نتایج جستجو برای: stratigraphic
تعداد نتایج: 4447 فیلتر نتایج به سال:
The Anthropocene, an informal term used to signal the impact of collective human activity on biological, physical and chemical processes on the Earth system, is assessed using stratigraphic criteria. It is complex in time, space and process, and may be considered in terms of the scale, relative timing, duration and novelty of its various phenomena. The lithostratigraphic signal includes both di...
Investigation of the climatic and environmental impacts of the Youngest Toba Tuff (YTT, ∼74 ka BP) eruption of Toba volcano, Sumatra, is crucial for understanding the consequences of the eruption for contemporaneous human populations. The Middle Son Valley, in India, was the first locality on the Indian subcontinent where the YTT was reported. The ash bed forms a discontinuous layer stretching ...
Well log data are routinely used for stratigraphic interpretation of the earth’s subsurface. This paper presents an automatic blocking scheme that transforms numerical well log data into a fuzzy symbolic representation. This representation maintains the character of the original log curves, which is essential for the stratigraphic interpretation, while making the interpretation task easier. Add...
Literature reports upper Cretaceous to Middle Eocene flysch/wildflysch deposits from Mexico, Guatemala, Jamaica, Cuba, Puerto Rico, Barbados, Granada, Trinidad, Venezuela, Colombia, Ecuador and Peru. Early papers recording their widespread distribution and noting their tectonic implications are often overlooked by popular palaeogeographic and plate tectonic reconstructions of the Caribbean area...
Several positive carbon isotope excursions in Lower Paleozoic rocks, including the prominent Upper Cambrian Steptoean Positive Carbon Isotope Excursion (SPICE), are thought to reflect intermittent perturbations in the hydrosphere-biosphere system. Models explaining these secular changes are abundant, but the synchronicity and regional variation of the isotope signals are not well understood. Ex...
Measures of stratigraphic fit to phylogeny and their sensitivity to tree size, tree shape, and scale
Measures of stratigraphic fit to phylogeny are analyzed to test how they are affected by the shape and size of the phylogenetic trees and by the number of stratigraphic intervals encompassed. Monte Carlo randomizations are used to investigate the sensitivity of three commonly used measures (SCI, GER and MSM*) approximating their distribution of possible values under certain conditions. All are ...
The Alberta Geological Survey (AGS) has been tasked with integrating digital stratigraphic data from a variety of sources to produce a regional 3-dimensional geological model of Alberta, often referred to as ‘The Framework’. This is a suitable model name, as it has been widely recognized that this model provides a framework to integrate our data and evaluate multidisciplinary correlations. The ...
The Karoo Basin has long been considered to contain the type stratigraphic succession for the terrestrial expression of the end-Permian mass extinction. A detailed extinction model, based on biostratigraphic and geologic data, has proposed rapid environmental change that coincides with a vertebrate biozone boundary, which was postulated to have been caused by increased aridity. Our sedimentolog...
A seismic volume of a certain stratigraphic layer may be decomposed into components for channel analysis. In the first case study of stratigraphic interpretation, the relative amplitude of the first component outlines the channel. The relative amplitude of the second component discovers different lithological or stratigraphical features inside the channel. The relative amplitude of the third co...
Completion of a global geological map of Venus has provided documentation of the relative age relationships, spatial distribution, and topographic configuration of the major geologic units and permitted us to address several important problems concerning the volcanic history of Venus. We use these data to: 1) assess the stratigraphic position of volcanic units and landforms, 2) determine their ...
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