Erosion and sedimentation as processes controlling the BSR-derived heat flow on the Eastern Nankai margin

In 2000, a 3D MCS survey was carried out on the Eastern Nankai Trough. A strong and widespread bottom-simulating reflector (BSR) was observed and mapped after a preserved amplitude 3D prestack migration of the seismic data. We use this BSR to calculate a heat flow map over the 3D survey area. This map presents some high and low heat flow areas, that cannot be correlated to known active wedge faults and previously observed fluid venting sites. Since the heat flow anomalies are not correlated to known major faults or fluid venting sites, large fluid circulation is not likely to explain the varying BSR-derived heat flow distribution. In order to explain this heat flow distribution quantitatively, we calculate the rates of erosion and sedimentation that are necessary to create these anomalies. These rates are in good agreement with observations on seismic profiles, and are locally consistent with a sedimentation rate calculated from slope basin depth, and reflect the distribution of erosion, landsliding and deposition on the margin slope. We therefore propose that the observed BSR-derived heat flow anomalies are mainly due to active erosion and sedimentation, and that heat flow distribution on the margin section of the 3D survey is controlled by surface processes. Fluid migration could occur where a BSR is absent, but is probably episodic or limited where a BSR is present, and does not affect the BSR-derived heat flow in this part of the margin. These surface processes are the consequence of the tectonic and seismic activity of the wedge and are influenced by the subduction of a wide oceanic ridge below the Eastern Nankai margin.     

Detrital geochronology of unroofing magmatic complexes and the slow erosion of Oligocene volcanoes in the Alps

Tectonic reconstructions and quantitative models of landscape evolution are increasingly based on detailed analysis of detrital systems. Since the definition of closure temperature in the 1960s, mineral ages of low-temperature geochronometers are traditionally interpreted as the result of cooling induced by erosion, whose rate is a simple, unique function of age patterns. Such an approach can lead to infer paradoxically high erosion rates that conflict with compelling geological evidence from sediment thickness in basins. This indicates that tectonic and landscape models that solely interpret mineral ages as due to cooling during exhumation may not be valid.Here we propose a new approach that takes into account the effects of both crystallization and exhumational cooling on geochronometers, from U–Pb on zircon to fission tracks on apatite. We first model the mechanical erosion of an unroofing magmatic complex and the resulting accumulation and burial of the eroded units in reverse order in the basin. Detrital mineral ages follow a regular pattern downsection. Some mineral ages, such as e.g. U–Pb ages of zircons, cluster around the “magmatic age”, i.e. the crystallization of the magma. Its value is constant along the stratigraphic column in the sedimentary basin; we refer to this behavior as “stationary age peak”. Some other mineral ages, such as e.g. apatite fission-track ages, are often younger than the magmatic age. When they vary smoothly with depth, they define a “moving age peak”, which is the only possible effect of undisturbed cooling during overburden removal, and can therefore be used to calculate an erosion rate.The predictions of our model were tested in detail on the extremely well-studied Bregaglia (Bergell) orogenic pluton in the Alps, and on the sedimentary succession derived from its erosion, the Gonfolite Group. The consistency between predicted and observed age patterns validates the model. Our results resolve a long-standing paradox in quantitative modelling of erosion–sedimentation, namely the scarcity of sediment during apparently fast erosion. Starved basins are the observational baseline, and modelling must be tuned to include a correct analysis of detrital mineral geochronology in order to reconcile perceived discrepancies between stratigraphical and geochronological information. In addition, our data demonstrate that volcanoes were active on top of the growing Oligocene Alps.This study illustrates rigorous criteria for detrital mineral geochronology that are applicable to any geological setting, including magmatic arcs and collision orogens, and provides fundamental interpretive keys to solve complex puzzles and apparent paradoxes in geological reconstructions.     

The impact of internal waves on upper continental slopes: insights from the Mozambican margin (southwest Indian Ocean)

Evidences of sedimentation affected by oceanic circulation, such as nepheloid layers and contourites are often observed along continental slopes. However, the oceanographic processes controlling sedimentation along continental margins remain poorly understood. Multibeam bathymetry and high-resolution seismic reflection data revealed a contourite depositional system in the Mozambican upper continental slope composed of a contourite terrace (a surface with a gentle seaward slope dominated by erosion) and a plastered drift (a convex-shape sedimentary deposit). A continuous alongslope channel and a field of sand dunes (mainly migrating upslope), formed during Holocene, were identified in the contourite terrace at the present seafloor. Seismic reflection data of the water column show internal waves and boluses propagating in the pycnocline near the upper slope. The channel and the dunes are probably the result of the interaction of the observed internal waves with the seafloor under two different conditions. The alongslope channel is located in a zone where intense barotropic tidal currents may arrest internal solitary waves, generating a hydraulic jump and focused erosion. However, upslope migrating dunes may be formed by bottom currents induced by internal solitary waves of elevation propagating landwards in the pycnocline. These small-scale sedimentary features generated by internal waves are superimposed on large-scale contouritic deposits, such as plastered drifts and contourite terraces, which are related to geostrophic currents. These findings provide new insights into the oceanographic processes that control sedimentation along continental margins that will help interpretation of palaeoceanographic conditions from the sedimentary record. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

Seabed erosion and deposition related to the typhoon activity of the past millennium on the southeast coast of China

Catastrophic events often interrupt long-term Earth surface processes. In coastal areas, although millennial-scale trends of climatic and sea-level changes determine the trajectory of sedimentary landform evolution, storm and/or tsunami activity can cause abrupt changes in depositional conditions that may alter the long-term sedimentary processes. Here, we report a sedimentary hiatus that is widely observed from the late Holocene sedimentary sequence at the seabed along the southeast China coast. This hiatus was discovered by close temporal sedimentary and radiocarbon dating analyses of a seabed sedimentary sequence in the mouth area of the Pearl River estuary. The results suggest that a couple of metres in the middle to late Holocene sediment at the seabed were eroded by a catastrophic event happening c. 1000–800 cal. Years BP. In theory, a mega-tsunami generated from the Manila Trench could have caused such erosion at the seabed, but there is a lack of direct geological and historical evidence to support such a hypothesis. Much more likely, a super-typhoon struck the coast and caused the erosion. This hypothesis is strongly supported by the region's historical and geological records, which suggest a period characteristic of intense typhoons ranging from the Medieval Warm Period to the climate transition phase (c. 1000–600 cal. Years BP). During the subsequent Little Ice Age, deposition of sandy sediment continued, suggesting frequent but weaker typhoon activity. Over the past two centuries the deposition of sandy sediment and gravels began, implying the beginning of a phase of intensifying typhoon conditions, possibly a result of the recent warming climate. © 2020 John Wiley & Sons, Ltd.     

DEVELOPMENT OF TRANSVERSE DRANAGES AND FORMATION OF WIND GAPS ON ACTIVELY GROWING FOLD: REVIEW AND CASE STUDY

The most compelling phenomena for transverse drainage in active fold belt are lateral diversion of channels and development of water/wind gaps. This phenomenon is the result of competition between uplift and erosion, which is controlled by fault vertical/lateral propagation and segment linkage, fault geometry, climate condition and lithology. Previous studies found that the higher the uplift rate is, the greater number of wind gaps form, and the variation of the uplift rate is also critical to the sustainability of transverse rivers. Lateral propagation and linkage of several separate folds in fold-and-thrust belts will lead to defeat of streams and diversion into a trunk drainage; if the trunk is still unable to keep pace with uplift, water gap will be abandoned and left as a wind gap. For lateral propagation of an anticline associated with development of tear faults, the locations of wind/water gaps are likely to coincide with the trace of tear fault and it's not quite clear about the relation between tear faulting and stream deflection. Nonzero dip of the underlying detachment induces a lateral surface slope in the direction of fault propagation, which in turn makes rivers deflection more efficient. Climate and rock erodibility control the water/sediment discharge, and further influence river transport/incision capacity. The changing climate and rock erodibility conditions enable river to abandon the current waterway to create a wind gap unless they could down-cut through a growing fold. However, the role of climate cycle in the formation of wind gap is still controversial. In addition, wind gaps are commonly developed along the divides where parts of longitudinal river have been captured by transverse catchments. Generally, the development of transverse drainages and the formation of wind gaps in nature are result from a combination of tectonic and fluvial process. The wind gap pattern and transverse drainage evolution in fold-and-thrust belts contain plenty of information on fault growth, interaction between tectonic uplift and fluvial erosion, and development of sedimentary basin. Such researches have significant implications in geomorphology, seismic hazard assessment and hydrocarbon exploration. However, there are still many knowledge gaps on the study of transverse river evolution in active fold areas. First, adequate chronology and geomorphic/strata mark to quantify fold growth and erosion is commonly not available, which leads to a poorly constrained rate in both river incision and lateral propagation of growing folds. In addition, more geological and geomorphological processes could influence the evolution of transverse drainages. For examples, (1)during the formation of a young range or anticline, the mechanism of fault-related folding may change over time, e.g. from fault-propagation folding to surface breaking; (2)Besides the knickpoint retreat in downstream, efficient lateral planation and downstream sweep erosion are also important in understanding the erosion of folds by rivers flowing through it. These processes make the development of transverse drainage across folds more complex and should be considered in more comprehensive models. There are lots of rivers originating from the Tibetan plateau and cutting through young surrounding mountains. These surrounding mountains, such as Qilian Mountains, Tianshan Mountains and Longmen Mountains, are ideal areas for the study of transverse river evolution and wind gap formation. In the end, combining with the geological and geomorphological features of the Heli Shan-Jintanan Shan, north of Hexi Corridor, we propose that the Heihe River has experienced deflection, beveling and incision since Mid Pleistocene. These processes have led to 1)the formation of a wind gap on the western Heli Shan, 2)a layer of fluvial gravels from the Qilian Shan preserved on the top surface of the Jintanan Shan, and overlying angular unconformity upon older strata, and 3)the incision of the Heihe River to form the Zhengyi Gorge through the linked structure between Heli Shan and Jintanan Shan. Thus, we propose a general model for the development of transverse drainages in the central Hexi Corridor: deflection-beveling-incision.     

Climate controls on coupled processes of chemical weathering,bioturbation, and sediment transport across hillslopes

Most hillslope studies examining the interplay between climate and earth surface processes tend to be biased towards eroding parts of landscapes. This limitation makes it difficult to assess how entire upland landscapes, which are mosaics of eroding and depositional areas, evolve physio‐chemically as a function of climate. Here we combine new soil geochemical data and published ¹⁰Be‐derived soil production rates to estimate variations in chemical weathering across two eroding‐to‐depositional hillslopes spanning a climate gradient in southeastern Australia. At the warmer and wetter Nunnock River (NR) site, rates of total soil (–3 to –14 g m^‐2 yr^‐1; negative sign indicates mass loss) and saprolite (–18 to –32 g m^‐2 yr^‐1) chemical weathering are uniform across the hillslope transect. Alternatively, the drier hillslope at Frog's Hollow (FH) is characterized by contrasting weathering patterns in eroding soils (–30 to –53 g m^‐2 yr^‐1) vs. depositional soils (+91 g m^‐2 yr^‐1; positive sign indicates mass addition). This difference partly reflects mineral grain size sorting as a result of upslope bioturbation coupled with water‐driven soil erosion, as well as greater vegetative productivity in moister depositional soils. Both of these processes are magnified in the drier climate. The data reveal the importance of linking the erosion–deposition continuum in hillslope weathering studies in order to fully capture the coupled roles of biota and erosion in driving the physical and chemical evolution of hillslopes. Our findings also highlight the potential limitations of applying current weathering models to landscapes where particle‐sorting erosion processes are active. Copyright © 2018 John Wiley & Sons, Ltd.     

青藏高原构造热演化的主要控制因素

从构造热演化的角度研究了青藏高原的形成模式,对形成机制中的两种主要假说:双地壳模型和叠瓦状模型进行了热模拟.在模拟时考虑了逆冲断层、均衡地壳抬升和沉积覆盖层对温度场的影响.结果表明,双地壳模型的热演化结果和实际观测资料明显不符;叠瓦状模型的结果在藏南地区能够较好地符合地球物理观测资料和解释地质构造运动.除较高的放射性元素含量外,断层的摩擦剪切热和沉积盖层热折射伴随地体的抬升侵蚀是喜马拉雅两条花岗岩带和反转的高温变质岩带的主要成因,并和现今上地壳水热活动有密切的关系.     

逆冲-褶皱造山过程中生长地层的识别及应用

生长地层记录了大量的构造变形和沉积历史信息,主要形成于逆冲-褶皱造山带前陆盆地边缘,在前陆盆地生长构造(如生长逆断裂-褶皱带)翼部或顶部与褶皱构造变形同期沉积的地层,是构造运动与沉积作用同时进行的产物,在构造横剖面上,整个生长地层序列在褶皱翼部具有楔形几何状态。根据其形成方式的不同,可以分为断层转折褶皱作用和断层传播褶皱及滑脱褶皱作用等。生长地层的最终形态受各种地质作用影响,其中主要因素是构造变形、沉积速率和侵蚀作用,三者之间在生长地层形成过程中通常具有“复合”作用。通过生长地层的详细研究,可以建立同构造生长地层模式,而广泛应用于确定前陆逆冲-褶皱带与相应地层的时代、变形速率,分析与逆冲推覆断层相关的褶皱几何形态,以及建立动力学模式等。生长地层的野外识别一般可从褶皱翼部和枢纽变化、翼部同沉积楔体、地层产状和厚度变化以及区域资料收集对比等几方面来综合分析,同时采用多模式、多手段的室内分析将是研究生长地层最为有效的方法,也是今后的重点发展方向。通过对生长地层的识别标志和模式的进一步认识,初步分析了六盘山山前宁夏固原寺口子剖面,认为寺口子盆地为逆冲-褶皱造山带前陆磨拉石盆地,其内可能存在有生长地层和生长不整合,但需     

青藏高原构造热演化的主要控制因素

从构造热演化的角度研究了青藏高原的形成模式,对形成机制中的两种主要假说:双地壳模型和叠瓦状模型进行了热模拟.在模拟时考虑了逆冲断层、均衡地壳抬升和沉积覆盖层对温度场的影响.结果表明,双地壳模型的热演化结果和实际观测资料明显不符;叠瓦状模型的结果在藏南地区能够较好地符合地球物理观测资料和解释地质构造运动.除较高的放射性元素含量外,断层的摩擦剪切热和沉积盖层热折射伴随地体的抬升侵蚀是喜马拉雅两条花岗岩带和反转的高温变质岩带的主要成因,并和现今上地壳水热活动有密切的关系.     

Application of fluid mechanic principles to the study of geodynamic processes at trench-arc-back arc systems

Geological processes at trench-arc-back arc systems are some of the most complex tectonic processes in need of study. A large amount of data based on geological and geophysical observations has been accumulated. To synthesize these data, mathematical models have proven to be very useful. Because geological processes are directly related to the dynamical behavior of the solid earth, many of them can be investigated in terms of fluid flow models. Some applications of fluid flow principles in studying tectonic processes at convergent plate boundaries are discussed in this paper. When mantle processes are modeled as convective systems, they are found to have direct implications for the determination of slab dip angles. Additionally, they can also account for the high heat flows in the back arc basins, provide a mechanism for back arc opening, and resolve the question whether subducted oceanic crust can reach melting at shallow depth for island arc magma generation. Besides mantle processes, flow models can also be used to study surface processes. A simple one-parameter plane flow theory is used to model the evolution of trench geometries. This model is able to fit simulataneously the trench curvature and the differential paleomagnetic rotation between volcanic islands for the Mariana. Despite the simplicity of many of these models, their ability to synthesize geological and geophysical data at convergent plate boundaries is quite remarkable.     

Paleozoic sedimentation and tectonics in Korea: A review

Abstract The geological history of the Korean Paleozoic is recorded in lower and upper Paleozoic strata, mostly distributed in two relatively large sedimentary basins, the Taebaeksan and Pyeongnam basins. The lower Paleozoic sedimentary rocks are exclusively of marine origin, dominated by shallow platform carbonate rocks with minor interbedded siliciclastic rocks. The development of the lower Paleozoic sequence was mostly controlled by eustatic changes, having cyclic sedimentation of various temporal scales. During the early Paleozoic the Korean Peninsula was located in a low‐latitude tropical region and experienced frequent storm activities. The upper Paleozoic sequence comprises paralic to non‐marine rocks with minor limestone intercalations in the lower part of the sequence. Upsection changes in sandstone composition and mudrock geochemistry of the upper Paleozoic Pyeongan Supergroup in the Samcheok coalfield indicate that sediments may have been derived from the continued uplift and unroofing of a collisional orogen source. There exists a great unconformity between the lower and upper Paleozoic strata, which spans the geological time from the Late Ordovician to Early Carboniferous. The unconformity period is conventionally thought to be of non‐deposition, but a recent study suggests that it is characterized by continuous sedimentation and significant removal (>1 km thick) of sediments by erosion. No Paleozoic tectonic history has been addressed so far, and thus it needs further study to elucidate geological events during the middle–late Paleozoic in the Korean Peninsula. Tectonostratigraphic correlation of the Korean Peninsula with neighboring Chinese blocks has been a hot issue for a long time. Although the eastward extension of the Chinese collision belt has been recently suggested to be the Imjingang belt located in the middle of the peninsula, further studies are needed to test this hypothesis because results of recent paleontological, sedimentological and stratigraphic studies on Paleozoic sediments are not in agreement with this possibility.     

挤压型盆地构造热演化模拟研究综述

挤压过程对地质构造和沉积盆地的形成演化具有重要的作用.研究挤压型盆地的构造热演化模拟对认识岩石圈内部应力分布、力学属性和流变结构具有重要意义.本文介绍了挤压型盆地构造模拟的弹性模型、粘弹性模型和深度控制的弹塑性模型,对比了这几种模型的优缺点和适用范围.简单介绍了前人在研究地壳隆升时用到的几种热演化模拟方法.虽然挤压过程的构造模拟已经取得了很大进展,挤压型盆地的热演化模拟则具有很大的发展空间,这应是进一步研究的重点.     

Combined hillslope diffusion and sediment transport simulation applied to landscape dynamics modelling

We present a new numerical approach for simulating geomorphic and stratigraphic processes that combines open‐channel flow with non‐uniform sediment transport law and semi‐empirical diffusive mass wasting. It is designed to facilitate modelling of surface processes across multiple space‐ and time‐scales, and under a variety of environmental and tectonic conditions. The physics of open‐channel flow is primarily based on an adapted Lagrangian formulation of shallow‐water equations. The interaction between flow and surface geology is performed by a non‐uniform total‐load sediment transport law. Additional hillslope processes are simulated using a semi‐empirical method based on a diffusion approach. In the implementation, the resolution of flow dynamics is made on a triangulated grid automatically mapped and adaptively remeshed over a regular orthogonal stratigraphic mesh. These new methods reduce computational time while preserving stability and accuracy of the physical solutions. In order to illustrate the potential of this method for landscape and sedimentary system modelling, we present a set of three generic experiments focusing on assessing the influence of contrasting erodibilities on the evolution of an active bedrock landscape. The modelled ridges morphometrics satisfy established relationships for drainage network geometry and slope distribution, and provide quantitative information on the relative impact of hillslope and channel processes, sediment discharge and alluviation. Our results suggest that contrasting erodibility can stimulate autogenic changes in erosion rate and influence the landscape morphology and preservation. This approach offers new opportunities to investigate joint landscape and sedimentary systems response to external perturbations. The possibility to define and track a large number of materials makes the implementation highly suited to model source‐to‐sink problems where material dispersion is the key question that needs to be addressed, such as natural resources exploration and basin analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

Approaches to Modelling Long-term Landscape Evolution: Lessons from Ice Sheet Modelling

Advances in the understanding of physical principles underlying geophysical processes have enabled us to develop complex numerical models of landscape evolution. These advances have shaped recent contributions to the long-running debates within geomorphology concerning the relative value of approaches which emphasize the unchanging (immanent) physical principles underlying geomorphic processes, compared with the historical (configurational) nature of landscapes which rely on circumstantial conditions for their existence. This paper uses examples from glaciology to assess the extent to which the developments in short-term process studies and numerical models assist us in understanding the long-term processes of landscape evolution. The implication is that while both developments stress the immanent nature of geophysics, their limitations highlight the need for a balanced approach incorporating both immanent and configurational approaches. The key is that it is possible to explain and understand long-term processes without necessarily being able to predict them with numerical models. Modelling approaches should stress the contexual nature of the studies by means of a full exploration of possible outcomes of different model components. © 1997 by John Wiley & Sons, Ltd.     

Magnitude and processes of bank erosion at a small stream in Denmark

River banks are important sources of sediment and phosphorus to fluvial systems, and the erosion processes operating on the banks are complex and change over time. This study explores the magnitude of bank erosion on a cohesive streambank within a small channelized stream and studies the various types of erosion processes taking place. Repeat field surveys of erosion pin plots were carried out during a 4‐year period and observations were supplemented by continuous monitoring of volumetric soil water content, soil temperature, ground water level and exposure of a PEEP sensor. Bank erosion rates (17·6–30·1 mm year^?1) and total P content on the banks were relatively high, which makes the bank an important source of sediment and phosphorus to the stream, and it was estimated that 0·27 kg P_tot year^?1 ha^?1 may potentially be supplied to the stream from the banks. Yearly pin erosion rates exceeding 5 cm year^?1 were mainly found at the lower parts of the bank and were associated with fluvial erosion. Negative erosion pin readings were widespread with a net advance of the bank during the monitoring period mainly attributed to subaerial processes and bank failure. It was found that dry periods characterized by low soil water content and freeze–thaw cycles during winter triggered bank failures. The great spatial variability, in combination with the temporal interaction of processes operating at different scales, requires new tools such as 3‐D topographical surveying to better capture bank erosion rates. An understanding of the processes governing bank erosion is required for riparian management using vegetational measures as root size and structure play different roles when it comes to controlling bank erosion processes. Copyright © 2010 John Wiley & Sons, Ltd.     

利用磷灰石裂变径迹资料反演合肥盆地古地温和估计沉降率与剥蚀率

利用合肥盆地内６个磷灰石裂变径迹样品资料,反演模拟了该盆地自侏罗纪晚期以来各时代地层古地温变化,估算了沉降率与剥蚀率．模拟结果与其他地质资料推论一致,它揭示出该盆地南北两地存在不同的构造变化和受热史,反映了大别山构造发展对盆地南北两地区影响的差异．盆地南部靠近大别山地区的晚侏罗世地层在白垩纪早期埋藏温度曾大于１２０℃;早白垩世后期的构造抬升（剥蚀率约１３０ｍ／Ｍａ）使温度降至３０—４０℃;自白垩纪后期始,该地区一直处于动荡的但总体为持续抬升的构造环境中．盆地北部地区晚侏罗世与早白垩世早期地层在白垩纪期间埋藏温度曾达到和超过１００℃,但随后的大幅度构造抬升（剥蚀率约１９０ｍ／Ｍａ）使其温度降至３０—６０℃;第三纪早期,局部区域的裂陷（沉降率约６０ｍ／Ｍａ）使温度又升至８０℃左右．指出合肥盆地构造演化大体可分形成、隆升、局部裂陷和再隆升４个阶段．     

利用磷灰石裂变径迹资料反演合肥盆地古地温和估计沉降率与剥蚀率

利用合肥盆地内６个磷灰石裂变径迹样品资料，反演模拟了该盆地自侏罗纪晚期以来各时代地层古地温变化，估算了沉降率与剥蚀率．模拟结果与其他地质资料推论一致，它揭示出该盆地南北两地存在不同的构造变化和受热史，反映了大别山构造发展对盆地南北两地区影响的差异．盆地南部靠近大别山地区的晚侏罗世地层在白垩纪早期埋藏温度曾大于１２０℃；早白垩世后期的构造抬升（剥蚀率约１３０ｍ／Ｍａ）使温度降至３０-４０℃；自白垩纪后期始，该地区一直处于动荡的但总体为持续抬升的构造环境中．盆地北部地区晚侏罗世与早白垩世早期地层在白垩纪期间埋藏温度曾达到和超过１００℃，但随后的大幅度构造抬升（剥蚀率约１９０ｍ／Ｍａ）使其温度降至３０-６０℃；第三纪早期，局部区域的裂陷（沉降率约６０ｍ／Ｍａ）使温度又升至８０℃左右．指出合肥盆地构造演化大体可分形成、隆升、局部裂陷和再隆升４个阶段．     

Synergy of satellite remote sensing and numerical modeling for monitoring of suspended particulate matter

Monitoring and modeling of the distribution of suspended particulate matter (SPM) is an important task, especially in coastal environments. Several SPM models have been developed for the North Sea. However, due to waves in shallow water and strong tidal currents in the southern part of the North Sea, this is still a challenging task. In general there is a lack of measurements to determine initial distributions of SPM in the bottom sediment and essential model parameters, e.g., appropriate exchange coefficients. In many satellite-borne ocean color images of the North Sea a plume is visible, which is caused by the scattering of light at SPM in the upper ocean layer. The intensity and length of the plume depends on the wave and current climate. It is well known that the SPM plume is especially obvious shortly after strong storm events. In this paper a quasi-3-D and a 3-D SPM transport model are presented. Utilizing the synergy of satellite-borne ocean color data with numerical models, the vertical exchange coefficients due to currents and waves are derived. This results in models that for the first time are able to reproduce the temporal and spatial evolution of the plume intensity. The SPM models consist of several modules to compute ocean dynamics, the vertical and horizontal exchange of SPM in the water column, and exchange processes with the seabed such as erosion, sedimentation, and resuspension. In the bottom layer, bioturbation via benthos and diffusion processes is taken into account.Responsible Editor: Jörg-Olaf Wolff     

Coastal sedimentation associated with the December 12th, 1992 tsunami in Flores,Indonesia

This paper presents the result of a detailed granulometric investigation of sediments deposited by a modern tsunami, the 1992 tsunami in Flores, Indonesia. Eyewitness accounts indicate that sediments were deposited upon coastal lowlands over wide areas as a result of the tsunami inundation. Distinctive vertical and lateral variations in particle size composition are characteristic features of the tsunami deposits and these are intimately related to sedimentary processes associated with flood inundation. The geomorphological and sedimentary evidence is used here to establish a preliminary model of tsunami sedimentation. This information is believed to be of great value in understanding sedimentary processes associated with tsunami flooding and in the interpretation of palaeo-tsunami deposits.