摘要:

AbstractThe lateral lithological variability of 18 stratigraphically close fluviatile cyclothems is analysed in three ways: (1) qualitatively, (2) by means of the upwards facies transition probability matrix, and (3) using the non‐parametric Mann‐Whitney U statistic. Some cyclothems are relatively very uniform over lateral distances comparable with 100 cyclothem thicknesses, whereas others have a lateral variability similar to the variability characteristic of the set of cyclothems. Hence some amongst stratigraphically close cyclothems are considered to show real differences, which may be attributed to allocyclic environmental factors operating on a relatively large time scale. The variation within cyclothems can be explained by shorter term autocyclic fact

ISSN:0072-1050    

DOI:10.1002/gj.3350090101

出版商:John Wiley&Sons Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe Ghirian volcanic province comprises three distinct units. An early (50–55 m.y.) phase of extensive plateau lava (basaltic hawaiite) eruption was followed by the emplacement of small phonolite domes (∼ 40 m.y.). After a long period of inactivity, a rejuvenation phase (<12 m.y.ago) led to the formation of scattered minor volcanic centres, generally of basanitic composition, and carrying Iherzolite fragments. 39 new analyses illustrate the distinctive chemical characteristics of each episode. Differences in volume and composition between early and late basic volcanicity can be related to regional episodes of strong mantle convection in the early Tertiary and weak convection in the late Tertiary. The phonolites may be fractionates of an intervening injection of basic magma trapped at moderate depth. Continuing structural control was exerted on a regional scale by the zone of uplift and fracturing connecting the Ghirian area with Tibe

ISSN:0072-1050    

DOI:10.1002/gj.3350090102

出版商:John Wiley&Sons Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA survey involving 860 gravity measurements over the Fylde area of Lancashire is described. A line of movement in the pre‐Permian basement rocks is shown to cross the area from north north east to south south west forming the eastern edge of a deep sedimentary basin. Displacement of the Carboniferous along this line has reached 1000 m in places and was probably an important influence on Permo‐Triassic deposition in Northwest Lancash

ISSN:0072-1050    

DOI:10.1002/gj.3350090103

出版商:John Wiley&Sons Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe principal structures of the Lower Palaeozoic rocks of Angelsey are described. Tight folding, with variably developed slaty cleavage and a first phase of reverse faulting, took place probably in late Silurian times, along axes which are parallel to pre‐Cambrian foliation trends. A second phase of reverse faulting followed basic dyke intrusion and was succeeded by normal faulting and mineralization. Joint production was a comparatively late feature. A technique for analysing fault data, in terms of stress axes, is outlined and applied to faulting within the Lower Palaeozoic rock

ISSN:0072-1050    

DOI:10.1002/gj.3350090104

出版商:John Wiley&Sons Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe Moine‐like rocks are shown to have major, southward‐leaning, isoclinal F2folds which may be synchronous with the nappe‐like Ballybofey Antiform of the overlying Dalradian rocks. The deformation of the immediately adjacent Dalradian rocks is consistent with a previous suggestion that they are in contact with the Moine‐like rocks along a major tectoni

ISSN:0072-1050    

DOI:10.1002/gj.3350090105

出版商:John Wiley&Sons Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractDetailed gravity and resistivity surveys have been made in the Vale south of Denbigh, and from the combined interpretations a Trias isopachyte map has been produced. The gravity interpretation indicates that the en echelon faults of the western side extend across to the Vale of Clwyd fault, and separate a complementary set of en echelon synclines. These structures are systematically arranged in a pattern that may be attributed to dextral wrenching, and are discussed against a range of literature on that subject. The wrenching may have been a prolonged activity that commenced during Carboniferous times.

ISSN:0072-1050    

DOI:10.1002/gj.3350090106

出版商:John Wiley&Sons Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractIn southwest Ireland 2,500 m of Upper Famennian to basal Namurian marine sandstones and mudstones, the Cork Beds, overlie rocks of Old Red Sandstone facies. Coastal exposures of the Cork Beds are interpreted as showing gradual upward change from alluvial strata, through thick subtidal and shelf sediments to pyritic muds. A review of recent palaeontological evidence shows that the thick shallow marine part of the Cork Beds is older than the major development of lime‐stones north of the Cork Harbour—Kenmare Une, whose equivalents to the south are in the condensed basinal sediments. The Lower Carboniferous portion of the Cork Facies is shown to be thicker in South Cork than in West Cork. In Lower Carboniferous times a positive area–the Glandore High–separated two sub‐basins with different depositional histories. Six palaeogeographic maps are used to demonstrate the progressive shift of facies belts as Lower Carboniferous marine transgression progressed. Finally, brief comparison is made with rocks of the same age in southwes

ISSN:0072-1050    

DOI:10.1002/gj.3350090107

出版商:John Wiley&Sons Ltd    

年代:1974

数据来源: WILEY