摘要:

AbstractThe lithology and sedimentology of the Meadfoot Group around Torbay are briefly discussed. The brachiopod fauna is tabulated, with ranges, and is considered to indicate an Emsian age. The fauna and environment of deposition of the Meadfoot facies (Lower‐Upper Emsian) and the Staddon facies (Upper Emsian) are discussed and are interpreted as representing Outer Shelf and Inner Shelf positions respectivel

ISSN:0072-1050    

DOI:10.1002/gj.3350200202

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractFour ductile phases of superimposed deformation are regionally mappable in the Ardnamurchan Moine in the Western Highlands of Scotland. These deformations are recognized on the basis of their individual geometrical characteristics and are named, in ascending order, the Kentra phase (D1), the Ardtoe phase (D2), the Glenmore phase (D3), and the Claish phase (D4). Non‐systematic earlier structures (pre‐D1), possibly coeval with the climactic metamorphism, are locally observable. Folds and fabrics produced by the D2, D1, and D4deformations, however, developed as conjugate sets.There is a significant spatial variation in the distribution and intensity of each of the D1‐D4phases. The regional deformation of the Moine schists is notably inhomogeneous due to the nature of the D1‐D4incremental strains. In the areas affected by large finite strains, pervasive, normally composite LS‐fabrics are developed. In the areas that persistently suffered negligible strain increments, right‐way‐up rocks commonly display several mineral foliations lying at various angles to bedding. The conjugate systems of folds and fabrics appear to be related to the evolution of a ductile shear belt in

ISSN:0072-1050    

DOI:10.1002/gj.3350200203

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractConfusion concerning the precise nature of the crinoid speciesCaleidocrinus multiramusis due to an erroneous description by Springer which was based on two specimens which were not types. The genusCaleidocrinusis unusual amongst inadunates in having interbrachial plates. The two recognized species are assigned to separate subgenera.C. multiramus, the type species, is assigned toCaleidocrinus s. s.subgen. nov, and has tall, shield‐like radials, concealed basals, and brachials with unsculptured latera.C. turgidulushas broad radial plates supported by triangular basals and brachials with lateral depressions adjacent to plate sutures. It is assigned toHwcleyocrinussubgen. nov.C. barrandeiis a synonym ofC. multiramus. Ristnacrinusis probably closely related to this genu

ISSN:0072-1050    

DOI:10.1002/gj.3350200204

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe primary and early diagenetic components of carbonate rocks are commonly arranged systematically in a sort of ‘relay’ along a gradient formed by one or several environmental factors. Such a relay, if present, can be revealed by the optimization of a matrix of similarity coefficients. The technique presented uses presence/absence data and is simple and rapid. An illustration is given using data from some Dinantian limestones in southwest Brit

ISSN:0072-1050    

DOI:10.1002/gj.3350200205

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA composite cross‐sectional model of a Mid‐Dinantian Waulsortian buildup and its lateral equivalents is assembled from 10 measured sections. Five of these are in the Furfooz reef southeast of Dinant and the others, well correlated, are in non‐reef facies in the Dinant and Namur synclinoria (ranging up to an original 100 km or more from the area of the buildups).This model provides the framework for a petrographic study (over 700 samples) in which 25 components, mainly allochems, were recorded. The distributions of 15 of the most interesting of these are figured and discussed. Major patterns, extending well beyond the limits of the Waulsortian facies, can be discerned. Four component assemblages (A‐D) are distinguished. Broadly arranged in strati graphic order (A at the bottom; D at the top), their constituents are.aEchinoderm (mainly crinoid) debris, fenestellid bryozoans, and ostracods.bAs A plus sponge spicules (notably the large, hyalosteliid ones) and moravamminids.cAs B plus plurilocular foraminifera, small gastropods, intraclasts and peloids.cAs C plus micritization, cryptalgal coatings on grains, and calcareous algae.The simple A assemblage typifies the classic Waulsortian facies–and many of its lateral equivalents. The others have increasing compositional diversity, with B and C occurring in the Waulsortian buildup facies and assemblage D mainly limited to flank deposits.Many components of these assemblages (calcareous algae, micritization, plurilocular foraminifera, etc.) have distribution patterns showing marked diachronismdownslopeon the flank of the buildup. This is interpreted as representing a lowering of critical depth thresholds for individual components due to a major drop in sea level late in Tournaisian times. Different components shift downwards ‘in step’ at slightly different stratigraphic levels and this allows construction of a relative depth scale. Taking the lower limits of the calcareous algae as a reference level (0 m), other lower limits are, approximately: micritization and cryptalgal coating (‐90 m), plurilocular foraminifera (‐120 m), hyalosteliid sponges (–150 m). This relative scale is tentatively converted into a water depth scale using as criteria the distribution of the calcareous algae, the limit of micritization and cryptalgal coating, and evidence indicating that the upper parts of the buildup were in the shallows at the end of Tournaisian times when the buildup had a sea floor relief of about 220 m.Changes in the depositional environments throughout the formation of the buildup are then traced, from initiation of growth in subphotic depths, probably exceeding 300 m, through shallowing phases possibly leading to emergence.Acknowledgements.We gratefully acknowledge: E. Groessens of the Service Géologique de Belgique for much unpublished information on conodonts, particularly for the sections at Pont‐à‐Lesse and Furfooz 2, 5, and 6; R. Conil and M. Laloux for help with various aspects of the micropalaeontology; V. Leclère for sampling and initial study of the Pont‐à‐Lesse section; L. Hance for information on biostratigraphic problems in the Lower Viséan and for useful comments on the manuscript; and M. Hennebert and J. Miller for c

ISSN:0072-1050    

DOI:10.1002/gj.3350200206

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractUsing detailed petrographic analysis and a new method of handling similarity coefficients, samples from over 30 Mid‐Dinantian (Upper Tournaisian‐Lower Viséan) carbonate buildups from Europe and North America are compared with the Waulsortian facies of Belgium. The same component types are present and they bear very similar relationships to. one another. This is very significant because the assemblages of components in Belgium have recently been interpreted in terms of water depth (Leeset al.1985).Four Waulsortian Phases are recognized, corresponding to the Belgian depth‐related assemblages. They represent growth in a range of marine environments from fairly deep, aphotic (probably more than 300 m) through to the photic zone (less than 120 m).Logging and mapping of phases allows growth patterns of individual buildups and buildup complexes to be interpreted as products of changing depositional environments. The very existence of the phases provides new information on the origin of the buildups. It also reveals that there was a fundamental growth mechanism independent of the preserved

ISSN:0072-1050    

DOI:10.1002/gj.3350200207

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350200208

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350200210

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350200211

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350200212

出版商:John Wiley&Sons Ltd    

年代:1985

数据来源: WILEY