AMINO-ACID GEOCHRONOLOGY OF RAISED BEACHES IN SOUTH WEST BRITAIN
AMINO-ACID GEOCHRONOLOGY OF RAISED BEACHES IN SOUTH WEST BRITAIN
复制标题
DOI：
10.1016/0277-3791(85)90003-4
复制
发表时间：
1985-01-01
影响因子：
4
通讯作者：
HARE, PE
中科院分区：
文献类型：
--
作者：
BOWEN, DQ;SYKES, GA;HARE, PE
本文根据（1）普通髌骨（Patella vulgata）、滨螺（Littorina littorea）、L. littoralis，L.（2）D-L比值的统计分析，（3）岩石地层和地貌评价，提出了三个D-L阶段。将测量的所有物种的D L比率转换为普通髌骨标准。这三个阶段（D L）是：1。(1)明钦洞阶（DL阶），DL比为0.175±0.014，定义于威尔士高尔明钦洞洞穴的层型。2. (2)由于目前没有合适的层型，暂时定义，但尚未命名（DL）阶段，DL比为0.135±0.014 3。(3)彭纳德阶（DL），DL比为0.105±0.016，定义于威尔士高尔明钦洞的层型。两个地质年代学模型的三个高海平面事件的D-L阶段的制约与海洋床夹层石笋铀系年龄测定Minchin孔和培根孔洞穴，高尔，威尔士。模型评价中的一个潜在“固定点”是相当于氧同位素子阶段5e（122 ka）的年龄测定。这两个模型是：氧同位素阶段和年龄（ka BP）（DL）阶段DL比率模型1a模型1b模型2 Pennard 0.105±0.016 5a（ca. 80)5e（122）5e（122）5c（ca. 100)未命名0.135±0.014 5e（122）7（194？）明钦孔0.175±0.014 7（186-245）7（186-245）7（216？）海滩的年龄被用来限制该地区冰川作用的时间和范围。晚德文斯冰期的范围是通过参考彭纳德（DL）阶段的海滩露出水面的地方，以及通过使用（未发表的）关于冰川沉积物中的软体动物的数据来确定的。两次前德文斯冰期早于明钦霍尔（DL）期。布里斯托海峡的爱尔兰海冰川作用（南威尔士的爱尔兰海“老漂移”/北德文郡的Fenggton Till）被归因于氧同位素10或更早，而帕维兰（威尔士）冰川作用被归因于氧同位素阶段8或更早。根据已知的威尔士产地在埃塞克斯的不规则性推断出一个较早的冰期（贝尔温冰期）。
Based on (1) the epimerization of l: isoleucine to d: alloisoleucine (D L ratios) in Patella vulgata, Littorina littorea, L. littoralis, L. saxatilis, Littorina species and Nucella lapillus from raised beaches in south west Britain,(2) statistical analysis of the D L ratios, and (3) lithostratigraphic and geomorphic evaluation, three (D L) Stages are proposed. The D L ratios for all the species measured are converted to a Patella vulgata standard. The three (D L) Stages are: 1.(1) The Minchin Hole (D L) Stage, D L ratios 0.175±0.014, defined at a stratotype in Minchin Hole Cave, Gower, Wales. 2.(2) A provisionally defined, but as yet, unamed (D L) Stage, because of the current unavailability of a suitable stratotype, with D L ratios of 0.135±0.014 3.(3) The Pennard (D L) Stage, D L ratios 0.105±0.016, defined at a stratotype in Minchin Hole Cave, Gower, Wales. Two geochronological models of the three high sea-level events representing the D L Stages are constrained by uranium-series age determinations on stalagmite interbedded with marine beds in Minchin Hole and Bacon Hole Caves, Gower, Wales. A potential ‘fixed point’in model evaluation is an age determination which is equivalent to Oxygen Isotope Sub-stage 5e (122 ka). The two models are: Oxygen Isotope Stage and age (ka BP)(D L) Stage D L Ratio Model 1a Model 1b Model 2 Pennard 0.105±0.016 5a (ca. 80) 5e (122) 5e (122) 5c (ca. 100) Unnamed 0.135±0.014 5e (122) 7 (194?) Minchin Hole 0.175±0.014 7 (186–245) 7 (186–245) 7 (216?) The ages of the raised beaches are used to constrain the timing and extent of glaciation in the area. The extent of the Late Devensian glaciation is fixed by reference to localities where raised beaches of the Pennard (D L) Stage outcrop, as well as by using (unpublished) data on molluscs incorporated into glacial deposits. Two pre-Devensian glaciations antedate the Minchin Hole (D L) Stage. The Irish Sea Glaciation of the Bristol Channel (Irish Sea ‘older drift’of South Wales/Fremington Till of North Devon) is ascribed to Oxygen Isotope 10 or earlier, while the Paviland (Welsh) Glaciation is ascribed to Oxygen Isotope Stage 8 or earlier. An earlier glaciation (Berwyn Glaciation) is inferred from erratics of known Welsh provenance in Essex.