نتایج جستجو برای: upper precambrian
تعداد نتایج: 206308 فیلتر نتایج به سال:
Some of the enigmatic Precambrian organisms in the Ediacaran Period grew large and stood tall above the seafloor. Canopy flow modeling suggests that their large size was optimized for access to flow in order to facilitate osmotrophic nutrient uptake in low-flow environments.
The Precambrian genesis plus Cambrian explosion scenario also implies a perplexing view of a major evolutionary radiation: a long period of cryptic speciation with increasing developmental complexity and anatomical sophistication, yet without substantial behavioural or ecological modification or diversification, followed by a sudden increase in morphological and ecological innovation. Page 1046...
Ghazan-Khanik complex is a small mafic-ultramafic intrusive body with Permian age at the extremity of NW of the Sanandaj-Sirjan zone, has intruded into the Precambrian metamorphic rocks. Field studies, geochemistry mineral compositions and assemblages of them demonstrate this complex has four lithological zones. The lower zone of non-layered gabbro is the fine-grain gabbronoritic component and ...
Gazestan magnetite-apatite deposit is located in Central Iran and Bafq region, which has been occurred in form of veins, veinlets, and small apatite lenses as well as magnetite in metasomatic rock types such as green chlorite-actinolite rock units. These rocks are situated in the carbonate-volcanic complex of Upper Precambrian-Lower Cambrian Rizo formation. In this study, staged factor analysis...
Cyanobacteria are among the most ancient of evolutionary lineages, oxygenic photosynthesizers that may have originated before 3.0 Ga, as evidenced by free oxygen levels. Throughout the Precambrian, cyanobacteria were one of the most important drivers of biological innovations, strongly impacting early Earth's environments. At the end of the Archean Eon, they were responsible for the rapid oxyge...
Magmatism, ore genesis and metamorphism are commonly associated processes that define fundamental features of the Earth’s crustal evolution from earliest Precambrian to Phanerozoic [...]
The provenance of the upper Cambrian to Upper Ordovician sedimentary rocks Tasmania and Waratah Bay in southern Victoria provides information about complex dynamic tectonic environment present during their deposition. This paper uses U–Pb detrital zircon data constrain stratigraphic comparisons reconstructions these rock sequences. Multivariate statistics are used investigate similarity between...
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