PALEOPROTEROZOIC METAVOLCANOSEDIMENTARY SEQUENCES OF THE YENISEI METAMORPHIC COMPLEX, SOUTHWESTERN SIBERIAN CRATON (Angara-Kan block): SUBDIVISION, COMPOSITION, AND U-Pb ZIRCON AGE

2019 ◽  
Keyword(s):  
Siberian Craton ◽  
Metamorphic Complex ◽  
Zircon Age

Precambrian Zircon Age of Orthogneiss in the Shuswap Metamorphic Complex, British Columbia

1975 ◽  
Vol 12 (2) ◽  
pp. 326-332 ◽  
Author(s):  
R. K. Wanless ◽  
J. E. Reesor
Keyword(s):  
British Columbia ◽  
Metamorphic Complex ◽  
Gneiss Dome ◽  
Zircon Age ◽  
Core Zone ◽  
The Core ◽  
Basement Rocks ◽  
Proterozoic Basement ◽  
Shuswap Metamorphic Complex ◽  
Age Determinations

Pb-U age determinations carried out on zircon from granodiorite gneiss of the core zone of Thor-Odin gneiss dome have provided isotopic evidence for involvement of Proterozoic basement rocks in the Mesozoic structures of the Shuswap Metamorphic Complex. The study has revealed that the zircons originally crystallized [Formula: see text] ago and suffered an episodic loss of lead [Formula: see text] ago.

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.

scholarly journals SHRIMP U-Pb Zircon Age of the Inishi Migmatite around the Kamioka Mining Area, Hida Metamorphic Complex, Central Japan

2006 ◽  
Vol 56 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Masatoshi Sakoda ◽  
Takashi Kano ◽  
C. Mark Fanning ◽  
Takaaki Sakaguchi
Keyword(s):  
Mining Area ◽  
Metamorphic Complex ◽  
Central Japan ◽  
Zircon Age

scholarly journals P-T path of metamorphism and U-Pb monazite and zircon age of the Kitoy terrane: Implication for Neoarchean collision in SW Siberian Craton

2020 ◽  
Vol 11 (6) ◽  
pp. 1915-1934
Author(s):  
Vasiliy P. Sukhorukov ◽  
Valentina B. Savel’eva ◽  
Yingde Jiang ◽  
Zhiyong Li
Keyword(s):  
Siberian Craton ◽  
Zircon Age ◽  
T Path

scholarly journals The first U-Pb (SHRIMP-II) evidence of the Franklin tectonic event at the western margin of the Siberian craton

2019 ◽  
Vol 486 (5) ◽  
pp. 567-571
Author(s):  
I. I. Likhanov ◽  
V. V. Reverdatto
Keyword(s):  
Siberian Craton ◽  
The Arctic ◽  
Spatial Proximity ◽  
Tectonic Event ◽  
Zircon Age ◽  
Western Margin ◽  
The North ◽  
Intraplate Magmatism ◽  
High Concentrations ◽  
Geochronological Evidence

Geochemical and isotope-geochronological evidence of the manifestation of Late Riphean intraplate magmatism within the Chernorechensky massif at the western margin of the Siberian craton were obtained. These rocks crystallized from high-temperature and anhydrous (water unsaturated) magmas with high concentrations of alkalis, iron, and, mostly incompatible elements, which is typical for anorogenic A-type granites in intraplate extension setting. Their U-Pb zircon age 723 ± 6 Ma can be correlated with the Franklin rift event widely manifested in the north of Laurentia, associated with the breakup of Rodinia. The synchronous successions and similar style of magmatic activity and concomitant rifting, as well as a similar sequence of tectonic-thermal events along the Arctic margin of Rodinia support the spatial proximity of Siberia and the North Atlantic cratons at this time as proposed for the paleogeographic reconstructions.

scholarly journals Supplemental Material: Mesozoic crustal melting and metamorphism in the U.S. Cordilleran hinterland: Insights from the Sawtooth metamorphic complex, central Idaho

2020 ◽  
Author(s):  
Chong Ma ◽  
et al.
Keyword(s):  
Trace Element ◽  
Trace Element Data ◽  
Metamorphic Complex ◽  
Zircon Age ◽  
Element Data ◽  
Data Table ◽  
Geologic Map ◽  
Elemental Data ◽  
Igneous Zircon ◽  
Spider Diagrams

Geologic map of the Sawtooth metamorphic complex (Fig. S1), sample outcrop photos (Fig. S2), whole-rock spider diagrams (Fig. S3), plots of igneous zircon trace element versus zircon age (Fig. S4), rare earth element patterns of igneous zircons (Fig. S5), details of analytical methods, sample information (Table S1), whole-rock elemental data (Table S2), zircon U-Pb data (Table S3), titanite U-Pb and trace element data (Table S4), zircon trace element data (Table S5), and zircon Lu-Hf data (Table S6).

scholarly journals Supplemental Material: Mesozoic crustal melting and metamorphism in the U.S. Cordilleran hinterland: Insights from the Sawtooth metamorphic complex, central Idaho

2020 ◽  
Author(s):  
Chong Ma ◽  
et al.
Keyword(s):  
Trace Element ◽  
Trace Element Data ◽  
Metamorphic Complex ◽  
Zircon Age ◽  
Element Data ◽  
Data Table ◽  
Geologic Map ◽  
Elemental Data ◽  
Igneous Zircon ◽  
Spider Diagrams

Geologic map of the Sawtooth metamorphic complex (Fig. S1), sample outcrop photos (Fig. S2), whole-rock spider diagrams (Fig. S3), plots of igneous zircon trace element versus zircon age (Fig. S4), rare earth element patterns of igneous zircons (Fig. S5), details of analytical methods, sample information (Table S1), whole-rock elemental data (Table S2), zircon U-Pb data (Table S3), titanite U-Pb and trace element data (Table S4), zircon trace element data (Table S5), and zircon Lu-Hf data (Table S6).

Ediacaran to Toarcian evolution of the Gasht Metamorphic Complex, Alborz Mountains, N Iran

2021 ◽  
Author(s):  
Leila Rezaei ◽  
Martin J. Timmerman ◽  
Uwe Altenberger ◽  
Mohssen Moazzen ◽  
Franziska D. H. Wilke ◽  
...  
Keyword(s):  
White Mica ◽  
Amphibolite Facies ◽  
Late Triassic ◽  
Metamorphic Complex ◽  
Zircon Age ◽  
Northern Margin ◽  
Basement Rocks ◽  
Late Neoproterozoic ◽  
Radiometric Ages ◽  
Uplift And Erosion

<p>The Alborz Mountains in N Iran underwent several tectono-metamorphic events that reflect the opening and closure of the Paleo- and Neotethys Oceans. Metamorphic rocks that recorded these are rare and discontinuously exposed. They range from the HP-LT Asalem-Shanderman Complex in the west, to the Gasht Metamorphic Complex (GMC, this study), to the Gorgan Schists, and Fariman Schists near Mashhad in the east. They are considered to have formed during the closure of the Paleotethys Ocean. The GMC comprises poorly exposed metasediments and amphibolite metamorphosed under greenschist- to amphibolite-facies conditions. In addition, smaller volumes of granite occur. As the evolution of the basement rocks of the Alborz Mountains is still poorly known and their radiometric ages are very limited, we applied different dating methods to selected samples of the GMC basement to better understand the geological evolution of this part of the Alborz Mountains.</p><p>The granite yielded an Ediacaran 551 ± 2.5 Ma LA-ICP-MS U-Pb pooled zircon age. Monazites in two amphibolite-facies metapelites (Bt-Ms-St ± And schists) yielded Triassic 226 ± 24 and 229 ± 25 Ma CHIME U-Pb ages. Foliation-defining biotite and retrograde white mica replacing andalusite porphyroblasts in metapelites and peak-metamorphic amphibole from an amphibolite yielded much younger 175.1 ± 0.5 Ma to 177.0 ± 0.4 Ma <sup>40</sup>Ar/<sup>39</sup>Ar plateau ages.</p><p>The Ediacaran crystallization age of the granite agrees with the late Neoproterozoic to Cambrian zircon age of the Lahijan granite in the eastern GMC reported by Guest et al. (2006) and indicates that the Alborz basement was a part of the northern margin of Gondwana at that time. It rifted and drifted away from Gondwana due to the opening of the Neotethys, probably in the Permian, along with other Iranian blocks (the so-called Cimmerian terranes). The mid to late Triassic monazite ages date the Barrovian peak metamorphism of the GMC and mark collision and accretion of a Cimmerian terrane following closure of the Paleotethys. The monazite ages overlap with the early Late Triassic age of deposition of the lowest parts of the unconformably overlying Shemshak Group in the central and eastern Alborz Mountains (ca. 213 Ma, Horton et al. 2008). Younger and very similar Toarcian <sup>40</sup>Ar/<sup>39</sup>Ar ages for both pro- and retrograde minerals with different nominal closure temperatures, reflect very rapid cooling of GMC basement below the Shemshak Group due to extension-triggered uplift. This late Toarcian to Aalenian extension event can be correlated with the regional Mid-Cimmerian unconformity of mid-Bajocian age (c. 170 Ma) that resulted from the tectonic movements causing rapid uplift and erosion (Fürsich et al. 2009). Extension probably started in the western Alborz Mountains in the Toarcian and culminated in the Aalenian in the eastern Alborz with the formation of a deep-marine basin and was triggered by the onset of the subduction of Neotethys oceanic crust beneath the Central Iranian Microcontinent (Wilmsen et al. 2009).</p><p> </p><p>Fürsich et al. 2009, Geol. Soc., London, Spec. Publ. 312, 189-203. Guest et al., 2006, GSA Bulletin 118, 1507-1521. Horton et al., 2008, Tectonophysics 451, 97–122. Wilmsen et al. 2009, Terra Nova 21, 211–218.</p>

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