Research Article| April 01, 1999 Evidence of sea-level fall in sequence stratigraphy: Examples from the Jurassic A. Hallam A. Hallam 1School of Earth Sciences, University of Birmingham, Birmingham B15 2TT, UK Search for other works by this author on: GSW Google Scholar Author and Article Information A. Hallam 1School of Earth Sciences, University of Birmingham, Birmingham B15 2TT, UK Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1999) 27 (4): 343–346. https://doi.org/10.1130/0091-7613(1999)027<0343:EOSLFI>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation A. Hallam; Evidence of sea-level fall in sequence stratigraphy: Examples from the Jurassic. Geology 1999;; 27 (4): 343–346. doi: https://doi.org/10.1130/0091-7613(1999)027<0343:EOSLFI>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The inference of relative sea-level change is fundamental to sequence stratigraphy, but in many situations determination of sea-level rise, with associated marine transgression, is more reliable than sea-level fall. This is especially true of epicontinental marine successions characterized by low subsidence and sedimentation rates and only limited influx of coarse siliciclastic sediments. In either the Exxon or Galloway schemes of sequence stratigraphy, offshore condensed sections are taken as evidence of sea-level rise and are normally associated with maximum flooding surfaces. However, condensed sections may grade into stratigraphic hiatuses or disconformities of a very different character from what are interpreted as sequence-bounding unconformities in the Exxon scheme. There may also be evidence of the erosion of significant amounts of consolidated rock, which is more plausibly accounted for by relative sea-level fall leading to emersion than to unusually intense storm or current activity in a submarine setting. Several examples from the European Jurassic are discussed here. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Abstract It is unusual in science for a major advance to be traceable to the publication of a single paper, but without question the study of mass extinctions received a huge stimulus, and considerable media interest, from the seminal paper in Science by Luis Alvarez, his son Walter and two nuclear chemist colleagues (Alvarez et al. 1980). Although phenomena from outer space had been invoked on a few previous occasions to account for mass extinctions, they were disregarded because of lack of evidence in support. This situation was changed radically with the discovery of a significant positive anomaly of the platinum-group trace metal iridium at the Cretaceous-Tertiary (K-T) boundary in Italy and elsewhere. This was held by Alvarez et al. to be most plausibly accounted for by the impact of an asteroid approximately 10 km in diameter. A few years later the impact hypothesis received strong support from an independent line of evidence, the presence of so-called shocked quartz at the K-T boundary in the North American Western Interior. Shocked quartz possesses distinctive multiple sets of lamellae which have only been recognised in rocks from well-established meteorite impact sites or at nuclear weapons test sites, and appears to signify the passage of shock waves under enormous pressures.
Events across the Triassic‐Jurassic boundary are a matter of great interest because this marks the time of one of the five biggest marine mass extinctions in the Phanerozoic. Some of the best sections across the boundary are in north west Europe; attention here is focussed on the basal Jurassic. Sedimentological and palaeoecological study has been undertaken of a number of sections in England and Germany, most of them borehole cores, and indicate a range of oxygen‐restricted facies, signifying episodic fluctuations between anoxic and dysoxic conditions. Analysis of the Th/U ratio in the coastal outcrop of St. Audrie's, Somerset, confirms this interpretation. The Triassic‐Jurassic boundary in north west Europe is characterised by a regression‐transgression couplet, with the corresponding sea‐level change being quite possibly of short duration.
An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.
SUMMARY A likely example of biochemical evolution in the nautiloids is demonstrated, based on X-ray fluorescence analysis of the Sr content of unaltered shells.
A review is presented from the Jurassic terrestrial and marine fossil record, and the record of sediments and clay minerals, insofar as it bears on the two principal climatic parameters, temperature and precipitation. It is shown that there is a generally good agreement between palaeoclimatic data derived from fossils and rocks and the results of modelling experiments, provided a substantially higher atmospheric content of carbon dioxide is assumed for Jurassic times. The Jurassic world was relatively equable compared with the present day, but there were probably strong seasonal contrasts of temperature within the large continental areas, as well as some polar ice. Monsoonal effects were dominant on the continents and rainfall in low and mid latitudes was probably strongly seasonal, with arid conditions prevailing at low latitudes. Significant changes of temperature through the course of the period cannot be discerned, but some evidence tentatively favours a slight increase. A notable spread of aridity in southern Eurasia in the late Jurassic can be related to orographic effects. Some minor cyclicity in the sedimentary sequence may relate to orbital forcing.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)