نتایج جستجو برای: microfossil
تعداد نتایج: 309 فیلتر نتایج به سال:
Doubly polished thin sections, originally prepared for fluid inclusion studies, present great advantages in the study of microfossils in volcanic rocks. Better visibility and light conditions, variation in thickness of the thin sections and the possibility to combine fluid inclusion studies with microfossil studies lead to a wide range of advantages over ordinary thin sections. This includes th...
Microfossils are very important in order to establish terrain correlations, allowing to determinate the age of geological layers with a high grade of accuracy. They are also the fund of any micropaleontological studies. Actual techniques used to extract microfossils are manual, and require of a high amount of time and human resources. This fact make interesting the study of other more complex t...
The Manchester Content Addressable Image Database is ageneric tool which has been designed for image informatics and computer vision problems. The system stores pre-compuied feature tokens, which are obtained by conventional processing of the input images, into a database which is accessed by a specialised query language (M VQL [1 ]). The M VQL is based on the creation and refinement of groups ...
The Paleoproterozoic (2.5-1.6 Ga) Era is a decisive time in Earth and life history. The paleobiological record (microfossils, stromatolites, biomarkers and isotopes) illustrates the biosphere evolution during a time of transitional oceanic and atmosphere chemistries. Benthic microfossil assemblages are recorded in a variety of oxygenated, sulfidic, and ferruginous environments representative of...
A new class of oriented, curvature sensitive filters are introduced. These filters provide a low-level detection facility for noisy curves without a prior edge extraction stage. The application of these filters to the detection of Carboniferous Foraminifers (a type of microfossil found in plane rock sections) is described. A symbolic representation of the detected curves is stored in a database...
Siliceous microfossil succession was analyzed in a 200,000-yr sediment sequence recovered from the Buguldeika Saddle in Lake Baikal, Russia. Siliceous microfossil abundance varied among core depths from no preserved microfossils during inferred colder climate conditions to recent interglacial sediments containing over 300 3 106 microfossils per g dry sediment. Depth-age microfossil assemblage z...
As part of the international cooperative Baikal Drilling Project, siliceous microfossil assemblage succession was analyzed in two short (~ 30-cm) sediment cores from Lake Baikal. One core was recovered from the north basin (Core 324, 55°15~N, 109°30~E), a second from between the central and southern basins (Core 316, 52°28'N, 106°5rE). The northern core had higher amounts of biogenic silica (40...
Using standard samples is a simple yet very effective method to control data quality. In the field of Quaternary science, it is a commonly applied approach for isotope and geochemical analyses, greatly increasing the general level of confidence in these analytical methods. Microfossil analysis, by contrast, does not normally have any such system to secure data precision and accuracy objectively...
Problematic microfossils dominate the palaeontological record between the Great Oxidation Event 2.4 billion years ago (Ga) and the last Palaeoproterozoic iron formations, deposited 500-600 million years later. These fossils are often associated with iron-rich sedimentary rocks, but their affinities, metabolism, and, hence, their contributions to Earth surface oxidation and Fe deposition remain ...
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