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1.
The Patras, Corinth, and northern Saronic gulfs occupy a 200-km-long, N120° trending Pleistocene rift zone, where Peloponnese drifts away from mainland Greece. The axes of Patras and Corinth basins are 25 km apart and linked by two transfer-fault zones trending N040°. The older one defines the western slope of Panachaïkon mountain, and the younger one limits the narrow Rion–Patras littoral plain. Between these two faults, the ca. 4-km-thick Rion–Patras series dips 20–30° SSW. It is part of the Patras gulf synrift deposits, which pile in an asymmetric basin governed by a fault dipping ca. 25–35° NNE, located in the southern Gulf of Patras. Mapping of this fault to the east in northern Peloponnese shows that it is an inactive north-dipping low-angle normal fault (0° to 30°N), called the northern Peloponnese major fault (NPMF). The structural evolution of the NPMF was different in the gulfs of Patras and Corinth. In the Gulf of Patras, it is still active. In northern Peloponnese, footwall uplift and coeval southward tilting flattened the fault and locked its southern part. Steeper normal faults formed north of the locked area, connecting the still active northern part of the NPMF to the surface. After several locks, the presently active normal faults (Psathopyrgos, Aigion, Helike) trend along the southern shore of the Gulf of Corinth. This migration of faults caused the relative 25 km northward shift of the Corinth basin, and the formation of NE–SW trending transfer-faults between the Corinth and Patras gulfs.  相似文献   

2.
In this paper, we investigate normal fault patterns produced by the sliding motion along a gently dipping normal fault by using analogue model tests and numerical modeling. The motivation for this study was offered by microseismic test data that indicate the existence of an active low-angle shear zone at a depth of 9–11 km in the extensional region of high seismic activity of the Gulf of Corinth (Greece). Both modeling techniques seem to support the hypothesis that the system of high-angle normal faults that are responsible for the final asymmetrical graben formation initiate at the tip of the active basal detachment nearest to the free surface. The normal faults propagate upwards with progressive sliding of the inclined basal plane, resulting in a first phase of symmetrical graben configuration that is delimited by a main synthetic fault and an antithetic fault forming a Rankine zone. Subsequent sliding on the inclined base induces a family of secondary antithetic normal faults, which are responsible for the asymmetry of the failure pattern and the diffusive character of deformation in that area. Shear deformation is more intense and localized along the synthetic normal fault than along the antithetic faults. Elaboration on the analogue test results has led to the phenomenological relations among four main parameters that describe the geometry of grabens, namely, (i) the width and (ii) the maximum subsidence of the graben, (iii) the dip angles of the conjugate normal faults, and (iv) the amount of sliding along the low-angle normal fault. However, analogue models do not produce the system of synthetic faults that is observed in the Gulf of Corinth. The effects of both friction angle variation along the detachment base and of the constitutive behavior of the model material on the configuration of the final structural pattern were also studied with a series of numerical continuum models. It was found that (a) the fault pattern of the Gulf of Corinth may be reproduced with either a strain-softening material with low elastic modulus or a constant strength material, and (b) two consecutive grabens, such as those of Gulfs of Corinth and Evia, may also be reproduced by an appropriate combination of variation of dip and frictional properties along the hypothesized detachment zone.  相似文献   

3.
The Gulf of Corinth is a graben, which has undergone extension during the Late Quaternary. The subsidence rate is rapid in the currently marine part whereas uplift now affects a large part of the initially subsiding area in the North Peloponnese. In this paper, we document the rates of subsidence/uplift and extension based on new subsurface data, including seismic data and long piston coring in the deepest part of the Gulf. Continuous seismic profiling data (air gun) have shown that four (at least) major oblique prograding sequences can be traced below the northern margin of the central Gulf of Corinth. These sequences have been developed successively during low sea level stands, suggesting continuous and gradual subsidence of the northern margin by 300 m during the Late Quaternary (last 250 ka). Subsidence rates of 0.7–1.0 m kyr− 1 were calculated from the relative depth of successive topset to foreset transitions. The differential total vertical displacement between the northern and the southern margins of the Corinth graben is estimated at about 2.0–2.3 m kyr− 1.

Sequence stratigraphic interpretation of seismic profiles from the basin suggests that the upper sediments (0.6 s twtt thick) in the depocenter were accumulated during the last 250 ka at a mean rate of 2.2–2.4 m kyr− 1. Long piston coring in the central Gulf of Corinth basin enabled the recovery of lacustrine sediments, buried beneath 12–13.5 m of Holocene marine sediments. The lacustrine sequence consists of varve-like muddy layers interbedded with silty and fine sand turbidites. AMS dating determined the age of the marine–lacustrine interface (reflector Z) at about 13 ka BP. Maximum sedimentation rates of 2.4–2.9 m kyr− 1 were calculated for the Holocene marine and the last glacial, lacustrine sequences, thus verifying the respective rates obtained by the sequence stratigraphic interpretation. Recent accumulation rates obtained by the 210Pb-radiometric method on short sediment box cores coincide with the above sedimentation rates. Vertical fault slip rates were measured by using fault offsets of correlated reflector Z. The maximum subsidence rate of the depocenter (3.6 m kyr− 1) exceeds the maximum sedimentation rate by 1.8 m kyr− 1, which, consequently, corresponds to the rate of deepening of the basin's floor. The above rates indicate that the 2.2 km maximum sediment thickness as well as the 870 m maximum depth of the basin may have formed during the last 1 Ma, assuming uniform mean sedimentation rate throughout the evolution of the basin.  相似文献   


4.
青藏铁路风火山段晚第四纪断裂活动分析   总被引：2，自引：2，他引：0  
地表地质调查发现,第四纪期间在风火山逆冲-褶皱构造带以发生近东西向的伸展变形为特征。在该构造带中形成切割早期近东西向挤压变形构造带、指示近东西向伸展变形、整体沿北60°东向展布的二道沟断陷盆地。断裂活动的地质、地貌证据表明,控制该盆地晚第四纪断陷的主边界断裂位于其北缘,是一条断续延伸达24 km左右、可能兼具左旋走滑性质的正断层。根据该区晚第四纪沉积物的分布和时代,并对断裂所错动的晚第四纪地质-地貌体进行初步的年代学分析,可以初步断定该断裂的晚第四纪垂直活动速率应该介于0.2~0.4 mm/a之间。  相似文献   

5.
We present a series of high-resolution seismic reflection lines across the Yizre'el valley, which is the largest active depression in Israel, off the main trend of the Dead Sea rift. The new seismic reflection data is of excellent quality and shows that the valley is dissected into numerous small blocks, separated by active faults. The Yizre'el valley is found to consist of a series of half grabens, rather than a single half graben, or a symmetrical graben. The faults are generally vertical and appear to have a dominant strike-slip component, but some dip-slip is also evident. A marked zone of compression near Megido is associated with the intersection of the two largest faults in the valley, the Carmel fault and the Gideon fault. Variable trend of the faults reflects the complexity of the local geology along the boundary between the wide NW–SE trending Farah–Carmel fault zone and the E–W trending basins and ranges in the Lower Galilee. This tectonic complexity is likely to result from a highly variable stress pattern, modified by the structures inside it. Normal faulting in the valley occurred at an early stage of its development as a tectonic depression. However, strike-slip motion on the Carmel fault, and possibly also on some of the other faults, appears to have started together with the onset of normal faulting. Earthquake hazard in the area appears to be uniform as faults are distributed throughout the Yizre'el valley.  相似文献   

6.
青藏高原中部第四纪左旋剪切变形的地表地质证据   总被引：7，自引：5，他引：2  
在青藏铁路的格尔木—拉萨段进行的活动断裂调查发现,在沱沱河—五道梁之间宽约150km的地段内发育了多条由北西西向次级断层左列分布构成的北西西向和北西向左旋张扭性断裂带,在断裂带之间则发育"S"型的北东向裂陷盆地和雁列分布的菱形裂陷盆地,盆地边界断裂也为左旋张扭性质。上述断裂带和裂陷带主要形成于第四纪,它们构成了宽约150km的不均匀的左旋简单剪切变形域,该变形域的整体活动性较弱,属于弱的不均匀剪切变形域。但其中的二道沟断陷盆地是个例外,该盆地边界断裂的垂直活动速率约为0 5mm/a,左旋活动速率介于0 8～1 0mm/a之间。而在整个左旋剪切变形带累计的左旋走滑速率不会超过6mm/a,它们所调节的昆仑山与唐古拉山之间的地壳南北缩短量也可能仅占总缩短量的15%～30%。上述弱剪切变形域与强烈左旋走滑的昆仑断裂系共同构成了高原中部的左旋剪切变形带,它们在印度板块与欧亚板块强烈碰撞的构造动力学背景下,起着调节青藏高原南北向缩短的重要作用。  相似文献   

7.
青藏高原新生代地堑构造研究中几个问题的讨论   总被引：6，自引：0，他引：6  
青藏高原新生代近南北走向地堑构造是高原现今最为显著的构造现象,对探讨青藏高原构造演化具有重要意义,也是现今高原研究的热点构造问题之一。针对目前地堑构造研究中存在的分布范围、形成时代和形成机制等关键问题,根据笔者新的研究和对以往研究资料综合分析认为,地堑构造广泛发育于喜马拉雅地体、冈底斯地体和羌塘地体,地堑构造形成于14～7Ma。地堑构造是高原地壳南北向强烈挤压短缩隆升之后,构造体制发生转变并在深部热动力学机制作用下快速隆升的结果,地堑构造标志着高原隆升作用由早期挤压短缩机制向晚期深部热动力机制的转变,并非高原隆升达到最大高度重力塌陷的标志。  相似文献   

8.
In this paper we expand over the whole of central Greece, the Moho map centered on the Gulf of Corinth from tomographic inversion of PmP traveltime profile data recorded by several tens of temporary stations. Our approach is based on Pn, Moho refracted waves, from a large regional earthquake recorded by both temporary stations and the permanent Hellenic network. The Moho map shows the large Moho depth under the Hellenides belt. It also highlights the shallower Moho domain towards the Aegean Sea south and east of the Corinth Gulf. The domain of shallow Moho is limited along a NE–SW prolongation ahead of the North Anatolian Fault, from the North Aegean Trough to the western tip of the Gulf of Corinth towards the Gulf of Patras. The Pn time-terms provide corrections for the permanent stations that can be used together with the 1D velocity–depth model for a first-order compensation of lateral heterogeneity and contribute to the accurate and fast location of earthquake hypocenters. As a test we relocated the 1995 Aigion earthquake in this way, using only the sparse data of the permanent stations. Hypocentral coordinates then shift close to those derived by a dedicated dense array deployed after the earthquake, implying improvement of the routine location.  相似文献   

9.
青藏高原内部的近东西向伸展变形在藏南地区形成了一系列近南北向裂谷带,对其中最东端的错那-沃卡裂谷带南段错那-拿日雍错地堑调查结果表明,它是第四纪活动明显的半地堑式断陷盆地。控制该盆地发育的主边界断裂带是近南北走向、倾向东侧和长80～110km左右的盆地西缘正断层,是区域内N90°～92°E方向伸展变形的产物。断裂活动速率的多种估算结果表明,该断裂带百万年时间尺度的平均垂直活动速率介于0.2～0.9mm/a之间;MIS 8和MIS 6以来的断裂平均活动速率的合理估计值是0.6±0.2mm/a;但末次冰期盛冰阶以来的断裂平均活动速率明显增加,介于1.0～2.1mm/a之间,合理的估计值为1.3±0.3mm/a,末次冰盛期以来断裂垂直活动速率的增加极可能是该断裂带进入地震丛集期的反映。该地堑近于严格的南北走向及其与当雄-羊八井地堑相似的活动强度,指示了下地壳物质侧向流动所产生的纵向拉张作用最有利于该区近南北向裂谷带的形成。  相似文献   

10.
One of the puzzling features of the southern end of the Rhine graben is the Dinkelberg-Tabular Jura block on the eastern shoulder of the graben. It is dissected by a large number of faults, the most notable ones forming a field of narrow little grabens and half-grabens whose bordering faults converge at the level of the Middle Triassic evaporites, which points to décollement at that horizon. The little grabens were traditionally considered to be of Oligocene age, coeval with the main taphrogenesis of the Rhine graben. Two hypotheses were offered for their formation, one ascribing them to extension on the extrados of large basement folds, the other to gravity sliding on paleoslopes. Recent field work uncovered overwhelming evidence for an Eocene age of the little grabens, the time of the initial phase of Rhine graben formation. At that time there were neither large basement folds nor paleoslopes of any significance, and therefore the two hypotheses offered until now do not work. However, the map-view pattern of the field of faults offers a somewhat unusual way out of the dilemma. This pattern is most prominently displayed in the Dinkelberg area north of the Rhine. There a lane of narrow décollement grabens with a mean NNE strike is confined within the NW- striking Dinkelberg graben, which is much wider and rooted in the basement. It is also very shallow, with a subsidence on the order of 100 m. The lane of décollement grabens forms a dextral en-échelon pattern with respect to the Dinkelberg graben, suggesting stretching of the post-evaporite sequence above a basement essentially extended by strike slip. This model, though not as clearly expressed, is also compatible with the data in the rest of the Dinkelberg-Tabular Jura block. It also fits surprisingly well a theoretical model by Withjack and Scheiner (1982) that predicts a dominance of strike-slip in the marginal area of a system consisting of extension superimposed on doming.  相似文献   

11.
Extension in the Afar depression occurs on steeply dipping normal faults of many scales. An estimate for cumulative extension can be derived by summing the heave of these faults using digital topographic data, supplemented by field observations of fault dip. If it can be established that the distribution of faults exhibits self-similarity, an estimate of the contribution from faults too small to appear on the digital imagery can be incorporated into the integrated estimate for cumulative extension. A field study of faulting was undertaken within the Dobe and Guma grabens of Central Afar. A fractal dimension of 0.48 was obtained for the measured population of fault throws (n = 92) in 3 traverses totaling 42 km, a value interpreted to represent the dominant contribution to extension from faults with large throw. The local extension rate across Guma graben is estimated to be between 0.06 and 0.24 mm/year. The higher topographic position of the floor of Guma graben, relative to the sediment filled, adjacent floors of Dobe and Immino grabens is perhaps an indication of a slower rate of extension across Guma graben as compared to Dobe and Immino grabens, assuming they all initiated at the same time.  相似文献   

12.
S.C. Stiros 《Geoarchaeology》1998,13(7):731-741
Archaeological and biological evidence indicates that the approximate sea level position of A.D. 150–250, the period of construction of the ancient harbor of Aigeira (Gulf of Corinth, Greece), can be identified at the height of 4 m above present sea level. The exposed ancient structure permits a direct observation of harbor construction techniques of the Roman period and study of the Late Holocene uplift of the area, characterized by a terrace staircase morphology. The harbor uplift is related to a series of earthquakes, one of which was possibly responsible for the demise of Aigeira in the 3rd century A.D. The corresponding rate of uplift is estimated to 2.4–3.0 mm/yr; it is consistent with available radiocarbon data and is among the highest uplift rates ever recorded in normal faulting environments. © 1998 John Wiley & Sons, Inc.  相似文献   

13.
The easternmost sector of the Gulf of Corinth, the Beotia area in Central Greece, is an area with active normal faults located between the two major rift structures of Central Greece, the Gulf of Corinth and the North Gulf of Evia. These active normal faults include WNW to E–W and NE to ENE-trending faults affect the landscape and generate basin and range topography within the Beotia. We study four normal fault zones and drainage basin geometry in the easternmost sector of the Gulf of Corinth to document the impact of active tectonics on the landscape evolution. Fault and drainage geometry are investigated based on detailed field mapping and high-resolution digital elevation models. Tectonic geomorphic analysis using several parameters of active tectonics provides information concerning the relative tectonic activity and fault growth. In order to detect areas of lateral stream migration that could indicate recent tectonic activity, the Transverse Topographic Symmetry Factor and the Asymmetry Factor are used to analyse drainage basin geometry in six large drainage basins and a drainage domain covering the study area. Our results show that vertical motions and tilting associated with normal faulting influence the drainage geometry and its development. Values of stream-gradient indices (SL) are relatively high close to the fault traces of the studied fault zones suggesting high activity. Mountain-front sinuosity (Smf) mean values along the fault zones ranges from 1.08 to 1.26. Valley floor width to valley height ratios (Vf) mean values along the studied fault zones range between 0.5 and 1.6. Drainage basin shape (BS) mean values along the fault zones range from 1.08 to 3.54. All these geomorphic parameters and geomorphological data suggest that the analyzed normal faults are highly active. Lateral fault growth was likely produced by primarily eastward propagation, with the WNW to E–W trending faults being the relatively more active structures.  相似文献   

14.
《International Geology Review》2012,54(14):1803-1821
ABSTRACT

In the Central Anatolia, the style of neotectonic regime governing the region has been a controversial issue. A tectonic study was carried out in order to contribute to this issue and better understand the neotectonic stress distribution and style of deformation in the west-southwest of the Konya region. From Middle Miocene to Recent time, Konya region was part of the Central Anatolia extensional province. The present-day topography in the west-southwestern part of Konya is characterized by alternating elongate grabens and horsts trending E-W and NW-SE. The grabens were developed upon low-grade metamorphic rocks of Palaeozoic and Mesozoic ages and ophiolite slabs of possibly Late Cretaceous age. The evolutionary history of grabens is episodic as evidenced by two graben infills; older and younger graben infills separated by an angular unconformity. The older infill consists of fluviolacustrine sequence intercalated with calc-alkaline lavas and pyroclastic rocks. This infill is folded; thrust faulted and Middle Miocene-Early Pliocene in age. The younger and undeformed basin fill comprises mainly of Plio-Quaternary conglomerates, sandstone-mudstone alternations of alluvial fan and recent basin floor deposits. Three major tectonic phases were differentiated based on the detailed mapping, morphological features and kinematic analysis. Approximately N-S trending extension began in the Middle Miocene-Early Pliocene in the region with the formation of E-W and NW-SE-trending grabens. Following NE-SW-directed compression which deformed the older basin fill deposits by folding and thrusting, a second period of ENE-WSW-trending extension began in the late Pliocene and continued to the present. The west-southwestern margin of the Konya depression is bounded by the Konya Fault Zone. It is an oblique-slip normal fault with a minor dextral strike-slip component and exhibits well-preserved fault slickensides and slickenlines. Recent seismicity and fault-related morphological features reveal that the Konya Fault Zone is an active neotectonic structure.  相似文献   

15.
杨文采 《地质论评》2014,60(5):945-961
本篇讨论大陆岩石圈拆沉、伸展与裂解作用过程。由于大陆岩石圈厚度大而且很不均匀,产生裂谷的机制比较复杂。大陆碰撞远程效应的触发,岩石圈拆沉,以及板块运动的不规则性和地球应力场方向转折,都可能产生岩石圈断裂和大陆裂谷。岩石圈拆沉为在重力作用下"去陆根"的作用过程,演化过程可分为大陆根拆离、地壳伸展和岩石圈地幔整体破裂三个阶段。大陆碰撞带、俯冲的大陆和大洋板块、克拉通区域岩石圈,都可能产生岩石圈拆沉。大陆岩石圈调查表明,拉张区可见地壳伸展、岩石圈拆离、软流圈上拱和热沉降;它们是大陆岩石圈伸展与裂解早期的主要表现。从初始拉张的盆岭省到成熟的张裂省,拆离后地壳伸展成复式地堑,下地壳幔源玄武岩浆侵位,断裂带贯通并切穿整个岩石圈,表明地壳伸展进入成熟阶段。中国东北松辽盆地和西欧北海盆地曾处于成熟的张裂省。岩石圈破裂为岩浆侵位提供了阻力很小的通道网。岩浆侵位作用伴随岩石圈破裂和热流体上涌,成熟的张裂省可发展成大陆裂谷。多数的大陆裂谷带并没有发展成威尔逊裂谷带和洋中脊,普通的大陆裂谷要演化为威尔逊裂谷带,必须有来自软流圈的长期和持续的热流和玄武质岩浆的供应。威尔逊裂谷带岩石圈地幔和软流圈为地震低速带,其根源可能与来自地幔底部的地幔热羽流有关。  相似文献   

16.
This study focuses on the detailed provenance evolution of young, syn- to post-orogenic extensional grabens in orogens like the Himalaya to trace the tectonic history of such late-stage basins, using the Neogene Thakkhola-Mustang Graben as a case study. The graben is situated within the Tibetan-Tethys zone and is filled with > 870 m of continental deposits of Miocene to Holocene age-. Based on logged sections within the predominantly alluvial to coarse-grained fluvial fill of the graben we investigated paleocurrent data and the petrology of sandstones and conglomerates including heavy minerals studies to interpret provenance and source areas in detail. Significant changes are recorded by slight differences in heavy mineral and pebble compositions.The sandstones can be classified as lithic greywackes, lithic arkoses and feldspathic litharenites. Sandstone, mudstone, quartzite and some granite clasts are dominant in conglomerates of the central part of the graben. Tetang Formation conglomerates of Miocene age comprise mostly clasts of Mesozoic rocks with an eastern provenance, consistent with measured paleocurrent directions. All paleocurrent data and compositional analyses of imbricated conglomerates of the Miocene–Pliocene Thakkhola Formation in the northeast of the graben suggest that clasts were derived from eastern source areas comprising mainly Mesozoic rocks whereas Paleozoic clasts of a western to northern source area predominate in the centre of the graben.Heavy mineral analysis indicates that tourmaline, staurolite, zircon, garnet and apatite constitute a significant proportion of the assemblages of all formations through time whereas epidote, andalusite, kyanite, chloritoid, hornblende, chrome-spinel, rutile and amphiboles are less common. These assemblages reflect in general stable minerals and low to high-grade metamorphic source rocks, and are principally controlled by reworking of older, passive margin sediments of the Tibetan-Tethys zone as indicated by provenance discrimination diagrams.Three successive stages in provenance evolution were recognized: (1) The Miocene Tetang Formation, characterized by higher kyanite values, corresponding to the Himalayan foreland evolution; (2) the Thakkhola Formation, characterized by granite clasts and significantly higher amounts of andalusite, indicating source area expansion and erosion of the Mustang-Mugu granites to the northwest; (3) the Upper Pleistocene/Holocene Kaligandaki Formation, bearing higher amounts of epidote/klinozoisite and ophiolite and high-pressure/low temperature detritus as indicated by chrome spinel and blue amphiboles, derived from the north-lying Indus-Tsangpo suture zone. The change in source areas from the Miocene/Pliocene to the Late Pleistocene/Holocene is interpreted as a result of the evolution from an initial stage of high-angle normal faulting and collapse basin formation to a low-angle extensional detachment basin system.  相似文献   

17.
Experiments on extensional faulting were performed with semi-brittle talc-sand beds resting on a ductile clay base. The experiments show that the development of graben in the talc-sand beds is controlled by the deformation in the ductile basement. Graben-like structures form only when there is a non-uniform stretching in the basement. Uniform extension at the basement level fails to produce any such structures. Grabens initiate as large synclinal structures (sag). The sag is generated either by a downward flexing of the talc-sand bed on a ductile basement or by non ****-uniform thinning of beds. Listric master faults bounding the grabens intersect the basement at high angles. The master faults that initiate as curved shear planes rotate further with continued extension. At the initial stage, the graben structures are associated with normal drags, and with progressive deformation, drag patterns change from normal to a reverse one.  相似文献   

18.
长江源地区近南北走向的地堑构造是该区现今最为显著的构造现象,也是青藏高原迄今发现的同类构造发育的最北部地区。长江源地区地堑构造包括温泉、常错、当拉错纳玛和沱沱河4个规模较大的近南北向地堑。断层年代学和断陷盆地沉积作用研究结果表明,研究区伸展变形至少自中新世末—上新世初就已开始,对长江源地区现今的地貌格局、水系型式具有显著的制约作用。长江源区主要水系是沿南北走向的地堑构造和正断层侵蚀发育而成的。青藏高原新生代伸展地堑构造是高原经历早期地壳强烈缩短变形之后,在深部动力学机制作用下快速隆升的产物。  相似文献   

19.
Down‐faulting at the north‐west margins of the Gulf of Aqaba is inferred to have triggered a catastrophic sedimentary event at 2.3 ka that killed the Elat fringing coral reef. Whereas segments of the Holocene reef were perfectly fossilized and preserved beneath a veneer of siliciclastic sediments, other segments were abraded, settled by nomads, and later re‐submerged under 4 m of water. Repeated damage triggered by down‐throwing earthquakes degenerate the fringing reefs of the north‐west end of the gulf. Conversely, on the north‐eastern and southern parts of the gulf, where earthquakes uplift the margins, modern reefs are thriving, attached to uplifted fossil reef terraces. Therefore, coastal subsidence moderates the development of fringing coral reefs during the late Holocene sea‐level stand still.  相似文献   

20.
Rocks of the Ventersdorp Supergroup were deposited in a system of northeast trending grabens on the Kaapvaal Craton approximately 2.64 Ga ago contemporary with a continental collision between the Kaapvaal and Zimbabwe Cratons. We suggest that it was this collision that initiated the Ventersdorp rifting. Individual grabens strike at high angles toward the continental collision zone now exposed in the Limpopo Province where late orogenic left-lateral strike-slip faulting and anatectic granites are recognized. We relate the Ventersdorp rift province to extension in the Kaapvaal Craton associated with the collision, and see some analogy with such rifts as the Shansi and Baikal Systems associated with the current India-Asia continental collision.  相似文献   

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