نتایج جستجو برای: stratigraphic boundary
تعداد نتایج: 163281 فیلتر نتایج به سال:
In 2001, Harris strongly emphasized the need for Geographical Information Systems (GIS) to force archaeologists to acknowledge the pre-eminent position of surfaces, rather than deposits in stratigraphic analysis and recording. This is certainly a problem since stratigraphic data is often recorded in a haphazard and incomplete fashion such that it disallows the accurate and convincing representa...
anomolously low A1203, low Ti02 and are enriched in chromium and nick~A We present petrographic and chemical c ata on the Kamloops Lake picritic tmalts as we1 I as the stratigraphic setting for thwe ultramafic lavas. Age constraints derive From field relationships, Mineral chemistry indicates th 31 these ultramafic rocks represent mantle-deri.ed material which has undergone: minimal differentia...
S U M M A R Y Geophysical inversion is often ill-posed because of inaccurate and insufficient data. Regularization is often applied to the inversion problem to obtain a stable solution by imposing additional constraints on the model. Common regularization schemes impose isotropic smoothness on solutions and may have difficulties in obtaining geologically reasonable models that are often suppose...
Integrated sequence stratigraphic and chemostratigraphic data yield a framework for correlations of stratigraphic units in the terminal Proterozoic to Cambrian Witvlei and Nama Groups of Namibia. Coupled with precise U-Pb zircon age constraints, these correlations make it possible to construct a composite reference section for use in calibrating terminal Proterozoic chronostratigraphy. The Nami...
When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal
We evaluate the boundary of the Anthropocene geological time interval as an epoch, since it is useful to have a consistent temporal definition for this increasingly used unit, whether the presently informal term is eventually formalized or not. Of the three main levels suggested e an ‘early Anthropocene’ level some thousands of years ago; the beginning of the Industrial Revolution at ~1800 CE (...
To first order, seismic data provides the geologist and the geophysicist with information on the geometrical relationships between subsurface lithologic boundaries. Generally, this spatial information is used to construct conceptual geologic and process models with which to explain the origins of stratigraphic features. From such models we infer lithologic content. Various methods (e.g. AVO, Co...
misson on Ordovician Stratigraphy and in 2002 ratified by the International Commission on Stratigraphy as the GSSP of the Second (Upper) Stage of the Lower Ordovician, is located on the Hunneberg Mountain in southwestern Sweden. The stratigraphic succession represents an outer shelf environment near the Baltic Shield margin. The shale-dominated, biostratigraphically complete, richly fossilifero...
Temporal gaps in the stratigraphic record have important implications for the interpretation of stratigraphically rapid geochemical and paleobiologic changes, for the development of high-resolution time scales (e.g., orbital time scales), and for deciphering the response of depositional systems to climatic change and basin evolution (e.g., accommodation space vs. sediment supply). In ancient pe...
Human impacts on Earth are now so great that they have led to the concept of a new geological epoch defined by this global human influence: the Anthropocene. While not universally accepted, the term is increasingly popular and widely used. However, even among proponents, there is considerable debate regarding when the epoch may have started, from coeval with the Holocene, through the Industrial...
The Izeh fault zone is a transverse fault zone with dextral strike slip (and some reverse component) in the Zagros Mountains (Iran). It causes some structural deformations. This fault zone is acting as eastern boundary of Dezful Embayment and forms subsidence of the embayment. The fault has been recognized using remote sensing techniques in conjunction with surface and subsurface analyses. The ...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید