal history is widely thought to be important to understand tectonics as well as oil and gas potential of basin. In order to investigate the Cenozoic tectono-thermal history of the Reed Bank Basin, we carried out thermal modeling on one drill well and 22 pseudo-wells using the multi-stage finite stretching model. Two stages of rifting during the time periods of ∼65.5–40.4 Ma and ∼40.4–28.4 Ma can be recognized from the tectonic subsidence rates, and there are two phases of heating corresponding to the rifting. The reconstructed average basal paleo-heat flow values at the end of the rifting events are ∼60 and ∼66.3 mW/m², respectively. Following the heating periods, this basin has undergone a persistent thermal attenuation phase since ∼28.4 Ma and the basal heat flow cooled down to ∼57.8–63.5 mW/m² at present. In combination with the radiogenic heat production of the sedimentary sequences, the surface heat flow of the Reed Bank Basin ranges from ∼60.4 to ∼69.9 mW/m².     

琼东南盆地古近纪幕式裂陷及构造、层序和沉积的综合响应过程

通过对区域性角度不整合、构造沉降阶段性演化以及断裂幕式活动和古构造格架变化等信息的识别与厘定,揭示了琼东南盆地古近纪构造活动的幕式演化过程及其特征。进一步结合层序地层与沉积充填综合分析,系统论述了幕式裂陷作用对沉积层序形成与演化的控制。研究表明：琼东南盆地古近纪经历了3个裂陷阶段,即裂陷Ⅰ幕（S₁₀₀-S₈₀）、裂陷Ⅱ幕（S₈₀-S₇₀）和裂陷Ⅲ幕（S₇₀-S₆₀）,分别对应盆地的初始断陷期、主断陷期和断坳转换期。裂陷活动早期以强烈的差异性块断作用为主导,而晚期逐渐被区域性坳陷作用和少量断裂活动共同控制的均一化沉降作用所取代,整体呈现出弱-强-弱的演化特征。裂陷作用的幕式过程及不同裂陷幕同沉积构造活动的差异性通过对可容纳空间、沉降速率、同沉积断裂活动和古构造格架的深刻影响,进而控制了盆地内层序地层单元与沉积旋回的整体发育、沉积与沉降中心的时空展布以及层序地层格架下沉积体系域的构成样式。     

Development of tectonostratigraphy in distal part of foreland basin in southwestern Taiwan

In the young and active tectonic belt of southwestern Taiwan, reconstructed stratigraphy in the distal part of the foreland basin reveals at least two regional unconformities with the younger ones covering the areas farther from the mountain belt. In contrast with the previously proposed monotonous basin development, the temporal–spatial distribution of the unconformities indicates the back-and-forth migration of the foreland basin margin. Three distinct episodes of rapid subsidence during the foreland basin development have also been identified. The onset of the basin development can be well constrained by the initial rapid subsidence at 4.4–4.2 Ma, which happened only in the proximal part of the basin. This was followed by two younger episodes of rapid subsidence events at 2–1.8 Ma and 0.45 Ma, which were encountered initially in the areas progressively farther from the orogenic belt.We propose a model of episodic tectonic evolution in the distal part of the foreland basin in southwestern Taiwan. During each episode of rapid subsidence, uplifting that corresponds to the forebulge began with a concurrent rapid subsidence in the areas closer to the basin center and was followed by rapid subsidence and deposition of widespread strata onlapping toward the basin margin. Part of the widespread strata and its overlying deposits would be eroded in the beginning of the next episode when the forebulge shifted toward the orogenic belt. In general, rate of forebulge migrating away from the orogenic belt during the early stage was slower than that derived from a previously proposed kinematic model of a steady migration of the orogenic belt. This might be due to a rifted and weaker lithosphere beneath the foreland basin. Once the foreland basin migrated onto the less stretched lithosphere, the basin would expand rapidly into the craton.     

Thermochronological insights into the structural contact between the Tian Shan and Pamirs,Tajikistan

Multi‐method thermochronology along the Vakhsh‐Surkhob fault zone reveals the thermotectonic history of the South Tian Shan–Pamirs boundary. Apatite U/Pb analyses yield a consistent age of 251 ± 2 Ma, corresponding to cooling below ~550–350°C, related to the final closure of the Palaeo‐Asian Ocean and contemporaneous magmatism in the South Tian Shan. Zircon (U–Th–Sm)/He ages constrain cooling below ~180°C to the end of the Triassic (~200 Ma), likely related either to deformation induced by the Qiangtang collision or to the closure of the Rushan Ocean. Apatite fission track thermochronology reveals two low‐temperature (<120°C) thermal events at ~25 Ma and ~10 Ma, which may be correlated with tectonic activity at the distant southern Eurasian margin. The late Miocene cooling is confirmed by apatite (U–Th–Sm)/He data and marks the onset of mountain building within the South Tian Shan that is ongoing today.     

Mesozoic thermal history of the Prebetic continental margin (southern Spain): Constraints from apatite fission-track analysis

Apatite fission-track analysis was applied to Triassic and Cretaceous sediments from the South-Iberian Continental Margin to unravel its thermal history. Apatite fission-track age populations from Triassic samples indicate partial annealing and point to a maximum temperature of around 100–110 °C during their post-depositional evolution. In certain apatites from Cretaceous samples, two different fission-track age populations of 93–99 and around 180 Ma can be distinguished. Track lengths associated with these two populations enabled thermal modelling based on experimental annealing and mathematical algorithms. These thermal models indicate that the post-depositional thermal evolution attained temperatures ≤ 70 °C, which is consistent with available vitrinite-reflectance data. Thermal modelling for the Cretaceous samples makes it possible to decipher a succession of cooling and heating periods, consisting of (a) a late Carboniferous–Permian cooling followed by (b) a progressive heating episode that ended approximately 120 Ma at a maximum T of around 110 °C. The first cooling episode resulted from a combination of factors such as: the relaxation of the thermal anomaly related to the termination of the Hercynian cycle; the progressive exhumation of the Hercynian basement and the thermal subsidence related to the rifting of the Bay of Biscay, reactivated during the Late Permian. Jurassic thermal evolution deduced from the inherited thermal signal in the Cretaceous sediments is characterized by progressive heating that ended around 120 Ma. This heating episode is related to thermal subsidence during Jurassic rifting, in agreement with the presence of abundant mantle-derived tholeiitic magmas interbedded in the Jurassic rocks. The end of the Jurassic rifting is well marked by a cooling episode apparently starting during Neocomiam times and ending at surface conditions by Albian times.     

准噶尔盆地侏罗系西山窑组沉降中心的分布及其构造控制

以准噶尔盆地21条典型的地震剖面上的329个取数据点资料为基础,应用EBM盆地模拟系统,对侏罗系西山窑组地层进行了沉降史回剥分析。从回剥的结果来看,盆地的沉降速率在不同时期显示出显著的不均一变化,其中在西山窑二段地层沉积时期的沉降速率在盆地南缘平均为70~90m/Ma,北缘及腹部地区只有30m/Ma左右;在西山窑一段地层沉积时期,盆地南缘的沉降速率则达到了120m/Ma,北缘及腹部相比前一阶段则没有太大变化。由此可以确定玛湖凹陷、乌伦古坳陷和昌吉凹陷是盆地在西山窑组地层沉积时期的沉降中心,盆地南缘的昌吉凹陷则是最主要和最大的的沉降中心。进一步分析,这些沉降中心的形成明显受到了周缘山系逆冲推覆作用的构造负载和盆地基底构造的制约,使盆地形成了隆坳相间的古地貌格局。由于沉降中心是低位三角洲砂体发育的重要部位,从而为隐蔽油气藏的勘探提供了方向。     

The key role of global solid‐Earth processes in preconditioning Greenland's glaciation since the Pliocene

After >500 Ma of absence, major Northern Hemisphere glaciations appeared during the Plio‐Pleistocene, with Greenland leading other northern areas. Here, we propose that three major solid‐Earth processes underpinned build‐up of the Greenland ice‐sheet. First, a mantle‐plume pulse, responsible for the North Atlantic Igneous Province at ~60 Ma, regionally thinned the lithosphere. Younger plume pulses led to uplift, which accelerated at ~5 Ma, lifting the parts of the East Greenland margin closest to Iceland to elevations of more than 3 km above sea level. Second, plate‐tectonic reconstruction shows a ~6° northward component of Greenland motion relative to the mantle since ~60 Ma. Third, a concurrent northward rotation of the entire mantle and crust towards the pole, dubbed True Polar Wander (TPW), contributed an additional ~12° change in latitude. These global geodynamic processes preconditioned Greenland to sustain long‐term glaciation, emphasizing the role of solid‐Earth processes in driving long‐term global climatic transitions.