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1.
A. V. Kudelsky 《Water Resources》2011,38(7):849-858
The issue of the geoenvironmental state of Black Sea basin, the final basin receiving the runoff of many large rivers of the
European continent (Danube, Dnieper, Don, etc.) and considerable runoff from the nearby watersheds, including Turkish, is
considered. The extent and geoenvironmental consequences of the large-scale changes in the hydrology, water balance, and hydrochemistry
of the sea basin under the effect hydrotechnical interception and industrial pollution of river runoff are discussed. The
genetic role of Black Sea rifting in one of the world’s largest oil-and-gas-bearing basins with its inherent thermal and geochemical
processes, geoenvironmental conditions, and risks is emphasized. Improved information is given about the genesis of hydrogen
sulfide dissolved in seawater and related to the processes of geochemical sulfate reduction of silt water sulfates under the
effect of hydrocarbon gases, which mostly form in zones of deep catagenesis of sedimentary formations and lower crust rock
metamorphism. It is emphasized that the ecological stability of a sea basin showing such complex and contradictory relationships
with natural and technogenic objects and processes can be ensured only by joint and well coordinated efforts of the countries
of the Black Sea and nearby regions aimed on rational nature and water management, including when laying pipelines on Black
Sea bed and developing the power resources of the Black Sea oil-and-gas-bearing basin. 相似文献
2.
A. A. Svitoch 《Water Resources》2008,35(2):165-170
The Late Pleistocene history of the Caspian and Black seas is considered. It is suggested that the New-Euxinian basin was to a great degree due to the penetration of the Caspian water through the Manych depression into the Black Sea during the Caspian-Early Khvalynian transgression. 相似文献
3.
A set of two hundred shear-wave velocity models of the crust and uppermost mantle in southeast Europe is determined by application
of a sequence of methods for surface-waves analysis. Group velocities for about 350 paths have been obtained after analysis
of more than 600 broadband waveform records. Two-dimensional surface-wave tomography is applied to the group-velocity measurements
at selected periods and after regionalisation, two sets of local dispersion curves (for Rayleigh and Love waves) are constructed
in the period range 8–40 s. The shear-wave velocity models are derived by applying non-linear iterative inversion of local
dispersion curves for grid cells predetermined by the resolving power of data. The period range of observations limits the
velocity models to depths of 70 km in accordance to the penetration of the surface waves with a maximum period of 40 s. Maps
of the Moho boundary depth, velocity distribution above and below Moho boundary, as well as velocity distribution at different
depths are constructed. Well-known geomorphologic units (e.g. the Pannonian basin, southeastern Carpathians, Dinarides, Hellenides,
Rodophean massif, Aegean Sea, western Turkey) are delineated in the obtained models. Specific patterns in the velocity models
characterise the southeast Carpathians and adjacent areas, coast of Albania, Adriatic coast of southern Italy and the southern
coast of the Black Sea. The models obtained in this study for the western Black Sea basin shows the presence of layers with
shear-wave velocities of 3.5 km/s–3.7 km/s in the crust and thus do not support the hypothesis of existence of oceanic structure
in this region. 相似文献
4.
We present the results of long-term deep geoelectric studies using the JASC (Japan Sea Cable) submarine communication cable in the region of the Sea of Japan. In the 2D inversion of the amplitude and phase’s apparent resistivity curves and the frequency dependences of the tipper, we invoked the geological and geophysical information about the region and on-shore electromagnetic observations to fit the model to the observations. The resulting geoelectrical cross section of the region of the Sea of Japan along the JASC cable obtained in this way agrees well with the experimental data. The upper part of the section contains a conductive block beneath the bottom of the Central basin of the Sea of Japan at a depth of 10–40 km, a fault submerging below the continent in the marginal part and a deep fault in the continental region. In the lower portions of the cross section, the high-resistivity block interrupts the continuity of the horizontal conductive layers beneath the Yamato Uplift, and the conductive bottom part of the geoelectric cross section submerges under the continent. In the continental segment of the cross section, there is a large block with reduced electric resistivity, which is located between the conductive layers at a depth interval of 200–560 km. We analyze the characteristic features of the geoelectric cross section and the deep section imaged by seismic tomography in the region of the Sea of Japan. 相似文献
5.
Introduction The present Bohai Sea is a half-closed shallow one in the continent, located at the northeast to North China, with an area about 7.3104 km2. Geologically, it is situated in the northern North China basin and of a short development history. Previous studies (WANG, LI, 1983; Institute of Oceanology, Chinese Academy of Sciences, 1985; HUANG, et al, 1993) show that the Fu-jian-Lingnan uplift in the East China Sea continental shelf sank gradually into the oceanic bottom, mak… 相似文献
6.
Velocity structure of the upper mantle of the East European platform according to seismic noise data
T. Yu. Koroleva T. B. Yanovskaya S. S. Patrusheva 《Izvestiya Physics of the Solid Earth》2010,46(10):839-848
Cross-correlation functions of noise are constructed on 119 interstation paths from seismic noise records at stations of Eastern Europe. Dispersion curves of the group velocity of Rayleigh waves obtained from the cross-correlation functions are used for constructing the three-dimensional distribution of the velocity of transverse waves on the East European platform and in adjacent regions by methods of surface-wave tomography. The mean velocity in the crust is minimum in the region of the Caspian depression and Black Sea basin (<3.3 km/s) and maximum in the Baltic shield area (>3.7 km/s). The upper mantle beneath the Baltic and Ukrainian shields is characterized by increased velocity and the absence of the asthenospheric layer. Reduced velocities are noted in the upper mantle of the Black Sea basin. A low-velocity anomaly in the shape of a vertical column is revealed at depths of 200–300 km in the central part of the Dnieper-Donets aulacogen, which confirms the existence of a paleorift in this region. 相似文献
7.
南海东北部及邻区,特别是洋陆转换带地区的复杂地壳结构特征一直是南海岩石层结构研究的热点.本文在Pn波地震层析成像结果和深部地震探测剖面的约束下,利用重力数据建立该区两条剖面的密度模型.两条重力剖面二度半密度正反演的拟合结果支持琼粤隆起至吕宋岛弧区一带的地壳结构中存在下地壳高速层的观点,同时认为台西南盆地的拟合结果表明南部凹陷区仍属于过渡型地壳.本文认为剖面AA′和剖面BB′的构造属性虽然均总体倾向于火山岩型,但二者的地质结构并不完全一致,表明了北部陆缘深部结构的横向差异与构造属性的复杂. 相似文献
8.
本研究拾取了中国数字测震台网固定台站记录的2008-2016年2级以上地震事件中的27233条高质量Pn到时资料,反演得到了郯庐断裂带及其邻区上地幔顶部Pn波速度和各向异性结构模型.结果显示,研究区上地幔顶部Pn波速度结构存在强烈的横向不均匀性,速度异常形态与区域地质构造较为吻合.太行山造山带、鲁西隆起、大别造山带、苏鲁褶皱带、胶辽隆起和华北盆地南端等隆起区表现为低波速异常,而黄海北、南部盆地、渤海湾和华北盆地北部等凹陷区均为高波速异常.壳内强震主要发生在Pn低波速异常和高低波速异常的横向过渡地带,说明强震的发生与上地幔结构的横向变化之间存在有一定关联.郯庐断裂带两侧Pn波速度以郯城地震为界其东北侧和西南侧分别分布有与断裂带近平行的低波速异常条带,而西北侧和东南侧分别分布有高波速异常条带,各向异性快波方向近乎沿断裂带走向,可能由于上地幔热物质沿郯庐断裂带上涌形成低速异常后断裂带发生左旋平移运动所致.华北盆地内上地幔顶部Pn波速度结构和各向异性的明显变化,反映华北克拉通破坏过程中经历了地幔热物质上涌、莫霍面隆升以及岩石圈拆沉等复杂构造变形. 相似文献
9.
Research on the dynamics of the South China Sea opening:Evidence from analogue modeling 总被引：15，自引：1，他引：15
SUN Zhen ZHOU Di ZHONG Zhihong XIA Bin QIU Xuelin ZENG Zuoxun JIANG Jianqun 《中国科学D辑(英文版)》2006,49(10):1053-1069
Independent of Indochina extrusion, the South China Sea experienced a process from passive continental rifting to marginal sea drifting. According to the fault patterns in the Beibu Gulf basin and the Pearl River Mouth basin, the continental rifting and early spreading stage from 32 to 26 Ma were controlled by extensional stress field, which shifted clockwise from southeastward to south southeastward. From 24 Ma on, the sea spread in NW-SE direction and ceased spreading at around 15.5 Ma. Integrated geological information with the assumption that the South China Sea developed along a pre-Cenozoic weakness zone, we did analogue experiments on the South China Sea evolu- tion. Experiments revealed that the pre-existing weakness zone goes roughly along the uplift zone between the present Zhu-1 and Zhu-2 depression. The pre-existing weakness zone is composed of three segments trending NNE, roughly EW and NEE, respectively. The early opening of the South China Sea is accompanied with roughly 15° clockwise rotation, while the SE sub-sea basin opened with SE extension. Tinjar fault was the western boundary of the Nansha block (Dangerous Ground), while Lupar fault was the eastern boundary of the Indochina, NW-trending rift belt known as Zengmu basin developed between above two faults due to block divergent of Indochina from Nansha. In the experiment, transtensional flower structures along NW-trending faults are seen, and slight inversion occurs along some NE-dipping faults. The existence of rigid massifs changed the orientations of some faults and rift belt, and also led to deformation concentrate around the massifs. The rifting and drifting of the South China Sea might be caused by slab pull from the proto South China Sea subducting toward Borneo and/or mantle flow caused by India-Asia collision. 相似文献
10.
V. V. Spichak 《Izvestiya Physics of the Solid Earth》2006,42(1):60-68
Various hypotheses of the geoelectric structure of the Transcaucasian region reflecting a priori geological and geophysical information and data from profile magnetotelluric (MT) soundings are analyzed. These hypotheses are used to construct simplified 3-D models of electrical conductivity differing in the patterns of the shallow and deep structure of the region. Numerical modeling of MT fields is performed. Comparative analysis of its results indicates that the most probable conductivity model consistent with the available data is a model involving a high-conductivity channel connecting the Black and Caspian seas. 相似文献
11.
Trends in mariculture development in Russia are studied. Global experience in controlling the after-effects of fish farm operation for the marine environment are analyzed. Statistical procesing of the data of field oceanographic surveys, carried out in 1957–1989 in a one-mile coastal zone in the Eastern Black Sea, was implemented. Results of studying natural factors determining the input of organic pollutants and the rate of their biogeochemical transformation, as well as the conditions of sediment accumulation and water aeration in the Russian part of the Black Sea coast were systematized. It was found that powerful natural self-purification mechanisms of aquatic environment act along the North Caucasian coast of the Black Sea. The conclusion on almost complete environmental safety of a marine underwater fish farm, which is under construction in the Sochi Region (Khosta Settl.) was made. Attention is attracted to the need to take into account the high hydrodynamic activity in the investigated region in the process of fixing keepnets on anchors while anchoring the fish farm. 相似文献
12.
It is established that the formation and evolution of the anaerobic zone of the Black Sea are associated with the beginning and development of the most recent salinization of the sea and the formation of pycnocline at intermediate depths; a deterioration of deep-water aeration and the formation of anaerobic conditions in deeper layers; the rate of sulfate-reduction first in the near-bed layer and later, as oxygen is depleted, in the water mass. Formalization of these processes based on refined present-day data on water balance enabled the reproduction of profiles of water salinity and vertical-exchange coefficient for different formation stages of salinity regime in the Black Sea. The vertical distribution of oxygen and hydrogen sulfide is reconstructed, and the rates of oxygen consumption in water column and sulfate reduction in the near-bed layer and at the upper boundary of the anaerobic zone are evaluated in numerical experiments. The obtained data show the transformation of the vertical distribution of oxygen and hydrogen sulfide in the Black Sea from the beginning of its most recent salinization to the present-day state. It is shown that the anaerobic zone rises from 2000 to 200 m within 500–600 years (in the period 3.9–4.5 Ka from the beginning of water exchange through the Bosphorus), and next the upper boundary of the anaerobic zone slowly ascends up to its present-day position (130–180 m). Mathematical modeling was used to evaluate the fluxes of oxygen and hydrogen sulfide at different formation stages of the anaerobic zone in the sea.__________Translated from Vodnye Resursy, Vol. 32, No. 3, 2005, pp. 307–321.Original Russian Text Copyright © 2005 by Leonov, Shaporenko. 相似文献
13.
Donna J. Shillington Nicky White Timothy A. Minshull Glyn R.H. Edwards Stephen M. Jones Rosemary A. Edwards Caroline L. Scott 《Earth and Planetary Science Letters》2008,265(3-4):360-378
Subsidence analysis of the eastern Black Sea basin suggests that the stratigraphy of this deep, extensional basin can be explained by a predominantly pure-shear stretching history. A strain-rate inversion method that assumes pure-shear extension obtains good fits between observed and predicted stratigraphy. A relatively pure-shear strain distribution is also obtained when a strain-rate inversion algorithm is applied that allows extension to vary with depth without assuming its existence or form. The timing of opening of the eastern Black Sea, which occupied a back-arc position during the closure of the Tethys Ocean, has also been a subject of intense debate; competing theories called for basin opening during the Jurassic, Cretaceous or Paleocene/Eocene. Our work suggests that extension likely continued into the early Cenozoic, in agreement with stratigraphic relationships onshore and with estimates for the timing of arc magmatism. Further basin deepening also appears to have occurred in the last ～ 20 myr. This anomalous subsidence event is focused in the northern part of the basin and reaches its peak at ～ 15–10 Ma. We suggest that this comparatively localized shortening is associated with the northward movement of the Arabian plate. We also explore the effects of paleowater depth and elastic thickness on the results. These parameters are controversial, particularly for deep-water basins and margins, but their estimation is a necessary step in any analysis of the tectonic subsidence record stored in stratigraphy. 相似文献
14.
利用中国、韩国和ISC台站的地震走时数据反演了黄海地区的地壳P波速度结构,对比重力异常和断裂体系、Pn波速度及其各向异性,分析了不同地球物理异常的相互关系以及黄海东部和西部的结构差异,为厘定黄海东部断裂暨中朝—扬子块体的拼合边界提供了新的信息.反演结果表明,北黄海和南黄海西部具有沉积盆地的地壳结构特征,P波速度明显偏低且深度较大,说明盆地内部沉积层较厚、沉降幅度较大,以北黄海、南黄海海州湾和苏北—南黄盆地最为突出.南黄海中部、胶东半岛、辽东半岛和朝鲜半岛显示出构造隆起区的地壳速度特征,其中南黄海中部的高速异常具有北东方向的伸展痕迹,与胶东地区的区域构造走向趋于一致,但是与朝鲜半岛的高速异常并不相连,其间存在明显的分界.据此推测南黄海与朝鲜半岛之间可能存在一个近南北方向的深断裂——黄海东部断裂,至于该断裂是否可以作为中朝—扬子块体在海区的拼合边界,尚需获取黄海东部及朝鲜半岛更详细的相关资料提供依据. 相似文献
15.
《中国科学D辑(英文版)》2008,(Z2)
The Tan-Lu fault zone across the eastern margin of the Cenozoic basins offshore the Bohai Sea is a NNE-trending right-lateral strike-slip fault system developed in the Cenozoic basin cover. It cuts through NE-to NNE-striking major extensional faults that controlled the formation of Paleogene basins. Recent petroleum exploration indicates that Cenozoic structural activities of the Tan-Lu fault system have directly or indirectly affected oil and gas distribution offshore the Bohai Sea. As part of a deep fault zone the Tan-Lu fault zone has been activated since the Oligocene,and obviously affected the tectonic evolution of offshore Bohai basins since then. The formation of Paleogene rift basins offshore the Bohai Sea has utilized the pre-existing structural elements of the Tan-Lu fault zone that developed in the late Mesozoic. 相似文献
16.
潮汕坳陷MZ-1井揭示的中生界为深入分析南海北部晚中生代的构造演化提供了关键性的资料.基于MZ-1井的标定,开展了系统的地震剖面构造-地层解释,在中生代地层内识别出Tm30区域性不整合面,同位素定年确定该界面发育于早白垩世末至晚白垩世初,落实了潮汕坳陷上白垩统的分布.此外,在研究区西南部识别出大型的兴宁—东沙逆冲推覆带,主要由多条NW—SE向延伸、西倾的叠瓦状逆冲断层及其伴生的不对称褶皱组成,其明显控制了上白垩统厚度分布.由此可见,上白垩统构造层不具有张裂盆地的典型特征,因此南海北部主动陆缘向被动陆缘的转换不会早于晚白垩世末.研究认为,在南海地区特提斯残留洋盆关闭的总背景下,在约80 Ma时期,南海地块与华南陆块强烈碰撞挤压,在靠近碰撞带处的礼乐滩、潮汕坳陷西南部形成褶皱冲断构造体系,进而控制了潮汕坳陷晚白垩世周缘前陆盆地的发育. 相似文献
17.
渤海位于渤海湾盆地的东部,是我国华北地区新构造活动最强烈的地区之一,盆地内的沉积盖层(N-Q)中断裂极为发育。许多研究者从不同角度对渤海新构造进行过研究,但认识不一。笔者基于以往的工作,对该区新构造作了较深入的分析,确定渤海新构造运动起始于中新世晚期(12~10Ma BP)。从三维空间分析盖层断裂,并按其与盆地基底断裂的成因关系,将新构造活动的断裂分为继续活动断裂和新生断裂,并划分出3条主要的新构造活动断裂带:北东(偏北)向营口-潍坊断裂带北段是继续活动构造带,右旋逆平移活动,活动性弱;北西西向北京-蓬莱断裂带亦为继续活动构造带,左旋正平移活动,活动性较强;北东向庙西北-黄河口断裂带为新生构造带,右旋平移活动,活动性强。后两者组成一对以庙西北-黄河口断裂带为主的偏共轭活动构造带,该区域地震活动与之关系密切。最后探讨了渤海地区新构造期北东东-南西西至近东西向水平挤压的构造应力场及其与新构造活动断裂带发育的关系。提出新构造应力场与古近纪盆地裂陷阶段的应力场截然不同,新构造为地壳共轭剪切破裂系统,古近纪盆地构造是发育于地壳上部的伸展构造系统,这是两期不同体制的构造系统。 相似文献
18.
The results of monitoring performed by Southern Research Institute of Marine Fisheries and Oceanography (YugNIRO) in 1990–1998 in the course of dredging operations with dumping in the Black Sea of soils dredged in Kerch Strait are analyzed. The study covered the soil physical properties and particle size distribution; the extent of the soil pollution by heavy metals, oil products, and organochlorine compounds; the amounts of such pollutants delivered into the sea with these soils; the extent of pollution of water and bottom sediment in the zone of soil dumping offshore Kerch Strait. The amounts of pollutants entering the Black Sea as a result of soil dumping are compared with those entering the sea from other pollutant sources, and the extent of environmental pollution in the dumping zone is compared with the background level of the sea pollution. The admissible rates of soil dumping are estimated, and potential consequences of this process are predicted. 相似文献
19.
20.
南海北部洋陆转换带是近年来基础科学研究和深水油气勘探热点地区.本文在详细研究南海北部洋陆转换带新采集的二维长电缆深反射地震剖面资料的基础上,采用挠曲悬臂梁模型和挠曲回剥模型算法,分别计算了上地壳、地壳和整个岩石圈拉伸系数,实验结果表明,研究区洋陆转换带盆地岩石圈发生了与深度相关的拉伸变形过程,并且随深度增加,拉伸量逐渐变大,该结果解释了南海北部盆地裂后阶段发生的加速沉降现象.同时,本文结合南海北部洋陆转换带盆地发育过程的特点,将洋陆转换带盆地演化划分为陆内裂陷阶段、裂后热沉降阶段和裂后加速沉降阶段.本研究将有助于认识南海北部深水盆地特征,并对大陆边缘动力学研究和陆缘盆地深水区油气勘探有重要意义. 相似文献