大陆伸展,剥离断层和被动大陆边缘的演化     

任建业 《地质科技情报》1992,11(2):11-17

在岩石圈伸展过程中,剥离断层起着重要的作用。剥离断层作用的一个显著特点是所形成的伸展构造和伸展区隆升拗陷历史具有不对称性。伸展区剥离断层模式同样适用于被动大陆边缘的形成和演化。大陆开裂、洋盆形成后,洋盆两侧对应发育两种被动大陆边缘,即上盘边缘和下盘边缘。这两种大陆边缘具有互补的不对称性,本文详细介绍了其构造特征。  相似文献   

Dewatering and extensional deformation of the Shikoku Basin hemipelagic sediments in the Nankai Trough     

Cynthia J. Bray  Daniel E. Karig 《Pure and Applied Geophysics》1988,128(3-4):725-747

The Shikoku Basin hemipelagic sequence, which underlies the Nankai Trough wedge, S.W. Japan, thins by 50% between the outer edge of the trench wedge and DSDP Site 582, 14 km arcward. A sedimentation model, which incorporates changes in sedimentation rates with time and with distance from the trench wedge toe, indicates that 57% of the total thinning occurs as a result of temporally varying sedimentation rates and a time transgressive facies boundary between the trench wedge turbidites and the underlying hemipelagites. Burial-induced consolidation beneath the wedgeshaped turbiditic overburden, accounts for the remaining 43% of arcward thinning within the hemipelagic unit. Rapid dewatering, modeled as one-dimensional consolidation suggests that the excess pore water pressures are quite low during this progressive dewatering. Thus, high pore water pressures should not be assumed to occur universally in convergent margin settings. Normal faults and vein structures in the hemipelagites suggest near-horizontal extension in addition to vertical consolidation. The estimates of excess pore water pressures together with fault geometries and horizontal extensional strains, determined from the geometry of the subducting oceanic plate, can be used to constrain the stress conditions at failure. The expulsion of hot water from the rapidly dewatering sediments in the Nankai Trough may help to explain anomalously high heat flow in the central part of the trough.  相似文献   

Upper-plate magma-poor rifted margins: Stratigraphic architecture and structural evolution     

《Marine and Petroleum Geology》2016

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Crustal structure across the Grand Banks–Newfoundland Basin Continental Margin – I. Results from a seismic refraction profile     

K. W. Helen Lau  Keith E. Louden  Thomas Funck  Brian E. Tucholke  W. Steven Holbrook  John R. Hopper †  Hans Christian Larsen ‡ 《Geophysical Journal International》2006,167(1):127-156

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Seismic images and magnetic signature of the Late Jurassic to Early Cretaceous Africa–Eurasia plate boundary off SW Iberia     

M. Rovere  C. R. Ranero  R. Sartori†  L. Torelli  N. Zitellini 《Geophysical Journal International》2004,158(2):554-568

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Three-dimensional modelling of an isolated carbonate buildup (Triassic, Dolomites, Italy)   总被引：1，自引：0，他引：1  

Wolfgang Blendinger  Peter Brack†  Arne Kristoffer Norborg‡  Erik Wulff-Pedersen§ 《Sedimentology》2004,51(2):297-314

The Middle Triassic carbonate buildups of the Dolomites show facies similarities with mud mounds but display apparent architectural elements of flat‐topped carbonate platforms. In order to test whether the facies similarities to mounds are also reflected in the internal buildup architecture, a three‐dimensional modelling study of the Middle Triassic Monte Cernera buildup has been carried out. The Cernera buildup exhibits apparent geometries suggesting a mounded platform in the lower and uppermost part of the buildup, separated by an interval with apparent platform geometry and a retrogradational platform interior, which is difficult to explain with a flat top platform model. For this purpose, a number of three‐dimensional models were constructed using the three‐dimensional modelling programme petrel ^TM. Key geological horizons were constructed based on outcrop measurements, intermediate horizons were calculated in the modelling program, and the intersections of the modelled layers with a digital topography surface were displayed and compared with outcrop photographs. The models were refined stepwise until a best fit with the actual bedding architecture was achieved. The best fit model shows that the mounded geometries in the lower and uppermost part of the buildup are real architectural elements. The intermediate platform stage, about 1·5 km across, had probably retained a mounded top with a relief of up to 50 m, which is difficult to distinguish from an absolutely flat top, but necessary to explain the retrogradational platform interior. The present study shows that Monte Cernera was dominated by mounded geometries at all stages of platform development. The mounded geometry plus facies data suggest that the platform is a deep‐water accumulation, below the zone of intense wave energy, but within the photic zone. The Cernera represents a tropical buildup type, which did not have the capacity to grow into continuously wave‐swept environments because of the small size and the absence of a wave‐resistant energy barrier. Such buildup types are probably common after major crises in earth history, when reef organisms were virtually absent.  相似文献   

Structural characteristics of the Suez rift margins     

A. R. Moustafa  A. K. El-Raey 《International Journal of Earth Sciences》1993,82(1):101-109

Field study of the Hadahid Block (the eastern margin of the central half-graben of the Suez rift) indicates two listric normal faults at its eastern and western boundaries, the rift-bounding fault and the Hadahid Fault, respectively. These faults were affected by two episodes of movement. The earlier movement (at the initial, Neogene rift opening) led to equal displacements on the two faults whereas the later movement (at the mid-Clysmic event, l7 Ma ago) caused the Hadahid Fault to bound the deep part of the central half-graben. A similar conclusion is also reached for the western margin of the southern half-graben of the rift (Esh El Mellaha and Zeit Blocks). The two listric faults bounding the margin blocks in these two oppositely tilted half-grabens (Hadahid and Esh El Mellaha Blocks) join at depth into a ramp-flat detachment. This geometry of the rift-bounding faults represents an intermediate stage in the evolution of rift basins. It is preceded by the early rifting stage where extension is less and oppositely tilted half-grabens are formed (e.g. the ancestral Red Sea-Gulf of Suez rift). Increased extension at later stages leads to the prevailance of one system of detachment instead of oppositely dipping detachments of adjacent half-grabens. The central and southern Red Sea have perhaps had this geometry before the onset of seafloor spreading.  相似文献   

Influence of the Iceland mantle plume on oceanic crust generation in the North Atlantic     

C. J. Parkin  R. S. White 《Geophysical Journal International》2008,173(1):168-188

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A seismic study along the East Greenland margin from 72°N to 77°N     

D. Berger  W. Jokat 《Geophysical Journal International》2008,174(2):733-748

Around 4370 km of new seismic reflection data, collected along the East Greenland margin between 71°30'N and 77°N in 2003, provide a first detailed view of the sediment distribution and tectonic features along the East Greenland margin. After processing and converting the data to depth, we correlated ODP-Site 913 stratigraphy into the new seismic network. Unit GB-2 shows the greatest glacial sediment deposits beneath the East Greenland continental shelf. This unit is characterized by the beginning of prograding sequences and has, according to our stratigraphic correlation, a Middle Miocene age. It might have been caused by rapid changes in sea level and/or glacial erosion by an early ice sheet or glaciers along the coast. A basement high, presumably a 360 km long basement structure at 77°N–74°54'N, prevents continuous sediment transport from the shelf into the deep sea area in times before 15 Myr. The origin of this prominent structure remains speculative since no rock sample from this structure is available. Seaward dipping reflectors at the eastern flank of this structure strongly support that it is a volcanic construction and is most likely emplaced on continental or transitional crust. The compilation of sediment thickness provide an insight into the regional sediment distribution in the Greenland Basin. An average sediment thickness of 1 km is observed. The north bordering Boreas Basin has a sediment thickness of 1.8 km close to the Greenland fracture zone (GFZ).  相似文献   

The lateglacial lakes of Glens Roy,Spean and vicinity (Lochaber district,Scottish Highlands)     

《Proceedings of the Geologists' Association. Geologists' Association》2017,128(1):32-41

This paper summarises the evidence for glacial ice advance into lower Glen Spean during the Loch Lomond Stadial which involved the blockage of westward-flowing drainage to form a series of ice-dammed lakes, the former surfaces of which are marked by prominent shorelines. Detailed mapping of glacigenic landforms and instrumental levelling of the shorelines reveals a dynamic interplay between the glacier margins and lake formation. Subsequent deglaciation led to lowering of the lake levels, at times by catastrophic drainage beneath the ice (jökulhlaup). The abandoned shorelines have been warped and dislocated in numerous places as a result of glacio-isostatic deformation, faulting and landslip activity. The pattern of retreat of the ice can be deduced from the mapped distributions of retreat moraines and the levelled altitudes of numerous kame and fluvial terrace fragments. The sequence of events outlined in this paper provides important context for understanding the evolution of the landscape of the Glen Roy area during the Loch Lomond Stadial, and a prelude to more recent studies reported in other contributions to this thematic issue.  相似文献