| 翻訳と辞書 |
| Cymru Terrane ： ウィキペディア英語版 |
Cymru Terrane
The Cymru Terrane is one of five inferred fault bounded terranes that make up the basement rocks of the southern United Kingdom. The other notable geological terranes are the Charnwood Terrane, Fenland Terrane, Wrekin Terrane and the Monian Composite Terrane.〔P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed〕 In this article the definition of terrane is that implying rocks associated with the composition of the Precambrian basement. The Cymru Terrane is bounded to the northwest by the Menai Strait Fault System and to the southeast by the Pontesford Lineament. The geological terrane to the west is the Monian Composite Terrane and to the east is Wrekin Terrane.〔 The majority of rocks in the area are associated with the outcrops that are evident at the faulted boundaries.〔Pharaoh, T.C., Gibbons, W., ''Precambrian Rocks in England and Wales south of the Menai Strait Fault System'', 1987 A Revised Correlation of the Precambrian Rocks in the British Isles〕〔J. N. Carney, J. M. Horak, et al., ''Precambrian Rocks of England and Wales'', ''Joint Nature Conservation Committee.'' Geological Conservation Review Series 20〕
The Proterozoic rocks of the Cymru Terrane are typified in North Wales by the Arfon Group, Sarn Complex and the Twt Hill Granite.〔P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed〕 The former is in the Bangor area (S & SW) with the latter two located on the Llyn Peninsula. The St Davids Granophyre and the Pebidian Supergroup are located on the coastline of St Davids Peninsula. Inferred Proterozoic volcanic deposits are noted in the Bryn-Teg Borehole (Trawsfynydd, Gwynedd).〔P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed〕〔P.M. Allen, A.A. Jackson ''Bryn-Teg Borehole, North Wales.'', 1978, Bulletin of the Geological Survey of Great Britain, 61 1-52〕
The Padarn Tuff, which is thought to be contemporaneous with the Sarn Complex, is unconformable with the overlying Fachwen Formation and the unconformity has been constrained with dates noted of 604.7 Ma+/-1.6Ma from the tuffs and 572.5 Ma+/-1.2Ma from the Fachwen Formation. 〔W. Compston, A. E. Wright, P. Toghill, ''Dating the Late Precambrian volcanicity of England and Wales.'' 2002, Journal of the Geological Society of London. 159 323-339.〕
Information on the basement is somewhat sparse with no zircons noted to be older than 617 to 638 Ma. 〔W. Compston, A. E. Wright, P. Toghill, ''Dating the Late Precambrian volcanicity of England and Wales.'' 2002, Journal of the Geological Society of London. 159 323-339.〕 However, there are outcrops of the Parwyd Gneiss which are retrogressed granitoid gneiss and garnet amphibolite that occur with the Llyn Shear Zone.〔P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed〕 This is conjectured to be one of two probabilities, either as an exotic sliver, or as a metamorphic slice from the Monian Composite Terrane. The Granitoid Gneiss has Sm-Nd ages of 1350 Ma which is in the same temporal region as the Sarn Granite 〔P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed〕〔W. Compston, A. E. Wright, P. Toghill, ''Dating the Late Precambrian volcanicity of England and Wales.'' 2002, Journal of the Geological Society of London. 159 323-339.〕
==Intrusive geology==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Cymru Terrane」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|