临邑洼陷圈闭类型及成因研究          下载免费PDF全文

段双国  高志卫  王顺华 《山东国土资源》2003,19(Z1):56-61

临邑洼陷是一个含油气层系较多,结构复杂的复式油气聚集区。本文重点介绍了临邑洼陷圈闭的类型及其成因,从圈闭角度对临邑洼陷油气藏的形成进行了概述,对临邑洼陷下步的勘探工作方向进行了分析。  相似文献   

River sediments,great floods and centennial‐scale Holocene climate change     

Mark G. Macklin  John Lewin 《第四纪科学杂志》2003,18(2):101-105

A new analysis of all 346 published ¹⁴C dated Holocene alluvial units in Britain offers a unique insight into the regional impacts of global change and shows how surprisingly sensitive British rivers have been to relatively modest but repeated changes in climate. Fourteen major but probably brief periods of flooding are identified bracketed within the periods 400–1070, 1940–3940, 7520–8100 and at ca. 10 420 cal. yr BP. There is a strong correspondence between climatic deteriorations inferred from mire wet shifts and major periods of flooding, especially at ca. 8000 cal. yr BP and since ca. 4000 cal. yr BP. The unusually long and complete British record also demonstrates that alterations in land cover have resulted in a step change in river basin sensitivity to variations in climate. This has very important implications for assessing and mitigating the impact of increasing severe flooding. In small and medium‐sized river basins land use is likely to play a key role in either moderating or amplifying the climatic signal. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

The Upper Pleistocene to Holocene sediments on the Mediterranean island of Lampedusa (Italy)     

C. Giraudi 《第四纪科学杂志》2004,19(6):537-545

The island of Lampedusa lies on the northern edge of the African continental shelf, but during some Quaternary marine lowstands it was joined to the African continent. The study and dating of the aeolian, alluvial, detrital sediments, calcareous crusts and speleothems have established that the climatic–environmental variations recorded on the island can be related chronologically to those known for northern Libya, Tunisia and the Italian peninsula. During the Last Glacial Maximum, phases of Saharan dust accumulation on Lampedusa occurred, and were coeval with dust accumulation in crater lakes and on high mountains in central‐southern Italy, and with phases of glacial advance in the Apennines and in the Alps. During the late Holocene, accumulation of Saharan dust on Lampedusa occurred but there was little accumulation of dust on the northern side of the Mediterranean Sea. With the new data from Lampedusa, it is possible to envisage two different scenarios of atmospheric circulation relating to the Last Glacial Maximum and to the late Holocene. During the Last Glacial Maximum, southerly atmospheric circulation brought rainfall to the southern slopes of the Alps and to the Apennines. During the late Holocene, a prevalent westerly atmospheric circulation became established in the northern Mediterranean. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Sea‐surface temperature and salinity changes in the northwest Pacific since the Last Glacial Maximum     

Tadamichi Oba  Masafumi Murayama 《第四纪科学杂志》2004,19(4):335-346

The oxygen isotope records of both benthic and planktonic Foraminifera in five piston cores, collected from the region between the Oyashio and Kuroshio Currents near Japan, clearly show the marked latitudinal shifts of these two currents during the past 25 kyr. Under the present hydrographic condition, a clear relationship between the sea‐surface temperature (SST) and oxygen isotope differences from benthic to planktonic Foraminifera is observed in this region. Using this relationship, we find decreased SSTs of 12–13°C (maximum 15°C) in the southernmost core site at the Last Glacial Maximum (LGM), indicating the Oyashio Current shifted southward. The SSTs at the southern two core sites abruptly increased more than 10°C at 10–11 ka, suggesting the Kuroshio Current shifted northward over these sites at 10–11 ka. In contrast, the northern two core sites have remained under the influence of the cold Oyashio Current for the past 25 kyr. With the reasonable estimate of bottom‐water temperature decrease of 2.5°C at the LGM, the SSTs estimated by this new method give exactly the same SST values calculated from Mg/Ca ratio of planktonic Foraminifera, allowing palaeosea‐surface salinities to be reconstructed. The result suggests that the ice volume effect was 1.0 ± 0.1‰ at the LGM. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Holocene activity of the Scilla Fault, Southern Calabria: Insights from coastal morphological and structural investigations     

L. Ferranti  C. Monaco  D. Morelli  F. Antonioli  L. Maschio 《Tectonophysics》2008,453(1-4):74

Integration of on-land and offshore geomorphological and structural investigations coupled to extensive radiometric dating of co-seismically uplifted Holocene beaches allows characterization of the geometry, kinematics and seismotectonics of the Scilla Fault, which borders the eastern side of the Messina Strait in Calabria, Southern Italy. This region has been struck by destructive historical earthquakes, but knowledge of geologically-based source parameters for active faults is relatively poor, particularly for those running mostly offshore, as the Scilla Fault does. The  30 km-long normal fault may be divided into three segments of  10 km individual length, with the central and southern segments split in at least two strands. The central and northern segments are submerged, and in this area marine geophysical data indicate a youthful morphology and locally evidence for active faulting. The on-land strand of the western segment displaces marine terraces of the last interglacial (124 to 83 ka), but seismic reflection profiles suggest a full Quaternary activity. Structural data collected on bedrock faults exposed along the on-land segment provide evidence for normal slip and  NW-SE extension, which is consistent with focal mechanisms of large earthquakes and GPS velocity fields in the region. Detailed mapping of raised Holocene marine deposits exposed at the coastline straddling of the northern and central segments supplies evidence for two co-seismic displacements at  1.9 and  3.5 ka, and a possible previous event at  5 ka. Co-seismic displacements show a consistent site value and pattern of along-strike variation, suggestive of characteristic-type behaviour for the fault. The  1.5–2.0 m average co-seismic slips during these events document M_e  6.9–7.0 earthquakes with  1.6–1.7 ka recurrence time. Because hanging-wall subsidence cannot be included into slip magnitude computation, these slips reflect footwall uplift, and represent minimum average estimates. The palaeoseismological record based on the palaeo-shorelines suggests that the last rupture on the Scilla Fault during the February 6, 1783 M_w = 5.9–6.3 earthquake was at the expected time but it may have not entirely released the loaded stress since the last great event at  1.9 ka. Comparison of the estimated co-seismic extension rate based on the Holocene shoreline record with available GPS velocities indicates that the Scilla Fault accounts for at least  15–20% of the contemporary geodetic extension across the Messina Strait.  相似文献   

Microbially mediated carbonates in the Holocene deposits from Sarliève, a small ancient lake of the French Massif Central, testify to the evolution of a restricted environment     

JEAN-GABRIEL BRÉHÉRET  AGATHE FOURMONT  JEAN-JACQUES MACAIRE  PHILIPPE NÉGREL† 《Sedimentology》2008,55(3):557-578

Both the mineralogy and facies of lacustrine bio‐induced carbonates are controlled largely by hydrological factors that are highly dependent upon climatic influence. As such they are useful tools in characterizing ancient lake environments. In this way, the study of the sedimentary record from the small ancient Sarliève Lake (Limagne, Massif Central, France) aims to reconstruct the hydrological evolution during the Holocene, using petrographical, mineralogical and geochemical analyses. The fine‐grained marls, mainly calcitic, display numerous layers rich in pristine Ca‐dolomite, with small amounts of aragonite, which are clearly autochthonous. As these minerals are rather unusual in the temperate climatic context of western Europe, the question arises about their forming conditions, and therefore that of the lacustrine environment. Ca‐dolomite prevails at the base of the sequence as a massive dolomicrite layer and, in the middle part, it builds up most of the numerous laminae closely associated with organic matter. Scanning electron microscope observations reveal the abundance of tiny crystals (tens to hundreds of nanometres) mainly organized as microspheres looking like cocci or bacilli. Such a facies is interpreted as resulting from the fossilization of benthic microbial communities by dolomite precipitation following organic matter consumption and extracellular polymeric substance degradation. These microbial dolomites were precipitated in a saline environment, as a consequence of excess evaporation from the system, as is also suggested by their positive ?¹⁸O values. The facies sequence expresses the following evolution: (i) saline pan, i.e. endorheic stage with a perennial lowstand in lake level (Boreal to early Atlantic periods); (ii) large fluctuations in lake level with sporadic freshening of the system (Atlantic); (iii) open lake stage (sub‐boreal); and (iv) anthropogenic drainage (sub‐Atlantic).  相似文献   

太湖平原西北部全新世古河道沉积特征及环境演变   总被引：1，自引：0，他引：1  

舒军武  王伟铭  陈晔 《地层学杂志》2008,32(2):146-152

粒度、磁化率定量数据分析在判明第四系沉积物的来源、识别沉积分异作用、解译古沉积相和环境方面有着重要作用。对太湖平原西北部卜弋桥ZK01钻孔上部全新统如东组进行了粒度和磁化率测试分析,结合该孔孢粉成果,揭示研究区全新世古河道沉积环境和气候明显经历了3个阶段:1)11000—9500cal.aBP,沉积物主要由粉砂组成,粒度证据表明水动力条件较强,孢粉证据显示该阶段气候较温暖湿润;2)9500—3900cal.aBP,沉积物砂组分含量大幅增加,粒度资料显示古河道水动力明显增强,孢粉植被表明该时期处于全新世大暖期,气候暖湿稳定;3)3900cal.aBP以来,粉砂组分在沉积物中占优势,粒度结果表明该阶段水动力显著减弱,孢粉资料和磁化率证据表明研究区自该阶段特别是后期以来逐步出现了明显的人类活动迹象。  相似文献   

新疆塔中南坡奥陶系的地层缺失和沉积相变化   总被引：4，自引：0，他引：4  

蔡习尧  李越 《地层学杂志》2008,32(4)

按照奥陶系内部6个组沉积的时间片段拟定塔中南坡不同区块存在不同程度的缺失。部分关键层段的牙形石和几丁虫组合特征证明一间房组和恰尔巴克组在塔中部分井区是存在的,但恰尔巴克组的分布范围最狭窄。总体上,塔中南坡隆起区地层缺失较多,古城墟隆起基本完整。据缺失状况和岩相展布,显示塔中南坡的沉积单元具有由东往西迁移的特征,且各时段迁移的距离与速度存在较大差异。  相似文献   

阿尔金断裂昌马大坝—宽滩山段全新世活动特征   总被引：9，自引：2，他引：7  

陈柏林  刘建生  王春宇  张永双  刘建民  董诚  吴乃芬 《地质学报》2008,82(4):433-440

阿尔金断裂是我国西部著名的巨型走滑断裂带之一,也是全新世活动断裂和发震断裂。该断裂昌马大坝—宽滩山段运动方式为以左行走滑占主导,伴有弱的垂直运动;在距今2.7ka以来发生过明显的新构造活动（和地震）。在沙坪—宽滩山段全新世左行走滑位移速率为0.9～2.2mm/a,明显低于阿尔金断裂东段昌马大坝以西地区4～5mm/a和中西段9～11mm/a的位移速率。阿尔金断裂东段在肃北和昌马大坝出现二次位移速率的锐减,锐减的部分分别转化为海原活动断裂西段（党河南山断裂）和祁连山北缘活动断裂西段的左行走滑和逆冲,且在位移速率数值上相互之间具有非常好的对应性。阿尔金断裂在肃北位移速率减少部分（4.6mm/a）与海原活动断裂西段（党河南山断裂）的位移速率（4～5mm/a）非常接近,同样阿尔金断裂在昌马大坝位移速率减少部分（3.2mm/a）与祁连山北缘活动断裂的位移速率（3.0mm/a）也非常接近。  相似文献   

Planktonic foraminifers in the southern Bering Sea: Changes in composition and productivity during the Late Pleistocene-Holocene     

M. P. Chekhovskaya  I. A. Basov  A. G. Matul  T. A. Khusid  S. A. Gorbarenko 《Stratigraphy and Geological Correlation》2008,16(3):328-342

Taxonomic composition and distribution of planktonic foraminifers are studied in section of Core GC-11 that penetrated through Upper Quaternary sediments of the Bowers Ridge western slope, the southern Bering Sea. As is shown, structure of foraminiferal assemblage and productivity have varied substantially during the last 32000 calendar years in response to changes in surface water temperatures and water mass circulation in the northern part of the Pacific, the Bering Sea included. The productivity was maximal during deglaciation epoch, being notably lower in the Holocene and minimal at the glaciation time.  相似文献