Morphology and development of an alluvial fan in a permafrost region, Aklavik Range, Canada
The objectives of this study are to describe the morphology and sedimentology of an alluvial fan, the Mount Goodenough North fan, in a permafrost region; and to interpret the processes responsible for the development of the fan, using both direct
observations and inferences from fan morphology and sedimentology.
Unravelling the patterns of alluvial fan development using mineral magnetic analysis : examples from the Sparta Basin, Lakonia, southern Greece
Mineral magnetic analysis of B-horizons of soils developing upon the surfaces of alluvial fans was undertaken in order to : differentiate and rank discrete fan surfaces by order of formation; establish whether fan surfaces formed simultaneously
in adjacent fan systems, and deduce probable patterns of fan development. Changes in climate are deemed to be the major control of fanhead incision, fan trenching and fan surface formation. However, the likely effects of long-term tectonic activity
and approximately 5 000 years of human occupation upon fan development in the Sparta Basin remain unclear.
Influence of lithologic erodibility on alluvial fan area, western White Mountains, California and Nevada
Lithology, through its influence on sediment production, may have an important effect on the size of alluvial fans and, hence, on fan-basin morphometric relations. The purpose of this study is to evaluate the influence of lithologic erodibility
on the relation between alluvial fan area and drainage basin area.
Structural geology and the dissection of alluvial fan sediments by mass movement : an example from the southern Italian Apennines
This paper describes how mass movement is dissecting a relict alluvial fan at the margin of the Sele Valley graben. Rock mass structure and neotectonics are treated here, not as controls upon fan sedimentation, but as a fundamental cause
of the instability of inactive fan sediments. The AA. use detailed geological and geomorphological mapping and interpretation to show how faulting and stratigraphic variations have created slump features, subsidence zones, scarpettes and cemented colluvium aprons
The application of mineral magnetic and extractable iron (Fe d) analysis for differentiating and relatively dating fan surfaces in central Greece
This paper presents the results of mineral magnetic and extractable iron analyses of Bt-horizons of soils developing on the surface of the Tithorea fan, central Greece. The aim of the combined analysis was to : test the reliability of detailed
topographic surveys in differentiating individual fan segments; establish the chronological order of formation of discrete fan surfaces identified; and deduce the probable pattern of fan development.
Deglacial flood origin of the Charleston alluvial fan, lower Mississippi alluvial valley
The main purpose of this research was to determine the genesis and age of the Charleston fan. The AA. reassessed the origin of the fan by comparing the geomorphology and sediment to that of adjacent areas. The age of the fan was constrained
by radiocarbon dating of sediment associated with the fan by establishing relationships with adjacent landforms and sediments and by comparing the record with known regional events.
of a torrential watershed, torrential channel and torrential fan is enough. For other methods, a mathematical tool (HEC-HMS) had to be applied in order to develop a hydrologic run-off model of precipitation that can trigger debris flows. Computed debris-flow
magnitudes were of the order between 6,500 m3 and 340,000 m3. Their values are a function of torrential watershed parameters, such as : watershed area, Melton number, fan gradient, and torrential channel gradient. The investigated fans were classified into 3
groups with regard to the debris-flow hazard : debris-flow with low possibility). A limit between debris-flow fans and torrential fans is proposed : Melton number 0.3 and torrential fan gradient 4°, that is 7%. Out of 24 investigated torrential fans, 13
fans were classified into the group of debris-flow fans, 5 fans were classified into the group of torrential fans, and the rest 6 fans were classified into the group of transitional fans. - (IKR)
Slope of alluvial fans in humid regions of Japan, Taiwan and the Philippines
This study constructed a database for 600 alluvial fans in humid regions of Japan, Taiwan and the Philippines, and analyzed their slopes and other morphometric parameters such as the area and relief ratio of the source area. About 60% of the fans
formed during the Holocene and the rest, 40%, formed during the Pleistocene. Mean fan slopes for both all the Quaternary fans follow a lognormal frequency distribution. The area and relief ratio of the source area, which correlate well with the fan slope
, also follow a lognormal distribution, indicating the dimensions of fan/basin systems vary gradually rather than abruptly.
A mathematical model which estimates the scale-independent sediment surface profile of alluvial fans has been developed. This model utilizes a diffusive sediment transport model and an unsteady, radial flow, conservation relationship. The model
suggests that the overall dimensionless morphology of alluvial fans is governed more by fundamental diffusion principles in sediment deposition than by individual environmental or basin characteristics. A preliminary comparison indicates that this model
provides useful qualitative and quantitative information relating to alluvial fan process and morphology.
Active and relict alluvial fans on contact karst of the Vrhpoljska brda hills, Slovenia
karst area two types of alluvial fans appear on carbonate bedrock. Members of the first type are ordinary alluvial fans with active alluvial processes where flysch derived sediment covered limestone surface in a distinct fan shape. - (L'A.).
Granulometric study of the Hanaupah Fan, Death Valley, California
The AA. present the results of a quantitative study of possible trends on the various fan surfaces with respect to grain-size distributions, clast sphericity, roundness and orientation, and examine the dependence of these parameters on size
and lithology of clasts. The purpose of this evaluation was to determine if such information could differentiate and characterize the various fan surfaces and other subenvironments. Of the examined parameters, clast orientation is the best predictor of relative
Controls on modern fan morphology in Calabria, Southern Italy
In order to understand if and to what extent fan types and their morphology are dependent on the physical environment, including characteristics and processes of the depositional site and drainage basin, the AA. performed a series of discriminant
analyses. Their database includes a sample population of 68 cases. Results of discriminant analysis based on fan and basin variables are much more significant than those based on fan variables only.
Response of alluvial fan systems to the late Pleistocene to Holocene climatic transition : contrasts between the margins of pluvial lakes Lahontan and Mojave, Nevada and California, USA
This paper deals with 2 contrasted mountain-front alluvial fan systems in the American Basin and Range province. An assessment is made of the extent to which differences in fan regime between the 2 areas over the period from the late Pleistocene
to the early Holocene, may be due to climatic, vegetation, or other differences between the fan environments. During the late Pleistocene, both fan systems terminated in pluvial lakes, Lake Lahontan in Nevada and Lake Mojave in California. In both cases, dated
lake shoreline provide good time-lines for the correlation, relative dating and interpretation of the fan sequences.
Relict alluvial fans of Matarsko Podolje and Vrhpoljska Brda, Slovenia
The main aim of this paper is description of alluvial fans and relict alluvial fans as contact karst features and to provide some morphological and morphometric properties of the fans. The purpose of the research is to deduct on basis of fieldwork
data in the area of Matarsko podolje in western Slovenia and in its northern extension, Vrhpoljska brda, which are the mechanisms of alluvial fan formation and mechanisms and reasons for transformation to the relict ones. The aim is also to provide some
evidence why on the contact karst alluvial fans instead of blind valleys are formed.
Surface variability of alluvial fans generated by disparate processes, eastern Depth Valley, CA
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
The role of alluvial fans in the mountain fluvial systems of southeast Spain: implications of climatic change
This paper deals with the mountain front alluvial fans in the semi-arid areas of Murcia and Almeria provinces. It attempts, by mapping the location of alluvial fans, then their classification into aggrading or dissecting fans, to identify the extent
to which the mountain fluvial systems are buffered by aggrading alluvial fans or exhibit channel continuity through the mountain front environment. It further considers the implications of climatically induced changes between aggradational and dissectional
Controls on fan development - evidence from fan morphometry and sedimentology; Sierra Nevada, SE Spain
The AA. have studied the morphology and the morphometric relations between alluvial fans and drainage basins in a bajada system including more than 20 coalescent fans developed since the Late Pleistocene as a result of the recent uplift
of the Sierra Nevada. 3 allocycles of tectonic origin were recognised across wich there is a clear evolution from debris flow to sheet flow dominated fans, in connection with a decrease in the volume of fines available in the source areas. The results help
Impacts of Holocene climatic variations on alluvial fan activity below snowpatches in subarctic Québec
In the Lake Guillaume-Delisle area of subarctic Québec, storm-generated alluvial fans have been active sporadically throughout the Holocene. In this study, the AA. 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 torential 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.
Morphometric controls and geomorphic responses on fans in the Southern Alps, New Zealand
Morphometric variables associated with 41 debris-flow and 18 fluvial fans and their basins in the Southern Alps of New Zealand are examined. The specific objectives are to test for significant differences between debris-flow and fluvial fans
and determine which morphometric variables can best differentiate the fans according to process; to investigate the relations between some morphometric variables at each type of fan; to attempt to explain the results of the morphometric analyses on the basis
of the underlying processes; and to explore the usefulness of morphometric thresholds for identification of debris-flow potential on fans.