نتایج جستجو برای: late neoproterozoic
تعداد نتایج: 196368 فیلتر نتایج به سال:
Re-evaluation of acoustic, gamma ray and dip meter logs from the Cominco American Federal No. 2 well in the Sevier Desert basin of west-central Utah sheds new light on the interpretation of Neoproterozoic and Cambrian stratigraphy and Mesozoic structure in a region that has been influential in the development of ideas about crustal shortening and extension. The most prominent of several major t...
The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100-200 m) at the Ediacaran-Cambrian boundary in the South Oman Salt Basin. In contrast, Meso-Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, ...
As the oldest exposed basement and the typical sedimentary cover of the Yangtze craton, the Huangling massif is a suitable place to decipher the tectonics of South China block. Structural analysis shows that the Huangling massif has an elliptic domal shape with N–S striking long axis, an asymmetric antiform with a steep western flank and a gentle eastern flank. There, three litho-tectonic units...
New calcite Sr/Sr data for 47 limestones from the metamorphosed and deformed Neoproterozoic–Cambrian Dalradian Supergroup of Scotland and Ireland are used to identify secular trends in seawater Sr/Sr through the Dalradian succession and to constrain its depositional age. Dalradian limestones commonly have Sr .1000 ppm, indicating primary aragonite and marine diagenesis. Low Mn, Mn/Sr ,0.6, O an...
The South China Craton comprises the Yangtze and Cathaysia blocks is one of largest Precambrian continental in East Asia. However, early geological geographical evolution block relatively poorly understood, due to sparse exposure pre-Neoproterozoic rocks reworking during Phanerozoic polyphase magmatism metamorphism. In this contribution, we carried out detrital zircon U-Pb geochronology sedimen...
A compilation of magnetic data acquired during the past three decades for a region in central Saudi Arabia where Precambrian basement is partly exposed on the Arabian shield and partly concealed by overlying Phanerozoic strata, shows a central sector of conspicuous N-S-trending anomalies, a heterogeneous western sector of short-wavelength, high-intensity anomalies, and an eastern sector of lowt...
A fully coupled ocean-atmosphere general circulation model (the Fast Ocean-Atmosphere Model) is used to simulate the Neoproterozoic climate with a reduced solar luminosity (95% of present-day), low atmospheric CO2 (140 ppmv), and an idealized tropical supercontinent. Two coupled simulations were completed with present-day and cold initial ocean temperatures. These experiments are compared with ...
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