摘要:

AbstractNew and accessible exposures are described in which the downward‐facing of folds in the axial‐zone of the Tay Nappe can be convincingly demonstra

ISSN:0072-1050    

DOI:10.1002/gj.3350080111

出版商:John Wiley&Sons Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractFifteen new radiocarbon datings from British Pleistocene deposits are described. The datings are related to the classic Pleistocene succession and shown to be consistent with the stratigraphic sequence of East Anglia. On the basis of these datings, an absolute chronology is developed. According to this chronology, the glacial drifts of East Anglia ought to postdate 40,000 B.P. and hence belong to the Last Glaciation of the British Isles. The Hoxnian interglacial of this chronology is dated between about 25,500‐21,000 B.P. The conventional age for the Hoxnian interglacial is 175,000–120,000 B.P. The validity of the radiocarbon datings is considered and some of the implications and problems of a revised age for the Hoxnian interglacial are revie

ISSN:0072-1050    

DOI:10.1002/gj.3350080112

出版商:John Wiley&Sons Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractInterbedded clays, or clay wayboards, from the Lower Carboniferous Limestones of Derbyshire and Staffordshire, are discussed in terms of their geological relationships, textural features and mineralogy, and comparison is made between these clays and other interbedded argillaceous materials from the area. It is concluded that the clay wayboards are the argillation products of contemporaneous volcanic ashfalls, and lie within the definition of K‐bentonites.Stratigraphical and palaeogeographical aspects of clay wayboard distribution are briefly discussed, and it is shown that despite the probable widespread extent of individual clay horizons they are only of limited value for the purposes of correlatio

ISSN:0072-1050    

DOI:10.1002/gj.3350080113

出版商:John Wiley&Sons Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe sequence and structure of the volcanic rocks of a small area lying within the main belt of plutons of the Peruvian Andes were mapped and are here described. Metamorphic zoning of the calcareous aureole minerals was shown to be similar to that described elsewhere, e.g. wollastonite, diopside, hornblende with increasing distance from the contact. The mineral assemblages and their spatial and textural character indicate rapid heating of the aureole, with only a short time at maximum temperatures. The complex mineralogy in individual rocks is interpreted in terms of changing physical conditions during the thermal event. The sequential assemblages are the result of changes in activity of CO2, H2O and Fe3+in particular.

ISSN:0072-1050    

DOI:10.1002/gj.3350080114

出版商:John Wiley&Sons Ltd    

年代:1972

数据来源: WILEY