نتایج جستجو برای: upper cambrian

تعداد نتایج: 207398  

The excellent preservation of the acritarchs, their great abundance, diversity and good stratigraphic control permit establishment of a detailed Middle and Late Cambrian acritarch biozonation. A total of 56 palynomorph species form the basis of 10 local acritarch assemblage zones. Assemblage zones I-II occur in the lower and middle parts of the Member C of the Mila Formation and suggest Early-m...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تهران 1384

چکیده ندارد.

2012
Mohammad Saleem Khan Amanat Ali Bhatti Syed Tahir Ali Gillani Muhammad Aamir Qadri Arshad Raza

Estimation of petrophysical properties of the rock formations played decisive role in all the processes of petroleum exploration. The Cambrian sequence is well established as reservoir rocks in the various parts of the world from where petroleum is being tapped. The Cambrian sequence has been encountered in the Potwar area and limited petroleum is being produced from the Adhi Oil Field. The Khe...

Journal: :The Journal of Geology 1903

2013
Zhifei Zhang Lars E. Holmer Christian B. Skovsted Glenn A. Brock Graham E. Budd Dongjing Fu Xingliang Zhang Degan Shu Jian Han Jianni Liu Haizhou Wang Aodhán Butler Guoxiang Li

The Lophotrochozoa includes disparate tentacle-bearing sessile protostome animals, which apparently appeared in the Cambrian explosion, but lack an uncontested fossil record. Here we describe abundant well preserved material of Cotyledion tylodes Luo et Hu, 1999, from the Cambrian (Series 2) Chengjiang deposits, reinterpreted here as a stem-group entoproct. The entoproct affinity is supported b...

2009
Wilson A. Taylor Paul K. Strother

animal life on land. The current benchmark for evidence of plants on land is about 450,000,000 years ago (Late Ordovician). Tantalizing microscopic fossils of chemically resistant spore walls occur in land-derived rocks around the world, and predate this Late Ordovician age by over 50,000,000 years (Upper Cambrian) and possibly beyond. Figuring out what kinds of organisms (algae, primitive plan...

2006
RUSSELL S. SHAPIRO STANLEY M. AWRAMIK

The distinctive, branched thrombolite, Favosamaceria cooperi new group and form, is found widely in the Great Basin, USA, where it is restricted to the Late Cambrian Saukia trilobite Zone. This thrombolite is distinguished by a hedgerow, mazelike organization of ridges similar to garden walls (maceriae) in plan view, branching of ridges into daughter ridges and columns, the polymorphic nature o...

2017
James D. Schiffbauer John Warren Huntley David A. Fike Matthew Jarrell Jeffrey Jay M. Gregg Kevin L. Shelton

Several positive carbon isotope excursions in Lower Paleozoic rocks, including the prominent Upper Cambrian Steptoean Positive Carbon Isotope Excursion (SPICE), are thought to reflect intermittent perturbations in the hydrosphere-biosphere system. Models explaining these secular changes are abundant, but the synchronicity and regional variation of the isotope signals are not well understood. Ex...

2017
Chao Li Chengsheng Jin Noah J. Planavsky Thomas J. Algeo Meng Cheng Xinglian Yang Yuanlong Zhao Shucheng Xie

The early–middle Cambrian (Fortunian to Age 4) is characterized by a significant increase in metazoan diversification. Furthermore, this interval is marked by a prominent environmental and ecological expansion of arthropodand echinoderm-rich biotas. Recent redox work has suggested that this shift occurred during stable or decreasing marine oxygen levels, suggesting that these paleobiological an...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید