نتایج جستجو برای: sulfidic mineralized zones
تعداد نتایج: 49927 فیلتر نتایج به سال:
We investigated replicated ecological speciation in the livebearing fish Poecilia mexicana and P. sulphuraria (Poeciliidae), which inhabit freshwater habitats and have also colonized multiple sulfidic springs in southern Mexico. These springs exhibit extreme hypoxia and high concentrations of hydrogen sulfide, which is lethal to most metazoans. We used phylogenetic analyses to test whether spri...
نظر به اهمیت کنودونتها در تقسیمات چینهنگاری پالئوزوئیک و گسترش قابل توجه نهشتههای دونین پسین و کربونیفر پیشین در منطقه کرمان سه برش چینهشناسی (حور، هوتک و شمس آباد) در شمال استان کرمان انتخاب و بویژه بر اساس کنودونتها و بقایای ماهیان مورد مطالعه قرار گرفتند. مجموعه کنودونتهای بدست آمده از برش حور شامل 20 گونه متعلق به دو جنس polygnathus و icriodus بوده و سنی معادل فرازنین پسین را نشان می...
In post-Cambrian time, life on Earth experienced 5 major extinction events, likely instigated by adverse environmental conditions. Biodiversity loss among marine taxa, for at least 3 of these mass extinction events (Late Devonian, end-Permian and end-Triassic), has been connected with widespread oxygen-depleted and sulfide-bearing marine water. Furthermore, geochemical and sedimentary evidence ...
The study of morphological and mineralogical changes within a natural acid saline seep affected landscape revealed that seasonal differences in surface mineralogy, reflecting the operation of sulfidization and oxidative sulfide weathering processes. During the wet season, the surface and near surface of the waterlogged seep and marsh areas is dominated by black sulfidic materials (pyrite) and m...
Oxygen Minimum Zones (OMZs) are expanding in modern oceans due to anthropogenically-driven climate and environmental change. In the Eastern Mediterranean Sea (EMS), OMZs developed early Holocene as a result of decreased intermediate water ventilation, increasing temperature, increased Nile discharge primary productivity. Here, we report benthic foraminiferal numbers (BFN) species abundances, to...
Terrestrial sulfidic springs support diverse microbial communities by serving as stable conduits for geochemically diverse and nutrient-rich subsurface waters. Microorganisms that colonize terrestrial springs likely originate from groundwater, but may also be sourced from the surface. As such, the biogeographic distribution of microbial communities inhabiting sulfidic springs should be controll...
This study was part of the International Tundra Experiment (ITEX) and examined the effects of increased winter snow depth and decreased growing season length on the phenology of four arctic plant species (Betula nana, Salix pulchra, Eriophorum vaginatum, and Vaccinium vitis-idaea) and seasonal nitrogen availability in arctic snowbed communities. Increased snow depth had a large effect on the te...
We investigated the in situ gene expression profile of sulfur-turf microbial mats dominated by an uncultured large sausage-shaped Aquificae bacterium, a key metabolic player in sulfur-turfs in sulfidic hot springs. A reverse transcription-PCR analysis revealed that the genes responsible for sulfide, sulfite, and thiosulfate oxidation and carbon fixation via the reductive TCA cycle were continuo...
The classification of mineralized areas into different groups based on mineral grade and prospectivity is a practical problem in the area of optimal risk, time, and cost management of exploration projects. The purpose of this paper was to present a new approach for optimizing the grade classification model of an orebody. That is to say, through hybridizing machine learning with a metaheuristic ...
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