نتایج جستجو برای: middle ordovician

تعداد نتایج: 156546  

2017
Xuhui Xu Qianglu Chen Chenglin Chu Guorong Li Cunge Liu Zheng Shi

Thick carbonate rocks were developed in the depression of the Tarim craton during the Cambrian-Middle Ordovician periods. The compressional tectonic movement during the Middle Caledonian-Hercynian created the paleouplifts, which became the base for the paleokarst in the Ordovician carbonate rocks. Based on the large quantity of seismic, drilling, and geological outcrop data, this study analyzed...

2002
BEN A. VAN DER PLUIJM

Van der Plmjm, B.A., 1987. Timing and spatial distribution of deformation in the Newfoundland Appalachians: a “multi-stage collision” history. In: H.J. Zwart, M. Martens, I. van der Molen, C.W. Passchier, C. Spiers and R.L.M. Vissers (Editors), Tectonic and Structural Processes on a Macro-, Mesoand Micro-Scale. Tectonophysics, 135: 15-24. The Newfoundland Appalachians have been interpreted as a...

2015
Olev Vinn Mark A. Wilson Ursula Toom William Oki Wong

The earliest bioeroded inorganic hard substrates in the Ordovician of Estonia appear in the Dapingian. Hardgrounds are also known from the Sandbian and Katian. Most of the bioerosion of inorganic hard substrates occurs as the boring Trypanites Mägdefrau, 1932 along with some possible Gastrochaenolites borings. North American hardground borings are more diverse than those in Baltica. In contrast...

Journal: :Scientific reports 2016
Christian M Ø Rasmussen Clemens V Ullmann Kristian G Jakobsen Anders Lindskog Jesper Hansen Thomas Hansen Mats E Eriksson Andrei Dronov Robert Frei Christoph Korte Arne T Nielsen David A T Harper

The Great Ordovician Biodiversification Event (GOBE) was the most rapid and sustained increase in marine Phanerozoic biodiversity. What generated this biotic response across Palaeozoic seascapes is a matter of debate; several intrinsic and extrinsic drivers have been suggested. One is Ordovician climate, which in recent years has undergone a paradigm shift from a text-book example of an extende...

2006
P. M. MYROW K. E. SNELL N. C. HUGHES T. S. PAULSEN N. A. HEIM S. K. PARCHA

A well-preserved Cambrian section in the Zanskar Valley of northern India has previously been interpreted to record the transition from a passive to an active tectonic margin related to Cambrian–Ordovician orogenesis. This interpretation has been used to support the tectonostratigraphic interpretation of other successions across the Tethyan Himalaya. Our detailed paleoenvironmental analysis sig...

2003
WILLIAM I. AUSICH

Taphonomic information is examined to evaluate the early history of connective tissues in the Crinoidea. The pattern of stalk segmentation of Middle and Late Ordovician crinoids is consistent with the two-ligament (intercolumnal and through-going ligaments) pattern present in living isocrinid crinoids and interpreted for fossil isocrinids, holocrinids, and Lower Mississippian crinoids. A single...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Seth Finnegan Noel A Heim Shanan E Peters Woodward W Fischer

Selectivity patterns provide insights into the causes of ancient extinction events. The Late Ordovician mass extinction was related to Gondwanan glaciation; however, it is still unclear whether elevated extinction rates were attributable to record failure, habitat loss, or climatic cooling. We examined Middle Ordovician-Early Silurian North American fossil occurrences within a spatiotemporally ...

2015
BRUCE SELLECK CHARLOTTE MEHRTENS

The Chazy, Black River and Trenton Groups are a well studied sequence of fossiliferous limestones, dolostones and sandstones in the Champlain Valley of New York, Vermont and southern Quebec. These rocks record shallow water cyclic sedimentation in the foreland basin of Laurentia prior to and during the initial stages of the Taconic Orogeny. This field trip reviews the stratigraphy of these unit...

Journal: :Geological Magazine 2023

Abstract The Sichuan Basin was a part of the Yangtze Carbonate Platform (YCP) during Cambrian–Ordovician, and marine carbonates were deposited in basin this interval. Although previous studies have evaluated paleogeography, paleoclimate paleoecology basin, they primarily focused on biological evolution basin; however, analysis paleogeography is lacking. This study integrated outcrop sedimentolo...

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