Palaeogeography of a shallow carbonate platform:The case of the Middle to Late Oxfordian in the Swis

来源 :Journal of Palaeogeography | 被引量 : 0次 | 上传用户:Anody12341234
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
The Oxfordian(Late Jurassic) carbonate-dominated platform outcropping in the Swiss Jura Mountains offers a good biostratigraphic,sequence-stratigraphic,and cyclostratigraphic framework to reconstruct changes in facies distribution at a time-resolution of 100 ka.It thus allows interpreting the dynamic evolution of this platform in much more detail than conventional palaeogeographic maps permit.As an example,a Middle to Late Oxfordian time slice is presented,spanning an interval of about 1.6 Ma.The study is based on 12 sections logged at cm-scale.The interpreted depositional environments include marginal-marine emerged lands,fresh-water lakes,tidal flats,shallow lagoons,ooid shoals,and coral reefs.Although limestones dominate,marly intervals and dolomites occur sporadically.Major facies shifts are related to m-scale sea-level changes linked to the orbital short eccentricity cycle(100 ka).The 20-ka precession cycle caused minor facies changes but cannot always be resolved.Synsedimentary tectonics induced additional accommodation changes by creating shallow basins where clays accumulated or highs on which shoals or islands formed.Autocyclic processes such as lateral migration of ooid and bioclastic shoals added to the sedimentary record.Climate changes intervened to control terrestrial run-off and,consequently,siliciclastic and nutrient input.Coral reefs reacted to such input by becoming dominated by microbialites and eventually by being smothered.Concomitant occurrence of siliciclastics anddolomite in certain intervals further suggests that,at times,it was relatively arid in the study area but there was rainfall in more northern latitudes,eroding the Hercynian substrate.These examples from the Swiss Jura demonstrate the highly dynamic and(geologically speaking) rapid evolution of sedimentary systems,in which tectonically controlled basin morphology,orbitally induced climate and sea-level changes,currents,and the ecology of the carbonate-producing organisms interacted to form the observed stratigraphic record.However,the interpretations have to be treated with caution because the km-wide spacing between the studied sections is too large to monitor the small-scale facies mosaics as they can be observed on modern platforms and as they certainly also occurred in the past. The Oxfordian (Late Jurassic) carbonate-dominated platform outcropping in the Swiss Jura Mountains offers a good biostratigraphic, sequence-stratigraphic, and cyclostratigraphic framework to reconstruct changes in facies distribution at a time-resolution of 100 ka. It allows interpreting the dynamic evolution of this platform in much more than conventional palaeogeographic maps permit. As an example, a Middle to Late Oxfordian time slice is presented, spanning an interval of about 1.6 Ma. The study is based on 12 sections logged at cm-scale. The depositional environments include marginal-marine pastures, fresh-water lakes, tidal flats, shallow lagoons, ooid shoals, and coral reefs.Although limestones dominate, marly intervals and dolomites occur sporadically. Major facies shifts are related to m-scale sea-level changes linked to the orbital short eccentricity cycle (100 ka). The 20-ka precession cycle caused minor facies changes but can not always be resolved. Synsedimentary t ectonics induced additional accommodation changes by creating shallow basins where clays accumulated or highs on which shoals or islands formed. Atocyclic processes such as lateral migration of ooid and bioclastic shoals added to the sedimentary record. Climate changes intervened to control terrestrial run-off and, , siliciclastic and nutrient input. Coral reefs reacted to such input by becoming dominated by microbialites and eventually by being smothered. Concomitant occurrence of siliciclastics and dolomite in certain intervals further suggests that, at times, it was relatively arid in the study area but there was rainfall in more northern latitudes, eroding the Hercynian substrate. these examples from the Swiss Jura demonstrate the highly dynamic and (geologically speaking) rapid evolution of sedimentary systems, in tectonically controlled basin morphology, orbitally induced climate and sea-level changes, currents, and the ecology of the carbonate-producing organisms interacted to form the observed stratigraphic record.However, the interpretations have to be treated with caution because the km-wide spacing between the studied sections is too large to monitor the small-scale facies mosaics as they can be observed on modern platforms and as they themselves certainly also occurred in the past.
其他文献
The article of Vérard et al.(2015) proposed an important academic problem “to reconstruct the altitude of oldlands and the water depth of palaeo-oceans of any
Vérard et al.(2015,Journal of Palaeogeography,4(1):64-84) claim that their global geodynamic model allows one to reconstruct the surface features of topography
《品德与社会课程标准》中提出“品德与社会课程是在小学中高年级开设的一门以儿童社会生活为基础,促进学生良好品德形成和社会性发展的综合课程”.小学品德学科课堂教学应树
期刊
数学在培养和提高人的思维能力方面有着其它学科不可替代的独特作用,数学高考坚持的能力立意很好的体现了这一点。在整个高中数学,加上学生已有对数学的一些认识,牵涉到的概念、
随着国内经济的发展,教育部门加大了对地域性设计教育的投入,更加注重设计给人们带来的文化和生态内涵.大多数学校对教学模式没有创新,教学效果不明显,起不到设计服务社会的
Vérard and co-workers proposed in an earlier issue of this journal a method to reconstruct the 3D palaeogeography “anywhere in the world at any time”.The pre
在21世纪已走过13年之时,我国开设中学生物课也历经了112周年的苍伤历程,整整一个多世纪的坎坷发展历程表明,中学生物学具有强大的生命力,它在过去、现在和未来都将为生命科学乃
期刊
孩子的天性是自然的,正如德国著名教育家弗里德里奇·福禄贝尔所说,“幼儿期是真正的人的教育、自然的教育”.rn最初,对于幼儿的发展来说是至关重要的,是儿童个性开始形成、
期刊
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
多年以来,我一直从事初中英语教学工作。让我感受最深的是,许多学生因为单词没掌握好而严重影响了他们的英语学习。因此,今天我想就如何利用音标读单词和记单词谈谈我的看法。
期刊