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Showing 1 to 20 of 39 for “"Ediacaran"”.
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Ediacaran Fronds from South Australia and Newfoundland
… evolution. Fronds occupied all tiers of the Ediacaran ecosystem and were the first animals with a construction allowing them to partition the water column macroscopically resulting in a tiering ecosystem similar to Phanerozoic marine ecosystems in structure. Elongate fronds were a rarity in …
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Sedimentology and diagenesis of Ediacaran phosphorites from South China
Ediacaran phosphorites provide a principal record of the paleoenvironmental and paleoecological conditions of the oceans during Earth's second major oxygenation and the evolution of complex life. Although the fidelity of this record is high, diagenesis and metamorphism frequently alter or overprint …
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Multibranched rangeomorphs from the Ediacaran Mistaken Point assemblage, Newfoundland, Canada
… to the latter half of the late Neoproterozoic Ediacaran Period (635Ma- 542Ma). These fossils represent an extinct higher level taxon characterized by a modular construction based on a single architectural unit: the centimeter-scale, chevron-shaped rangeomorph element which displays several …
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Contributions to late Ediacaran geobiology in South China and southern Namibia
The Ediacaran, particularly the late Ediacaran-Cambrian (E-") boundary (551-541 Ma), has been noted as a major time of biological and biochemical transition, including: the rise of predators, the emergence of skeletons, the radiation of bioturbators, and large fluctuations in oceanic chemical …
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Geochronological constraints on the Trinity diamictite in Newfoundland : Implications for Ediacaran glaciation
The Avalon terrane in Newfoundland includes the Ediacaran Gaskiers Formation, which has been associated with a Snowball glaciation event. The complicated regional stratigraphy and lack of precise geochronological constraints has made it difficult to determine the spatial and temporal extent of the …
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Paleoecology and Taphonomy of Ediacaran macrofossils from the Khatyspyt Formation, Olenek Uplift, Siberia
The Ediacaran Period (635 – 541 Ma) is a critical transition in the history of the Earth and life. It is marked by the appearance of enigmatic Ediacara-like fossils and macroalgae, which had existed since the early Proterozoic, but started to diversify morphologically and ecologically during this …
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Carbon and sulfur isotopic constraints on Ediacaran biogeochemical processes, Huqf supergroups, Sultanate of Oman
… and evolutionary change is investigated in the Ediacaran Period (- 635 - 541 million years ago (Ma), an interval where we see the emergence of macroscopic animals along with large perturbations to the carbon and sulfur cycles. Paleoenvironmental reconstruction used the carbon and sulfur isotopic …
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Constraining the Ediacaran-Cambrian boundary in South China using acanthomorphic acritarchs and Palaeopascichnus fossils
The Ediacaran-Cambrian boundary is arguably the most critical transition in Earth history. This boundary is currently defined by the GSSP (Global Stratotype Section and Point) at Fortune Head (Newfoundland, Canada) at a point that was once regarded as the first appearance of the branching trace …
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Sedimentology, provenance, and salt-sediment interaction in the Ediacaran Pound subgroup, Flinders Ranges, South Australia
… margin of the Australian subcontinent during the Ediacaran, a key time in Earth history just prior to the development of multicellular life. Field investigations reveal that the Bonney Sandstone is primarily comprised of sands and shales, often in progradational parasequences that become …
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The Mall Bay Formation (Ediacaran) and the Protracted Onset of the Gaskiers Glaciation in Newfoundland, Canada
… Formation. This study extends evidence for Ediacaran cold periods over a longer and earlier period and has broader implications for understanding the evolution of Ediacaran glacial systems. Additionally, a prolonged paraglacial state before the appearance of the Ediacara biota implies that …
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Using high resolution Sr isotope data from the Nama Group, South Africa, to constrain global stratigraphic relationships and continental weathering rates in the terminal Ediacaran
… in shallow marine environments during the late Ediacaran (~550 Ma). The trigger for the appearance of these hard-bodied animals is still debated but it was probably related to ecological and/or environmental change. Continental weathering fluxes into the oceans can influence redox conditions and …
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Redefining the Treptichnus pedum zone at the Global Boundary Stratotype Section and Point (GSSP): A critical reassessment of the Ediacaran-Cambrian boundary.
… a continuous record through the late Ediacaran-early Cambrian. The Chapel Island Formation (CIF) of the Burin Peninsula, Newfoundland, provides an exceptional record of these innovations. Currently, the Global Boundary Stratotype Section and Point (GSSP) for the basal Cambrian boundary …
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Contributions to the Proterozoic and Cambrian Evolution of Eukaryotes
… was low but increased in the Mesoproterozoic and Ediacaran, with a plateau in between. There was also a significant increase in thallus surface/volume ratio and maximum canopy height of the Ediacaran macroalgal communities. The prolonged plateau between the Mesoproterozoic and Ediacaran may be …
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Time and process in sedimentary rocks at the dawn of animal life
… 5 focus on the sedimentary rock record of the Ediacaran Period (635-541 Ma). Chapter 3 describes new Re-Os age constraints on Earth's largest negative carbon isotope excursion, the Shuram excursion. Chapter 4 presents additional Re-Os age constraints on the Ediacaran succession of Oman to …
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Evolutionary Ecology of the First Animal Ecosystems
The late Ediacaran (~574 – 564 Ma) strata of Newfoundland, Canada preserve entire early animal communities in situ under volcanic ash. These communities lie at a key juncture between the preceding microbe-dominated world of the Proterozoic, and the subsequent animal-dominated world that we inhabit …
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Integrated High-resolution Stratigraphy of the Doushantuo Formation, South China
The Ediacaran Period (635-542 Ma) just preceded the radiation of animals, yet witnessed profound changes in biological innovation, including the first appearance of large spiny acritarchs called the acanthomorphic acritarch, followed by the radiation of the Ediacara biota (575-542 Ma), and earliest …
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Palaeoenvironments and position of the Precambrian–Cambrian boundary within the lower Vanrhynsdorp Group of South Africa: sedimentary facies analysis, U-Pb series zircon geochronology and micropalaeontology
… world-famous Nama Group, which features diverse Ediacaran-Cambrian fossils. To date, no body fossils have been discovered in the Vanrhynsdorp Group. Through U-Pb dating of detrital zircons using LA-ICP-MS, radiometric ages for the middle part of the Vanrhynsdorp Group (Besonderheid Formation) …
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Assessing the Role of Solution Chemistry and Organic Matter in the Genesis of the Dengying Formation Dolostones at Sichuan Basin, China
… laboratory experiments constructed to emulate Ediacaran seawater chemistry (ESW) with abundant microbial mats. The constructed Ediacaran solution chemistry accounted for alkalinity, pH, temperature, and dissolved sulfate. Experimental variables included differing Mg:Ca (1:1) ratios, the …
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Taphonomic studies of fossil preservation in coarse-grained siliciclastic environments
Ediacaran and early Cambrian sandy and silty sediments commonly preserve microbial fossils and textures as well as the fossils of soft-bodied organisms. The rarity of similar fossils and textures in coarse-grained siliciclastic strata of the later Phanerozoic suggests that a taphonomic window …
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Estilo estrutural e contexto tectonoestratigráfico do Grupo Ubajara no NW do Ceará
The Ubajara Group is a neoproterozoic (of ediacaran age) low grade metassedimentary unit (ediacaran) that occurs adjacent to the TransbrasilianoKandi Lineament, in NW Ceará. This lineament corresponds to a NE-trending dextral strike-slip mega-shear zone related to the Brasiliano orogenic cycle. The …
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