Evidence for multiple ice centres during the late Palaeozoic ice age in Oman: outcrop sedimentology and provenance of the Late Carboniferous–Early Permian Al Khlata Formation

2012 ◽  
Vol 368 (1) ◽  
pp. 229-256 ◽  
Author(s):  
Joe R. Martin ◽  
Jonathan Redfern ◽  
Brian P. J. Williams
Keyword(s):  
Late Carboniferous ◽  
Ice Age ◽  
Early Permian ◽  
Late Palaeozoic

scholarly journals Late palaeozoic magmatism in the basement rocks Southwest of Mt. Olympos, Central Pelagonian zone, Greece: Remnants of a permo-carboniferous magmatic arc

2001 ◽  
Vol 34 (3) ◽  
pp. 985 ◽  
Author(s):  
T. REISCHMANN ◽  
D. K. KOSTOPOULOS ◽  
S. LOOS ◽  
B. ANDERS ◽  
A. AVGERINAS ◽  
...  
Keyword(s):  
Late Carboniferous ◽  
Early Permian ◽  
Magmatic Evolution ◽  
Geochronological Data ◽  
Magmatic Arc ◽  
Late Palaeozoic ◽  
Basement Rocks ◽  
Evaporation Technique ◽  
Single Zircon ◽  
Pelagonian Zone

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 1976, Mountrakis 1983, De Bono 1998, Engel & Reischmann 2001). However, the ages obtained in the present study are identical, within error, to the muscovite Ar-Ar cooling ages from Mt. Ossa (Lips 1998). Our geochronological data show that the magmatic evolution for this part of the basement of the Pelagonian Zone lasted at least 30 Ma.

Bimodal magmatism produced by delamination: geochemical evidence from late Palaeozoic volcanic rocks from the Yili Block, Western Tianshan, Northwestern China

2020 ◽  
pp. 1-15
Author(s):  
Genwen Chen ◽  
Rui Liu ◽  
Teng Deng ◽  
Lixing Wang
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Volcanic Rocks ◽  
Orogenic Belt ◽  
Late Carboniferous ◽  
Early Permian ◽  
Asthenospheric Mantle ◽  
Late Palaeozoic ◽  
Depleted Mantle ◽  
Western Tianshan

Abstract The Western Tianshan orogenic belt is essential for understanding the evolution of the Central Asian orogenic belt. However, no agreement exists among geologists about its tectonic environment during the Late Palaeozoic. The volcanic rocks of the Yishijilike and Wulang Formation in the Yili Block, Western Tianshan, formed in the Late Carboniferous to Early Permian, mainly consist of a bimodal suite of basalts – basaltic andesites and rhyolites, with only some intermediate rocks. Mafic rocks are slightly enriched in light rare earth elements (LREE) and depleted in Nb, Ta, Zr and Hf, suggesting a subduction-modified depleted mantle source. Some mafic samples in the Early Permian bimodal volcanic rocks have high Ti contents with relatively high concentrations of Nb and high field strength elements (HFSE) and low contents of heavy rare earth elements (HREE). These rocks are similar to the continental flood basalts, which suggests that they formed from an asthenospheric mantle. This paper indicates that mafic members were created by the partial melting of the asthenospheric mantle material and subduction-modified lithospheric mantle mixture. Some rhyolites and dacites in the Wulang formation were enriched in Ga, Nb, Zr, Ce and Y and depleted in Sr and Eu. Additionally, they showed fractionation of rare earth elements (REE) with negative Eu anomalies, which is indicative of an A-type affinity of felsic rocks. The genesis of mafic members and an A-type affinity of felsic members indicate that the Late Carboniferous – Early Permian magmatism in the Western Tianshan area formed as a result of an extensional setting. This study also reveals bimodal magmatism produced by delamination in an extensional tectonic setting.

Re-calibrating the Late Palaeozoic palynostratigraphy in the basins of the southern domain of the Variscan Belt (southwestern Europe).

2020 ◽  
Author(s):  
Manuel A. Juncal ◽  
José B. Diez ◽  
Joan Lloret ◽  
Raúl de la Horra ◽  
Nicola Gretter ◽  
...  
Keyword(s):  
Ice Age ◽  
Solid Base ◽  
Time Interval ◽  
Variscan Belt ◽  
Late Permian ◽  
Early Permian ◽  
Border Effect ◽  
Seasonally Dry ◽  
Extinction Rates ◽  
Late Palaeozoic

<p>The Late Carboniferous - early Permian was a time-interval of major geological and climatological changes, mostly due to the transition to greenhouse conditions from the maximum glacial coverage (Late Palaeozoic Ice Age or LPIA). This climatic change produced an increase of the extinction rates on land plants and a variation on the constitution and distribution of palaeofloras during this time. The restructuring of ecosystems during Late Pennsylvanian is interpreted as the "collapse of the rainforests". A replacement of hygrophytic (“Stephanian flora”) by mesophytic and meso-xerophytic flora (“Autunian flora”) that tolerate seasonally dry climate is described.</p><p>In the Euramerican Province, the continental vegetation during the Pennsylvanian was a hygrophilous flora comprising pteridosperms, marattialean ferns, lycopsids, <em>Calamites</em> and <em>Cordaites</em> trees. At the Late Pennsylvanian-early Permian, the “Carboniferous hygrophilous flora” proliferated in the wet depressions (lowlands) and the mesophilic or even meso-xerophytic flora, grew on the heights (uplands) in the dewatered habitats. Later, this xerophytic flora will be dominant in the landscapes during the middle and late Permian.</p><p>There are detailed palynostratigraphic studies that allow precise palynological datings for the Carboniferous period in the Euramerica Province. However, few palynological works have been published relative to the early Permian sedimentary record in this province. In a broad sense, these latter studies only differentiate the early Permian flora (“Autunian flora”) due to the presence of sporomorph taxa as <em>Potonieisporites novicus</em> and <em>Vittatina costabilis</em>, and the middle-late Permian (“Thuringian flora”) mainly characterised by <em>Lueckisporites virkkiae</em> and<em> Nuskoisporites dulhuntyi</em>. This lack of precision was probably due to the different sedimentation rates in the intramontane basins and the “border effect” (as a phytogeographic barrier) caused by the Variscan Belt.</p><p>The number of works and the wrong use of non-chronostratigraphic terms like “Autunian” and “Thuringian”, making it necessary to re-calibrate the palynological assemblages in the Euramerica Province. A detailed biostratigraphic study allows us to show here, for the first time, a new palynostratigraphic chart derived from palynological studies from some of the best known low-latitude basins radiometrically dated (Pyrenees, Autun, Lodève, Collio and Tregiovo basins) and from basins with well-known internal lithostratigraphic correlation (e.g., the Cantabrian Mountains and the Iberian Ranges).</p><p>Based on the results obtained here, the microflora evolution in the early-middle Permian has been described at low latitudes of the Euramerican Province. Furthermore, this study provides a solid base for stabilising the palynozones for the Permian in the southern domain of the Variscan Belt.</p>

Late Carboniferous-early Permian tectono-sedimentary cycles and climate proxies in the Pyrenean and Basque-Cantabrian basins, N Spain.

2020 ◽  
Author(s):  
José F. Barrenechea ◽  
Joan Lloret ◽  
Raúl de la Horra ◽  
Nicola Gretter ◽  
Violeta Borruel-Abadía ◽  
...  
Keyword(s):  
Transition Period ◽  
Subsequent Development ◽  
Late Carboniferous ◽  
Ice Age ◽  
Time Interval ◽  
Global Changes ◽  
Early Permian ◽  
Fold Belt ◽  
Multidisciplinary Study ◽  
Climate Transition

<p>The late Carboniferous to early Permian interval was a time of major global changes on Earth. It encompassed the final consolidation of the Pangaea supercontinent and the subsequent development and infill of continental basins. This interval also witnessed a climate transition towards warmer conditions, including the substantial retreat of the extensive continental ice sheets developed during the Late Palaeozoic Ice Age (LPIA). The end of this climate transition represented an evolution form an icehouse to a greenhouse period at the early to middle Cisuralian, which in turn was a time of important tectonic changes in Pangaea. However, our understanding of this whole chain of processes still has many gaps and many of its features still generate debate, especially those concerning the origin and the end of this transition period. This study focuses the late Carboniferous to early Permian interval by means of a multidisciplinary study in the Pyrenean (P) and Basque-Cantabrian (BC) basins, that constitute a near equatorial complex extensional structure located in the middle of the late-Variscan fold belt. The present-day Pyrenean Ranges, extending E-W along almost 1000 Km, from the Mediterranean coast to the Basque-Cantabrian Cordillera, is the result of intense inversion of previous Permian to Cretaceous extensional to transtensional rift basins. In those basins, the time-interval has been traditionally studied in two separated structural units: Basque-Cantabrian Pyrenees and Aragonese-Catalan Pyrenees. However, this multidisciplinary study, proposes the existence of a lateral tectono-sedimentary connection for the entire basin.  Nine late Carboniferous - early Permian sub-basins have been studied in the Basque-Cantabrian and Pyrenean domain. From west to east they are: Frieres, Sotres, Carmona, Anayet, Aragorn-Bearn, Castejón-Sas, Erill Castell, Gramós and Camprodón. Three lithological units, separated by unconformities and dated by means of pollen associations and radiometric data, represent the Permian record of these basins. They constitute three cycles of sedimentation of similar age (Gzhelian-Asselian, Asselian-Sakmarian, and Sakmarian-Kungurian) related to the same post-Variscan geodynamic stages of evolution affecting the whole Pyrenean and Basque-Cantabrian basins. The two younger cycles broadly coincide with other similar cycles defined in SE France and Sardinia, thus pointing to a common tectono-sedimentary evolution for the westernmost continental Peri-Tethys domain during this time-interval. In addition, the middle cycle (Asselian-Sakmarian) mostly represents a calc-alkaline volcano-sedimentary event in most of the sub-basins, related to a post-Variscan extensional phase. Detailed studies of paleosols, sedimentology, and mineralogy indicate a progressive evolution towards warmer conditions that were accelerated during the Artinskian, probably related to the end of the global icehouse period associated to the LPIA in the equatorial late-Variscan fold belt domain.</p>

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