Large-scale current-induced erosion and deposition in the path of the 1929 Grand Banks turbidity current   总被引：2，自引：0，他引：2  

JOHN E. HUGHES CLARKE  ALEXANDER N. SHOR†  DAVID J. W. PIPER‡  LARRY A. MAYER 《Sedimentology》1990,37(4):613-629

New observations concerning the degree of current-induced erosion and deposition in the path of the 1929 Grand Banks turbidity current are presented. Most of the observations are available from Eastern Valley, Laurentian Fan. Seabeam and SeaMARC I data reveal widespread current erosion along the valley over a distance of 200 km from the shelfbreak. Erosional valley-floor channels are preferentially developed adjacent to the valley margins and the flanks of intravalley highs. Asymmetric transverse bedforms (herein termed gravel waves) are moulded in a deflationary pebble and cobble lag that overlies the eroded valley floor. In contrast, at the distal limit of Eastern Valley, thick deposits of massive granule gravel indicate deposition beneath a decelerating turbidity current. Symmetrical transverse bedforms (herein termed macrodunes) are developed within these granule gravel sediments. The spatial distribution of both bedforms and the areas of erosive excavation suggest that the turbidity current in 1929 was accelerating over the first 100 km from the shelfbreak and was eroding and entraining sediment from the valley floor over a distance of at least 200 km. With the loss of lateral constraint at the distal limit of Eastern Valley the turbidity current spread laterally and started depositing sediment as it decelerated. Current-induced erosion of the valley floor represented a potential source of between 50 and 100 km3 of sediment for incorporation into the resulting turbidite.  相似文献   

A scanning electron microscope study of surface textures of quartz grains from glacial environments     

W. BRIAN WHALLEY  DAVID H. KRINSLEY 《Sedimentology》1974,21(1):87-105

Surface textures of quartz sand grains from several glacial environments at the Feegletscher, Switzerland examined by means of scanning electron microscopy are described. The difference between supraglacial and subglacial material is very slight. At the moment the interpretation of these textures must be done with care until the full statistical relation to environments can be ascertained. This does not necessarily invalidate earlier investigations although it does mean that glacial and extraglacial environments in the vicinity of glaciers are apparently not distinguishable. Examination of surface precipitation features suggests a sequence of events which can be used to help discriminate between different ages of deposits in an area. A similarity between some of the surface debris from moraine samples and those seen in loess and quickclay deposits is also suggested.  相似文献   

A reconnaissance of the sedimentology of lower Silurian mudstones, English Lake District     

DAVID J. W. PIPER 《Sedimentology》1975,22(4):623-630

Polished slabs and thin sections of lower Silurian graptolitic mudstones and interbedded barren mudstones show three main lithologies are present (a) unfossili-ferous green mudstones, sometimes with indistinct silt laminae, (b) a similar black pyritic lithology, with rare graptolites, (c) striped mudstones, with prominent carbonaceous and silt laminae, and common graptolites. The abundance of silt laminae suggests that the striped mudstone facies represents the highest energy depositional conditions. Comparison of sedimentary structures with modern deep sea muds suggests this facies is distal turbidite. Graptolite preservation was favoured by rapid burial.  相似文献   

AN APPLICATION OF REFLECTED-LIGHT DIFFERENTIAL-INTERFERENCE MICROSCOPY: BEACH STUDIES IN EASTERN LONG ISLAND—A DISCUSSION     

DAVID H. KRINSLEY 《Sedimentology》1971,17(1-2):115-116

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The role of transient eddies in low-frequency zonal variations of the Southern Hemisphere circulation   总被引：1，自引：0，他引：1  

DAVID J. KAROLY 《地球，A辑:动力气象学与海洋学》1990,42(1):41-50

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Water vapor transport in the NCAR CCM2   总被引：1，自引：0，他引：1  

DAVID L. WILLIAMSON  PHILIP J. RASCH 《地球，A辑:动力气象学与海洋学》1994,46(1):34-51

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Influence of tidal‐range change and sediment compaction on Holocene relative sea‐level change in New Jersey,USA     

BENJAMIN P. HORTON  SIMON E. ENGELHART  DAVID F. HILL  ANDREW C. KEMP  DARIA NIKITINA  KENNETH G. MILLER  W. RICHARD PELTIER 《第四纪科学杂志》2013,28(4):403-411

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New Lateglacial fauna and early Mesolithic human remains from northern England     

IAN R. SMITH  DAVID M. WILKINSON  HANNAH J. O'REGAN 《第四纪科学杂志》2013,28(6):542-544

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Relationship of diagenetic chlorite rims to depositional facies in Lower Cretaceous reservoir sandstones of the Scotian Basin   总被引：1，自引：0，他引：1  

KATHLEEN GOULD  GEORGIA PE‐PIPER  DAVID J. W. PIPER 《Sedimentology》2010,57(2):587-610

The relationship between diagenetic chlorite rims and depositional facies in deltaic strata of the Lower Cretaceous Missisauga Formation was investigated using a combination of electron microprobe, bulk geochemistry and X‐ray diffraction data. The succession studied comprises several stacked parasequences. The delta progradational facies association includes: (i) fluvial or distributary channel sandstones (some with tidal influence); (ii) thick‐bedded delta‐front graded beds of sandstone interpreted as resulting from fluvial hyperpycnal flow during floods and storms; and (iii) more distal muddier delta‐front and prodeltaic facies. The transgressive facies association includes lag conglomerate, siderite‐cemented muddy sandstone and mudstone, and bioclastic sandy limestone. Chlorite rims are absent in the fluvial facies and best developed in thick sandstones lacking mudstone baffles. Good quality chlorite rims are well correlated with Ti in bulk geochemistry. Ti is a proxy for Fe availability, principally from the breakdown of abundant detrital ilmenite (FeTiO₃). Under conditions of sea floor diagenesis, the abrupt decrease in sedimentation rate at transgressive surfaces caused progressive shallowing of the sulphate‐depletion level and of the overlying Eh‐controlled diagenetic zones, resulting in conditions suitable for diagenetic formation of berthierine to migrate upwards through the packet of reservoir sandstones. This early diagenetic berthierine suppressed silica cementation and later recrystallized to chlorite. Thick euhedral outer chlorite rims were precipitated from formation water in sandstone lacking muddy baffles on this chlorite substrate and inhibited late carbonate cementation. This study thus shows that the preservation of porosity by chlorite rims is a two‐stage process. Rapidly deposited delta‐front turbidite facies create early diagenetic conditions that eventually lead to the formation of chlorite rims, but the best quality chlorite rims are restricted to sandstones with high permeability during burial diagenesis.  相似文献   

Sedimentary evidence for a major glacial oscillation and proglacial lake formation in the Solway Lowlands (Cumbria,UK) during Late Devensian deglaciation     

STEPHEN J. LIVINGSTONE  COLM Ó COFAIGH  DAVID J.A. EVANS  ADRIAN PALMER 《Boreas: An International Journal of Quaternary Research》2010,39(3):505-527

Livingstone, S. J., Ó Cofaigh, C., Evans, D. J. A. & Palmer, A. 2010: Sedimentary evidence for a major glacial oscillation and proglacial lake formation in the Solway Lowlands (Cumbria, UK) during Late Devensian deglaciation. Boreas, Vol. 39, pp. 505–527. 10.1111/j.1502‐3885.2010.00149.x. ISSN 0300‐9483. This paper is a sedimentological investigation of Late Devensian glacial deposits from the Solway Lowlands, northwest England, in the central sector of the last British–Irish Ice Sheet. In this region, laminated glaciolacustrine sediments occur, sandwiched between diamictons interpreted as subglacial tills. At one location the laminated sediments are interpreted as varves, and indicate the former presence of a proglacial lake. Correlation of these varves with other laminated sediments indicates that the glacial lake was at least 140 km² in area and probably much larger. Extensive beds of sand, silt and gravel throughout the Solway Basin associated with the lake demonstrate ice‐free conditions over a large area. Based on the number of varves, the lake was in existence for at least 261 years. The stratigraphic sequence of varves bracketed by tills implies a major glacial oscillation prior to the Scottish Re‐advance (16.8 cal. ka BP). This oscillation is tentatively correlated with the Gosforth oscillation at c.19.5 cal. ka BP. Subsequent overriding of these glaciolacustrine sediments during a westward‐moving re‐advance demonstrates rapid ice loss and then gain within the Solway Lowlands from ice‐dispersal centres in the Lake District, Pennines and Southern Uplands. It is speculated that the existence of this and other lakes along the northeastern edge of the Irish Sea Basin would have influenced ice‐sheet dynamics.  相似文献