نتایج جستجو برای: trace fossils
تعداد نتایج: 80653 فیلتر نتایج به سال:
The Kashkan Formation (Paleocene to Middle Eocene), consists of conglomerate, sandstone, and siltstone in the Zagros Folded zone, southwest Iran. Type of the sedimentary facies, architectural elements and trace fossils show that Kashkan deposits were formed in a low sinuosity braided stream system, with north to south flow direction. The formation displays coarsening-upward succession reflects ...
The up to 304 m thick, turbiditic, siliciclastic Ashin Formation (Upper Ladinian to Lower Carnian?) crops out widely in the Nakhlak area of central Iran. The rocks consist mainly of turbiditic volcaniclastic sandstones and shales that were deposited in distal parts of submarine fans of the continental slope to abyssal plain. Trace fossils occur commonly in the lower parts of the turbiditic volc...
upper devonian sediments of the kuh-e zard area northwest of zefreh, central iran, arecomposed mainly of brown and grey limestones with sandstone and shale intercalations. they contain tracefossils such as chondrites isp., diplocraterion parallelum, fustiglyphus annulatus, lockeia isp., phycodesisp., and taenidium barretti. these trace fossils indicate a shallow marine environment
the kashkan formation (paleocene to middle eocene), consists of conglomerate, sandstone, and siltstone in the zagros folded zone, southwest iran. type of the sedimentary facies, architectural elements and trace fossils show that kashkan deposits were formed in a low sinuosity braided stream system, with north to south flow direction. the formation displays coarsening-upward succession reflects ...
The increase in trace fossil diversity across the Neoproterozoic-Cambrian boundary often is presented in terms of tabulations of ichnogenera. However, a clearer picture of the increase in diversity and complexity can be reached by combining trace fossils into broad groups defined both on morphology and interpretation. This also focuses attention on looking for similarites between Neoproterozoic...
The Ediacaran biota is the earliest diverse community of macroscopic animals and protoctists. Body and trace fossils in the Clemente Formation of northwestern Sonora extend downward the geologic range of Ediacaran forms. Taxa present in the Clemente Formation include cf. Cyclomedusa plana, Sekwia sp., an erniettid (bearing an air mattress-like "pneu" body construction), and the trace fossils Lo...
Pecoits et al. (Reports, 29 June 2012, p. 1693) describe bilaterian trace fossils and assign them an Ediacaran age based on the age of a granite interpreted as intrusive. We argue that the granite is not intrusive but in fact represents the basement of the sedimentary succession. Moreover, we show that identical trace fossils occur in nearby Carboniferous-Permian glacigenic rocks.
Some Precambrian trace fossils have been presented as evidence for the early origin of bilaterians; the recent finding that large amoeboid protists leave macroscopic traces at the bottom of the deep ocean questions the metazoan nature of early trace fossils, stressing the importance of single-cell organisms in Precambrian biota.
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