Search results for "Paleozoic"
showing 10 items of 76 documents
Short note of field workshop on Neoproterozoic ophiolites, ophiolitic mélanges and other rock units in the Eastern Desert of Egypt and comparison wit…
2016
The Neoproterozoic Arabian–Nubian Shield (ANS) and the latest Mesoproterozoic to late Palaeozoic Central Asian Orogenic Belt (CAOB) are two large and long-lived accretionary orogens. Both are mostl...
Séries charbonneuses dans des séquences rétrogradantes: cas du bassin houiller paralique westphalien de Jérada (Maroc)
1998
Abstract Several orders of stacked genetic sequences in the Westphalian C of the Jerada Basin are defined from detailed sedimentological data. Eight coal seams were formed in this paralic basin as distal facies passed laterally into proximal facies in retrogradational stages. These stages are related to base level rises that curtailed detrital influx and induced the development of swamps and the preservation of organic matter below anoxic water levels. The base level variations are related to active faulting along the basin margins and to sea level changes in the Palaeo-Tethys.
Sedimentation in the Kandi extensional basin (Benin and Niger): fluvial and marine deposits related to the Late Ordovician deglaciation in West Africa
2003
Abstract The Lower Paleozoic detrital succession of the half-graben Kandi Basin in West Africa (Niger-Benin) is about 600 m thick and rests unconformably on the Pan-African basement. Along the western edge of the basin, the base of the succession locally features large glacial fault-bounded paleovalleys. These valleys are filled by the lowermost continental deposits of the Were Formation characterized by massive diamictites with dropstones, and coarse to conglomeratic sandstones associated with large-scale channel structures and internal erosional truncations. The uppermost braided-river deposits of the Were Formation deposited across the entire basin are overlain by the Late Ordovician–Ear…
Book Review: The trace-fossil record of major evolutionary events.
2020
Book Review: M. Gabriela Mangano & Luis A. Buatois (eds) (two volumes). 2016. The trace-fossil record of major evolutionary events. Volume 1: Precambrian and Paleozoic. Springer. Topics in Geobiology, 39, 358 pp. (ISBN 978-94-017-9599-9). M. Gabriela Mangano & Luis A. Buatois (eds) (two volumes). 2016. The trace-fossil record of major evolutionary eventsThe trace-fossil record of major evolutionary events. Volume 2: Mesozoic and Cenozoic. Springer. Topics in Geobiology, 40, 485 pp. (ISBN 978-94-017-9596-8).
Life in the Palaeozoic: an overview of land and sea ecosystems
2017
The Palaeozoic Era, lasting from 541-252 million years ago, was a time of dramatic geographical, climatic, and evolutionary changes. During this Era, life experienced a tremendous transformation and many critical macroevolutionary events took place, including important biotic radiations and diversifications, and three of the five major mass extinctions on the Earth history (Raup&Sepkoski 1982). The advent and diversification of most modern metazoan phyla occurred during the Cambrian and Ordovician periods, in the so-called Cambrian Explosion and Great Ordovician Biodiversification Event (GOBE) (Servais et al. 2010). During the Ordovician, tectonic movements lead to a global cooling that cul…
Late palaeozoic magmatism in the basement rocks Southwest of Mt. Olympos, Central Pelagonian zone, Greece: Remnants of a permo-carboniferous magmatic…
2001
We dated basement rocks from several localities southwest of Mt. Olympos, as well as from a locality near the top of the mountain using the single zircon Pb/Pb evaporation technique. For the samples southwest of the mountain, the ages obtained range from ca. 280 to 290 Ma, with only a few zircon grains being around 300 Ma. By contrast, the sample from near the top of the mountain appears to be slightly younger, with ca. 270 Ma. These ages imply that the granitoids crystallized during Late Carboniferous - Early Permian times, and are therefore younger than the basement gneisses of other regions of the Pelagonian zone, which yielded zircon ages of around 300 Ma (e.g. Yarwood & Aftalion 19…
Tropical marine climate during the late Paleozoic ice age using trace element analyses of brachiopods
2009
Abstract The late Paleozoic ice age can be considered an important analogue to the modern ice age, but comparisons between the two time intervals have been hampered by the difficulty of resolving climatic changes that occur over short (e.g., seasonal) time scales in the Paleozoic record. As a first step toward overcoming these limitations, this study employed Mg/Ca trace element ratios sampled across the growth bands of six specimens of the brachiopod Composita to assess differences in tropical marine mean temperature and seasonality in Visean and Moscovian time. These time intervals bracket the onset of the late Paleozoic ice age, which occurred in mid-Serpukhovian time, and thus provide a…
Palaeogeographical and palaeoecological aspects of the Cambro–Ordovician radiation of echinoderms in Gondwanan Africa and peri-Gondwanan Europe
2003
Abstract Ecology and tempo of the Lower Palaeozoic radiation of echinoderms are discussed in this paper based on comparison of the diversity patterns observed in Cambro–Ordovician faunas from Laurentia and the northern Gondwana margin. The Cambrian ‘agronomic revolution’ triggered a global radiation of echinoderms, with the progressive disappearance of biomat-related lifestyles, and the colonisation of new environments. Both in Laurentia and on the northern Gondwana margin, soft-substrate echinoderm assemblages related to cold and/or deep environments were dominated by blastozoans and stylophorans. These assemblages show a pattern of continuous diversification from the Middle Cambrian to th…
Lower Ovetian (Lower Cambrian) trilobites and biostratigraphy of the Pedroche Formation (Sierra de Córdoba, southern Spain)
2005
The low Lower Cambrian rocks from the Sierra de Cordoba, which consist of well exposed mixed facies and abundant fossil assemblages showing long stratigraphic ranges throughout the Pedroche Formation, represent one of the best successions of this age in Europe. The fossil assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobia, trace fossils and stromatolites. Trilobites are still poorly known, and thus they are the main objective of this work. The trilobites studied originate from three sections. At the Arroyo de Pedroche 1 section, cf. Bigotinella and Bigotina bivallata are replaced towards the top by Lemdadella linaresae, Lemdadella perejoni sp.…
Palaeozoic evolution of the North Tianshan based on palaeomagnetic data – transition from Gondwana towards Pangaea
2017
We present new palaeomagnetic data for Cambrian and Ordovician volcanic and sedimentary rocks from the Kyrgyz North Tianshan (NTS) and review available data from the southwestern Central Asian Orogenic Belt (CAOB) to elucidate the tectonic history and evolution of this region during the early Palaeozoic. We observed a coherent evolution of the NTS and the Kazakhstan continent (or Kazakhstania) with a constant northwards movement between the Cambrian and Devonian at ∼5 cm/a. After the northwards movement ceased in the Devonian, the accreted terrane assemblage of Kazakhstania occupied a stable latitudinal position at ∼30°N until the final amalgamation of Eurasia occurred in the late Carbonife…