摘要:

AbstractSeven phases of deformation are recognised in Dalradian metasediments within the NW aureole of the Main Donegal Granite. Major NW facing F2 folds (the Aghla Anticline and Errigal Syncline) refold an originally NW facing slaty cleavage, which is usually parallel to bedding. D3 structures cross‐cut the major F2 folds and verge and face to the SE on their normal limbs. A fourth phase of deformation intensifies towards the granite contact and is shown to be broadly coeval with intrusion and responsible for a major structure in the aureole. Three later phases are variably developed throughout the aureole. The kinematics of F4 folds in relation to the granite intrusion are briefly discusse

ISSN:0072-1050    

DOI:10.1002/gj.3350120201

出版商:John Wiley&Sons Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractA series of ultramafic igneous bodies occurs in the Pre‐Cambrian (Monian) metasedimentary rocks of Anglesey. The latter are finely‐banded semi‐pelites of greenschist facies and have undergone two main phases of deformation. Most of the structures are weakly developed near the intrusions where an irregular zone of epidote hornfels was produced. The ultramafic bodies were emplaced as peridotite magmas immediately prior to D. Thorough serpentinization followed and the resulting serpentinites have a variety of appearances. A later carbonatization was intense in places. The structures and textures of the intrusive rocks can be correlated with regional events. Various melagabbroic rocks, now highly altered, may be comagmatic with the peridotite although intruded rather

ISSN:0072-1050    

DOI:10.1002/gj.3350120202

出版商:John Wiley&Sons Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe distribution of foraminifers, ostracods, diatoms and pollen is studied in cores from submarine boreholes. This reveals that the history of the Flandrian transgression is largely the record of the infilling of meltwater channels cut during the early Late Glacial with transgressive estuarine and finally marine deposits. It also supports the idea of the ‘climatic earliness’ of the Welsh seaboard at all stages. Estuarine deposits in excess of —51 m O.D. suggest that Late Glacial sea levels were initially as low as —60 m O.D. and support the idea that the Welsh ice withdrew before 14,000 years B.P. The sea‐level rise plots as a smooth curve but was probably episodic in its ear

ISSN:0072-1050    

DOI:10.1002/gj.3350120203

出版商:John Wiley&Sons Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractEvidence for the age of the Bray Group in southeastern Ireland is very limited. In this paper, a sample from the Gaskin's Leap Formation of the Bray Group succession in the Howth peninsula is shown to contain acritarchs of probable Lower Cambrian age.

ISSN:0072-1050    

DOI:10.1002/gj.3350120204

出版商:John Wiley&Sons Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractMarginal Triassic deposits in Glamorgan, South Wales, occur beneath and laterally equivalent to the Keuper Marl. They consist of coarse elastics, locally interbedded with finer sediments, limestones and replaced evaporites. Fluviatile sediments are chiefly sorted conglomerates and cross‐bedded sandstones of stream‐flood origin. Other conglomerates and sandstones, associated with siltstone and calcrete, are interpreted as the deposits of semi‐permanent streams with well‐developed floodplains. Ill‐sorted breccias accumulated as screes against former cliffs. Matrix‐supported conglomerates of mudflow origin are a minor facies. Thin graded beds were deposited from sheet floods and other finer clastic sediments formed on floodplains and playas. Lacustrine shore‐zone elastics, limestones and evaporites are also present.The distribution of the various facies is related to the Trassic geomorphology, which was controlled by the structure of the underlying Palaeozoic. The South Wales Coalfield formed an upland area bounded to the south by an escarpment. Stream‐flood conglomerates of the Radyr‐Llandaff area were part of an alluvial fan which formed at the foot of this escarpment, perhaps at the mouth of a canyon on the site of the present‐day Taff gorge. South of the escarpment semi‐permanent streams with well‐developed floodplains occupied a broad valley, draining eastwards and cut into the axial region of the plunging Cowbridge anticline. South of the anticline, stream‐flood and sheet‐flood deposits interdigitated with wave‐rippled and desiccated siltstones deposited on playas. The latter, together with the shore‐zone sediments, were marginal to the lake in which the Keuper Marl accumulated. With rising base‐level during the Norian, the Keuper Marl facies spread north and west into the Vale of Glamorgan, covering the Marginal Triassic and i

ISSN:0072-1050    

DOI:10.1002/gj.3350120205

出版商:John Wiley&Sons Ltd    

年代:1977

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350120206

出版商:John Wiley&Sons Ltd    

年代:1977

数据来源: WILEY