The time of the formation and destruction of the Meso-Cenozoic peneplanation surface in East Sayan

The history of the peneplain in East Sayan was studied using apatite fission-track analysis (AFTA). This method is suitable for determining the formation time of the erosional surface and estimating its denudation rate. The largest known relic of the peneplanation surface in this area is the Oka Plateau, separated from the Kropotkin Ridge by the Oka–Zhombolok fault. The AFTA shows that the peneplain on the Oka Plateau formed in the Late Jurassic–Early Cretaceous. This peneplain is much younger than the erosional surfaces that persist today in the Tien Shan, Gobi Altai, and Mongolian Altai (Early Jurassic). However, it is older than the peneplain on the Chulyshman Plateau, Altai (Late Cretaceous), suggesting asynchronous formation of the ancient peneplain in Central Asia. The similar exhumation histories of samples from the Oka Plateau and Kropotkin Ridge indicate that these morphotectonic structures developed from Jurassic to late Miocene as a single block, which underwent continuous slow denudation at an average rate of 0.0175 mm/yr. Active tectonic processes in the Late Miocene caused the destruction of the peneplanation surface and its partial uplifting to different altitudes. The rate of Pliocene–Quaternary vertical movements along the Oka–Zhombolok fault is roughly estimated at 0.046–0.080 mm/yr, which is several times higher than the denudation rate in this area. During the Pliocene–Quaternary, the Oka Plateau has not undergone any significant morphologic changes owing to its intermediate position between the summit plain and datum surface of East Sayan and to its partial shielding by basaltic lavas.     

Evidence for right-lateral strike-slip environment in the Kutch basin of northwestern India from moment tensor inversion studies

The Kutch region located in northwestern part of India is an ancient rift basin that was active until Cretaceous period. The region falls close to the India–Arabia and the India–Eurasia plate boundaries and has experienced devastating earthquakes in the past, namely the 1819 Allah Bund earthquake, the 1956 Anjar earthquake and the 2001 Bhuj earthquake. To understand the tectonics of this region with respect to the adjacent plate boundaries, we invert seismic waveform data of 11 earthquakes in this region recorded by a network of the Institute of Seismological Research (ISR) during 2007–2009. The study yields focal mechanism solutions of reverse fault and strike-slip type mechanism. The inferred fault planes correlate well with the local trends of the known tectonic faults while the principal stress directions derived from stress inversion based on a linearized least squares approach, trend agreeably with the ambient stress field directions. A consistently right-lateral sense of shear is found on all the local faults as derived from each of the matching planes of the focal mechanism solutions computed in the present study. It is inferred that in the Kutch region a right-lateral strike-slip environment prevails along predominantly EW to NW-SE oriented deep-seated pre-existing faults in an otherwise compressive stress regime. This, in conjunction with the left-lateral movements along the Girnar mountain in southern Saurashtra, inferred from previous studies, indicates a westward escape of the Kutch–Saurashtra block as a consequence of the northward collision of the Indian plate with respect to the Eurasian landmass.     

Evidences of Cenozoic strike-slip dislocations of the red river fault system in Paleozoic carbonate strata of Cat Ba Island (Northern Vietnam)

The structural researches of carbonate strata in the northeastern segment of the framework of the Red River Fault System (Cat Ba Island, Northern Vietnam) has been carried out. It was found that weakly deformed carbonate strata are cut by NW-trending (300–310°) strike-slip faults. Development of plicative and disjunctive dislocations occurred along predominantly sinistral strike-slip fault zones formed as a result of ENE regional compression (80°) during the Oligocene-Miocene phase of deformation. Late dislocations confined to the Pliocene-Quaternary phase of deformation (NNW regional compression 330–350°), are relatively less developed. Seismic monitoring data show that both plicative and disjunctive dislocations have continued to the present.     

Tectonic settings of porphyry Cu–Mo–Au deposits in the Himalayan–Tibetan orogen,East Tethys

Porphyry Cu (Mo–Au) deposits in the Himalayan–Tibetan orogen formed during the Late Triassic, Early Cretaceous, Eocene, Oligocene, and Miocene and can be classified into different metallogenic belts according to their petrologic features, mineralization ages, and tectonic settings. A close spatial relationship to regional strike–slip faults is evident in all five belts. Porphyry Cu (Mo–Au) deposits exist in a wide range of tectonic environments, including island arc, syn-collision, post-collisional convergence, and continental-transform plate boundaries.

Porphyry Cu deposits cluster in the southernmost part of the Yidun–Zhongdian Belt, along the N–S-trending Gaze River dextral strike–slip fault. Porphyry Cu deposits in the Lijiang–Jinping Belt lie along the Ailaoshan–Red River continental–transform shear zone and the associated strike–slip faults. The Yulong–Malasongduo porphyry belt is controlled by the Cesuo Fault, a NNW-trending regional dextral transcurrent fault that is associated with Palaeogene westward continental oblique subduction along the Jinsha suture. In the Gangdis Belt, Miocene porphyry Cu deposits are localized along N–S-trending normal faults, which were produced by transpression within the regional NW–SE-trending Karakoram–Jiali fault zone (KJFZ). A close spatial relationship between porphyry Cu deposits and strike–slip faults also exists for the Bangong–Nujiang Belt.     

Regularities in the orientation of bottom lineaments and faults in the Russian segment of the Sea of Japan

The configuration of the lineament-disjunctive network in the Russian segment of the Sea of Japan (sheets K-52 and K-53) was studied with structural zoning of the region using geophysical and geomorphologic data. The constructed rose diagrams revealed systematic orientation of lineaments and faults in the region as a whole and some of its areas. The orientation of linear structures in the Russian segment of the Sea of Japan is compared with that characteristic of the global disjunctive network. This allowed the following inferences: (1) the region is characterized by a single lineament-disjunctive system with four main directions of dislocations: submeridional (0–5°), sublatitudinal (86–90°), diagonal northeastern (36–65°), and diagonal southeastern (136–140°); (2) the directions of these dislocations coincide with the orientation of four main systems in the global disjunctive network (planetary fracturing); (3) the revealed disjunctive network is substantially of the Earth’s rotation genesis; (4) regularities in the distribution and orientation of faults and lineaments are determined by two interacting factors: the stress concentration in areas of the layer thickness gradient and variations in the Earth’s rotation velocity (the former controls localization of faults and the latter, their orientation).     

河西走廊西段花海断裂几何学、运动学及区域构造意义

花海断裂位于河西走廊西段花海盆地内,总体走向NNW-SSE,长约38 km,为一条隐伏断裂,研究其空间展布、运动性质和活动历史对于理解青藏高原北缘的构造变形和扩展方式有重要意义.基于卫片解译、野外实地和槽探,结合光释光测年和地球物理资料,发现沿双泉子、大泉至小泉一带,发育一段长约8 km的地形陡坎,代表断裂控制下褶皱作...     

Tertiary tectonic evolution along the Arne-Elin Trend in the Danish Central Trough

Tertiary sequence boundaries are mapped on reflection seismic sections in the northern part of the Danish Central Trough, North Sea. The geometry of the sequence boundaries and the isopach maps of the sequences are used as indicators of differential subsidence. The Tertiary tectonic evolution is subdivided into: (i) Late Palaeocene and Early Oligocene episodes of inversion along the NNW–SSE striking Arne–Elin Trend (ii) Early Oligocene to Pliocene episodes of differential subsidence across pre-Tertiary fault trends. The observed differential subsidence and inversion is related to pre-Tertiary faults and fault trends, and dating of the sequences shows that the tectonic phases were contemporaneous with tectonic events in NW Europe. It is suggested that the differential subsidence-inversion is controlled by reactivation of pre-Tertiary faults/fault-trends by block movements due to an interaction of the Alpine collision and the opening of the Atlantic.     

Structure and tectonic evolution of the Late Jurassic–Early Cretaceous Wandashan accretionary complex,NE China

The Late Jurassic–Early Cretaceous Wandashan accretionary complex (AC) in NE China is a key region for constraining the subduction and accretion of the Palaeo-Pacific Ocean; however, the protoliths and structure of the region remain poorly understood, resulting in debates regarding crustal growth mechanisms and subduction-related accretionary processes in Northeast China. In this contribution, we integrate detailed field observations, ocean plate stratigraphy (OPS) reconstruction, and associated geological data to determine the structure and tectonic evolution of the Wandashan AC. The Wandashan AC formed through the progressive incorporation of OPS units along an oceanic trench. The observed OPS comprises, in ascending order, Permian basalt and limestone, Middle Triassic–Early Jurassic chert, Middle Jurassic siliceous shale and mudstone, and Late Jurassic–Early Cretaceous turbidite. Numerous NNE–SSW-striking thrust faults have segmented the OPS into a series of bedding-parallel tectonic slices that were successively thrust over the Jiamusi massif along a basal thrust (the Yuejinshan Fault), producing a large-scale imbricate thrust system. The Wandashan AC underwent oceanward accretion via multiple deformational processes. The OPS units were detached and rearranged along or within a decollement through offscraping, underplating, thrusting, and duplexing. The units were then emplaced over the Jiamusi massif along the basal thrust. The timing of accretion and thrusting is constrained to the latest Middle Jurassic to earliest Early Cretaceous (ca. 167–131 Ma). Reconstructed accretion-related structural lines within the Wandashan AC trend dominantly NE–SW, close to the direction of Jurassic extension at the eastern Asian continental margin. Large-scale left-lateral strike-slip movement on the Dunmi Fault during the late Early Cretaceous resulted in the folding of structural lines within the Wandashan AC, producing their present-day westward-convex orientation.     

Geodynamic hazard and risk assessments for sites close or in tectonic zones with shear movements

No region is excluded from actions of recent geodynamic short- or long-term effects which can be observed even on the Earth’s surface. The article delivers a geodynamic hazard assessment for the anthropogenic objects threatened by permanent shear movements occurring along tectonic faults and a way how to mitigate and/or eliminate the object risk. The proposed approach is applied to a case example of a motorway tunnel leading through rock masses where dynamically active zones with shear movements along their faults are expected. To detect the shear movements among rock masses, the contemporary satellite geodetic GPS methodology was used.     

Fold deformations of the paleozoic basement roof in the Chunkurchak Trough,Kyrgyz Ala-Too Range

A structural–geological study has been performed on the northern slope of the Kyrgyz Ala-Too Range. Deformations of the peneplaned Paleozoic basement surface, structures of granite disintegration, and morphostructural manifestation of Late Cenozoic tectonic movements have been investigated. Based on the location of pre-Paleocene peneplain remnants with the retained weathering mantle partly overlapped by Paleocene–Miocene sedimentary complexes, we have reconstructed the morphology of the folded surface of the Chunkurchak Trough separated from the Chu Basin at the early Miocene. The dome–fold forms, the morphology and arrangement of which are controlled by disintegration of the basement, have been described for the basement surface. It has been established that granites are broken by systems of steeply dipping, fanshaped, and gently dipping faults and fractures. Variously oriented insignificant offsets along slickensides, as well as displacements deduced from the geometry of fracture intersections, are a result of volumetric cataclastic flow of rocks. The tectonic mobility of disintegrated granites, which are abundant in the Paleozoic–Precambrian basement, explains the complexity and scale of tectonic processes initiated by Cenozoic activation. In paleotectonic reconstructions, which take into consideration tectonic flow and the redistribution of basement masses, the estimates of Cenozoic relative rapprochement of the Chu Basin and the Kyrgyz Ala-Too Range decrease substantially to 4–6 km.     

Late Cretaceous Transpressional Fault System: A Case Study of the Yishu Fault Belt, Shandong Province, Eastern China

On the basis of field observations of the structures of three profiles from the Linshu region, deformation characteristics and the tectonic background of the Yishu fault belt in the Late Cretaceous–Early Cenozoic have been discussed in detail.Three structural profiles, whose deformations consist mainly of earlier transpressional faults and later normal faults, were developed for the Mengtuan Formation of the Lower Cretaceous Dasheng Group.Typical positive flower structures, duplex structures, and break-through faults were found in these profiles.On the basis of analyses of the structural deformation and previous geochronological studies, it was concluded that the earlier transpressional faults of the profiles were triggered by the sinistral transpression of the Yishu fault belt in the Late Cretaceous–Early Paleogene, and that the later normal faults, formed during the Late Paleogene–Neogene extension, truncated the earlier transpressional faults.With consideration of the tectonic evolution of the Tan-Lu fault belt and the different drift directions of the Pacific plate since the Cretaceous, we suggest that the major tectonic events of the Late Cretaceous–Neogene in eastern China were mainly controlled by the subduction of the Pacific plate.     

Neotectonics and geodynamics of the Kuznetsk Basin

This work describes the peculiarities of neotectonics and geodynamic development of the Kuznetsk Basin since the Oligocene. The complex of studies included structural-geomorphological analysis with interpretation, satellite image data processing, and field observations. The studies we carried out allowed us to reveal that the modern dislocations in the Kuznetsk Basin are characterized by an arched-block style of tectonic movement. The modern structural pattern of the Kuznetsk Basin is a combination of wide uplifts separated by narrow depressions and weak zones (fault zones, fracture zones, and zones of rock disintegration) of northwestern, northeastern, submeridional, and sublatitudinal strike. As a result of these studies, the relationships between modern and ancient tectonic structures and the geodynamic features of the development of modern dislocations that depend on the degree of activization of tectonic structures have been revealed. Statistical analysis of the results of the interpretation allowed us to reveal areas of high permeability and higher dislocation density in the geological setting with a higher concentration of methane.     

The structural history of the Mont Blanc massif with regard to models for its recent exhumation

The tectonic evolution of the Mont Blanc range with regard to its cooling and exhumation history has been discussed and debated over many years and is still controversial. Recently, several low-temperature thermochronology studies have determined the cooling history of the massif in considerable detail and various tectonic models proposed to explain the young and fast exhumation signal established from these studies. Here we present detailed field data from the wider Mont Blanc area and assess possible exhumation processes in terms of these field constraints. Our observations indicate that none of the major faults or shear zones around the Mont Blanc massif (i.e. Mont Blanc shear zone, Mont Blanc back-thrust, Penninic thrust) was active in Late Neogene times and that young exhumation is therefore not controlled by movements along these structures. We demonstrate that the position of Mont Blanc in the bend of the western Alps plays an important role in its tectonic history and that simple 2D models are insufficient to explain its evolution. Interference between NW–SE compression and orogen-parallel extension along the Rhône-Simplon fault system resulted in a complex regional structural pattern, with strike-slip movements on both sides of the Mont Blanc massif. Young brittle faults are predominantly strike slip without significant vertical offset. The young (<2 Ma) rapid exhumation of Mont Blanc is more broadly distributed and cannot be directly linked to discrete faults bounding the massif. The mechanisms driving this recent accelerated exhumation must similarly be of broader scale.     

郯庐断裂带安徽段活断层特征与成因

详细的野外地质调查表明,郯庐断裂带安徽段活断层广泛存在,自北向南分别沿着嘉山盆地的东、西边界、合肥盆地东界与大别造山带东界分布。走向上自北向南由北北东向转为北东向,倾向上与早期盆缘正断层一致。这些活断层以逆右行平移活动为主,显示了逆冲分量随着断层倾角变小而增大的现象。依据一系列活断层擦痕实测数据的反演,指示它们活动时的应力状态为北东东-南西西向挤压,与现代应力状态一致。从多种现象综合分析,本文认为郯庐断裂带安徽段活断层的最新活动时代应为中更新世,从而该段没有强震记录或小震群集现象。本次工作表明,区内活断层主体上是早期盆缘正断层直接复活成因。由于其第四纪期间有限的累计垂直位移分量,并没有改变白垩-古近纪盆地发育阶段的地貌格局。     

Quaternary tectonics of recent basins in northwestern Armenia

New data on the stratigraphy, faults, and formation history of lower to middle Pleistocene rocks in Late Cenozoic basins of northwestern Armenia are presented. It has been established that the low-mountain topography created by tectonic movements and volcanic activity existed in the region by the onset of the Pleistocene. The manifestations of two geodynamic structure-forming factors became clear in Pleistocene: (i) collisional interaction of plates due to near-meridional compression and (ii) deep tectogenesis and magma formation expressed in the distribution of vertical movements and volcanism. The general uplift of the territory, which was also related to deep processes, reached 350–500 m in basins and 600–800 m in mountain ranges over the last 0.5 Ma. The early Pleistocene (~1.8 Ma) low- and medium-mountain topography has been reconstructed by subtraction of the latest deformations and uplift of the territory. Ancient human ancestry appeared at that time.     

Kinematics and strain partitioning in the southeast Hellenides (Greece)

New kinematic and structural data from the tectonic windows of eastern Crete and the Dodecanese Islands combined with strain and quartz fabric analysis have enabled us to determine a detailed structural evolution of the region and to present a plate tectonic scenario for the southeast Hellenides. During the Early Mesozoic, the southeastern part of Apulia was separated from North Africa and the adjacent microplates by WNW‐trending rift zones and NE‐trending transfer faults. Displacement along the transfer faults has locally reoriented these rift zones into an ENE–WSW direction. Finite strain and quartz fabric asymmetry data indicate that in Late Cenozoic time, NNW‐directed nappe movements caused a nearly coaxial deformation along the ENE–WSW trending rift segments and non coaxial top‐to‐the‐southeast shearing along the WNW‐trending rift segments, as well as along the pre‐existing NE‐trending transfer faults. Tectonic style along the margin varies in response to the obliquity of the principal shortening direction with respect to the margin. These variations could be due to the pre‐convergence geometry of the southern margin of Eurasia and to local strain partitioning effects. Furthermore, a tectonic model is presented in which syncompressional uplift and vertical buoyancy of the subducted crustal slice caused the rapid exhumation of metamorphic units in the south Hellenides. Copyright © 2003 John Wiley & Sons, Ltd.     

西藏南部同位素地质年龄的测定与喜马拉雅运动的分期

作者对1973-1975年中国科学院青藏高原综合科学考察队和1975年中国登山队科考分队地质组,在西藏南部和珠穆朗玛峰（以下简称珠峰）地区采集的部分同位素地质年龄样品,经镜下鉴定,选择适宜者用钾氩法做了同位素地质年龄的测定,从而对本区广泛出露的岩浆岩和变质岩的时空分布特征加深了认识。在工作中钾是用火焰光度法测定的。放射成因氩的含量大部分是用体积法测定,小部分用以Ar³⁸为稀释剂的稀释法测定。     

Early Tertiary epithermal gold mineralization, Bahcecik prospect, northeastern Turkey

The Bahcecik prospect is located in the eastern Pontide tectonic province of the eastern Black Sea region of Turkey. It is one of the first low sulfidation epithermal systems to be described from this area of Turkey. Gold mineralization occurred within Late Cretaceous to early Tertiary volcanic rocks and is localized along east-trending normal faults and lithologic contacts. An early quartz–sericite alteration event was focused along the major fault in the area and resulted in precipitation of arsenian (?) pyrite with anomalous gold. A later, more spatially extensive, advanced argillic alteration event overprinted the quartz–sericite event. Native gold was precipitated during this event as disseminations and fracture fillings in quartz. Gold mineralization is restricted to the high-temperature portion of the alteration zone characterized by quartz veins with diaspore–pyrophyllite selvages. The prospect area was subjected to Tertiary to Holocene supergene alteration.     

Mountain building processes in intracontinental oblique deformation belts: Lessons from the Gobi Corridor,Central Asia

This paper presents a review of the Quaternary–Recent deformation field and mountain building processes within the Gobi Corridor region of Central Asia, which includes the North Tibetan foreland, Beishan, Gobi Altai and easternmost Tien Shan. The region can be considered the ‘soft core’ of Central Asia which has been reactivated due to the continuing Indo-Eurasia collision to the south. Favourable preconditions for reactivation of Gobi Corridor basement include a mechanically weak Palaeozoic terrane collage sandwiched between rigid Precambrian basement blocks to the north and south, thermally weakened crust due to Jurassic–Miocene volcanism and widespread Palaeozoic–Mesozoic granitic magmatism with associated high radiogenic heat production, and crustal thinning due to widespread Cretaceous rift basin development. The network of Quaternary–Recent faults within the entire region defines a diffuse sinistral transpressional deformation field that has generated a transpressional basin and range physiographic province. Typically, thrust and oblique-slip thrust faults are WNW-striking and reactivate basement faults and fabrics, whereas left-lateral strike-slip faults are ENE-striking and cut across basement trends. The angular relationship between SHmax and pre-existing basement structural trends is the fundamental control on the kinematics of Late Cenozoic deformation. Along-strike and across-strike growth and coalescence of restraining bends, other transpressional ranges and thrust ridges is an important mountain building process. Thrust faults throughout the region are both NNE and SSW directed and thus there is no common structural vergence, nor orogenic foreland or hinterland. Root structures appear to be vertical faults, not low-angle decollements and flower structure fault geometries within individual ranges are common. Published earthquake and geodetic data are consistent with a diffusely deforming continental interior region with tectonic loading shared amongst a complex network of faults. Therefore, earthquake prediction is likely to be more complex than in plate boundary settings and extrapolation of derived Late Quaternary fault slip rates is not straightforward. Modern mountain building within the Gobi Corridor demonstrates that reactivation of ancient accretionary and collisional orogens within continental interiors can play an important role in continental evolution and the life cycle of orogenic belts.     

Middle Jurassic-Lower Cretaceous tectonic-eustatic cyclites of the Southern East European Craton

A methodical approach to assessment of the role played by vertical tectonic movements in the of tectonic-eustatic cyclicity and the facial appearance of the Middle Jurassic-Lower Cretaceous deposits on the eastern part of the East European Craton has been suggested. Resulting from comparison between the global and regional eustatic curves, the modeling of probable versions of the lithological composition for sediments during eustatic oscillations, and the comparison of modeling results with the chronostratigraphic scheme, the global eustatic component and regional ??tectonic noise?? have been identified. It has been found that the vertical tectonic movements formed the boundaries of the most distinguished cyclites on the eastern part of the East European Craton. The spatial-temporal uniformity in the material composition of cyclites, related to the long periods of stable high-stand sea level, caused their mineralogenic specialization for a broad range of non-ore mineral resources.