نتایج جستجو برای: cambrian

تعداد نتایج: 2615  

Journal: :Journal of sedimentary research. Section A, Sedimentary petrology and processes : an international journal of SEPM 1998
B Z Saylor A J Kaufman J P Grotzinger F Urban

Integrated sequence stratigraphic and chemostratigraphic data yield a framework for correlations of stratigraphic units in the terminal Proterozoic to Cambrian Witvlei and Nama Groups of Namibia. Coupled with precise U-Pb zircon age constraints, these correlations make it possible to construct a composite reference section for use in calibrating terminal Proterozoic chronostratigraphy. The Nami...

2012
Rudy Lerosey-Aubril Thomas A. Hegna Carlo Kier Enrico Bonino Jörg Habersetzer Matthieu Carré

Despite being internal organs, digestive structures are frequently preserved in Cambrian Lagerstätten. However, the reasons for their fossilisation and their biological implications remain to be thoroughly explored. This is particularly true with arthropods--typically the most diverse fossilised organisms in Cambrian ecosystems--where digestive structures represent an as-yet underexploited alte...

2003
Joseph L. Kirschvink Timothy D. Raub

The dramatic diversification of animal groups known as the Cambrian Explosion (evolution’s ‘Big Bang’) remains an unsolved puzzle in Earth Science. The Vendian–Cambrian interval is characterized by anomalously high rates of apparent plate motion, interpreted as True Polar Wander (TPW), and by more than a dozen large, high-frequency perturbations in carbon isotopes that dwarf all others observed...

Journal: :Energies 2021

This study is predominantly about the differences in shale pore structure and controlling factors of gas content between Lower Silurian Cambrian from upper Yangtze plate, which are great significance to occurrence mechanism gas. The field emission scanning electron microscopy combined with Particles (Pores) Cracks Analysis System software, CO2/N2 adsorption high-pressure mercury injection poros...

Journal: :Journal of Geography (Chigaku Zasshi) 1962

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