我国南海历史性水域线的地质特征

40a的海洋地质、地球物理实测研究表明,九段线不仅是显示我国南海主权的历史性水域线,而且总体上也是南海与东部、南部和西部陆区及岛区的巨型地质边界线。根据实测数据,本文将从地质成因、来源、演化的角度论述此南海历史性水域线的合理性。主要结论包括:历史性水域线的东段在地形上基本与马尼拉海沟一致,海沟西侧为南海中央海盆洋壳区,东侧为菲律宾群岛。根据国际地质研究的资料,菲律宾群岛始新世以前位于较偏南的纬度,后来于中晚中新世(距今16~10Ma)仰冲于南海中央海盆之上,因此菲律宾群岛是一个外来群岛。而黄岩岛在马尼拉海沟以西,是中央海盆洋壳区的一个岛礁,与菲律宾群岛成因不同。南海历史性水域线的南段在地形上基本与南沙海槽一致,伴随南沙地块由北部陆缘向南裂离,古南海洋壳沿此海槽以南俯冲至加里曼丹岛陆壳之下,因此南沙地块与加里曼丹陆块为两个来历不同的地块。南海历史性水域线西段的分布在地形上与越东巨型走滑断裂带基本一致,可能与西沙地块、中沙地块、南沙地块从南海北部陆缘向南滑移有关。南沙地块北缘陡直的正断层结构,突显中央海盆是拉裂形成,其基底和中新生代地层与北部珠江口盆地的地层结构可以对比,说明南沙岛礁原属我国华南大陆南缘,后因南海的形成裂离至现今的位置。     

Crustal seismic structure beneath the West Philippine Sea, 17°–18° North

Crustal seismic structures beneath the West Philippine Sea are determined by using explosive sources (0.5–108.6 kg) and ocean bottom seismometers to measure refracted compressional waves. Total crustal thicknesses are shown to be thinner in the eastern part of the ocean basin, approaching only 3.5 km. Crustal thinning toward the east is consistent with the Palau Kyushu Ridge being a remnant transform fault connecting the Central Basin Ridge and the Kula Pacific Ridge in the past. A velocity-depth inversion from the westernmost refraction profile indicates the upper transitional crust layer to have strong velocity gradients which gradually decrease with depth; the lower crust is characterized by a nearly constant velocity gradient. The western part of the ocean basin is also shown to have more typical oceanic thicknesses, as is found in deep ocean basins of the Pacific. Spectral energy models using WKBJ synthetic seismograms suggest that there is a sharp seismic discontinuity between the crust and moho in the western part of the basin. Predicted water depths for the West Philippine Basin using an age-depth relation and corrected for an isostatic response to the measured crustal thicknesses, are still 300 meters shallower than observed depths. The depth anomaly can not be fully reconciled by thinner crust in the eastern part of the basin. This observation implies that a deeper seated anomaly is present beneath the West Philippine Basin.     

Volcanism and Tectonics of the Central Deep Basin,Sea of Japan

The paper presents the results of a study on the geomorphic structure, tectonic setting, and volcanism of the volcanoes and volcanic ridges in the deep Central Basin of the Sea of Japan. The ridges rise 500–600 m above the acoustic basement of the basin. These ridges were formed on fragments of thinned continental crust along deep faults submeridionally crossing the Central Basin and the adjacent continental part of the Primorye. The morphostructures of the basin began to submerge below sea level in the Middle Miocene and reached their contemporary positions in the Pliocene. Volcanism in the Central Basin occurred mostly in the Middle Miocene–Pliocene and formed marginal-sea basaltoids with OIB (ocean island basalt) geochemical signatures indicating the lower-mantle plume origin of these rocks. The OIB signatures of basaltoids tend to be expressed better in the eastern part of the Central Basin, where juvenile oceanic crust has developed. The genesis of this crust is probably related to rising and melting of the Pacific superplume apophyse.     

菲律宾海底层水体在1990s—2010s之间的暖化*

跨菲律宾海的重复断面水文观测揭示: 菲律宾海底层水体从1990s到2010s增暖了0.002~0.01℃。在西马里亚纳海盆和四国海盆, 较冷的下层绕极深层水(Lower Circumpolar Deep Water, LCDW)减少, 较暖的LCDW增加; 而在菲律宾海盆, 较冷的变性LCDW减少, 较暖的变性LCDW增加。菲律宾海盆4000dbar的热通量是0.0413W·m^-2, 而西马里亚纳海盆和四国海盆的是0.0221W·m^-2。菲律宾海盆由于深层海洋热膨胀引起的局地海平面上升速度是0.0621mm·yr^-1, 而西马里亚纳海盆和四国海盆的是0.0333mm·yr^-1。     

3-D Shear Wave Velocity Structure of the Crust and Upper Mantle in South China Sea and its Surrounding Regions by Surface Wave Dispersion Analysis

In this study, we construct a 3-D shear wave velocity structure of the crust and upper mantle in South China Sea and its surrounding regions by surface wave dispersion analysis. We use the multiple filter technique to calculate the group velocity dispersion curves of fundamental mode Rayleigh and Love waves with periods from 14 s to 120 s for earthquakes occurred around the Southeast Asia. We divide the study region (80° E–140° E, 16° S–32° N) into 3° × 3° blocks and use the constrained block inversion method to get the regionalized dispersion curve for each block. At some chosen periods, we put together laterally the regionalized group velocities from different blocks at the same period to get group velocity image maps. These maps show that there is significant heterogeneity in the group velocity of the study region. The dispersion curve of each block was then processed by surface wave inversion method to obtain the shear wave velocity structure. Finally, we put the shear wave velocity structures of all the blocks together to obtain the three-dimensional shear wave velocity structure of crust and upper mantle. The three-dimensional shear wave velocity structure shows that the shear wave velocity distribution in the crust and upper mantle of the South China Sea and its surrounding regions displays significant heterogeneity. There are significant differences among the crustal thickness, the lithospheric thickness and the shear wave velocity of the lid in upper mantle of different structure units. This study shows that the South China Sea Basin, southeast Sulu Sea Basin and Celebes Sea Basin have thinner crust. The thickness of crust in South China Sea Basin is 5–10 km; in Indochina is 25–40 km; in Peninsular Malaysia is 30–35 km; in Borneo is 30–35 km; in Palawan is 35 km; in the Philippine Islands is 30–35 km, in Sunda Shelf is 30–35 km, in Southeast China is 30–40 km, in West Philippine Basin is 5–10 km. The South China Sea Basin has a lithosphere with thickness of about 45–50 km, and the shear wave velocity of its lid is about 4.3–4.7 km/s; Indochina has a lithosphere with thickness of about 55–70 km, and the shear wave velocity of its lid is about 4.3–4.5 km/s; Borneo has a lithosphere with thickness of about 55–60 km, and the shear wave velocity of its lid is about 4.1–4.3 km/s; the Philippine Islands has a lithosphere with thickness of about 55–60 km, and the shear wave velocity of its lid is about 4.2–4.3 km/s, West Philippine Basin has a lithosphere with thickness of about 50–55 km, and the shear wave velocity of its lid is about 4.7–4.8 km/s, Sunda Self has a lithosphere with thickness of about 55–65 km, and the shear wave velocity of its lid is about 4.3 km/s. The Red-River Fault Zone probably penetrates to a depth of at least 200 km and is plausibly the boundary between the South China Block and the Indosinia Block.     

晚上新世以来菲律宾海盆XT4孔黏土矿物特征及其古环境意义

菲律宾海是典型风尘汇聚区,菲律宾海远离吕宋岛的深海沉积物是重建构造尺度亚洲风尘演化历史的良好载体.选取菲律宾海盆XT4孔沉积物开展了黏土矿物研究,并结合前人研究成果,在明确该孔黏土矿物来源的基础上,探讨了晚上新世以来亚洲风尘的演化历史及其可能的影响机制.菲律宾海盆XT4孔黏土矿物以伊利石为主,平均含量为39％,蒙脱石含...     

海水光衰减变化与颗粒有机碳估算——以菲律宾海为例

2004年夏季在菲律宾海进行了上层水体光衰减(660 nm)剖面测量和海水取样分析,提出了海区悬浮颗粒有机碳的光学统计模型。根据大量的现场观测资料,得到了菲律宾海上层水体高分辨率颗粒有机碳断面,对颗粒有机碳分布与变化特征进行了探讨。研究表明,菲律宾海上层水体颗粒有机碳和叶绿素a的比值约为400~2000,浮游植物现存量与颗粒有机碳现存量变化趋势一致。     

莱州湾、渤海湾及渤海中央盆地沉积物岩芯地球化学的初步研究

本文对莱州湾、渤海湾、渤海中央盆地的海洋底质沉积环境进行了研宄,通过对17柱沉积物岩芯样品中Fe,Al,Mn,Ti的测定和分析,论述了四元素在底质表层沉积物中及在岩芯沉积物中的含量和分布规律,用数理统计的方法分析了渤海中央盆地Fe,Al,Mn,Ti的丰度值,为渤海环境背景值及环境背景历史的研究提供了重要参数。     

Basalts from the Solomon and Bismarck Seas

Volcanic rocks collected from the Solomon Sea Basin are mostly ferrobasalt lavas similar to evolved MORB; an exception is a single sample of basaltic crystal tuff invaded by later basalt. The rocks contain labradorite, aluminous diopsidic augite, and titanomagnetite, with olivine and pigconite in the more vitrophyric samples, and segregation vesicles in some. Cobbles dredged from Gudaraba Canyon, south of the Solomon Sea Basin, include both MORB-like glassy lava and K-metasomatised basalt and andesite(?). Two small pieces of volcanic glass from the southern Bismarck Sea are more primitive MOR-type basalts.     

菲律宾海及其邻近海区的水文特征

根据国内外的有关资料,对非律宾海及其邻近的水文特征进行了分析与研究,得出了菲律宾海及其邻近海区的潮汐、海流、海浪、盐度、水温、透明度及水色等水文要素的特点和特征,进一步闸明菲律宾及其邻近海区水文要素的分布特征及季节变化规律,为船舶在海上航行和海洋学研究,提供可靠的参考数据。     

Cross-section restoration and one-dimensional basin modeling of the Central Subbasin in the southern Kunsan Basin,Yellow Sea

The petroleum system of the Kunsan Basin in the Northern South Yellow Sea Basin is not well known, compared to other continental rift basins in the Yellow Sea, despite its substantial hydrocarbon potential. Restoration of two depth-converted seismic profiles across the Central Subbasin in the southern Kunsan Basin shows that extension was interrupted by inversions in the Late Oligocene-Middle Miocene that created anticlinal structures. One-dimensional basin modeling of the IIH-1Xa well suggests that hydrocarbon expulsion in the northeastern margin of the depocenter of the Central Subbasin peaked in the Early Oligocene, predating the inversions. Hydrocarbon generation at the dummy well location in the depocenter of the subbasin began in the Late Paleocene. Most source rocks in the depocenter passed the main expulsion phase except for the shallowest source rocks. Hydrocarbons generated from the depocenter are likely to have migrated southward toward the anticlinal structure and faults away from the traps along the northern and northeastern margins of the depocenter because the basin-fill strata are dipping north. Faulting that continued during the rift phase (∼ Middle Miocene) of the subbasin probably acted as conduits for the escape of hydrocarbons. Thus, the anticlinal structure and associated faults to the south of the dummy well may trap hydrocarbons that have been charged from the shallow source rocks in the depocenter since the Middle Miocene.     

帕里西维拉海盆西北部表层沉积物中粘土矿物的分布特征及物源分析

提要应用X射线衍射(XRD)方法对菲律宾海帕里西维拉海盆西北部的257个表层沉积物样品<2μm粘土组分进行了分析。结果表明,本研究区粘土矿物的组合特点是伊利石含量最高(平均含量47%),蒙皂石含量次之(平均含量35%),高岭石和绿泥石含量均很低(平均含量小于10%)。根据该区表层粘土矿物中伊利石、蒙皂石相对含量的分布,可以大体上分为两种含量组合类型,据此也可以划分出两个组合分区:Ⅰ.富伊利石分区,主要位于帕劳海脊和帕里西维拉海沟之间的大部分区域的地形平坦处;Ⅱ.富蒙皂石分区,主要位于研究区东部帕里西维拉海沟附近和南部零星区域。根据粘土矿物的平面分布特征,结合个别样品的扫描电子显微镜(SEM)和X射线能谱(EDS)分析,认为伊利石主要来源于研究区以西陆地及周边岛屿。伊利石的化学指数和结晶度指数表明,伊利石形成于物理风化较强的气候环境并可能与中国内陆黄土有关系,区内大部分蒙皂石具有富铁并含少量镁的特征,基性火山物质的蚀变是其主要成因,高岭石和绿泥石以陆源为主;风力的吹扬是研究区伊利石物质来源的主要输送方式,洋流作用对粘土矿物,尤其是蒙皂石矿物的分布具有一定影响。     

Refining the model of South China Sea’s tectonic evolution: evidence from Yinggehai-Song Hong and Qiongdongnan Basins

The Cenozoic Yinggehai-Song Hong and Qiongdongnan Basins together form one of the largest Cenozoic sedimentary basins in SE Asia. Detail studying on the newly released regional seismic data, we observed their basin structure and stratigraphy are clearly different. The structure of the NW–SE elongation of the Yinggehai-Song Hong Basin is strongly controlled by the strike–slip faulting of steep Red River Fault. And the basement is covered by heavy sediments from the Red River. However, structures closely related with rifting are imagined on the seismic data from the Qiongdongnan Basin. This rifting and thinning on the northern continental margin of the South China Sea is necessary to be explained by the subduction of a Proto-South China Sea oceanic crust toward the NW Borneo block during the Eocene–Early Miocene. To test how the strike–slip faulting in the Yinggehai-Song Hong Basin and rifting in the Qiongdongnan Basin develop together in the northwest corner of the South China Sea, we reconstructed the tectonics of the northwest corner of the South China Sea and test the model with software of MSC MARC. The numerical model results indicate the South China Sea and its surrounding area can be divided into a collision-extrusion tectonic province and a Proto-South China Sea slab pull tectonic province as suggested in previous works. We suggested that offshore Red River Fault in the Yinggehai-Song Hong Basin is confirmed as a very important tectonic boundary between these two tectonic provinces.     

Deep hydrographic structure along 12°N and 13°N in the Philippine Sea

Hydrographic casts down to the bottom along two zonal sections at 12°N and 13°N (from 144°E to 127°E) were made with a CTD. Their analysis verified the existence of cold and saline abyssal water between the Mariana Ridge and the Kyushu-Palau Ridge. This result provides evidence of flow into the Philippine Sea through the deep gap called the Yap-Mariana Junction. The properties of deep water are variable in the West Mariana basin but quite homogeneous in the Philippine Basin, indicating the transitional nature in the West Mariana Basin and the existence of older bottom water in the Philippine Basin. A close examination suggests that the bottom water is slightly colder in the western part of the Philippine Basin than in the eastern part of the basin. This slightly colder deep water with a hundred kilometer scale in the western Philippine Basin might be related to a broad western boundary current flowing equatorward along the eastern rise of the Philippine Trench.     

东海陆架盆地南部中生代构造演化与原型盆地性质

东海陆架盆地南部夹持于欧亚板块、太平洋板块与印度板块之间,是发育在前中生代基础之上的中、新生代叠合盆地。其构造演化受古太平洋板块俯冲及特提斯-喜马拉雅构造域的联合影响,经历了印支末期基隆运动、燕山期渔山和雁荡运动的叠加改造。结合浙闽隆起带中生代火成岩事件、盆地构造变形、沉积学的一些证据,通过海陆对比研究,认为东海陆架盆地南部早-中三叠世可能为面向古太平洋的被动大陆边缘盆地;晚三叠世-侏罗纪古太平洋板块已对中国大陆有较强的俯冲作用,东海陆架盆地及南部原型盆地为活动大陆边缘弧前盆地;白垩纪受控于滨海断裂表现为活动大陆边缘走滑拉分盆地;古新世-始新世火山岛弧向东移动,东海陆架变为弧后裂谷盆地。     

ORIGIN AND EVOLUTION OF THE EAST CHINA SEA BASIN

Based on the infotmadon and samples of sediments obtained from the geophysical and bathy-metric surveys over an area about 450,000 km2 (scale 1/1,000,000) in the East China Sea by the Natonal Bureau of Oceanography this peper describes the influence on the margin of the East Asia Continent exerted by the interaction of the Eurasian Pacific and Indo Plates since the Indo-China Movement, especially by the formation of the Philippine Sea Plate, which were the factors controlling the development of the sea domain. The origin and evolution of the East China Sea Basin, and the geotectonic characteristics and subdivision of the East China Sea are discussed.     

菲律宾海深水环境下浅地层沉积特征分析

本文依托菲律宾海浅地层剖面资料,结合前人已发表的该区域样品资料和钻孔资料,对九州-帕劳海脊以及与海脊相邻的西菲律宾海盆和帕里西维拉海盆浅层沉积物特征进行了初步研究.研究认为海底以下浅层沉积物一般存在3个波阻抗界面,根据其反射特征划分为4个基本类型,并对剖面特征的成因进行了初步探讨,认为在沉积物的沉积过程中,沉积物供给、...     

Cenozoic tectonic and stratigraphic development of the Central Vietnamese continental margin

The East Vietnam Boundary Fault Zone (EVBFZ) forms the seaward extension of the Red River Shear Zone and interacted with the extensional rift systems in basins along the Central Vietnamese continental margin. The structural outline of the central Vietnamese margin and the timing of deformation are therefore fundamental to understanding the development of the South China Sea and its relation to Indochinese escape tectonism and the India-Eurasia collision. This study investigates the structural and stratigraphic evolution of the Central Vietnamese margin in a regional tectonic perspective based on new 2-D seismic and well data. The basin fill is divided into five major Oligocene to Recent sequences separated by unconformities. Deposition and the formation of unconformities were closely linked with transtension, rifting, the opening of the South China Sea and Late Neogene uplift and denudation of the eastern flank of Indochina. The structural outline of the Central Vietnamese margin favors a hybrid tectonic model involving both escape and slab-pull tectonics. Paleogene left-lateral transtension over the NNW-striking EVBFZ, occurred within the Song Hong Basin and the Quang Ngai Graben and over the Da Nang Shelf/western Phu Khanh Basin, related to the escape of Indochina. East of the EVBFZ, Paleogene NE-striking rifting prevailed in the outer Phu Khanh Basin and the Hoang Sa Graben fitting best with a prevailing stress derived from a coeval slab-pull from a subducting proto-South China Sea beneath the southwest Borneo – Palawan region. Major rifting terminated near the end of the Oligocene. However, late stage rifting lasted to the Early Miocene when continental break-up and seafloor spreading commenced along the edge of the outer Phu Khanh Basin. The resulting transgression promoted Lower and Middle Miocene carbonate platform growth on the Da Nang Shelf and the Tri Ton High whereas deeper marine conditions prevailed in the central part of the basins. Partial drowning and platform retreat occurred after the Middle Miocene due to increased siliciclastic input from the Vietnamese mainland. As a result, siliciclastic, marine deposition prevailed offshore Central Vietnam during the Pliocene and Pleistocene.     

Possible northward extension of the Philippine Fault Zone offshore Luzon Island (Philippines)

The Philippine Fault Zone, a system of left-lateral strike-slip faults traversing the length of the Philippine Islands, is associated with the oblique convergence between the Philippine Sea Plate (PSP) and the Eurasian Plate (EP). Although it is a major deformational structure within the diffuse PSP–EP convergent boundary, some of its segments, particularly its marine extensions, are not well studied. To investigate the crustal deformation in the marine prolongation of the Philippine Fault Zone offshore Luzon Island, multi-channel seismic (MCS) data, gravity data and centroid moment tensor solutions were used in this study. Focal mechanism solutions from the Global CMT catalog were inverted to determine the average principal stress directions and consequently understand the prevailing stress regime in the study area. The stress inversion results indicate that the direction of maximum compression (σ1) is 321°N, which coincides with the PSP–EP convergence direction. From the MCS profiles, the study area was subdivided into deformation zone and a relatively stable zone. Thrust faulting, folding and general uplift are observed in the deformation zone. This zone is further subdivided into the active and inactive segments. In the active segment, uplift is occurring in the submarine ridge. This deformation pattern can be related to the ongoing uplift in some regions bisected by the PFZ. The inactive segment, characterized by intense folding of the sequences and faulting of the basement and overlying sequences, is suggested as the precursor of the Philippine Fault Zone. Deformation appears to be recently shifted to the east as delineated by an uplifted N-NW trending submarine ridge offshore NW Luzon Island.     

The formation and tectonic evolution of Philippine Sea Plate and KPR

The Philippine Sea Plate has an extremely special tectonic background. As an oceanic plate, it is almost entirely surrounded by subduction zones with complex internal tectonic features. On the basis of enormous published literature, this paper offers a comprehensive overview of the tectonic and evolution history of the Philippine Basin and the Kyushu-Palau Ridge (KPR) in the Philippine Sea Plate, and discusses the geological features of KPR. Referring to relevant definitions of various "ridges" stipulated in United Nations Convention on the Law of the Sea, so the KPR is believed to be a remnant arc formed during the opening of the Parece Vela and Shikoku Basins in the Philippine Sea Plate. It is a submarine ridge on oceanic plate rather than a submarine elevation. And thus, it is not a natural component of the Japan continental margin.