Discussion on sea-level change and facies development across potential Triassic–Jurassic boundary horizons, SW Britain
Discussion on sea-level change and facies development across potential Triassic–Jurassic boundary horizons, SW Britain
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讨论海平面变化和跨潜在三叠纪-侏罗纪边界层的相发育，英国西南部
DOI：
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发表时间：
2004
影响因子：
2.7
通讯作者：
F. Surlyk
中科院分区：
文献类型：
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作者：
T. Hallam;P. Wignall;S. Hesselbo;S. Robinson;F. Surlyk
Tony Hallam和Paul Wignall写道：我们欢迎Hesselbo等人的论文。(2004)对一组重要的系统边界地层的环境意义进行了透彻的描述和仔细的评价，但对一些关键点提出了异议。
(1)最重要的是，虽然我们同意Cotham段内部存在退缩阶段的证据，但我们坚持认为，在朗波特段(Lilstock组)和Blue Lias的交界处也存在急剧的退缩，然后是快速的海侵，这与他们的观点形成了鲜明对比。在讨论英格兰西南部的证据之前，有必要进一步考虑到更广泛的欧洲背景(Hallam&Wignall，1999年，其中引用了许多相关的参考文献)。这一证据在德国尤为明显，在德国，最近的拉提亚盆地出现了广泛的浅水，其特点是页岩上的砂岩堆积。在北部的弗兰科尼亚(巴伐利亚)，河流相砂岩充填水道，切割成雷提亚晚期海相地层，并被海相HetTangian覆盖。最早期的海平面上升明显迅速，德国南部东部边缘海相砂岩的极限被推后，整个海相阶段的页岩被完全海相页岩破坏到最大程度。
在欧洲北部和南部，都可以推断出海平面连续下降和上升的相似模式。丹麦盆地可识别出明显的末三叠世海退脉动，而瑞典南部和波兰西北部均缺失上Rhaetian，侏罗系底部存在不整合。在奥地利北部富含钙质的阿尔卑斯山，人们认识到在三叠纪末期广泛出现，在浮现的礁体上形成了岩溶表面，而…
Tony Hallam & Paul Wignall write: we welcome the paper by Hesselbo et al . (2004) for its thorough description and careful evaluation of the environmental significance of an important group of system boundary strata, but beg to take issue on a number of key points.
(1) Most importantly, while we agree with the evidence of a regressive phase within the Cotham Member, we maintain in marked contrast to their opinion that there was also a sharp regression followed by a rapid transgression at the junction of the Langport Member (of the Lilstock Formation) and Blue Lias. It is pertinent before discussing the evidence in SW England further to take into account the broader European context (Hallam & Wignall 1999, with many relevant references cited therein). The evidence is especially clear in Germany where there was extensive shallowing in the latest Rhaetian marked by progradation of sandstone over shales. In northern Frankonia (Bavaria) fluvial sandstones infill channels incised into late Rhaetian marine strata and are overlain by marine Hettangian. The sea-level rise in the earliest Hettangian ( planorbis Zone) was evidently rapid, with the limit of marginal marine sandstones in the eastern part of southern Germany being pushed back at the expense of fully marine shales to the maximum extent achieved during the whole Hettangian Stage.
Both in the north and south of Europe a similar pattern of successive sea-level fall and rise can be inferred. A clear end-Triassic regressive pulse can be recognized in the Danish Basin, while both in southern Sweden and NW Poland the upper Rhaetian is missing and there is an unconformity at the base of the Jurassic. In the Northern Calcaerous Alps of Austria, widespread emergence at the end of the Triassic is recognized, with the creation of karst surfaces on emergent reef complexes, while …