Extinction of Cloudina and Namacalathus at the Precambrian-Cambrian boundary in Oman

  title={Extinction of Cloudina and Namacalathus at the Precambrian-Cambrian boundary in Oman},
  author={Joachim E. Amthor and John P. Grotzinger and Stefan Schr{\"o}der and Samuel A. Bowring and Jahandar Ramezani and Mark W. Martin and Albert Matter},
Biostratigraphic, carbon isotope, and U-Pb zircon geochronological data from the Ara Group of Oman indicate an abrupt last appearance of Cloudina and Namacalathus coincident with a large-magnitude, but short-lived negative excursion in the carbon isotope composition of seawater that is globally coincident with the Precambrian-Cambrian boundary. U-Pb zircon age data from an intercalated ash bed directly define this negative excursion to be at 542.0 ± 0.3 Ma, consistent with previous age… Expand
U-Pb Ages from the Neoproterozoic Doushantuo Formation, China
U-Pb zircon dates from volcanic ash beds within the Doushantuo Formation (China) indicate that its deposition occurred between 635 and 551 million years ago, indicating synchronous deglaciation. Expand
The Cambrian index fossil Treptichnus pedum is reported from the Puerto Blanco Formation near Pitiquito, Sonora, Mexico, and new occurrences of the Neoproterozoic index fossil Cloudina are reportedExpand
Origin and Variability of the Late Precambrian-Cambrian Athel Silicilyte, South Oman Salt Basin
The Precambrian-Cambrian Athel Silicilyte is an enigmatic chert unit of up to 390 m thick found as slabs (each slab ≈ 2 × 6 km across) entrapped within salt domes at a depth of 4-5 km in the SouthExpand
An expanded record of Early Cambrian carbon cycling from the Anti-Atlas Margin, Morocco
We present a δ13C record from the Anti-Atlas mountains of Morocco and place it in the context of a detailed regional tectonostratigraphy. We place the litho- and chemostratigraphic record in aExpand
Unravelling the Neoproterozoic accretionary history of Oman, using an array of isotopic systems in zircon
The Omani basement is a critical window into the Neoproterozoic tectonic geography of the Mozambique Ocean and the amalgamation of Gondwana. It is located east of the juvenile arc terranes of theExpand
Reconstruction of early Cambrian ocean chemistry from Mo isotopes
The Neoproterozoic–Cambrian transition was a key time interval in the history of the Earth, especially for variations in oceanic and atmospheric chemical composition. However, two conflicting viewsExpand
Carbon and oxygen isotopic composition of the Vendian-Cambrian carbonate rocks and paleoecological reconstructions
The carbon isotopic composition of carbonate rocks is widely used for the reconstruction of sedimentation paleoenvironment. Of special interest is the study of the Upper Proterozoic-CambrianExpand
Toward a Neoproterozoic composite carbon-isotope record
Glacial deposits of Sturtian and Marinoan age occur in the well-studied Neoproterozoic successions of northern Namibia, South Australia, and northwestern Canada. In all three regions, the MarinoanExpand
Mo isotopes in the Lower Cambrian formation of southern China and its implications on paleo-ocean environment
Over the past decade, as one of nontraditional stable isotopes, Mo isotope has developed rapidly and now become an important geochemical proxy to trace paleo-oceanic and atmospheric evolution throughExpand
A large epeiric methanogenic Bambuí sea in the core of Gondwana supercontinent?
Abstract Carbon isotope compositions of both sedimentary carbonate and organic matter can be used as key proxies of the global carbon cycle and of its evolution through time, as long as they areExpand


Biostratigraphic and Geochronologic Constraints on Early Animal Evolution
Two distinct evolutionary pulses, represented by the Vendian Ediacaran fauna and Cambrian small shelly faunas, are generally thought to characterize the emergence of macroscopic animals at the end ofExpand
Carbon isotopic record of the Latest Proterozoic from Oman
The carbon isotopic ratios of marine carbonate rocks from the latest Precambrian to possibly earliest Cambrian were studied to evaluate possible changes in organic carbon burial and hence in theExpand
Oceanic anoxia at the Precambrian-Cambrian boundary
The Precambrian-Cambrian (PC-C) boundary separates fossils representing two discrete evolutionary phases: the Neoproterozoic soft-bodied Ediacarian biotas and Cambrian small shelly faunas. TheExpand
New U-Pb zircon dates for the Neoproterozoic Ghubrah glaciation and for the top of the Huqf Supergroup, Oman
The Huqf Supergroup, Oman, contains volcanic horizons with the potential to calibrate Neoproterozoic events and chemostratigraphy using U-Pb zircon geochronology. A tuffaceous bed near the base,Expand
Calibrating rates of early Cambrian evolution.
Uranium-lead zircon data from lower Cambrian rocks located in northeast Siberia indicate that the Cambrian period began at approximately 544 million years ago and that its oldest (Manykaian) stage lasted no less than 10 million years. Expand
Burrowing below the basal Cambrian GSSP, Fortune Head, Newfoundland
The range of Treptichnus pedum, the index trace fossil for the Treptichnus pedum Zone, extends some 4 m below the Global Standard Stratotype-section and Point for the base of the Cambrian Period atExpand
Namacalathus-Cloudina assemblage in Neoproterozoic Miette Group (Byng Formation), British Columbia: Canada's oldest shelly fossils
The uppermost part of the Miette Group (Windermere Supergroup) in eastern British Columbia has yielded shelly macrofossils in cliff-forming biostromal carbonates (Byng Formation). The biostromes areExpand
A composite reference section for terminal proterozoic strata of southern Namibia.
By comparing sediment accumulation rate in the radiometrically calibrated Namibian stratigraphy with sediment accumulation rates in correlative sections in Arctic Canada and Oman, a maximum age of 564 Ma is estimated for the end of the younger Varanger glaciation, 25 m.y. younger than previous estimates. Expand
Complex trace fossils from the terminal Proterozoic of Namibia
We document for the first time the occurrence of the complex trace fossil Treptichnus from the terminal Proterozoic Nama Group, Namibia. These traces differ in detail from the Cambrian index fossilExpand
Calcified metazoans in thrombolite-stromatolite reefs of the terminal Proterozoic Nama Group, Namibia
Abstract Reefs containing abundant calcified metazoans occur at several stratigraphic levels within carbonate platforms of the terminal Proterozoic Nama Group, central and southern Namibia. TheExpand