ISSN:0267-8179    

DOI:10.1002/jqs.3390020102

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe loamy ‚brickearth’︁ deposits overlying coarse cold climate Kempton Park, Lynch Hill and Taplow Gravels of the R. Thames in west London are dated by thermoluminescence and mineralogical comparisons with loesses of three known ages. Although much of the ‚brickearth’︁ resembles loess, it often contains more sand or clay than typical loess, and the mineralogical studies suggest that even the coarse silt (16–63 μm) fraction is rarely similar in composition to any known English loess. The thermoluminescence measurements suggest that most of the ‚brickearth’︁ on the Taplow and Lynch Hill Gravels was deposited in the late Devensian, whereas that on the Park Gravel is mainly Flandrian. It is suggested that the latter is mainly floodloam, whereas the earlier ‚brickearth’︁ is a mixed aeolian sediment derived from various local sources in and

ISSN:0267-8179    

DOI:10.1002/jqs.3390020103

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe following events have been identified from a complex sequence of Midlandian (Devensian) sediments recently exposed at Aghnadarragh, County Antrim: (1) A lower till interpreted as Early Midlandian was deposited by a major lowland ice sheet which moved south‐eastwards from central Ulster across the Lough Neagh depression. (2) Deglacial conditions were followed by a periglacial phase characterised by ice‐wedge growth and sedimentation by gravelly debris flows. The latter contain the oldest known remains ofMammuthus primigeniusin Ireland. (3) An Early Midlandian interstadial is represented by a woody detritus peat, with evidence ofBetula, PinuosandPiceawoodlands and a rich beetle fauna. Wood from this horizon has been shown to be beyond the range of radiocarbon dating (>48 180 BP). (4) Interstadial conditions were succeeded by a cold, non‐glacial phase dominated by in‐channel gravelly flows and deposition of organic muds which contain plant and insect fossils. These horizons are older than 46 850 BP. (5) An upper, non‐drumlinised till was deposited during the Late‐Midlandian by a major lowland ice sheet which moved generally eastwards across the Lough Neagh Lowlands from central Ulster. This glaciation probably reached its maximum at ca 20–24 ka. (6) Drumlin formation occurred in the Lough Neagh Lowlands towards the end of the Late‐Midlandian. The limiting moraines are dated to 17 ka. The lower till at Aghnadarragh is the first positive record of a major lowland ice sheet in Ireland during the early part of the last cold stage. The Early Midlandian interstadial peats have not been documented elsewhere in Ireland and correlate broadly with the Chelford Interstadial complex of the English Midlands. Related exposures elsewhere in Ulster confirm that the middle part of the last cold stage was free of major lowland ice masses but deposits of this period are absent fr

ISSN:0267-8179    

DOI:10.1002/jqs.3390020104

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractBased on detailed stratigraphic investigations on a 200.6m long core (BGS borehole No. 81/26) from the Fladen Ground area (British sector), core material from the Sleipner field (Norwegian sector) and shallow seismic profiles between the core‐sites, the following conclusions are drawn: (1) The North Sea was glaciated sometime during th elaterpart of Matuyama reversed period. A complete glacial‐interglacial‐glacial cycle is recorded in these sediments. (2) In a period of marine sedimentation in the Middle Pleistocene, a transgression‐regression cycle under boreal‐arctic regime is recorded. (3) The Fladen area has subsided between 0.9 and 0.6 m/ka through the later parts of the Quaternary (4) A major glacial event dated at between 130 and 200 ka is recorded as a thick till unit in 81/26. This till, which was deposited by ice moving from the southwest (Scotland), probably represents a period when the Scandinavian and British ice sheets coalesced in the North Sea. (5) Based on the seismic data and the stratigraphy of the Sleipner core, an ice‐free, open embayment/dry land is favoured for the central North Sea during the Late Weichselian. (6) From the amino‐acid data, it is shown that there has been an episodic style of sedimentation through the Quaternary. (7) of the investigated sediments (which span the last 1 mill. year) ca 98% have been deposited under arctic to boreal‐ar

ISSN:0267-8179    

DOI:10.1002/jqs.3390020105

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract14C dating and pollen analytical evidence is presented relating to the usefulness of arctic‐alpine Brown Soils for palaeoenvironmental reconstruction. A present‐day soil has been examined together with its continuation beneath the outermost ‚Little Ice Age’︁ end moraine of the glacier Vestre Memurubreen at a location well above the tree‐line in the mid‐alpine belt of southern Norway. Fourteen14C dates from chemically‐fractionated soil samples, which range in age from 495 ± 5514C yr in the uppermost 1 cm to>400014C yr within 13 cm of the buried soil surface, demonstrate near‐linear age/depth gradients in the palaeosol. Continuous development of the palaeosol over at least 5000 calendar yr prior to burial confirms that Vestre Memurubreen attained its Neoglacial maximum extent in the ‚Little Ice Age’︁. Pollen stratification in buried and unburied profiles indicates a single vegetation change from a low‐alpine dwarf‐shrub heath to a mid‐alpine ‚grass’︁ heath, reflecting an altitudinal lowering of vegetation belts and a possible climatic cooling of 2‐4°C. Surface additions of allochthonous (aeolian) mineral particles appear to have contributed to soil development, whilst mixing processes have been relatively unimportant at this site. The immobilisation of resistant organic residues and the ineffectiveness of biological and chemical activity are major reasons for the preservation of a palaeoenvironmen

ISSN:0267-8179    

DOI:10.1002/jqs.3390020106

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractMineral magnetic methods of characterising glacial diamicts and their associated sediments are applied to deposits within the Manx Quaternary sequence. The possible advantages of these techniques over more traditional methods of sediment characterisation are outlined, and the results obtained in a pilot study are examined. Results show that both distinctions and similarities exist within the magnetic mineral assemblages of the four diamict units studied. The possible implications of these results for interpreting the Late Quaternary history of the Isle of Man and the future potential of the techniques are briefly discussed.

ISSN:0267-8179    

DOI:10.1002/jqs.3390020107

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0267-8179    

DOI:10.1002/jqs.3390020108

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0267-8179    

DOI:10.1002/jqs.3390020109

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0267-8179    

DOI:10.1002/jqs.3390020110

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0267-8179    

DOI:10.1002/jqs.3390020101

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY