Tectonic landforms and quaternary tectonics in Japan

The study of tectonic landforms is one of the main themes of geomophological research in Japan, characterized as a tectonically active area along the subducting oceanic plates. The recent trends in the studies of tectonic landforms which include an arrangement or distribution of major ranges and plains, vertical displacement of low-relief erosion surfaces and of marine terraces, and various kinds of deformed features due to active faulting or folding, are introduced here with special reference to the Quaternary geomorphic development. A regionality of each tectonic landforms is also summarized. Further, some fundamental concept of the Quaternary tectonics, for instance, an accumulative character of each type of deformation and sequence of rate of tectonic movement, reconstruction of former stress field as well as a relation between the Quaternary tectonic movement and seismic deformation in present and historic time are discussed on the basis of analysis of the tectonic landforms. The Quaternary tectonics of the Japanese Islands are essentially characterized by the compressional stress, originated from the subduction of oceanic plates, and regionality can be interpreted as the result of the different response of each tectonic region to island arc tectonics.     

La branche orientale de l'arc de Chypre. Morphostructure d'une frontière de plaques d'après les résultats de la campagne BLAC (2003)

The eastern bend of the Cyprus Arc, at the transition between the submerged Mediterranean subduction and the onshore fault zones that underline the Eurasian, African and Arabic plates boundaries is a submarine feature undergoing a complex tectonic deformation. The BLAC marine geophysical survey helps to better assess the type of the deformation that affects the Messinian to Quaternary sediments along this plate boundary. The deformation, focussed between two tectonic corridors, displays compressive and transpressive features in the central part, becoming thrusting when moving westward in connection with the Cyprus accretionnary wedge. The northeastern end of this submarine range connects with the Latakia Ridge, which is, together with its continental extension, under a tensional tectonic regime. To cite this article: J. Benkhelil et al., C. R. Geoscience 337 (2005).     

Sedimentary processes and provenance of Quaternary marine formations from the Tangier Peninsula (Northern Rif, Morocco)

This work deals with new lithostratigraphic, sedimentological, petrographic and geochemical data collected from coastal Quaternary formations of the Tangier Peninsula along the Northern Atlantic and Mediterranean coasts in the southern side of the Gibraltar Strait (Morocco).The sedimentological features of the analyzed sections reflect a palaeoenvironment evolution from a submerged beach-type to a high energy littoral depositional system, namely lower shoreface to beachface environment with a regressive trend to thickening- and coarsening-upward sequences. Other successions, located nearby Larache city and in the Sidi Kankouch area, are also characterized by a positive trend to fining- and thinning-upward sequences, reflecting an evolution from lower beachface or upper shoreface to lower shoreface. It is possible that the transgressive to regressive trend inversion could be related to fluctuations of sediment input rate versus accommodation space during the progradation of a coastal palaeoenvironment.The lateral and vertical evolution of the studied marine formations is related to late Quaternary neotectonics, mainly to the last repercussions of isostatic rebound of the External and Flysch Basin Domains, during a period of relatively uniform sea level between 280,000 and 125,000 years B.P.The provenance of arenites of these Quaternary marine formations, studied by means of modal counting and geochemical analysis, seems to be linked mainly to Middle-Upper Miocene and Pliocene terrigenous successions, unconformably resting on various formations of the Neogene accretionary prism. The latter has been built by the stacking of Flysch Nappes and External Units of the Northern Rif Chain.     

Overview of the Late Tertiary–Recent tectonic and palaeo-environmental development of the Mediterranean region

The Late Tertiary history of the Mediterranean region exemplifies processes of ocean basin closure and continental collision, as determined from integrated land and marine evidence. During the Mesozoic–Early Tertiary, tectonic settings were dominated by evolution of Neotethys. This ocean generally widened eastwards, with a number of oceanic strands in the Eastern Mediterranean area. Great diversity of tectonic settings and palaeo-environments developed during the Tertiary closure history of these oceanic basins. In the Eastern Mediterranean region, more northerly Neotethyan strands were closed by the Mid Tertiary, while oceanic crust remained in the south in the present Eastern Mediterranean Sea area. Northwards subduction of the remaining southerly Neotethyan strand was probably active by the Early Miocene. Different areas exhibit different stages of convergence and ocean basin closure. In the east, the amalgamated Eurasian plate had collided with the Arabian margin (Africa) by the Late Miocene, while oceanic crust still persisted further west. Steady-state subduction during the Late Tertiary gave rise to the Mediterranean ridge, as a substantial mud-dominated accretionary wedge. In the Aegean area, sufficient northward subduction took place to activate arc volcanism and pervasive back arc extension, short of marginal basin opening. In the easternmost Mediterranean, only limited subduction took place, associated with supra-subduction zone extension (e.g. in Cyprus). Today, steady state-subduction continues only locally, where vestiges of Neotethys remain (e.g. Herodotus abyssal plain). In the Western Mediterranean area, suturing of the African and Eurasian plates initially took place in the Betic region (Early–Mid Tertiary), where the Neotethys had existed only as a narrow connection with the Central North Atlantic. In the Central Mediterranean region, where the Western Neotethys was wider, northward subduction was active, apparently as early as the Late Cretaceous. In a widely accepted interpretation, an Andean-type magmatic arc developed along the southern margin of Europe and was then rifted off in the Late Oligocene-Early Miocene, to form the Corsica-Sardinia Block, opening the North Balearic marginal basin in its wake. The migrating subduction zone and microcontinent then collided diachronously with North Africa-related continental units (North Africa and Apulia) from Late Oligocene-Early Miocene, giving rise to collisional thrust belts in the Northern and Southern Apennines and along the North African continental margin (i.e. the Maghrebian chain) to the Betic-Rif area. From the Early Miocene onwards, a separate subduction system became active, related to removal of Neotethyan oceanic crust to the southeast (Ionian Sea), fueling suprasubduction zone extension and opening of the Tyrrhenian Sea. ‘Orogenic collapse’ is an alternative mechanism of such extension, and is widely believed to have caused divergent thrusting in the Betic and Rif regions of the westernmost Mediterranean, at the same time as crustal extension and subsidence of the Alboran Sea.     

Review of evidence for late Tertiary shorelines occurring on South Atlantic coasts

Recognition of (late) Tertiary shorelines on continental coasts is becoming increasingly common. It is argued that the elevations of such features are central to their approximate dating and the demonstration of contemporaneity with similar features elsewhere. South Atlantic coasts have not had a long history of investigation, yet there exist many diffuse observations, in both time and space, which are here drawn together into a preliminary synthesis and the case for widespread occurrences of late Tertiary shorelines in the region reviewed. This allows comparison with other areas from which Tertiary shorelines are known, the Atlantic seaboards of the Southeastern United States and Northwest Europe, for example.The coasts of oceanic islands are probably the best places to examine the legacy of late Cenozoic sea-level changes. It is suggested that, since many of the cliffed shores of these islands appear to be the result of a rapid emergence, coastal features predating this event might be preserved on the cliff-tops. Possible late Tertiary shorelines from South Atlantic islands are described, as are those which have been positively dated to this period, in the Eastern Canary Islands, for instance. Sedimentary and morphological indicators of Tertiary high sea-levels are described from Antarctic coasts. South American and African Atlantic continental margins. Evidence from the latter two areas is most suspect, owing to their generally more complex Quaternary tectonic histories. A summary of the evidence for Tertiary shorelines on South Atlantic coasts is tabulated.Methods which have been or could be used to date late Tertiary shorelines are described. Minimum age can be deduced from that of deposits resting on an erosional surface, maximum age from that of the youngest formation across which a surface is cut. More precise age can be estimated where a marine surface is sandwiched between datable non-marine formations or where periods of tectonic activity (responsible for differential surface deformation) can be dated. Elevations of surfaces can be used to estimate ages. Problems in both recognising and dating Tertiary shorelines are discussed. Recognition of their origin is made more difficult by their degraded state and, if they occur within a Quaternary erosional sequence, their antiquity may not be realised.It is suggested that fluctuations in the Antarctic ice sheet during the late Tertiary induced substantial glacio-eustatic changes of sea-level which may have been most marked in adjacent areas. This is considered to be the mechanism through which late Tertiary shorelines in the area were formed yet, considering the paucity of the morphological and sedimentary data, these should not be used as the basis for a eustatic chronology.     

Seismic stratigraphy of the NW Moroccan Atlantic continental shelf and Quaternary deformation at the offshore termination of the southern Rif front

A recent high resolution seismic survey was carried out along the North-West Moroccan Atlantic continental shelf to perform sequence stratigraphy and to better understand the link between the onshore observations across the western termination of the Rif front and the multibeam bathymetric data previously collected across the Gulf of Cadiz. Seismic interpretation clearly shows evidence of deformation affecting the Pleistocene sedimentary cover. This is mainly located between the Lalla Zahra ridge and the Neogene nappes that outcrop at the seabed to the North of Larache, where the identified structures bound the upper part of a gravitationally spreading lobe and are interpreted to be developed by activation of the major tectonic structures located at the southern front of the Rif Cordillera. The offshore extension of the Lalla Zahra Ridge is characterised by an east-west trending major folded and faulted corridor. This structure marks the active front of Prerifan area and corresponds to a major Quaternary kinematic boundary in the western prolongation of the ENE-WSW trending Jebha fault.     

Long-term and short-term vertical velocity profiles across the forearc in the NE Japan subduction zone

We estimated the long-term vertical velocity profile across the northeastern Japan forearc by using the height distribution of late Quaternary marine and fluvial terraces, and we correlated the ages of the two marine terraces with marine isotope stages (MIS) 5.5 and 5.3 or 5.1 by cryptotephra stratigraphy. The uplift rate, estimated as 0.11-0.19 m ka^− 1 from the relative heights between the terrace surfaces and eustatic sea levels, was nearly equal to, or slightly slower than, the uplift rate farther inland (0.15-0.19 m ka^− 1), as determined from the relative heights of fill terrace surfaces. In contrast, the short-term vertical velocity profile, obtained from GPS observations, showed that the forearc is currently subsiding at a maximum rate of 5.4 ± 0.4 mm yr^− 1. Thus, the current short-term (geodetic) subsidence does not reflect long-term (geological) tectonic movement. Short-term vertical deformation is probably driven by subduction erosion or elastic deformation caused by interplate coupling, or both. However, long-term uplift is probably due not to moment release on the mega-thrust but to crustal thickening.     

Environmental controls on 10Be‐based catchment‐averaged denudation rates along the western margin of the Peruvian Andes

We present ¹⁰Be‐based basin‐averaged denudation rates for the entire western margin of the Peruvian Andes. Denudation rates range from c. 9 mm ka^?1 to 190 mm ka^?1 and are related neither to the subduction of the Nazca plate nor to the current seismicity along the Pacific coast and the occurrence of raised Quaternary marine terraces. Therefore, we exclude a tectonic control on denudation on a millennial time‐scale. Instead, we explain >60% of the observed denudation rates with a model where erosion rates increase either with mean basin slope angles or with mean annual water discharge. These relationships suggest a strong environmental control on denudation.     

The geology and morphology of the Antakya Graben between the Amik Triple Junction and the Cyprus Arc

In southeastern Turkey, the NE-trending Antakya Graben forms an asymmetric depression filled by Pliocene marine siliciclastic sediment, Pleistocene to Recent fluvial terrace sediment, and alluvium. Along the Mediterranean coast of the graben, marine terrace deposits sit at different elevations ranging from 2 to 180 m above present sea level, with ages ranging from MIS 2 to 11. A multisegmented, dominantly sinistral fault lying along the graben may connect the Cyprus Arc in the west to the Amik Triple Junction on the Dead Sea Fault (DSF) in the east. Normal faults, which are younger than the sinistral ones, bound the graben’s southeastern margin. The westward escape of the continental ?skenderun Block, delimited by sinistral fault segments belonging to the DSF in the east and the Eastern Anatolian Fault in the north caused the development of a sinistral transtensional tectonic regime, which has opened the Antakya Graben since the Pliocene. In the later stages of this opening, normal faults developed along the southeastern margin that caused the graben to tilt to the southwest, leading to differential uplift of Mediterranean coastal terraces. Most of these normal faults remain active. In addition to these tectonic movements, Pleistocene sea level changes in the Mediterranean affected the geomorphological evolution of the area.     

六盘山东麓泾河上游河流阶地的形成年代及新构造运动意义

六盘山是研究青藏高原东北缘隆升与构造变形的关键部位,其东麓泾河河流阶地是第四纪以来六盘山构造隆升的地貌载体。通过对泾河上游河流阶地的剖面实测,厘定了河流阶地的级序,泾河上游主要发育5级河流阶地T5-T1,不同地段阶地的形态类型不同,柳树沟T5、T4和T3为堆积阶地,T2和T1为基座阶地,高家山均为侵蚀或基座阶地;利用光释光(OSL)、电子自旋共振(ESR)测年并与黄土-古土壤序列进行对比,建立了河流阶地的年代格架,T5-T1年代分别为541 ka B.P.、477 ka B.P.、279 ka B.P.、60 ka B.P.和8 ka B.P。阶地的形态类型、形成年代与气候阶段的对应关系研究表明,泾河上游河流阶地以构造隆升驱动为主,气候变化影响为辅;541~279 ka B.P.期间柳树沟地区为堆积区,堆积速率为0.31 m/ka,而高家山为构造隆升区,河流下切速率为0.37 m/ka,堆积速率与侵蚀速率基本一致,说明T5、T4和T3阶面上较厚的砾石层是六盘山隆升的相关沉积;279 ka B.P.时期由于六盘山快速隆升驱使山前柳树沟地区由堆积区转为侵蚀区,河流侵蚀作用加强造成T2、T1平均下切速率增大为1.13 m/ka,这次地貌转换事件是在青藏高原扩展隆升的背景下六盘山向东挤出隆升的结果。研究结果为青藏高原东北缘以面积和体积扩张的观点提供了新的依据。     

北天山山前安集海河阶地形成的时代及意义

北天山山前几条主要河流普遍发育河谷阶地。安集海河发育６～８级阶地,通过年代测定及区域对比,可得出安集海河阶地形成于中更新世晚期一晚更新世早期（约１２～１４万年左右）。第四纪以来构造活动及气候变化控制着河流下切和侧蚀作用的进行,安集海河阶地的形成和发育明显受第四纪晚期构造活动和气候变化等因素的影响。     

Quaternary marine terraces on Sal Island (Cape Verde archipelago)

The Quaternary sedimentary record of Sal Island includes marine and related aeolian and alluvial fan deposits. The substratum of the island is volcanic, with ages between 25 and 0.6 Ma. Quaternary marine units generally occur as raised marine terraces forming a broad staircase between elevations of 55–60 m and present sea level. Terraces include a basal conglomerate overlaid by calcarenite; both host corals, algae and molluscs.A chronostratigraphic framework for the Middle Pleistocene to Holocene units has been generated based on a geomorphologic map of the Quaternary landforms and associated deposits and morphosedimentary analysis, with support of laboratory dating: U-series by TIMS in corals, ¹⁴C analyses, palaeomagnetic measurements, and K/Ar ages from other literature. U-series dating of corals from marine terraces provides benchmarks for the Last Interglacial (Oxygen Isotope Substage 5e) and Holocene deposits. The present elevation of the marine terraces and their staircase arrangement suggest a change in vertical movement trend around 330 ka from an uplift to either subsidence or stabilization.     

Stream analysis of small drainage basins in an ancient landform,Korean Peninsula

Much of the topography of Korea is ancient, but many Quaternary fault outcrops and marine terraces have been observed in the southeastern part of the Korean Peninsula. Sufficient evidence of a Quaternary fault is lacking in the geological features of the commercially developed Jukbyun and Uljin areas. Knickpoints that develop on streams can be formed by tectonic activity such as faulting and folding, or can result simply from the differential erosion rates of bedrock. In this study, we investigated the relationship between stream steepness and faults in the Jukbyun area. Stream profile analyses of the Bugu and Namdae basins were performed using a digital elevation model to estimate Quaternary tectonic movements. Stream parameters obtained from analysis of the longitudinal stream profiles of the Bugu and Namdae drainage basins in the northeastern part of the Korean Peninsula indicated neotectonic movement. Thirty of the thirty-nine knickpoints that developed in the downstream areas of the fluvial channels corresponded to fault zones. It is thought that fault activity results in knickpoints in river systems. The normalized relative slope (K_sn) value (54.9) of the BS1 stream in the Bugu drainage basin was higher than that (28.8–36.3) of the other streams in both basins, despite a similar lithology to NS1 and NS2. Therefore, we concluded that stream steepness might be a result of tectonic forcing rather than a product of rock strength in the study area and that stream parameters could provide indirect evidence of Quaternary tectonics in ancient landforms.     

Lithospheric boudinage in the Western Mediterranean back-arc basin

The western Mediterranean is composed of irregular troughs formed as back-arc basins in the hanging wall of the W-directed Apenninic subduction which retreated eastward during Neogene and Quaternary times. The basins are progressively younger toward the east, ageing from late Oligocene–early Miocene (Valencia, Provençal, Alboran and Algerian basins), to middle Miocene–Pleistocene (Tyrrhenian Sea). The basins isolated boudins of continental lithosphere, the Sardinia–Corsica block representing the largest. The boudinage has a wavelength of 100–400 km and facilitated stretching of the continental lithosphere with formation of new oceanic crust in the Provençal, Algerian, Vavilov and Marsili basins. The boudins developed both in the earlier Alpine–Betic orogen (Alboran basin) and in its foreland (Provençal and Valencia troughs). The extension appears clearly asymmetric due to its eastward polarity, accommodated by E-dipping master low-angle normal faults. Moreover the thinning shows variations in boudinage wavelength and is characterized by several along-strike transfer zones and heterogeneities. The western Mediterranean back-arc setting is comparable with Atlantic and western Pacific back-arc basins associated with W-directed subduction zones that show similar large-scale lithospheric boudinage.     

Coastal geoindicators of environmental change in the humid tropics

The primary geoindicators appropriate for monitoring environmental changes in the humid tropics are transitory surface water levels, shoreline position, wetlands distribution, coral reefs, landforms, and sediment sequence and composition. Lateral zonations and temporal successions of vegetation also can be used as geoindicators of riverine and shoreline changes. All of these coastal geoindicators are sensitive to regional tectonic processes and anthropogenic alterations and they typically reflect significant changes in coastal conditions such as fluvial processes, coastal energy, water quality, relative sea level, and sediment supply. Where humid tropical coasts coincide with active tectonic margins, indicators of seismic activity are critical to understanding coastal changes associated with co-seismic subsidence or uplift, tsunamis, and liquefaction of coastal sediments. Coastal landforms and sedimentary deposits that record late Quaternary environmental changes include perched fluvial and marine terraces, delta-plain morphologies, crevasse-splay deposits, peats and other paleosols, beach ridges, mud capes, and mud volcanoes. Although these features and deposits typically reflect environmental changes spanning more than 100 years, they are relevant to modern processes, management of coastal lands and resources, and prediction of future conditions. In some regions of the humid tropics, large coastal areas are unaffected by hurricanes or typhoons. Nevertheless, these tropical coasts are vulnerable to other non-storm processes, such as El Niño events, tsunamis, and monsoons that increase water levels, and cause widespread flooding and beach erosion. The environmental and political significance of coastal geoindicators increases when they are integrated and applied to issues of human safety and health such as hazards mapping, risk assessment, and dispersion of contaminated sediments. However, to be relevant, those socio-environmental applications demand accurate predictions of future trends and rates of change.     

Strath terraces of Jinshaan Canyon, Yellow River, and Quaternary tectonic movements of the Ordos Plateau, North China

ABSTRACT Studies of the strath terraces in Jinshaan Canyon − where the Yellow River cuts through the Ordos Plateau in the continental interior of China − provide an opportunity to solve some of the critical problems associated with Quaternary tectonic movement of the plateau. Six strath terraces indicate that five episodes of regional epeirogenic uplift affected the Ordos Plateau during the Quaternary. The local tectonic deformation is superimposed on the regional epeirogenic uplift, expressed either as faulting or as non-uniform uplift induced by local arching. The results have important implications for understanding the relationship between the regional epeirogenic uplift of the Ordos Plateau and the uplift of the Qingzang Plateau, time lines of climate change in the regional epeirogenic uplift landscape, and the genesis of strath terraces associated with the through-flowing plateau drainage in the continental interior.     

川西岷江松潘段第四纪与新构造运动特征分析

在已有调查研究的基础上,通过野外地质调查和剖面测量,重点分析了岷江松潘段的漳腊盆地、斗鸡台盆地地貌特征、第四纪沉积物类型、物质成分、空间分布等特征,并系统测量和研究了松潘段岷江干流及其支流的河流阶地特征。研究表明,新构造运动控制了松潘段第四纪盆地的形态和地貌演化过程,漳腊盆地和斗鸡台盆地形成于中新世末至上新世初,西侧控盆断裂为东倾正断层,东侧为西倾逆断层,盆地为断块发生西降东升的翘板式断块运动过程中形成的,称之为"翘板式箕状盆地"。松潘段岷江河谷地貌呈现出宽谷和窄谷交替出现的特点,岷江干流及其支流中发育多处湖相地层,沉积特征表现为堰塞湖。岷江上游松潘段最多发育6级阶地,以侵蚀阶地和堆积阶地为主,主要形成于中更新世晚期—全新世时期。阶地级数具有分段性特点,不同区段阶地阶面宽窄不一,受区内新构造活动控制明显。岷江上游新构造运动表现为南北条带性和东西向差异掀斜抬升的特点,红桥关以上整体为构造隆升区,至少具有3次构造隆升,岷江上游斗鸡台盆地构造隆升强度整体上大于漳腊盆地。在尕米寺地区可能发生了6次构造抬升,红桥关一带构造抬升明显要强于漳腊盆地。     

Holocene coastal evolution and uplift mechanisms of the northeastern Raukumara Peninsula,North Island,New Zealand

The coastal geomorphology of the northeastern Raukumara Peninsula, New Zealand, is examined with the aim of determining the mechanisms of Holocene coastal uplift. Elevation and coverbed stratigraphic data from previously interpreted coseismic marine terraces at Horoera and Waipapa indicate that, despite the surface morphology, there is no evidence that these terraces are of marine or coseismic origin. Early Holocene transgressive marine deposits at Hicks Bay indicate significant differences between the thickness of preserved intertidal infill sediments and the amount of space created by eustatic sea level rise, therefore uplift did occur during early Holocene evolution of the estuary. The palaeoecology and stratigraphy of the sequence shows no evidence of sudden land elevation changes. Beach ridge sequences at Te Araroa slope gradually toward the present day coast with no evidence of coseismic steps. The evolution of the beach ridges was probably controlled by sediment supply in the context of a background continuous uplift rate. No individual dataset uniquely resolves the uplift mechanism. However, from the integration of all evidence we conclude that Holocene coastal uplift of this region has been driven by a gradual, aseismic mechanism. An important implication of this is that tectonic uplift mechanisms do vary along the East Coast of the North Island. This contrasts with conclusions of previous studies, which have inferred Holocene coastal uplift along the length of the margin was achieved by coseismic events. This is the first global example of aseismic processes accommodating uplift at rates of >1 mm yr⁻¹ adjacent to a subduction zone and it provides a valuable comparison to subduction zones dominated by great earthquakes.     

The Mazafran river (western Sahel of Algiers): superimposition or antecedence?

At the western Sahel of Algiers, the watercourse of the Mazafran river is perpendicular to the Sahel fold, forming a gorge that has developed in a tectono-eustatic context characteristic of the Sahel region. This gorge has formed in a regime of superimposition which involves the evolution of antecedence in relation to the Sahel uplift. This deduction is the result of multiple analyses that are based on a stratigraphic study which characterizes the succession of continental and marine deposits and the analyses of lineament map of tectonic evolution during the Quaternary which is marked by the Sahel folding. In order to correlate the chronology between the fluvial and marine sedimentary dynamics, a geomorphological study of the Mazafran alluvial terraces associated with the paleoshorelines was realized. The obtained results reveal that the development of the Mazafran river gorge is complex.     

太行山南缘新生代的隆升与断陷过程

作者通过太行山南缘夷平面、河流阶地、山前盆地和中新生代断裂的调查研究,揭示了太行山南缘新生代的断陷与隆升过程,认为太行山南缘地区新生代以来的构造活动以断裂的断陷、隆升为特征,分为三个相对稳定夷平时期和三个快速隆升阶段,形成三级夷平面.第四纪以来的快速隆升过程可进一步划分为六次相对快速抬升和六个相对稳定堆积时期,形成六级阶地.古近纪断陷活动强烈,第四纪除山前断裂以外,其它断裂未见活动.