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1.
In the Lake Guillaume-Delisle area of subarctic Québec, storm-generated alluvial fans have been active sporadically throughout the Holocene. In this study, we propose that the persistence of late-lying snowpatches in fan catchments during Holocene cold episodes promoted alluvial fan activity by lowering the precipitation threshold required to trigger a torrential event. This hypothesis was tested by characterizing the depositional processes responsible for alluvial fan formation below snowpatches, and by reconstructing the Holocene alluvial fan activity. Stratigraphic and sedimentary analyses conducted on seven alluvial fans revealed that they were deposited by torrential activity leading to waterlaid, transient, or hyperconcentrated deposition. The chronology of the storm-generated alluvial fans — based on 22 radiocarbon dates — indicates that torrential activity was enhanced during the cooler Late Holocene (i.e., after ca. 3500 cal. yr BP). Snowier winters and cooler summers were beneficial to nival activity, allowing the persistence of larger snowpatches throughout the summer and fall seasons. Rainfall-induced thaw of such snowpatches during rainstorm events is inferred to have contributed to alluvial fan activity by increasing water availability. Three peaks of alluvial activity occurred during the Late Holocene (2950–2750, 1900–1400, and 800–300 cal. yr BP) and are indicative of increased storminess resulting in higher fan activity. Increased fan activity during cooler episodes was concurrent with increased runoff activity in the immediate pronival area. This stresses the importance of nivation below snowpatches and pinpoints the role of nivation in enhancing geomorphological activity during period of cooler and more humid climate in subarctic environments. 相似文献
2.
祁连山、贺兰山与吕梁山山前冲积扇上的农地对比 总被引：2，自引：0，他引：2
不同地区冲积扇上农地发育特征的对比可以揭示环境条件与农地发育的关系。本文以Lansat卫星ETM+遥感影像、DEM和野外考察资料为基础,研究了祁连山、贺兰山与吕梁山三个地区山前冲积扇的地貌特征和扇上农地的发育特征,探讨了影响冲积扇上农地发育的因素。结果表明,吕梁山地区扇上农地比例最高,自扇顶到扇缘均有农地发育,其次为祁连山地区,农地主要发育在一些被黄土覆盖的冲积扇的老扇面上,贺兰山地区冲积扇上农地比例最低,农地多分布在扇缘区域;物质组成是影响冲积扇上农地发育的直接因素;相关性分析表明,祁连山和吕梁山地区冲积扇上的农地发育受黄土沉积过程影响显著,而贺兰山前冲积扇上农地发育更多地受冲积扇地貌过程的影响。 相似文献
3.
《自然地理学》2013,34(5):343-365
Soils buried by alluvial fan deposits in southwest Nebraska record several intervals of increased sediment yield from small watersheds during the Holocene. These intervals, which began at ca. 9000, 5800, 4000, 3000, and 1000 14C yrs. B.P., were probably caused by some sort of change in regional climatic conditions. Existing evidence of Holocene climate change suggests that increased sediment yields were caused by periodic shifts toward drier climatic conditions, except for the intervals that began at 5800 and 4000 14C yrs. B.P. The cause of increased sediment yields at those times is unclear, although an increased frequency of large intense storms may have been a contributing factor. The record of soil burial exhibits considerable spatial variability both within individual fans and between fans. This is partly due to practical limitations on the number of buried soils that could be sampled on each fan. But it is also due to the inherent spatial variability of depositional processes and to differences in the geomorphic development of the four fans. Thus, researchers who use data from fans to reconstruct sediment-yield histories need to investigate several sites on several fans in order to obtain as complete a record as possible of changing sediment yields. 相似文献
4.
Stratigraphic, geomorphic, and paleoecological data were collected from upland watersheds in the Great Basin of central Nevada to assess the relationships between late Holocene climate change, hillslope processes and landforms, and modern channel dynamics. These data indicate that a shift to drier, warmer climatic conditions from approximately 2500 to 1300 YPB led to a complex set of geomorphic responses. The initial response was massive hillslope erosion and the simultaneous aggradation of both side-valley alluvial fans and the axial valley system. The final response was fan stabilization and axial channel incision as fine-grained sediments were winnowed from the hillslope sediment reservoirs, and sediment yield and runoff processes were altered. The primary geomorphic response to disturbance for approximately the past 1900 years has been channel entrenchment, suggesting that the evolutionary history of hillslopes has produced watersheds that are prone to incision. The magnitude of the most recent phase of channel entrenchment varies along the valley floor as a function of geomorphic position relative to side-valley alluvial fans. Radial fan profiles suggest that during fan building, fan deposits temporarily blocked the flow of sediment down the main stem of the valley, commonly creating a stepped longitudinal valley profile. Stream reaches located immediately upvalley of these fans are characterized by low gradients and alternating episodes of erosion and deposition. In contrast, reaches coincident with or immediately downstream of the fans exhibit higher gradients and limited valley floor deposition. Thus, modern channel dynamics and associated riparian ecosystems are strongly influenced by landforms created by depositional events that occurred approximately 2000 years ago. 相似文献
5.
We study the geophysical controls on the size of alluvial fans. Simple relationships between catchment characteristics, sediment yield, subsidence patterns and fan size are developed. As predicting fan size is essentially a conservation of mass problem, our analysis is general, applying to all types of fan landform. The importance of spatially variable subsidence rates has gone largely unrecognized in previous studies of modern fans. Here we stress that the distribution of subsidence rates in the depositional basin is a primary control on relative fan size. Both free coefficients in the oft-cited power-law correlation of fan area and catchment area can be shown to be set primarily by the tectonic setting, taken to include source area uplift rate and the subsidence distribution in the depositional basin. In the case of a steady-state landscape, relative fan size is shown to be independent of both climate and source lithology; only during times of significant departure from steady state can relative fan size be expected to vary with either climate or source lithology. Transients associated with (1) a sudden increase in rock uplift rate, (2) a sudden change in climate and (3) the unroofing of strata with greatly differing erodibilities may produce variation of relative fan areas with both climate and source lithology. Variation of relative fan size with climate or lithology, however, requires that catchment–fan system response to perturbations away from steady state is sensitive to climate and lithology. Neither the strength of transient system responses nor their sensitivity to climate or lithology are known at present. Furthermore, internal feedbacks can significantly dampen any climatic or lithological effect. Thus theoretical considerations of the importance of climatic and lithological variables are inconclusive, but suggest that climatic and lithological effects are probably of secondary importance to tectonic effects. Field data from an unsteady landscape in Owens Valley, California, support and illustrate theoretical predictions regarding tectonic control of fan size. Field data from Owens Valley allow, but do not prove, a secondary dependence on source lithology. In addition, the Owens Valley field data indicate no relationship between relative fan size and climate. Headward catchment growth and enhanced sediment bypassing of fans during times of increased sediment yield (glacial) are put forward as plausible explanations. 相似文献
6.
The evolution of the Oued es Seffaia alluvial fan during the last 50,000 years is analyzed in the light of chronometric data derived from AMS radiocarbon and optical dating techniques. These ages have enabled the temporal constraint of the distalward progression of the intersection point (the upper limit of the locus of deposition) which has resulted in the telescopic segmentation of the fan. Comparison of these data with the Late Quaternary climatic history of the Maghreb highlights several problems of interpretation; due both to our limited knowledge of regional palaeoclimates and of the response of dryland fluvial systems to climate changes. However, our data provide some evidence to suggest that fan incision and formation of telescopic segments occurs in response to changes from arid to less arid conditions, supporting the conclusions of some of the work from other areas. 相似文献
7.
Rebekah M. Harries Linda A. Kirstein Alex C. Whittaker Mikael Attal Ian Main 《Basin Research》2019,31(5):866-891
Grain size trends in basin stratigraphy are thought to preserve a rich record of the climatic and tectonic controls on landscape evolution. Stratigraphic models assume that over geological timescales, the downstream profile of sediment deposition is in dynamic equilibrium with the spatial distribution of tectonic subsidence in the basin, sea level and the flux and calibre of sediment supplied from mountain catchments. Here, we demonstrate that this approach in modelling stratigraphic responses to environmental change is missing a key ingredient: the dynamic geomorphology of the sediment routing system. For three large alluvial fans in the Iglesia basin, Argentine Andes we measured the grain size of modern river sediment from fan apex to toe and characterise the spatial distribution of differential subsidence for each fan by constructing a 3D model of basin stratigraphy from seismic data. We find, using a self‐similar grain size fining model, that the profile of grain size fining on all three fans cannot be reproduced given the subsidence profile measured and for any sediment supply scenario. However, by adapting the self‐similar model, we demonstrate that the grain size trends on each fan can be effectively reproduced when sediment is not only sourced from a single catchment at the apex of the system, but also laterally, from tributary catchments and through fan surface recycling. Without constraint on the dynamic geomorphology of these large alluvial systems, signals of tectonic and climate forcing in grain size data are masked and would be indecipherable in the geological record. This has significant implications for our ability to make sensitive, quantitative reconstructions of external boundary conditions from the sedimentary record. 相似文献
8.
The Late Glacial and Holocene geomorphology of the Manx uplands has received scant attention in previous researches. Solifluction deposits and terraces provide the earliest evidence for geomorphic activity after deglaciation. Fluvial incision into drift-choked valleys is correlated with the formation of the large mountain front alluvial fans that flank the Manx uplands. Formation of these alluvial fans is constrained to 15,000–10,500 cal. years BP by 14C dates on organic deposits beneath and above the alluvial fan gravels. Alluvial fan and river terraces along four valleys postdate this incision. Optically Stimulated Luminescence (OSL) and 14C dating provide a tentative chronology for these landforms. The higher terraces are Late Glacial fluvial surfaces that were probably occupied by rivers into the Holocene. Incision during the Late Holocene led to the abandonment of the higher surfaces, producing a suite of younger river terraces and alluvial fan surfaces. Independent dating constrains this fluvial activity to post-Bronze Age (3500–2800 cal. years BP). Increased human activity and climatic change during the Late Holocene are possible causes for this increased geomorphic activity. 相似文献
9.
Geologic and chronometric studies of alluvial fan sequences in south-central Australia provide insights into the roles of tectonics and climate in continental landscape evolution. The most voluminous alluvial fans in the Flinders Ranges region have developed adjacent to catchments uplifted by Plio-Quaternary reverse faults, implying that young tectonic activity has exerted a first-order control on long-term sediment accumulation rates along the range front. However, optically stimulated luminescence (OSL) dating of alluvial fan sequences indicates that late Quaternary facies changes and intervals of sediment aggradation and dissection are not directly correlated with individual faulting events. Fan sequences record a transition from debris flow deposition and soil formation to clast-supported conglomeritic sedimentation by ∼30 ka. This transition is interpreted to reflect a landscape response to increasing climatic aridity, coupled with large flood events that episodically stripped previously weathered regolith from the landscape. Late Pleistocene to Holocene cycles of fan incision and aggradation post-date the youngest-dated surface ruptures and are interpreted to reflect changes in the frequency and magnitude of large floods. These datasets indicate that tectonic activity controlled long-term sediment supply but climate governed the spatial and temporal patterns of range-front sedimentation. Mild intraplate tectonism appears to have influenced Plio-Quaternary sedimentation patterns across much of the southern Australian continent, including the geometry and extent of alluvial fans and sea-level incursions. 相似文献
10.
The purpose of this study was to elucidate the floristic and structural characteristics of simple alluvial fan vegetation of southern Sinai and to relate them to environmental variation. The main question addressed was: how does the floristic composition of fan habitats, species richness and life-form vary in relation to environmental change? Thirty-seven alluvial fans, randomly selected in two mainwadis(WadiFeiran andWadiDahab) were analysed quantitively. Two-way Indicator Species Analysis (TWINSPAN) classification and Canonical Correspondence Analysis (CCA) were applied in successive stages of the data analysis to describe vegetational variation in relation to physical gradients. Seven main clusters of fans were defined on the basis of environmental variation. These clusters are divided into three main groups of species richness. Species richness varied along a moisture gradient. The richest fans were the driest habitats, indicating that maximum species richness did not occur at high moisture availability. The moisture gradient is a complex gradient correlated with elevation, slope, climatic aridity, soil texture and the nature of the soil surface. Fine sand, silt plus clay and calcium carbonate showed significant differences between the internal groups and subgroups of the first and second level of the TWINSPAN classification. 相似文献
11.
Sediment supply from landslide-dominated catchments: implications for basin-margin fans 总被引：1，自引：0，他引：1
The sediment flux from a mountainous catchment can be expressed as a function of a landslide rate constant κ which accounts for the vigour of hillslope erosion. Since the incising drainage network flushes all or a portion of the products of hillslope erosion to a range front where fan deposition takes place, a conservation of solid sediment volume allows the fan area and progradation distance to be calculated. These parameters are related primarily to the discharge of sediment from the catchment and to local tectonic subsidence.
A survey of modern alluvial fans in a wide range of climatic and tectonic settings shows that the effects of climate and bedrock lithology cannot be discriminated in the scatter of data of catchment area vs. fan area. However, by focusing on over 100 fans in the arid and semiarid zone of SW USA, the impact of tectonic subsidence rate is unambiguous. Although further quantitative data on local tectonic subsidence rates are urgently required, our preliminary analysis suggests considerable potential for reconstructing palaeocatchments where basin tectonic subsidence rates can be estimated. The progradation distances of fans from the northern and southern margins of the Middle Devonian Hornelen Basin of Norway, and the western and north-eastern margins of the Mio-Pliocene Ridge Basin, California, allow catchment sizes and denudation rates to be approximated. Although unique solution sets are not possible, an iteration of parameter values allows plausible parameter combinations to be calculated which shed light on the tectonic and sedimentary history of the proximal basin and upland source regions. Model results suggest significant asymmetry in basin subsidence rates, catchment slopes and transport mechanics between the two margins. 相似文献
A survey of modern alluvial fans in a wide range of climatic and tectonic settings shows that the effects of climate and bedrock lithology cannot be discriminated in the scatter of data of catchment area vs. fan area. However, by focusing on over 100 fans in the arid and semiarid zone of SW USA, the impact of tectonic subsidence rate is unambiguous. Although further quantitative data on local tectonic subsidence rates are urgently required, our preliminary analysis suggests considerable potential for reconstructing palaeocatchments where basin tectonic subsidence rates can be estimated. The progradation distances of fans from the northern and southern margins of the Middle Devonian Hornelen Basin of Norway, and the western and north-eastern margins of the Mio-Pliocene Ridge Basin, California, allow catchment sizes and denudation rates to be approximated. Although unique solution sets are not possible, an iteration of parameter values allows plausible parameter combinations to be calculated which shed light on the tectonic and sedimentary history of the proximal basin and upland source regions. Model results suggest significant asymmetry in basin subsidence rates, catchment slopes and transport mechanics between the two margins. 相似文献
12.
A vast bajada consisting of coalescing low-gradient (< 0.3°) alluvial fans exceeding 100 km in length formed along the southwestern margin of the Oman Mountains. It comprises an old fan sequence of inferred Miocene to Pliocene age termed Barzaman Formation, diagenetically highly altered to dolomitic clays, and a thin veneer of weakly cemented Quaternary gravels. A combination of remote sensing, lithological analyses and luminescence dating is used to interpret the complex aggradation history of the Quaternary alluvial fans from the interior of Oman in the context of independent regional climate records. From satellite imagery and clast analysis four fans can be discerned in the study area. While two early periods of fan formation are tentatively correlated to the Miocene–Pliocene and the Early Pleistocene, luminescence dating allows the distinction of five phases of fan aggradation during the Middle–Late Pleistocene. These phases are correlated with pluvial periods from Marine Isotope Stage (MIS) 11 through 3, when southern Arabia was affected by monsoonal precipitation. It is concluded that the aggradation of the alluvial fans was triggered by the interplay of increased sediment production during arid periods and high rainfall with enhanced erosion of hillslopes and transport rates during strong monsoon phases. However, the lack of fine-grained sediments, bioturbation and organic material implies that although the Quaternary fans are sourced by monsoonal rains they formed in a semi-arid environment. Thus, it appears that, in contrast to the Oman Mountains, the interior was not directly affected by monsoonal precipitation. 相似文献
13.
Accurate magnetostratigraphic dating of Plio-Pleistocene alluvium in the Palomas half-graben permits correlation of transverse and axial deposits, thus enabling analysis of the movement of alluvial facies belts in time and space for the first time. Northern areas show evidence for basinward progradation of footwall-sourced Matuyama-age alluvial fan deposits over axial channel belt deposits of the ancestral Rio Grande, despite both deposits having similar deposition rates. This gradual ‘forced’ westward migration of the axial belt was in opposition to ongoing eastward growth of hangingwall-sourced fans and tectonic tilt imposed by the bounding Caballo normal fault. Fan growth was coincident with a recently proposed gradual climatic shift that may have increased sediment flux out of transverse catchments. It is also possible that continuing tectonic footwall uplift and divided retreat caused catchment areas to increase, contributing to these trends. Southern areas of the Palomas half-graben feature late Gilbert/early Gauss deposits indicative of rapid westwards progradation of large low-gradient, footwall-sourced fans over axial deposits. This ‘forced’ migration of the ancestral Rio Grande may have occurred due to footwall catchment and fan growth consequent upon initiation and growth of the Red Hills Fault. Subsequent eastward movement of the axial channel belt in late Gauss and Matuyama times overwhelmed these large fans. We attribute this to continued tilting on the Red Hills Fault and to development of the Jornada Fault to the south-east, the axial river belt avulsing north and eastwards through a developing Red Hills/Jornada crossover transfer zone. We conclude generally that facies architecture of axial and transverse elements in half-graben must reflect both climatic influences and the effects of fault development. Careful field mapping, accurate dating and palaeoclimatic studies are all necessary to determine the relative importance of these controls. Although adequate as broad guides, previous purely ‘fixist’ tectonosedimentary models allow for no fault growth, decay or climatic modulation of facies trends and are thus generally inadequate to explain important aspects rift basin stratigraphy. 相似文献
14.
In arid mountain areas, the dating and correlation of alluvial depositional surfaces is often uncertain. Especially in regions where the geomorphology is not well known, surface modification by the development of soil and desert pavement may allow the correlation of geomorphic surfaces and estimation of at least their relative ages. Pleistocene wadi terraces and associated alluvial fans occur in Wadi Al-Bih, U.A.E. and Oman, for which correlations and age relationships are not known. Three age-related groups of fans and terraces have been identified and mapped on the basis of their morphostratigraphic relationships. Deposition of the oldest terrace sediments and associated fans followed a long period of sustained incision after Miocene uplift of the region. The younger two groups of terraces and fans are inset within the older group. To identify the gross effects of pavement development, comparisons have been made between terrace surface and subsurface particle-size distributions. The older terraces have finer surface sediments and a greater contrast between finer surface and subsurface sediments than the younger terraces. This reflects the degree of pavement development. Particle size on the fan surfaces is comparable with that on the equivalent terrace surfaces. Criteria for the classification of pavements were developed based on clast fracturing and angularity, size, sorting, packing, and surface texture, from which a simple index of pavement development has been derived. Other properties, rock varnish and weathering characteristics, were also recorded; but these proved to be less discriminatory than pavement characteristics. The pavement data have been augmented by observations on soils. Detailed studies of pavements on terraces (8 sites, 12 samples covering the three age groups) and fans (5 sites, 10 samples covering the three age groups) allow differentiation between age-groups. The three terraces show three different age-related pavement types, expressed by differences in the pavement development index. Weakly-developed pavements (little fracturing, sub-rounded clasts, some modification of the depositional fabric, incipient soil development, stage I CaCO3 accumulation) occur on the youngest terrace and fan surfaces. Moderately-developed pavements (clast fracturing, sub-angular clasts, moderate sorting and packing, deeper soil development, stage II CaCO3 accumulation) occur on the middle terrace and fan surfaces. Well-developed pavements (complete clast fracturing into small angular fragments, mature sorting and packing of the pavement surface, deep soil development with strong horizonation, stage III CaCO3 accumulation) occur on the highest terrace and oldest fan surfaces. There are minor differences between the youngest pavements on terraces and fans, which reflect initial sedimentological differences. These differences become less as the pavements develop. On the basis of comparative studies, the oldest terrace is estimated to date from sometime prior to ca. 100 ka BP, the second terrace and the most extensive fan surface from the Late Pleistocene, and the youngest terrace and fan phase from the Latest Pleistocene or Early Holocene. 相似文献
15.
Antony R. Orme 《自然地理学》2013,34(2):131-146
Comparatively little is known about net aggradation on alluvial fans, despite fan construction wherever sediment-delivery rates from uplands exceed sediment-removal rates from receiving basins. In January 1983, 20 alluvial fans in the forested Cascade foothills, northwest Washington, experienced net aggradation in response to debris torrents and stream floods triggered by intense warm rains falling on antecedent snow. Five trenches were excavated to 5 m depth on the Mills Creek fan to place the 1983 event in temporal perspective. The deposits reflect normal streamflow, hyperconcentrated streamflow and debris torrent (flow) conditions. One trench revealed residues of 7 events since 1720 BP. Net rates of Holocene aggradation, based on sediments overlying late Pleistocene fluvioglacial deposits, average 0.42 m ka-1. Net rates for later Holocene time range from 2.17 m ka-1 since 1720 BP to 2.36 m ka-1 since 430 BP. These recent rates exceed the local value for the entire Holocene and rates for humid temperate fans elsewhere. This suggests that accelerated aggradation may characterize later Holocene times, a view that contrasts with the widespread belief that the later Holocene has been dominated by fan-head incision and net degradation. More comparative data are needed to test this observation. Locally, large debris-producing events in 1917 and 1983 are consistent with later Holocene recurrence intervals and thus appear to be independent of timber harvesting. [Key words: alluvial fan, debris torrent, debris flow, streamflow, Washington.] 相似文献
16.
黄河冲积扇发育研究述评 总被引：1，自引：0，他引：1
黄河冲积扇是第四纪以来多期沉积建造的冲积扇复合体,它既是来自黄土高原的泥沙强烈堆积的地貌单元,又是历代河流决口改道的地区,也是华夏文明的发源地。在回顾了黄河冲积扇发育的研究历史的基础上,详细介绍了黄河冲积扇的形成时代、地貌类型与沉积速率,形成过程与特点等方向的研究进展,系统地论述了河道变迁、地质构造、气候变化以及人类活动等因素对黄河冲积扇形成的影响作用。并指出目前黄河冲积扇的发育研究中还存在着研究深度不够和时空的广度不完整等问题。史前黄河冲积扇的发育研究将成为今后研究中的难点。 相似文献
17.
This study explores the surface variability of alluvial fans from digital elevations model (DEM) derivatives generated from 1-m planimetric resolution airborne laser swath mapping data. Channel and interfluve dimensions of debris flow (DF) fans and fans generated from predominantly fluvial flows and some older debris flows (mixed flow [MF]) are extracted with the aid of a planimetric curvature classification. Significant differences are identified between the fan surface topography of DF and MF fans. MF fans tend to have smaller channel and interfluve widths, have smaller elevation differences between the crest of the interfluve and channel, and are more dissected than DF fans. The morphometric differences between the two fan classes can be explained by differences in the primary processes that develop the surficial features, but also the preponderance for secondary erosional processes acting on the MF fans. 相似文献
18.
近2000年来内蒙后套平原黄河河道演变 总被引：6，自引：0，他引：6
通过遥感影像、地貌沉积、历史文献与地图等相关资料分析集成研究,将后套平原分为西部冲积扇平原,东部是泛滥冲积平原,并详细探讨了近2000年来本区黄河河道的演变。公元前2世纪时,后套西部平原南 (上) 冲积扇停止发育, 北(下) 冲积扇河道发育,黄河主河道的位置与现代不同,它偏于泛滥平原北部的阴山山前东流;公元6世纪后套平原西部北 冲积扇上黄河河道向东移,在东部泛滥平原上黄河明显地分为南北两汊,而黄河主流仍位于河套平原北部山前;18世纪早期至末期,黄河主河道从河套平原的北部山前南移至平原南部;19世纪中叶‘北河’淤塞,现代黄河形成。 相似文献
19.
冲洪积扇与泥石流扇的遥感影像特征辨析 总被引：1，自引：0，他引：1
在揭示冲洪积扇和泥石流扇在发育规模、物质成分及分选性、赖以形成的地形地貌条件等方面的差异特征的基础上 ,阐述它们在航天和航空遥感图像上的影像特征 ,以及识别它们的实践意义 相似文献
20.
David J. P. Somerville Nigel P. Mountney Luca Colombera Richard E. Ll. Collier 《Basin Research》2020,32(4):764-788
Models to explain alluvial system development in rift settings commonly depict fans that are sourced directly from catchments formed in newly uplifted footwalls, which leads to the development of steep-sided talus-cone fans in the actively subsiding basin depocentre. The impact of basin evolution on antecedent drainage networks orientated close to perpendicular to a rift axis, and flowing over the developing hangingwall dip slope, remains relatively poorly understood. The aim of this study is to better understand the responses to rift margin uplift and subsequent intrabasinal fault development in determining sedimentation patterns in alluvial deposits of a major antecedent drainage system. Field-acquired data from a coarse-grained alluvial syn-rift succession in the western Gulf of Corinth, Greece (sedimentological logging and mapping) has allowed analysis of the spatial distribution of facies associations, stratigraphic architectural elements and patterns of palaeoflow. During the earliest rifting phase, newly uplifted footwalls redirected a previously established fluvial system with predominantly southward drainage. Footwall uplift on the southern basin margin at an initially relatively slow rate led to the development of an overfilled basin, within which an alluvial fan prograded to the south-west, south and south-east over a hangingwall dip slope. Deposition of the alluvial system sourced from the north coincided with the establishment of small-scale alluvial fans sourced from the newly uplifted footwall in the south. Deposits of non-cohesive debris flows close to the proposed hangingwall fan apex pass gradationally downstream into predominantly bedload conglomerate deposits indicative of sedimentation via hyperconcentrated flows laden with sand- and silt-grade sediment. Subsequent normal faulting in the hangingwall resulted in the establishment of further barriers to stream drainage, blocking flow routes to the south. This culminated in the termination of sediment supply to the basin depocentre from the north, and the onset of underfilled basin conditions as signified by an associated lacustrine transgression. The evolution of the fluvial system described in this study records transitions between three possible end-member types of interaction between active rifting and antecedent drainage systems: (a) erosion through an uplifted footwall, (b) drainage diversion away from an uplifted footwall and (c) deposition over the hangingwall dip slope. The orientation of antecedent drainage pathways at a high angle to the trend of a developing rift axis, replete with intrabasinal faulting, exerts a primary control on the timing and location of development of overfilled and underfilled basin states in evolving depocentres. 相似文献