Structural characteristics of the KPR-CBR triple-junction inferred from gravity and magnetic interpretations,Philippine Sea Plate

The intersection of the Kyushu-Palau Ridge (KPR) and the Central Basin Rift (CBR) of the West Philippine Basin (WPB) is a relic of a trench-trench-rift (TTR) type triple-junction, which preserves some pivotal information on the cessation of the seafloor spreading of the WPB, the emplacement and disintegration of the proto-Izu-Bonin-Mariana (IBM) Arc, and the transition from initial rifting to steady-state spreading of the Parece Vela Basin (PVB). However, the structural characteristics of this triple-junction have not been thoroughly understood. In this paper, using the newly acquired multi-beam bathymetric, gravity, and magnetic data obtained by the Qingdao Institute of Marine Geology, China Geological Survey, the authors depict the topographic, gravity, and magnetic characteristics of the triple-junction and adjacent region. Calculations including the upward continuations and total horizontal derivatives of gravity anomaly are also performed to highlight the major structural features and discontinuities. Based on these works, the morphological and structural features and their formation mechanisms are analyzed. The results show that the last episode amagmatic extension along the CBR led to the formation of a deep rift valley, which extends eastward and incised the KPR. The morphological and structural fabrics of the KPR near and to the south of the triple-junction are consistent with those of the western PVB, manifesting as a series of NNE-SSW- and N-S-trending ridges and troughs, which were produced by the extensional faults associated with the initial rifting of the PVB. The superposition of the above two reasons induced the prominent discontinuity of the KPR in deep and shallow crustal structures between 15°N–15°30′N and 13°30′N–14°N. Combined with previous authors’ results, we propose that the stress produced by the early spreading of the PVB transmitted westward and promoted the final stage amagmatic extension of the CBR. The eastward propagation of the CBR destroyed the KPR, of which the magmatism had decayed or ceased at that time. The destruction mechanism of the KPR associated with the rifting of the PVB varies along strike the KPR. Adjacent to the triple-junction, the KPR was destroyed mainly due to the oblique intersection of the PVB rifting center. Whereas south of the triple-junction, the KPR was destroyed by the E-W-directional extensional faulting on its whole width.©2021 China Geology Editorial Office.     

论菲律宾海板块大地构造分区

菲律宾海板块是毗邻中国大陆的一个独特的小型板块。除南端表现十分复杂外,它的构造边界多以海沟为界,比较清楚,然而次级大地构造单元划分则比较复杂。本文根据近年来的研究成果,按照块体构造理论注重统一的地球物理场、相似的地壳结构、有机的成因联系等3个基本原则,将菲律宾海板块划分为3个具有不同构造演化特征的单元,即西菲律宾海块体、四国—帕里西维拉块体和伊豆—博宁—马里亚纳块体。西菲律宾海块体包括两部分:一个是西菲律宾海盆,始新世以来受太平洋板块和印澳板块近南北向的相对俯冲作用影响,并顺时针旋转形成了现今的构造样式,于30 Ma左右停止扩张。另一个包括大东盆岭、花东盆地、帕劳海盆和吕宋岛弧蛇绿岩等洋壳在内的白垩纪洋盆。根据形成年代和形成时的扩张方向可将四国—帕里西维拉块体分为两部分:四国海盆和帕里西维拉海盆,两者以索夫干断裂为界。伊豆—博宁—马里亚纳块体沿博宁高原南缘分为南北两部分,两者表现出不同的地质特征。     

Characteristics of gravity and magnetic fields and deep structural responses in the southern part of the Kyushu-Palau Ridge

The southern part of the Kyushu-Palau Ridge (KPR) is located at the conjunction of the West Philippine Basin, the Parece Vela Basin, the Palau Basin, and the Caroline Basin. This area has extremely complex structures and is critical for the research on the tectonic evolution of marginal seas in the Western Pacific Ocean. However, only few studies have been completed on the southern part, and the geophysical fields and deep structures in this part are not well understood. Given this, this study finely depicts the characteristics of the gravity and magnetic anomalies and extracts information on deep structures in the southern part of the KPR based on the gravity and magnetic data obtained from the 11th expedition of the deep-sea geological survey of the Western Pacific Ocean conducted by the Guangzhou Marine Geological Survey, China Geological Survey using the R/V Haiyangdizhi 6. Furthermore, with the data collected on the water depth, sediment thickness, and multichannel seismic transects as constraints, a 3D density model and Moho depths of the study area were obtained using 3D density inversion. The results are as follows. (1) The gravity and magnetic anomalies in the study area show distinct zoning and segmentation. In detail, the gravity and magnetic anomalies to the south of 11°N of the KPR transition from high-amplitude continuous linear positive anomalies into low-amplitude intermittent linear positive anomalies. In contrast, the gravity and magnetic anomalies to the north of 11°N of the KPR are discontinuous and show alternating positive and negative anomalies. These anomalies can be divided into four sections, of which the separation points correspond well to the locations of deep faults, thus, revealing different field-source attributes and tectonic genesis of the KPR. (2) The Moho depth in the basins in the study area is 6–12 km. The Moho depth in the southern part of KPR show segmentation. Specifically, the depth is 10–12 km to the north of 11°N, 12–14 km from 9.5°N to 11°N, 14–16 km from 8.5°N to 9.5°N, and 16–25 km in the Palau Islands. (3) The KPR is a remnant intra-oceanic arc with the oceanic-crust basement.which shows noticeably discontinuous from north to south in geological structure and is intersected by NEE-trending lithospheric-scale deep faults. With large and deep faults F3 and F1 (the Mindanao fault) as boundaries overall, the southern part of the KPR can be divided into three zones. In detail, the portion to the south of 8.5°N (F3) is a tectonically active zone, the KPR portion between 8.5°N and 11°N is a tectonically active transition zone, and the portion to the north of 11°N is a tectonically inactive zone. (4) The oceanic crust in the KPR is slightly thicker than that in the basins on both sides of the ridge, and it is inferred that the KPR formed from the thickening of the oceanic crust induced by the upwelling of deep magma in the process of rifting of remnant arcs during the Middle Oligocene. In addition, it is inferred that the thick oceanic crust under the Palau Islands is related to the constant upwelling of deep magma induced by the continuous northwestward subduction of the Caroline Plate toward the Palau Trench since the Late Oligocene. This study provides a scientific basis for systematically understanding the crustal attributes, deep structures, and evolution of the KPR.©2021 China Geology Editorial Office.     

Configuration of subducting Philippine Sea plate and crustal structure in the central Japan region

A seismic experiment with six explosive sources and 391 seismic stations was conducted in August 2001 in the central Japan region. The crustal velocity structure for the central part of Japan and configuration of the subducting Philippine Sea plate were revealed. A large lateral variation of the thickness of the sedimentary layer was observed, and the P-wave velocity values below the sedimentary layer obtained were 5.3–5.8 km/s. P-wave velocity values for the lower part of upper crust and lower crust were estimated to be 6.0–6.4 and 6.6–6.8 km/s, respectively. The reflected wave from the upper boundary of the subducting Philippine Sea plate was observed on the record sections of several shots. The configuration of the subducting Philippine Sea slab was revealed for depths of 20–35 km. The dip angle of the Philippine Sea plate was estimated to be 26° for a depth range of about 20–26 km. Below this depth, the upper boundary of the subducting Philippine Sea plate is distorted over a depth range of 26–33 km. A large variation of the reflected-wave amplitude with depth along the subducting plate was observed. At a depth of about 20–26 km, the amplitude of the reflected wave is not large, and is explained by the reflected wave at the upper boundary of the subducting oceanic crust. However, the reflected wave from reflection points deeper than 26 km showed a large amplitude that cannot be explained by several reliable velocity models. Some unique seismic structures have to be considered to explain the observed data. Such unique structures will provide important information to know the mechanism of inter-plate earthquakes.     

Configuration of the subducting Philippine Sea slab in the eastern part of southwestern Japan with seismic array and Hi-net data

It is important to know the shape of a subducting slab in order to understand the mechanisms of inter-plate earthquakes and the process of subduction. Seismicity data and converted phases have been used to detect plate boundaries. The configuration of the Philippine Sea slab has been obtained at the western part of southwestern Japan. At the eastern part of southwestern Japan, however, the configuration of the Philippine Sea slab has not yet been confirmed. A spatially high-density seismic network makes it possible to detect the boundaries of the Philippine Sea slab. We used a spatially high-density temporal seismic array in the area. The configuration of the Philippine Sea plate is obtained at the eastern part of southwestern Japan using the temporal seismic array and permanent seismic network data and comparing the seismic structure obtained from the results of refraction surveys. The configuration of the Philippine Sea plate obtained by this study does not bend sharply compared to previous models obtained from receiver function analyses. We delineated the upper boundary of the slab to a depth of about 45 km. The weak image of the boundary, which corresponds to the upper mantle reflector beneath the source area of the 2000 Western Tottori earthquake, was detected using the spatially dense array.     

Plate tectonic control on the formation and tectonic migration of Cenozoic basins in northern margin of the South China Sea

The tectonic evolution history of the South China Sea(SCS) is important for understanding the interaction between the Pacific Tectonic Domain and the Tethyan Tectonic Domain,as well as the regional tectonics and geodynamics during the multi-plate convergence in the Cenozoic.Several Cenozoic basins formed in the northern margin of the SCS,which preserve the sedimentary tectonic records of the opening of the SCS.Due to the spatial non-uniformity among different basins,a systematic study on the various basins in the northern margin of the SCS constituting the Northern Cenozoic Basin Group(NCBG) is essential.Here we present results from a detailed evaluation of the spatial-temporal migration of the boundary faults and primary unconformities to unravel the mechanism of formation of the NCBG.The NCBG is composed of the Beibu Gulf Basin(BBGB),Qiongdongnan Basin(QDNB),Pearl River Mouth Basin(PRMB) and Taixinan Basin(TXNB).Based on seismic profiles and gravity-magnetic anomalies,we confirm that the NE-striking onshore boundary faults propagated into the northern margin of the SCS.Combining the fault slip rate,fault combination and a comparison of the unconformities in different basins,we identify NE-striking rift composed of two-stage rifting events in the NCBG:an early-stage rifting(from the Paleocene to the Early Oligocene) and a late-stage rifting(from the Late Eocene to the beginning of the Miocene).Spatially only the late-stage faults occurs in the western part of the NCBG(the BBGB,the QDNB and the western PRMB),but the early-stage rifting is distributed in the whole NCBG.Temporally,the early-stage rifting can be subdivided into three phases which show an eastward migration,resulting in the same trend of the primary unconformities and peak faulting within the NCBG.The late-stage rifting is subdivided into two phases,which took place simultaneously in different basins.The first and second phase of the early-stage rifting is related to back-arc extension of the Pacific subduction retreat system.The third phase of the earlystage rifting resulted from the joint effect of slab-pull force due to southward subduction of the proto-SCS and the back-arc extension of the Pacific subduction retreat system.In addition,the first phase of the late-stage faulting corresponds with the combined effect of the post-collision extension along the Red River Fault and slab-pull force of the proto-SCS subduction.The second phase of the late-stage faulting fits well with the sinistral faulting of the Red River Fault in response to the Indochina Block escape tectonics and the slab-pull force of the proto-SCS.     

渤海西部海域新生代构造与演化及对油气聚集的控制

渤海西部处于渤海湾盆地黄骅坳陷中北区,东与渤中坳陷衔接,周临多个新生代富(含)烃洼陷,该区具有较大的油气勘探潜力。本文利用区内现有的大量勘探资料对其基本构造特征、演化史及其对油气聚集的控制作用进行了详细的研究与探讨。认为研究区整体构造格架受近东西向、北东向、北西向3组基底断裂控制,近东西向和北西向断层控制古近纪断陷及区内整体构造格局,而北东向与北西向断层在新近纪发生较强烈的走滑活动; 研究区新生代经历了多阶段演化过程,同时又整体表现出具隆拗过渡、整体隆升的演化背景; 复杂多阶段的演化过程使得区内油气多层位复式成藏; 另外,新近纪晚期构造活跃使得区内油气多在新近系浅层晚期成藏,并沿北西向与北东向断层优势成藏展布。     

Provenance and tectonic setting of the Klondyke and Zigzag Formations: Implications on the oceanic to island arc evolution of the Baguio Mineral District, Philippine

Petrographic and geochemical studies were made on the sedimentary units of the Baguio Mineral Dis-trict and its adjacent areas. These analyses are par-ticularly useful in providing clues on the geologic evolution not just of Northern Luzon but of the Phil-ippine island arc system as well. Results on the petrography of the clastic rock units of the Baguio Mineral District reveal that the Zigzag Formation samples contain more quartz but less plagioclase compared to samples of the Klondyke, Amlang and Cataguintingan formations. It is also noted that lithic fragments are more abundant in the Klondyke Formation sandstone samples.     

Structural characteristics and evolution of the South Yellow Sea Basin since Indosinian

Based on the seismic data gathered in past years and the correlation between the sea and land areas of the Lower Yangtze Platform, the structural characteristics of the South Yellow Sea Basin since the Indosinian tectonic movement is studied in this paper. Three stages of structural deformation can be distinguished in the South Yellow Sea Basin since the Indosinian. The first stage, Late Indosinian to Early Yanshanian, was dominated by foreland deformation including both the uplifting and subsidence stages under an intensively compressional environment. The second stage, which is called the Huangqiao Event in the middle Yanshanian, was a change for stress fields from compression to extension. While in the third stage (the Sanduo Event) in the Late Himalayan, the basin developed a depression in the Neogene-Quaternary after rifting in the Late Cretaceous-Paleogene. The long-time evolution controlled 3 basin formation stages from a foreland basin, then a fault basin to a final depression basin. In conclusion, since the Indosinian, the South Yellow Sea Basin has experienced compressional fold and thrust, collisional orogen, compressional and tensional pulsation, strike-slip, extensional fault block and inversion structures, compression and convergence. The NE, NEE, nearly EW and NW trending structures developed in the basin. From west to east, the structural trend changed from NEE to near EW to NW. While from north to south, they changed from NEE to near EW with a strong-weak-strong zoning sequence. Vertically, the marine and terrestrial facies basins show a “seesaw” pattern with fold and thrust in the early stages, which is strong in the north and weak in the south and an extensional fault in later stages, which is strong in the north and weak in the south. In the marine facies basin, thrust deformation is more prevailing in the upper structural layer than that in the lower layer. The tectonic mechanism in the South Yellow Sea Basin is mainly affected by the collision between the Yangtze and North China Block, while the stress environment of large-scale strike-slip faults was owing to subduction of the Paleo-Pacific plate. The southern part of the Laoshan uplift is a weak deformation zone as well as a stress release zone, and the Meso-Paleozoic had been weakly reformed in later stages. The southern part of the Laoshan uplift is believed, therefore, to be a promising area for oil and gas exploration.     

Topographic and geomorphological features and tectogenesis of the southern section of the Kyushu-Palau Ridge (KPR) and its adjacent areas

The Philippine Sea is the largest marginal sea in the Western Pacific Ocean and is divided into two parts by the Kyushu-Palau Ridge (KPR). The western part is the West Philippine Basin, and the eastern part consists of the Shikoku and Parece Vela basins. Based on surveyed data of massive high-resolution multibeam bathymetric data and sub-bottom profiles data collected from the southern section of the KPR from 2018 to 2021, this paper analyzes the topographic and geomorphological features, shallow sedimentary features, and tectonic genesis of the southern section of the KPR, obtaining the following conclusions. The southern section of the KPR has complex and rugged topography, with positive and negative topography alternatingly distributed and a maximum height difference of 4086 m. The slope of seamounts in this section generally exceeds 10° and is up to a maximum of 59°. All these contribute noticeably discontinuous topography. There are primarily nine geomorphological types in the southern section of the KPR, including seamounts, ridges, and intermontane valleys, etc. Among them, seven independent seamount groups are divided by five large troughs, forming an overall geomorphological pattern of seven abyssal seamount groups and five troughs. This reflects the geomorphological features of a deep oceanic ridge. Intramontane basins and intermontane valleys in the southern section of the KPR are covered by evenly thick sediments. In contrast, sediments in ridges and seamounts in this section are thin or even missing, with slumps developing locally. Therefore, the sediments are discontinuous and unevenly developed. The KPR formed under the control of tectonism such as volcanic activities and plate movements. In addition, exogenic forces such as underflow scouring and sedimentation also play a certain role in shaping seafloor landforms in the KPR.©2021 China Geology Editorial Office.     

塔里木盆地温宿凸起构造特征新认识

温宿凸起位于塔里木盆地西北缘, 平面上呈北东-南西向展布。本文从温宿凸起周缘及内部断裂构造解释入手, 结合区域地质结构特征、构造单元划分和构造演化研究, 认为温宿凸起的形成和演化主要受古木别孜和沙井子两条主断裂控制, 表现为夹持在乌什凹陷和阿瓦提凹陷中间的一个古隆起。温宿凸起内部发育一系列次级断裂, 将其划分为阿克苏低凸带、阿克雅断凸带、古木别孜断裂带和沙井子过渡带4个构造单元。温宿凸起具有长期隆升、短期沉降的特点: 在加里东晚期-喜马拉雅早期, 受两条边界主断裂形成并持续活动的影响, 温宿凸起长期隆升, 造成了其地层的广泛剥蚀; 喜马拉雅中期为温宿凸起稳定沉降阶段, 沉积了新近系吉迪克组碎屑岩沉积。喜马拉雅晚期差异隆升形成西高东低的大型鼻状构造背景, 东部接受了新近系康村组、库车组沉积, 西部高部位未接受沉积。边界断裂定型后, 温宿凸起亦最终定型, 形成了现今的构造面貌。综合研究认为, 温宿凸起和塔北隆起构造性质有显著差异, 二者为不同构造单元, 应将其归属为柯坪断隆而非塔北隆起。喀拉玉尔滚断裂为塔里木盆地一级构造单元塔北隆起和柯坪断隆的界线。本文研究成果对指导温宿凸起勘探生产、重新认识塔里木盆地西北部构造演化和构造格局有重要意义。

     

东菲律宾海新型富铁锰结壳的古海洋环境记录

尝试恢复东菲律宾海新型深水水成富铁锰结壳典型样品生长过程中所记录的古海洋环境.通过对其微间距取样样品的地球化学和铀系年代学综合研究, 得到了该结壳的3个主要生长阶段及其对应的古海洋环境.第一阶段为晚中新世晚期-早上新世的结壳快速生长期, 壳层结构疏松并含有较多的火山碎屑物质, 对应着中中新世初期-上新世早期的南极底流活跃和降温; 第二阶段为早、中上新世的结壳生长间断期, 形成深海粘土沉积, 表明此时南极底流的减弱和升温; 第三阶段为中上新世以来的结壳缓慢生长期, 指示着南极底流的再次活跃和强降温, 其强度和范围均超过第一阶段, 更利于致密和高纯壳层的发育.研究区的这段古海洋学历史在以往研究中一直不甚明了.      

东海盆地中、新生代盆架结构与构造演化

基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。     

渤海海域侏罗—白垩纪沉积与构造演化

覆盖区侏罗—白垩系分布、变形特征及构造演化对理解华北克拉通破坏过程具有重要意义。根据编制的地层分布图和地震资料解释,研究了渤海海域侏罗—白垩纪时期沉积、构造变形及演化特征。渤海海域燕山期构造变形与板块俯冲引起的地幔上拱有关。早-中侏罗世,库拉—伊泽奈崎板块北西向俯冲,地层展布继承了印支期古构造格局,呈近东西向,属于坳陷成盆期。晚侏罗—早白垩世,库拉—伊泽奈崎板块北北西向俯冲,火山活动强烈,为热拱断陷期。受郯庐断裂左行活动影响,地层展布具有明显分带性,多呈北东—南西向和北西西—南东东向。晚白垩世,太平洋板块北西向俯冲挤压,岩浆冷凝,进入萎缩隆褶期。     

日本海陨击事件与新生代东亚大地构造演化

北太平洋及东亚地区在始新世左右发生了一系列重大地质事件:日本海发生开裂;日本西南和中国板块北部发生顺时针旋转(>20°);NNW向运动的太平洋板块突然改变方向开始NWW向运动;郯庐断裂带由强烈断陷造成快速冷却事件;渤海湾盆地出现地幔热异常开始形成裂谷系;阿尔金断裂开始脉冲式走滑;贝加尔湖裂谷开始形成。这些重大地质事件的发生都与日本海陨击事件相关。     

南海北部陆缘盆地形成的构造动力学背景

摘要：南海北部陆缘盆地处于印度板块与太平洋及菲律宾海板块之间,但三大板块对南海北部陆缘盆地的影响是不同的。通过对三大板块及古南海演化的研究,可知南海北部陆缘地区应力环境于晚白垩世发生改变。早白垩世处于挤压环境,晚白垩世以来转变为伸展环境并且不同时期的成因不同。晚白垩世-始新世,华南陆缘早期造山带的应力松弛、古南海向南俯冲及太平洋俯冲板块的滚动后退导致其处于张应力环境。始新世时南海北部陆缘裂陷盆地开始产生,伸展环境没有变,但因其是由太平洋板块向西俯冲速率的持续降低及古南海向南俯冲引起的,南海北部陆缘盆地继续裂陷。渐新世-早中新世,地幔物质向南运动及古南海向南俯冲导致南海北部陆缘地区处于持续的张应力环境;渐新世早期南海海底扩张;中中新世开始,三大板块开始共同影响着南海北部陆缘盆地的发展演化。     

数字地质调查中多源地学数据在造山带构造单元划分和大地构造演化研究方面的应用——以青海民和地区为例

多源地学数据包括遥感、地球化学和地球物理数据,介绍了利用多源地学数据进行造山带构造单元划分的方法。遥感数据在确定区域构造边界及活动断层方面的应用非常广泛,遥感影像在解译线形构造即断层方面有非常明显的效果,可以根据不同构造单元的影像差异,区分不同的地质体、线性构造及活动断层,同时用遥感数据叠加三维地形数据分析线性构造可以更加直观地解译线性构造。地球化学数据在确定大的构造边界方面具有一定的指示意义,可以根据水系沉积物的地球化学特点,运用因子分析方法确定大的构造边界。地球物理数据提供的是地质体及构造边界在深部的延伸情况,可以为研究断裂的运动学和动力学特征提供证据。     

贺兰山构造带构造—地层层序及构造演化

贺兰山构造带及邻区形成演化经历有多期叠加改造和多个伸展—聚敛旋回构造运动,形成了区域内多套构造—地层层序,因此,开展贺兰山构造带构造—地层层序及构造演化研究对深入理解其地质结构和油气勘探有着重要的意义。本文旨在综合利用野外调查、地震数据和1：50 000区域地质资料,采用野外实地调查和地震剖面精细解析相结合的方法对研究区区域不整合面的分布特征和规律进行详尽分析研究,根据区域不整合面的发育特征,建立区域地层年代格架,划分构造—地层层序,进而对盆地演化阶段进行探讨。研究表明,研究区自下至上发育Pt2Ch-Jx/Pt1、∈1/An ∈、C2/O、T/P、J1-2/An J、K1/An K1、E3q—N/AnE,据此将研究区垂向上划为7个构造—地层层序：基底构造层、中元古界构造层、震旦系—奥陶系构造层、石炭系—三叠系构造层、侏罗系构造层、下白垩统构造层、新生界构造层。贺兰山构造带构造演化经历中新元古代—早古生代陆缘盆地坳陷—裂谷演化阶段;晚古生代—中三叠世陆相盆地坳陷沉积阶段;晚三叠世局部伸展;中侏罗世—早白垩世大规模逆冲推覆阶段,普遍发育多条大型北东向逆冲断裂;始新世开始进入盆—岭构造形成阶段。     

西菲律宾海盆表层沉积物中的轻碎屑分区及物质来源

海洋沉积物中轻碎屑(0125~0063mm)种类的特征和分布样式对于沉积物源区的判别具有重要的指示意义。取自西菲律宾海219个表层沉积物样品中的轻碎屑种类包括生物碎屑、石英、长石、褐色火山玻璃、无色火山玻璃、风化碎屑、火山渣,以及含量极低的一些矿物如磷酸盐（鱼牙）、片状矿物（黑云母和白云母）、硅灰石、黑曜石以及极少量的球粒状、椭球状宇源颗粒。分析结果表明,本区的轻碎屑分布可以分为三个区： (Ⅰ)菲律宾海沟以东区,轻碎屑主要源于钙质或硅质生物,邻近的岛弧也贡献了一定量的火山碎屑。(Ⅱ)中部区,石英、长石和无色火山玻璃可能源于中酸性熔岩海山或者是正在活动的中酸性岩浆事件的产物。(Ⅲ) 帛琉—九州海岭以西区,本区的物质来源相对比较复杂。长石、石英的含量较低,可能主要来源于中酸性熔岩海山或者是正在活动的中酸性岩浆事件的产物,火山渣主要是源于喷发在帛琉—九州海岭之上的火山。可以认为：① 研究区的生物碎屑含量与水深紧密相关,生物碎屑的数量主要受控于碳酸盐补偿深度(CCD)。② 来自菲律宾岛弧的火山碎屑对本区沉积作用贡献较小,可能通过海流或风等途径向深海盆进行短距离搬运。海底高原(如本哈姆高原)和邻近海岭(如帛琉—九州海岭)火山岩的风化产物对本研究区轻碎屑沉积作用有着重要贡献,其影响范围主要依赖于海底风化作用的强度。③ 来自中国大陆及菲律宾等邻近岛弧的陆源碎屑物质对本区的沉积作用影响很小。本区可能存在的中酸性熔岩海山是长英质轻碎屑物质的主要源区。     

从东海石油地质重要进展看西太平洋大陆边缘新生代盆地的构造演化——一种海沟向洋后退的残余弧后盆地演化模式

东海盆地石油地质研究在近二十年里主要取得五方面的进展 :证明了盆地是由一组大陆边缘新生界由西向东逐个变新的“盆地群体”组成 ,建立了陆架地区以组为单位的整个新生代地层单元 ,详细划分了西湖凹陷的内部地质结构 ,认定了煤和煤系沉积是东海陆架区的主力油气源岩 ,通过大量钻井验证了盆地中三类不同成因的圈闭。从环西太平洋盆地形成的地球动力学背景看 ,西太平洋是一个自北而南的沟—弧—盆 (陆缘海 )系统 ;大体以台湾海峡为界 ,东海盆地是一个由转换或被动边缘演化而来的聚敛边缘 ,而南海属于由活动或聚敛边缘转化而来的被动边缘。东海盆地与菲律宾海盆地具有相似的时空演化特征 ,由此论证了东海新生代盆地属于残余弧后向洋后退盆地