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1.
A number of ‘weathering’ horizons have been identified within glacigenic sediment sequences in North Wales and have been instrumental in determining various proposed Late Quaternary event chronologies. This paper applies the techniques of mineral magnetic analysis to such a sediment sequence at Glanllynnau. The presence (or otherwise) of evidence for weathering processes on the upper surface of the Criccieth Till, which is overlain by further glacial materials, is examined. Despite a marked colour variation between the ‘weathered’ and non-weathered components of the Criccieth Till, their mineral magnetic properties suggest little or no variation in iron oxide assemblages. The consequences of this for the environmental interpretation of the sediment sequence are discussed.  相似文献   

2.
ABSTRACT Stratigraphy presupposes a hierarchy of scales of spatial organization supplemented at the small‐scale end by sedimentological concepts (beds, bed sets and bed cosets) and, at larger spatial scales, by sequence‐stratigraphic concepts (systems tracts, parasequences, sequences). Between these two end‐members are intermediate‐scale bodies described as ‘lithofacies’, or simply ‘facies’. A more restricted concept, granulometric facies, can be described in terms of horizontal grain‐size gradients (‘facies change’) and cyclic vertical grain‐size gradients (‘stratification’). Assemblages of facies so defined (also called depositional systems) are not random, but occur in a limited suite of patterns. Such assemblages may be linked to two classes of bounding surfaces, a source diastem (the immediate source of the sediment) and a surface of closure (if preserved), between which is sandwiched a transgressive or regressive, basinward‐fining facies succession. Systems‐bounding surfaces are notably more continuous than internal (gradational) facies boundaries. By thus restricting the definition of a facies assemblage (depositional system), it is possible to describe the Quaternary of the Virginia coast with as few as 12 systems. Depositional systems in the Quaternary of the Virginia coast are allometric, in that any system can be derived from any other by plastic expansion of one or more facies relative to another, or by simple symmetry operations. Self‐similarity prevails across this intermediate scale of stratigraphic organization. Facies assemblages (depositional systems) consist of event beds, which themselves have erosional basal boundaries and internal successions of microfacies. At larger spatial scales, depositional systems are repeated, either autocyclic repetitions forced by processes within the basin of deposition or allocyclic repetitions, as ‘parasequences’ and high‐frequency sequences. In the Virginia Quaternary, systems architecture is compatible with sequence architecture and nests conformably within its framework, but analysis of systems architecture reveals rules beyond those governing sequence architecture.  相似文献   

3.
The formulation of viscoelastic solutions from elastic equations using the ‘correspondence principle’ and an inverse Laplace transform has been discussed extensively in the literature. Because this method has been developed, many time-dependent solutions can be obtained from closed form elastic solutions and conditions have been delineated in which the ‘quasi-elastic’ approximation of the viscoelastic solution is within acceptable tolerance. This communication shows the feasibility of the application of these methods to formulate approximate nonlinear viscoelastic solutions with nonlinear stress-strain materials, and for want of a specific nonlinear model to demonstrate this, the hyperbolic model was selected. The ‘power law’ is used to model the relaxation modulus of the viscoelastic materials. There are five related development that are discussed here using a simple numerical example to illustrate each of them and they are: (1) a linear elastic solution, (2) a linear viscoelastic solution, (3) a nonlinear elastic solution, (4) a nonlinear viscoelastic solution and finally, (5) a ‘regression’ approximation of the nonlinear viscoelastic solution which is suggested by the series form of the elastic solution. All of these are related to one another and each provides an acceptably accurate solution of the problem it addresses. The latter is of particular practical interest since it can be used to provide answers to problems involving nonlinear viscoelastic materials while requiring only very small calculation times. The problem used as an example is the calculation of the displacement of a circular hole in an infinite plate made of a material with a nonlinear time-dependent stress-strain relationship. The nonlinear elastic form of the solution was developed by matching results from nonlinear finite element analysis.  相似文献   

4.
The ‘Red Clay’ is an important deposit underlying the Quaternary loess–palaeosol sequence in the Chinese Loess Plateau, being regarded as an excellent record of palaeoclimate changes in the late Tertiary. Several properties of the ‘Red Clay’ have been measured previously in order to derive climatic information. However, the sedimentary processes involved and the origin of the materials remain controversial. Here we present results of grain‐size analyses of the ‘Red Clay’ from four representative sites in the Chinese Loess Plateau. In particular their grain‐size distribution is compared with that of typical Quaternary aeolian loess–palaeosol, as well as lacustrine and fluvial sediments. It appears from the sedimentological evidence that the major part of the ‘Red Clay’ is of aeolian origin. It is rather similar in some of its properties to the Quaternary loessic palaeosols. The dust forming the ‘Red Clay’ was transported by a wind system that was weaker than that involved in the accretion of the Quaternary loess. Furthermore, the ‘Red Clay’ sediment has been modified by post‐depositional weathering. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

5.
Microfocus X-ray computed tomography (µCT) is a useful tool for non-destructive analysis of corroded archaeological glass objects and for monitoring restoration and conservation processes for these materials. This was demonstrated by µCT analysis of artificially corroded laboratory-produced glasses and corroded archaeological glasses retrieved from soil environments. Corrosion layers with a thickness of 20 µm or more can be detected as areas with lower X-ray attenuation values than the non-corroded glass. Features that are revealed by µCT analyses include the degree and patterns of corrosion and the presence of various internal structures in the corrosion layers. The study of restored corroded glasses demonstrates that mechanical and laser cleaning can be monitored efficiently. The study of consolidation practices, using test objects, requires the use of additives to increase X-ray attenuation values of the organic compounds that are used.  相似文献   

6.
Depositional theme of a marginal marine evaporite   总被引：1，自引：0，他引：1  
We have reconstructed the depositional environment of the gypsum-carbonate-shale sequence that comprises the Upper Permian Bellerophon Formation of the southeastern Alps in northern Italy. This formation, which reaches a maximum thickness of 600 m, is roughly divided into two facies: (a) a lower dolomite-gypsum facies, and (2) an upper micritic-skeletal limestone facies. It directly overlies, with transitional contact, a thick red-bed sequence (alluvial fanglomerates, fluviatile sandstones and flood-plain siltstones) and is sharply overlain by Lower Triassic calcarenites (oolites, grapestones, pellets, flat-pebble conglomerates). The lower evaporite facies rocks are found in well-defined cycles, each of which, from bottom to top, consists of (A) thin-bedded, worm-burrowed, vuggy ‘earthy’ micritic dolomite, (B) massive to poorly laminated dark grey to black sandy dolomite carrying isolated gypsum nodules, (C) layered (thin-bedded) nodular gypsum (commonly with ‘enterolithic’ folds) with fragmented partings of dolomite, and (D) massive ‘chicken-wire’ nodular gypsum. At Passo di Valles, just east of Predazzo, and 50 km from the basin margin, we measured forty-six consecutive complete cycles, with an average thickness of 3 m per cycle. We interpret the cyclic sequence as having been deposited in a prograding shallow lagoon—sabkha complex. The worm-burrowed ‘earthy’ dolomite mud accumulated in a shallow hypersaline subtidal lagoon. The black sandy dolomite was an ‘intertidal’ sand-flat devoid of algal mats and constantly churned by burrowers (likely crustaceans). As the shoreline prograded lagoonward evaporative concentration of the groundwater induced diagenetic growth of anhydrite nodules (now gypsum) within the porous sandy dolomite. The layered nodular and ‘chicken-wire’ gypsum of the cycle cap is an extreme product of such displacive intra-sediment growth of anhydrite (now gypsum) above the water table of a completely exposed sabkha, such as is found in the Persian Gulf today. We have observed the same cyclically arranged lithologies in two other evaporite sequences in Italy: the Triassic Raibl Formation of the Southern Alps and the Upper Triassic Burano Formation of the central Apennines. We suggest that this mode of deposition is likely a very common one for at least the early stages of marine evaporite accumulation.  相似文献   

7.
The ‘Appropriate Sampling for Optimised Measurement’ (ASOM) approach considers measurement to be the focus of the sampling process, and sampling to be only the first part of the measurement process. To achieve ASOM, the uncertainty of measurements, including its contribution from sampling, needs to be estimated and optimised in order to achieve fitness‐for‐purpose. Such samples are then ‘sufficiently’ representative. The ‘Theory of Sampling’ (TOS) focuses on the processes of primary sampling and sample preparation and assumes that samples are ‘representative’ if they are correctly prepared by nominally ‘correct’ protocols. It defines around ten sampling ‘errors’, which are either modelled or minimised to improve sampling quality. It is argued that the ASOM approach is more effective in achieving appropriate measurement quality than in applying TOS to just the first part of the measurement process. The comparison is made less effective by the different objectives, scopes, terminology and assumptions of the two approaches. ASOM can be applied to in situ materials that are too variable to be modelled accurately, or where sources of uncertainty are unsuspected. The proposed integration of ASOM with TOS (Esbensen and Wagner 2014, Trends in Analytical Chemistry, 57, 93–106) is therefore effectively impossible. However, some TOS procedures can be useful within the ASOM approach.  相似文献   

8.
In a dry valley near Ventnor, Isle of Wight, thick subaerial slope deposits of Devensian Late-glacial age overlie the Chalk. The deposits are crudely stratified chalk muds and rubble produced by frost-shattering, and moved downslope by the release of water from melting snow-fields and frozen ground. A laterally extensive humic horizon of a rendzina soil occurs within the sequence, clearly reflecting a period of relative slope stability. In places this horizon divides and its upper surface appears to have been disturbed, possibly by cryoturbation. Micromorphological and other analyses confirm the pedogenic origin of this humic horizon, but also demonstrate the occurrence of pedological features both above and below it. The humic horizon therefore is not a ‘buried’ soil in the strictest sense, but is part of a vertical sequence representing a single complex soil with transported, accretionary and welded components. Molluscan analyses reveal that the sequence can be divided into four local mollusc zones, showing a progressive increase in faunal diversity throughout the profile. This succession is broadly similar to other Late-glacial sequences described from south-east England. Minute fragments of charcoal from the lower part of the humic horizon have yielded an AMS date of 11690 ± 120 vr BP, demonstrating formation during the ‘Allerød phase’ of the Late-glacial Interstadial. This humic horizon is correlated provisionally with the ‘Pitstone Soil’, even though existing dates from its type-site in Buckinghamshire are somewhat younger.  相似文献   

9.
One of six galena samples from the Pilbara of Western Australia, located in a ‘greenstone’ sequence, appears from its lead‐isotope ratios to be of great age. ‘Linear Model III’ ages of Cumming & Richards (1975) agree with available geological evidence for this, and for one other younger sample located in the Shaw Batholith. Two of the other samples, also from Archaean granitic host rock, appear to be significantly younger than the host; the other two, from within the Lower Proterozoic Fortescue Group, suggest that its age is not yet well known. Previously‐published age information has been adapted to the newly‐accepted values for the decay constants throughout this discussion.  相似文献   

10.
This paper examines what it means to be an ‘expatriate’ in Cairo through the lens of movement and space-making. Inquiring into a set of migrant (im)mobilities, spatial practices, relations, and imaginations, it argues that as a ‘spatialised’ identity category ‘expatriate’ narrates and enacts migratory privileges linked to wider hierarchies of social difference. It contributes to a growing literature examining the social and political dimensions of ‘expatriate’ migration and further engages scholarship thinking space and movement in relational and socio-historical terms. Rather than denoting an easily distinguishable group of migrants, ‘expatriate’ emerged as a contingent and ambiguous category of practice. As such, ‘expatriate’ stands in a productive relationship with privileged movement and socio-spatial processes. Like other migrants, respondents skillfully navigated the global differences in wealth, power and status they were presented with. Yet, unlike many other migrants, they did so from a privileged position within the global power-geometries of international migration. Migrants’ personal geographies were further shaped by how bodies were racialised and gendered in entangled, intersecting and sometimes counter-intuitive ways. This diversity and complexity of ‘expatriate’ geographies highlights the necessity of intersectional and situated analyses of privilege.  相似文献   

11.
A typical stratigraphy below a streamlined till plain in Northumberland, England, consists of cross-cutting lodgement till units, within and between which occur repeated shoestring interbeds of ‘cut and fill’ channels. Till units have erosional lower contacts; in certain cases marked changes in erratic content and local ice flow direction are evident from one till unit to another. These lodgement till complexes have hitherto been described by ‘tripartite’ schemes of lower grey till (s) and upper reddened till (s) identified with respect to ‘middle’ fluvial horizons; regional correlation proceeding on the basis of matching ‘middle’ horizons, with the whole sequence commonly interpreted as evidence for multiple glaciation. Data indicates, by way of contrast, that these lodgement till complexes were deposited during a single phase of subglacial deposition. Till deposition was not continuous but was interrupted by erosional episodes. Changes in the mix of bedrock lithologies transported by the glacier down a single flow line or by lateral displacement of basal ice flow units within the glacier result in till units of different facies to be emplaced when deposition recommences, a process referred to as ‘unconformable facies superimposition’. Subglacial meltwater flow was also a characteristic of the glacier bed; channeled glaciofluvial sediment bodies are found as ribbon-like inclusions in the till and appear to have been deposited rapidly. These so-called ‘middle’ fluvial horizons occur repeatedly in section, their lateral extent at any given exposure being dependent upon the orientation of the exposure with respect to former ice flow direction. These lenses act as internal drainage blankets and have accelerated postglacial soil formation in the drier climate of eastern Britain accounting for the reddened colour of upper till(s). It is suggested that this model of subglacial deposition can be employed in other areas of northern England characterized by subglacial (lodgement till plain) terrains.  相似文献   

12.
This paper explores how migration infrastructure conditions migrant mobilities within receiving states. The paper examines two infrastructural case studies, language testing and housing markets, in relation to Asian ‘middling’ migrants, that is, the relatively educated and skilled but not elite, who arrive in Australia on temporary visas. The analysis highlights the interplays and dependencies of different ‘logics of operation’ (Xiang and Lindquist, 2014) of infrastructure in relation to these migrants’ status mobilities and housing mobilities within the receiving society. The paper draws on data from in-depth narrative interviews with migrants to also understand how infrastructure produces perceptions and meaning-making around the migration process. This analysis reveals that, in this empirical context, migration infrastructure produces varied kinds of spatio-temporal insecurity as much as it mediates mobility.  相似文献   

13.
《Geoforum》1988,19(2):189-200
The spatial shopping behaviour of the urban elderly has received increasing attention from researchers in a variety of disciplines including geography, marketing, city planning, and social gerontology. Relevant literature from these diverse sources is reviewed within an organizational framework based on two ‘behavioural’ approaches to retail geography: ‘empirical-behavioural’ and ‘cognitive-behavioural’. Overall, the research findings suggest that the elderly represent a distinctive consumer segment with special problems and needs. In particular, many older shoppers are subject to a wide variety of mobility constraints which ultimately restrict their access to shopping opportunities. However, some work has discovered important differences in the spatial behaviours of subgroups of elderly consumers defined on the basis of such characteristics as health, age, household composition, marital status, income level, and residential location. It is suggested that further research needs to explore more fully how these characteristics may impose variable personal and environmental constraints upon the shopping activities of the urban elderly.  相似文献   

14.
The ‘granite’ pluton previously shown by Durney (1972) to be unconformably overlain in the Jones Creek area of Western Australia by a boulder conglomerate and a younger greenstone sequence has a Rb-Sr total rock age of 2689 ± 17 Ma. Two boulders analysed from the conglomerate are not distinguished isotopically from the underlying ‘granite’. Biotite ages from the ‘granite’ reflect the final effects of a regional upper greenschist facies metamorphism at approximately 2622 ± 15 Ma. Potassium feldspars in the ‘granite’ indicate ages less than 2600 Ma and are presumably related to late stage tectonic adjustments.Thus the isotopic dating shows that the ‘granite’, now formally named the Mount Keith Granodiorite, belongs to the early part of the 2750–2600 Ma Yilgarn age group (Compston and Arriens, 1968) and places an older limit on the age of the upper greenstone sequence. This greenstone was laid down within a period of 70 Ma or less and was followed by metamorphism which had ended by 2622 Ma, the time of closure of the biotite Rb-Sr system.Details of the petrography, particularly the metamorphic textures and paragenesis, indicate that despite their externally massive appearance, all the samples except the pegmatite have been recrystallized to varying degrees. Major-element analyses are given also, to aid in the chemical classification of the Granodiorite and in understanding its petrogenesis.  相似文献   

15.
The cartographic, sedimentological and micropalaeontological analysis of remnants of Middle–Upper Cretaceous turbiditic basins from the ‘Pays de Sault’ (Aude, French Pyrenees) shows their diachronism (interpreted on a wider scale) and their sequence diversity. The ‘Gesse breccias’ are regarded as the proximal deposits of a Turonian narrow foreland basin, principally supplied by the erosion of the Jurassic–Lower Cretaceous cover of the High Primary Range to the south, induced by a strike-slip and overthrusting faulting within the en-échelon North-Pyrenean Fault Zone. More to the north, the North-Pyrenean ‘Axat Basin’ consists of two successive backstepping turbiditic wedges, respectively corresponding to an Upper Albian distal flysch and to a Middle–Upper Cenomanian more proximal flysch, all the series unconformably overlying structures that were folded then eroded before the Upper Albian. The previous concept of carbonate olistoliths included within the Axat Cenomanian flysch is also refuted: these large-size blocks are now interpreted as belonging to a tectonic slice destroyed and partly collapsed on the southern slope of the Rebenty Valley during the Quaternary. To cite this article: M.-J. Fondecave-Wallez, B. Peybernès, C. R. Geoscience 336 (2004).  相似文献   

16.
Richly fossiliferous and disconformity-bounded facies successions, termed Mid-Cycle Condensed Shellbeds (MCS), occupy a mid-cycle position within depositional sequences in the Castlecliff section (mid-Pleistocene, Wanganui Basin, New Zealand). These shell-rich intervals (0.1–4.5 m thick) comprise the upper of two loci of shell accumulation in Castlecliff sequences. The lower disconformable contacts are sharp and variably burrowed, and are interpreted as submarine transgressive surfaces formed by storm or tidal current erosion at the feather-edge of contemporary transgressive systems tracts. Above (i.e. seaward) of this erosion surface, macrofossil remains (mainly bivalves and gastropods) accumulated, with little reworking, on the inner-shelf under conditions of reduced terrigenous sediment supply. The upper contacts are sharp transitions from shell-rich to relatively shell-poor lithofacies; parautochthonous shell accumulation was ‘quenched’by downlapping highstand systems tract shelf siltstones and muddy fine sandstones. Castlecliff MCS, together with the basal shell-rich part of overlying highstand systems tracts, occupy a stratigraphic position which corresponds to the condensed section that forms at the transgressive/highstand systems tract boundary in the sequence model of Haq et al. (1987). Palaeoenvironmental analysis indicates that Castlecliff MCS are substantially, if not entirely, transgressive deposits. This study therefore shows that the ‘condensation maximum’within a depositional sequence does not necessarily bracket the transgressive systems tract/highstand systems tract boundary.  相似文献   

17.
Uppermost Tortonian to lower Messinian temperate carbonates crop out in the Agua Amarga Basin (SE Spain). They consist of four units. The lower three units can be tentatively assigned to the lowstand systems tract of a fourth-order sequence, constituting in turn the lowstand (‘megatrough unit’), transgressive (‘breccia unit’) and highstand (‘bedded unit’) stages of a higher-order cycle. All these materials were deposited in a small pull-apart basin related to the sinistral Carboneras strike-slip fault system. The best represented is the bedded unit (up to 25 m thick), which consists of bioclastic, bryozoan/bivalve-dominated calcarenites/calcirudites with abundant fragments of echinoids, barnacles, benthic foraminifers, coralline algae, brachiopods and solitary corals. Facies trends within this unit are roughly arranged in an E-W direction, with the coastline to the north of the basin. The depositional model is that of a gentle ramp with prograding beaches and shoals in its higher parts. Seaward of the shoals was the ‘factory area’, where most organisms lived and maximum carbonate production took place. From this area some of the skeletons were washed landwards by waves and/or currents during storms and incorporated into the shoals and beaches, and others moved downslope along the ramp as mass-flows, accumulating to form the ‘fan-bedded zone’. The factory-area and fan-bedded sediments intercalate five well-defined, thick beds of calcarenites/fine-grained calcirudites. They show bar morphologies (single or amalgamated), or make up sand-waves with very consistent tabular cross-bedding pointing landwards. These beds formed in a very shallow, wave/current-influenced, coastal environment. The bars and sand waves in the fan-bedded zone developed during lowstands, while those located higher up in the ramp interbedded with the factory facies are related to transgressive stages. Prograding beaches, shoals, factory facies and fan-bedded layers developed during the highstands. Net skeletal production occurred mainly during the highstands. Sediment-accretion values of these sediments are similar to those of present and ancient shallow-marine, temperate carbonates considering that the whole bedded unit was deposited in a 100 000-year interval (equivalent to the short eccentricity cycle). The five cycles inside the bedded unit would therefore correspond to the c. 20 000-year precession cycles of the Milankovitch band.  相似文献   

18.
In the Lower Saxonian Basin, cores from three drill holes provide a cross-section from the basin centre towards the margin through the upper Barremian/lowermost Aptian pyritic claystones and marls. Microscopic analyses distinguish six types of pyrite (I: ‘cones and tubes’, II: ‘tubes’, III: ‘isometric crystal aggregates’, IV: ‘pseudomorphs of fossils’, V: ‘star-like concretions’, and VI: ‘filiform pyrite-marcasite intergrowths’) which are associated with subordinate amounts of Fe carbonate, chalcopyrite, sphalerite and wurtzite. The crystal morphology of these sulphides shows a clear-cut diagenetic sequence from pyrite crystals dominated by the octahedron to those dominated by the cube. Among these early to late diagenetic pyrites, the conversion of crystal habits is accompanied by a striking variation in trace element contents, some of which have extremely low values (e.g. Au, Se, Te, Tl, Co). In this context, classification of crystal habits and analyses of As and Ni establishes a sequence of pyritization which may help define a basin zonation for these argillaceous sedimentary rocks, categorized as ‘normal facies’—oxygenated bottom waters—interrupted by short episodes of bottom water oxygen depletion (‘bituminous facies’). Substitution of the cube for the octahedron in the Fe bisulphide aggregates led to a continuous removal of As and Ni from the pyrite, attesting to a steady decrease of those elements in the pore fluids with time. By contrast, within each type of pyrite, As and Ni contents increase from the margin towards the centre of the basin, owing to pre-concentration of both elements in the basinal sediments, which are more abundant in organic matter. Some other elements, however, such as Mn, Cu, Sb and Ag, do not follow this trend and are unrelated to the lattice transformation of the Fe bisulphides. Their sometimes anomalously high quantities in Fe bisulphides are controlled by the host rock chemistry (presence of volcaniclastic material) and accessory minerals intergrown with pyrite (e.g. chalcopyrite). Pyrite I through III formed in tubular hollows of burrowing organisms, and type IV in tests of fossils. Types V and VI did not result from replacement or void filling but were generated by diffusion of sulphate along inhomogeneties, such as bedding planes, shrinkage cracks or water escape structures.  相似文献   

19.
Understanding the age and construction quality of embankments used for road and rail infrastructure is critical in the effective management and maintenance of our transport networks, worth £billions to the UK economy. This paper presents for the first time results from full-scale, carefully controlled experiments on a unique model embankment conducted over the 4-year period between 2008 and 2011. It combines point location and spatially distributed measurements of pore water pressures and water content with outputs from hydrological modelling to draw conclusions of significance to both ongoing research in this field and to the asset management practices of infrastructure owners. For researchers, the paper highlights the crucial importance of transient permeability and soil water retention behaviour of fill materials in controlling the magnitude and distribution of pore water pressure in response to climate and weather events. For practitioners, the work demonstrates that there are significant differences in pore water pressure behaviour across the embankment, which is influenced by construction-related issues such as compaction level, aspect and presence of a granular capping material. Permeability was also observed to vary across the embankment both spatially and with depth, being dependent on degree of saturation and macroscale effects, particularly within a ‘near surface zone’. It is proposed that this ‘near surface zone’ has a critical effect on embankment stability and should be the focus of both ongoing scientific research and inspection and monitoring as encompassed by asset management regimes.  相似文献   

20.
Palaeoseismological and archaeological analysis of a trench enabled us to estimate the Holocene slip rates on the East Helike Fault, flanking the south-western Gulf of Corinth. We recognized two major fault strands within the trench: the ‘north fault’ controls a succession of three colluvial wedges and the deposition of a 2.7 m thick sedimentary sequence. The ‘south fault’ controls the deposition of a 2.9-m thick brownish-red colluvium. Based on colluvial stratigraphy, radiocarbon dating of the sediments suggests that the slip rate was c. 0.3 mm yr−1 from 10 250 to c. 1400 bp , when it increased dramatically to c. 2.0 mm yr−1 after a strong earthquake event near 1400 bp . The faster slip rate evidently increased the sedimentation rate.  相似文献   

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