Deformation Patterns of an Accretionary Wedge in the Transition Zone from Subduction to Collision Offshore Southwestern Taiwan

Swath bathymetry data and seismic reflection profiles have been used to investigate details of the deformation pattern in the area offshore southwestern Taiwan where the Luzon subduction complex encroaches on the passive Chinese continental margin. Distinctive fold-and-thrust structures of the convergent zone and horst-and-graben structures of the passive margin are separated by a deformation front that extends NNW-ward from the eastern edge of the Manila Trench to the foot of the continental slope. This deformation front gradually turns into a NNE–SSW trending direction across the continental slope and the Kaoping Shelf, and connects to the frontal thrusts of the mountain belt on land Taiwan. However, the complex Penghu submarine canyon system blurs the exact location of the deformation front and nature of many morphotectonic features offshore SW Taiwan. We suggest that the deformation front offshore SW Taiwan does not appear as a simple structural line, but is characterized by a series of N–S trending folds and thrusts that terminate sequentially in an en-echelon pattern across the passive Chinese continental slope. A number of NE–SW trending lineaments cut across the fold-and-thrust structures of the frontal accretionary wedge and exhibit prominent dextral displacement indicative of the lateral expulsion of SW Taiwan. One of the prominent lineaments, named the Yung-An lineament, forms the southeastern boundary of the upper part of the Penghu submarine canyon, and has conspicuous influence over the drainage pattern of the canyon     

Large-scale distributed deformation controlled topography along the western Africa–Eurasia limit: Tectonic constraints

In the interior of the Iberian Peninsula, the main geomorphic features, mountain ranges and basins, seems to be arranged in several directions whose origin can be related to the N–S plate convergence which occurred along the Cantabro–Pyrenean border during the Eocene–Lower Miocene time span. The Iberian Variscan basement accommodated part of this plate convergence in three E–W trending crustal folds as well as in the reactivation of two left-lateral NNE–SSW strike-slip belts. The rest of the convergence was assumed through the inversion of the Iberian Mesozoic Rift to form the Iberian Chain. This inversion gave rise to a process of oblique crustal shortening involving the development of two right lateral NW–SE shear zones. Crustal folds, strike-slip corridors and one inverted rift compose a tectonic mechanism of pure shear in which the shortening is solved vertically by the development of mountain ranges and related sedimentary basins. This model can be expanded to NW Africa, up to the Atlasic System, where N–S plate convergence seems also to be accommodated in several basement uplifts, Anti-Atlas and Meseta, and through the inversion of two Mesozoic rifts, High and Middle Atlas. In this tectonic situation, the microcontinent Iberia used to be firmly attached to Africa during most part of the Tertiary, in such a way that N–S compressive stresses could be transmitted from the collision of the Pyrenean boundary. This tectonic scenario implies that most part of the Tertiary Eurasia–Africa convergence was not accommodated along the Iberia–Africa interface, but in the Pyrenean plateboundary. A broad zone of distributed deformation resulted from the transmission of compressive stresses from the collision at the Pyrenean border. This distributed, intraplate deformation, can be easily related to the topographic pattern of the Africa–Eurasia interface at the longitude of the Iberian Peninsula.Shortening in the Rif–Betics external zones – and their related topographic features – must be conversely related to more “local” driven mechanisms, the westward displacement of the “exotic” Alboran domain, other than N–S convergence. The remaining NNW–SSE to NW–SE, latest Miocene up to Present convergence is also being accommodated in this zone straddling Iberia and Morocco, at the same time as a new ill-defined plate boundary that is being developed between Europe and Africa.     

Analysis of digital elevation data for palaeosurfaces in south-western Sweden

A 3873-km² large rectangular area of the Precambrian basement in south-western Sweden has been investigated regarding gross morphology of palaeosurfaces. GIS and digital elevation data were used to construct maps of relative and absolute relief and E–W trending height profiles. Three different palaeosurfaces were recognised and delimited; the very even sub-Cambrian peneplain in the east at an intermediate altitudinal position, an uplifted and broken part of the sub-Cambrian peneplain in the centre at the highest present elevation, and in the western coastal areas a joint-aligned valley landscape with high relative relief, probably an exhumed Mesozoic etch-surface. Phanerozoic faulting has dissected the different palaeosurfaces into tectonic blocks, which are shown from trend surface analysis to be tilted in different directions and to different degrees, characteristic and decisive for the morphological development.     

Major neotectonic features of eastern Marmara region,Turkey: development of the Adapazarı–Karasu corridor and its tectonic significance

Eastern Marmara region consists of three different morphotectonic units: Thrace–Kocaeli Peneplain (TKP) and Çamdağ–Akçakoca Highland (ÇAH) in the north, and Armutlu–Almacık Highland in the south of the North Anatolian Fault Zone (NAFZ). The geologic‐morphologic data and seismic profiles from the Sakarya River offshore indicate that the boundary between the TKP in the west and ÇAH in the east is a previously unrecognized major NNE–SSW‐trending strike‐slip fault zone with reverse component. The fault zone is a distinct morphotectonic corridor herein named the Adapazarı–Karasu corridor (AKC) that runs along the Sakarya River Valley and extends to its submarine canyon along the southern margin of the Black Sea in the north. It formed as a transfer fault zone between the TKP and ÇAH during the Late Miocene; the former has been experiencing extensional forces and the latter compressional forces since then. East–West‐trending segments of the NAFZ cuts the NE–SW‐trending AKC and their activity has resulted in the formation of a distinct fault‐bounded morphology, which is characterized by alternating E–W highlands and lowlands in the AKC. Furthermore, this activity has resulted in the downward motion of an ancient delta and submarine canyon of the Sakarya River in the northern block of the NAFZ below sea level so that the waters of the Black Sea invaded them. The NE–SW‐trending faults in the AKC were reactivated with the development of the NAFZ in the Late Pliocene, which then caused block motions and microseismic activities throughout the AKC. Copyright © 2004 John Wiley & Sons, Ltd.     

构造地貌及其分析方法述评

构造地貌是指受构造内动力作用控制,通过内外地质动力的相互作用所奠定的能够反映一定构造特征的地貌形式.构造地貌学的研究内容为:地貌与构造的关系、构造地貌发生和发展过程以及构造地貌过程所揭示的地球内部构造动力过程;其分析方法可归纳为构造地貌格局分析法、构造地貌形态分析法、构造地貌相关沉积分析法和构造地貌年代分析法.构造地貌学从地形地貌的角度来分析构造过程,涉及不同圈层间的相互作用,响应了当前地球系统科学的研究思路,可以预见,构造地貌学将在圈层作用研究中发挥重要作用,同时朝着信息化、定量化的方向发展.     

Evidences for Incipient Hydrothermal Event(s) in the Central Indian Basin: A Review

1 IntroductionMetalliferous sediments and mounds occur in all majortectonic settings in the oceans (e.g., the Galapagos Rift,East Pacific Rise (EPR), Bauer Deep and Central Basin ofthe Pacific; Heath and Dymond, 1977). Further, massivesulphide deposits and high-temperature vents have beenreported along the mid-ocean ridges (MOR). In the IndianOcean, an inactive hydrothermal field and a hydrothermalplume site have been discovered along the Central IndianRidge (CIR). The SONNE Hydro…     

Neotectonics and seismicity in southern Patagonia

Research for evaluation of geologic hazards involving earthquakes and volcanic eruptions in southern Argentina seems to have historically received little attention. Nevertheless, the relatively small work done indicates a Neogene tectonic architecture in the area with capability of generating potential hazardous earthquakes in a growing population region. Seismicity and some morphotectonic evidences of Quaternary activity of the Magallanes–Fagnano left‐lateral fault system in the transform boundary between South America and Scotia plates, are analysed in this paper. This fault system is considered to be an important seismogenic source, responsible for large earthquakes that have occurred in southern Argentina. Some examples from the South and Austral Andean Volcanic Zones are also examined in order to show recent volcanic activity which also generated crustal seismicity. Preliminary hazard estimation clearly shows the presence of both potentially active volcanic centres in southern Patagonia that may also trigger seismicity and the high probability for large crustal earthquake generation. Copyright © 2015 John Wiley & Sons, Ltd.     

Sea-level curves: Perplexities of an end-user in morphotectonic applications

Several sea-level curves, from the classical ones to some of the most recently published, are analysed and compared. Although this short paper is not a review of the original data and analytical methods used by the different authors, similarities and mainly differences between published sea-level curves are emphasised especially as concern the suggested height and age of the highstand sea-level peaks during the last 450 ka. The perplexities of an end-user when attempting to exploit different curves for investigating uplifted marine terraces are discussed and recommendations are suggested.