نتایج جستجو برای: late neoproterozoic early cambrian schists
تعداد نتایج: 817880 فیلتر نتایج به سال:
cambrian sediments are widely exposed in the kerman province. parts of these deposits are containing trilobite fossils. one of the suitable areas for paleontological studies is kamar siah section. this section located about 60 km north east of kerman. these sediments have 200 m thickness with fossil invertebrates of trilobites, brachiopod, gastropods and stromatolite which includes kuhbanan and...
Embryos have been found in ‘old’ rocks on four continents, especially in Siberia, Nevada, Australia and China. They have been discovered in sedimentary rocks of even Late Neoproterozoic age, assuming the evolutionary geological column1 (figure 1). The Neoproterozoic is the period, so called, between 1 billion and 550 million years ago. This discovery was in the Doushantuo Formation, Guizhou Pro...
The Hellefjord Schist, a volcaniclastic psammite-pelite formation in the Caledonides of Arctic Norway contains discoidal impressions and apparent tube casts that share morphological and taphonomic similarities to Neoproterozoic stem-holdfast forms. U-Pb zircon geochronology on the host metasediment indicates it was deposited between 437 ± 2 and 439 ± 3 Ma, but also indicates that an inferred ba...
Evidence from a variety of research areas, including phylogenetic palaeobiogeographic studies of trilobites, indicates that there may be a fuse to the Cambrian radiation, with a duration on the order of 20–70 myr. Evolution in trilobites appears to have been powerfully influenced by the tectonic changes occurring at the end of the Neoproterozoic: especially the breakup of Pannotia. This contine...
Fossil Foraminifera appear in the Early Cambrian, at about the same time as the first skeletonized metazoans. However, due to the inadequate preservation of early unilocular (single-chambered) foraminiferal tests and difficulties in their identification, the evolution of early foraminifers is poorly understood. By using molecular data from a wide range of extant naked and testate unilocular spe...
The Capiru Group is a Neoproterozoic metasedimentary unit that crops out in the Curitiba terrane, Southern Ribeira Belt, Brazil. A detailed geological mapping of this was performed during 2016 to 2020. Original interpretations and new map were compiled integrated with past field data state (MINEROPAR) national (CPRM) surveys, unpublished recent published studies. This compilation represents mos...
The Cambrian 'explosion' is widely regarded as one of the fulcrum points in the history of life, yet its origins and causes remain deeply controversial. New data from the fossil record, especially of Burgess Shale-type Lagerstätten, indicate, however, that the assembly of bodyplans is not only largely a Cambrian phenomenon, but can already be documented in fair detail. This speaks against a muc...
Delbar metamorphic complex is located in 130 Km south of Shahrood (Biarjmand area) in Northern margin of the central Iran zone. The varied metamorphic rocks including meta-psammite, meta-greywacke, meta-pelite, marble and amphibolite and mylonitized granites and leucogranites intrusions are exposed in this complex. The field and petrography evidences indicated the evolutions resulted of the inc...
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