Early Carboniferous (Viséan) emplacement of the collisional Kłodzko–Złoty Stok granitoids (Sudetes, SW Poland): constraints from geochemical data and zircon U–Pb ages

2013 ◽  
Vol 102 (4) ◽  
pp. 1007-1027 ◽  
Author(s):  
Stanisław Z. Mikulski ◽  
Ian S. Williams ◽  
Bogusław Bagiński
Keyword(s):  
Early Carboniferous ◽  
Geochemical Data ◽  
Sw Poland

Geochronology, geochemistry, and Hf isotopic compositions of early Permian syenogranite and diabase from the northern Great Xing’an Range, northeastern China: petrogenesis and tectonic implications

2020 ◽  
Vol 57 (12) ◽  
pp. 1478-1491 ◽  
Author(s):  
Yong-gang Sun ◽  
Bi-le Li ◽  
Feng-yue Sun ◽  
Qing-feng Ding ◽  
Ye Qian ◽  
...  
Keyword(s):  
Early Carboniferous ◽  
Northeastern China ◽  
Geochemical Data ◽  
Late Paleozoic ◽  
Crustal Material ◽  
Early Permian ◽  
Geodynamic Evolution ◽  
Isotopic Compositions ◽  
Great Xing’An Range ◽  
T Values

Geodynamic evolution in the late Paleozoic is significant for understanding the final amalgamation of the Central Asian Orogenic Belt (CAOB). No consensus has yet been reached regarding the late Paleozoic geodynamic evolution of the northern Great Xing’an Range (GXR) in northeastern China, the eastern CAOB. Furthermore, late Paleozoic syenogranite–diabase dyke association is present in the Xiaokele area in northern GXR. It provides an important opportunity to understand the nature of magmatism and the geodynamic evolution during this period. This paper presents new zircon U–Pb ages, zircon Hf isotopic compositions, and geochemical data of whole rocks for Xiaokele syenogranite and diabase. Zircon U–Pb dating suggests that the Xiaokele syenogranite (292.5 ± 0.9 Ma) and diabase (298.3 ± 1.5 Ma) were emplaced during the early Permian. The Xiaokele syenogranites have high SiO2 contents, low MgO contents, and enriched zircon εHf(t) values, suggesting that their primary magma was generated by the partial melting of the juvenile crustal material. The Xiaokele diabases have low SiO2 contents, high MgO contents, are enriched in large-ion lithophile elements, depleted in high-field-strength elements, and exhibit enriched zircon εHf(t) values. They derived from a lithospheric mantle source that had previously been metasomatized by slab-derived fluids. Combined with previous research results, we believe that the continent–continent collision between the Xing’an and Songliao blocks occurred during the late early Carboniferous – early late Carboniferous (330–310 Ma), and the two blocks were transformed into a post-collisional extensional setting during the latest Carboniferous – early Permian.

Early Devonian tectonic conversion from contraction to extension in the Chinese Western Tianshan: A response to slab rollback

2020 ◽  
Author(s):  
Xin-Shui Wang ◽  
Reiner Klemd ◽  
Jun Gao ◽  
Tuo Jiang ◽  
Xi Zhang
Keyword(s):  
Early Carboniferous ◽  
Igneous Rocks ◽  
Geochemical Data ◽  
Precambrian Basement ◽  
Metamorphic Complex ◽  
Zircon Age ◽  
Early Devonian ◽  
Angular Unconformity ◽  
Slab Rollback ◽  
Western Tianshan

Extensive angular unconformities that occur across the Tianshan Orogen provide insight into the Paleozoic tectonic evolution of the southwestern Central Asian Orogenic Belt. This study presents new geochronological and geochemical data to unravel the age and origin of a pronounced angular unconformity in the Baluntai domain of the Chinese Western Tianshan. The angular unconformity separates a ductilely deformed metamorphic complex from overlying unmetamorphosed sequences. Detrital zircon age spectra suggest that the sedimentary samples received detritus from both the Precambrian basement and contemporaneous igneous rocks in the Central Tianshan and Yili blocks. The youngest detrital and metamorphic zircons in metasediments from the metamorphic complex reveal that their protoliths were deposited at ca. 419 Ma, and subsequently overprinted by metamorphism and ductile deformation at ca. 409 Ma. Along with ca. 532−407 Ma metavolcanics and foliated intrusions, the metamorphic complex constitutes a diachronous stratigraphic unit deposited during early Cambrian to late Silurian times, rather than a Precambrian basement as previously thought. The youngest detrital zircon age data from siliciclastic samples immediately above the angular unconformity constrain their deposition to ca. 407−397 Ma. In conjunction with a ca. 406 Ma rhyolitic tuff in the lower terrestrial siliciclastic unit and an early Carboniferous paleontological age of carbonates in the upper shallow-marine unit, it is suggested that the overlying unmetamorphosed sequences were accumulated during the early Devonian to the early Carboniferous. Thus, the angular unconformity in the Baluntai domain was formed between ca. 409 and 407 Ma. New and already published geochemical data reveal that the early Paleozoic (ca. 530−410 Ma) and late Paleozoic (ca. 410−320 Ma) igneous rocks are mainly medium- to high-K calc-alkaline I-type granitoids, which exhibit typical subduction-related geochemical signatures despite contrasting structural features. These geochronological and geochemical results are in accordance with those of similar early Devonian angular unconformities and Paleozoic igneous rocks in the southern Yili Block. The early Paleozoic igneous rocks display highly scattered zircon ɛHf(t) values, while the late Paleozoic rocks show a progressively increasing trend toward more positive values, attributed to slab rollback of the northward subducting South Tianshan Ocean under the Yili and Central Tianshan blocks. Thus, we propose that the formation of the angular unconformity was caused by tectonic conversion from contraction to extension due to slab rollback during the early Devonian. This study highlights the significance of geological and geochronological investigations of angular unconformities in the context of associated episodic magmatism and slab behavior in order to unravel distinct tectonic processes in the long-lived accretionary evolution of the Chinese Western Tianshan.

Blueschist-facies metamorphism in the Kaczawa Mountains (Sudetes, SW Poland) of the Central-European Variscides: P-T constraints from a jadeite-bearing metatrachyte

2011 ◽  
Vol 75 (1) ◽  
pp. 241-263 ◽  
Author(s):  
R. Kryza ◽  
A. P. Willner ◽  
H.-J. Massonne ◽  
A. Muszyński ◽  
H.-P. Schertl
Keyword(s):  
Peak Pressure ◽  
Early Carboniferous ◽  
White Mica ◽  
Collision Zone ◽  
Pressure Maximum ◽  
Sw Poland ◽  
Mineral Compositions ◽  
Subduction Setting ◽  
Metamorphic Gradient ◽  
European Variscides

AbstractSodic pyroxene is reported from an Ordovician metatrachyte of the Kaczawa Mountains, SW Poland. Its composition ranges from Jd0.98Ae0.02 to Jd0.15Ae0.85. Relict jadeite and phengite (up to 3.75 Si atoms per fomula unit) belong to the peak-pressure assemblage of an early HP-LT event. Later greenschist-facies stages are represented by riebeckite, biotite, chlorite, low-Si potassic white mica and actinolite. P-T pseudosections calculated for the range 200–450°C, 3–13 kbar allow evaluation of the conditions of formation of jadeite in the metatrachyte and derivaton of a P-T path. Considering the position of prograde, peak and retrograde metamorphic assemblages and respective mineral compositions, we can derive the following equilibration stages: 8.5±0.5 kbar, 270±20°C for the pressure maximum, 6.0±1.0 kbar, 310±20°C for the temperature maximum and 3.5±0.5 kbar, 280±20°C as well as <3.5 kbar, <280°C for the retrograde stages.The metamorphic gradient for the peak-pressure is estimated at ∼10°C/km, which is typical of a subduction setting involving subducted continental crust, in particular of an exhumation channel within a collision zone of a microplate. Based on earlier structural observations, the ESE-oriented subduction in the NE Bohemian Massif was confined with WNW thrusting and followed by extension and ESE backward normal faulting during Devonian–Early Carboniferous times.

A new species of lambdarina (rhynchonellida, brachiopoda) from the viséan of central sudetes (Poland) and its phylogenetic position

2014 ◽  
Vol 64 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Jolanta Muszer
Keyword(s):  
New Species ◽  
Full Range ◽  
Morphological Features ◽  
Phylogenetic Position ◽  
Growth Stages ◽  
Tropical Waters ◽  
Marginal Seas ◽  
Sw Poland ◽  
A New Species

Abstract A new species of micromorphic articulate brachiopod (Rhynchonellida) Lambdarina jugowiensis sp. nov., from the upper Visean (Sokolec Beds) of central Sudetes, SW Poland, is described. The studied specimens are calcified, what makes them unique in respect of their state of preservation. The material is represented by a full range of growth stages; from brephic to gerontic. Based on its morphological features and the palaeogeographical distribution of all its known species, two main evolutionary lines are proposed for the genus; the Australian and the European ones. Lambdarina was widely distributed in the equatorial-tropical waters of marginal seas of the Palaeotethys Ocean, mostly during Mississippian time.

The first results of isotopic (U-Pb, ID-TIMS) dating of individual zircon grains from dolerite dikes of the Eastern zone of the Urals

LITOSFERA ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 224-230
Author(s):  
V. N. Smirnov ◽  
K. S. Ivanov ◽  
T. V. Bayanova
Keyword(s):  
Isotope Geochemistry ◽  
Early Carboniferous ◽  
Dynamic Mode ◽  
Middle Urals ◽  
Volcanic Complex ◽  
The Urals ◽  
Electron Multiplier ◽  
The Middle Urals ◽  
Eastern Zone ◽  
First Results

Research subject. The article presents the results of dating two dolerite dikes differing in geochemical features from a section along the Iset river in the area of Smolinskoe settlement (the Eastern zone of the Middle Urals). Materials and methods. The dating was performed by an U-Pb ID-TIMS technique for single zircon grains using an artificial 205Pb/235U tracer in the laboratory of geochronology and isotope geochemistry of the Geological Institute of the Kola Science Centre of the Russian Academy of Sciences. The lead isotopic composition and uranium and lead concentrations were measured using a Finnigan-MAT (RPQ) seven-channel mass spectrometer in dynamic mode using a secondary electron multiplier and RPQ quadrupole in ion counting mode. Results. The dikes were dated 330 ± 3 Ma and 240 ± 2 Ma. Conclusions. The research results indicate different ages of dolerite dikes developed within the Eastern zone of the Middle Urals. The oldest of the two established age levels corresponds to the Early Carboniferous era. This fact, along with the proximity of the dolerites to the petrochemical features of the basaltoids of the Early Carboniferous Beklenischevsky volcanic complex, allows these bodies to be considered as hypabyssal comagmates of these volcanics. The youngest obtained age level – Triassic – indicates that the introduction of some dolerite dikes was associated with the final phases of the trapp formation developed rarely within the eastern outskirts of the Urals and widely further east in the foundation (pre-Jurassic basement) of the West-Siberian Plate.

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