摘要:

AbstractThe correlation of borehole logs, together with evidence from temporary exposures, shows the relationship between glacial deposits and the overlying Flandrian strata. The courses of buried channels in‐filled with Flandrian strata have been plotted. Radiocarbon assays and pollen and diatom analyses have mainly been confined to samples taken from near the main lithological boundaries, but some radiocarbon assays have been undertaken onin situtree stumps and on bone. New thick buried channel sequences are described, and an outline chronology fromc.6420 years BP is proposed for the Flandrian coastal sequence of the North Wirral. The data can be applied to the interpretation of sea‐level change and coastal archaeol

ISSN:0072-1050    

DOI:10.1002/gj.3350210102

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe Caradoc volcanic rocks of the Lleyn Peninsula represent a major episode of rhyolite‐dominated eruption (total volume up to 560 km3) within the Southern British Caledonides. New geochemical data reveal the original chemical characteristics of the basic, intermediate, and acid lavas. The basalts are interpreted as having predominantly within‐plate character and are associated with intermediate lavas (trachybasalts) and high‐Zr, originally peralkaline, trachytes, and rhyolites. A low‐Zr, originally high‐K, subalkalic group of rhyolites, and a basalt with transitional island arc tholeiite‐MORB characteristics are unrelated to these lavas. The volcanic rocks are interpreted to have been erupted onto a complex, rapidly evolving, active continental margin dominated by crus

ISSN:0072-1050    

DOI:10.1002/gj.3350210103

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA pronounced coal seam split, one of many within the Lower Westphalian B (Upper Carboniferous) sequence of the Durham coalfield, northeast England, occurs in the vicinity of the village of Burnhope. This feature involves the division of the combined Main/Fivequarter coal into its two component parts, which become separated by up to 8 m of clastic sedimentary rocks over a horizontal distance of 150 m.Three‐dimensional outcrop data from an opencast (surface) coal mine straddling the split, supported by extensive subsurface information, have allowed detailed study of the seam split geometry, in addition to that of three overlying coal seams and intervening clastic facies.The study suggests that deposition of the interval as a whole, including the split, was strongly influenced by compaction‐controlled subsidence, and not by either contemporary fault movements or channel sedimentation.A substantially greater aggregate thickness of coal is preserved over the five seam interval where the Main/Fivequarter is unsplit than where split. This relationship is consistent with the coal depositional model proposed by Fielding (1984a), which proposed that thick coals in the Durham area are located adjacent to, but not within, coal seam splits. It further implies that attractive sites for future opencast development in the area may be predicted from a regional knowledge of coal seam spl

ISSN:0072-1050    

DOI:10.1002/gj.3350210104

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe Latterbarrow Formation, 400 m thick, has been mapped and subdivided informally into three members. These consist of quartz wacke sandstone and, in the upper member only, intercalated mudstones. The formation unconformably overlies the fossiliferous Skiddaw Group of late Tremadoc to middle Arenig age and is overlain disconformably by volcanic rocks that have been attributed to the Borrowdale Volcanic Group. Chemically, the sandstones are characterized by very low concentrations of CaO, Na2O, and K2O and unusually high total iron. MnO and MgO, such that iron, as Fe2O3, exceeds Al2O3. Mudstone in the upper member is illite rich, has a high K2O content and is compositionally similar to K‐bentonites derived from volcanic ash. Sedimentary structures and petrography suggest that the sediments were deposited in a sandy estuary and were derived from a similar source area to that of the Skiddaw Group. Throughout the succession there is evidence of distal volcanism, probably representing the earliest eruptions of the Borrowdale volcanic episode.The Redmain Formation, 100 m thick, is unconformably overlain by Carboniferous rocks but its relationship to the underlying Skiddaw Group is unknown. Though this lithic arenite shows some petrographic and geochemical similarities with the Latterbarrow sandstone, differences are such that it is possible they are not equivalent in age. The Redmain sandstone may be derived from the erosion of Skiddaw Group rock

ISSN:0072-1050    

DOI:10.1002/gj.3350210105

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210106

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210107

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210109

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210110

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210111

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210113

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY