Late Permian Granitoids Research Articles

Subduction and Collision of the Jinsha River Paleo‐Tethys: Constraints from Zircon U‐Pb Dating and Geochemistry of the Ludian Batholith in the Jiangda–Deqen–Weixi Continental Margin Arc

AbstractThe Jiangda–Deqen–Weixi continental margin arc (DWCA) developed along the base of the Changdu–Simao Block and was formed as a result of the subduction of the Jinsha River Ocean Slab and the subsequent collision. The Ludian batholith is located in the southern part of the DWCA and is the largest batholith in northwest Yunnan. Granite samples from the Ludian batholith yield an early Middle Permian age of 271.0 ± 2.8 Ma. The geochemical data of the early Middle Permian granitoids show high Si2O, low P2O5 and MgO contents that belong to calc‐alkaline series and peraluminous I‐type rocks. Their ∊Hf(t) values range from –5.01 to +0.58, indicating that they were formed by hybrid magmas related to the subduction of the Jinsha River Tethys Ocean. The monzonite and monzogranite samples yield Late Permian ages of 250.6 ± 1.8 Ma and 252.1 ± 1.3 Ma, respectively. The Late Permian granitoids are high‐K calc alkaline and shoshonite series metaluminous I‐type rocks. Their ∊Hf(t) values range from –4.12 to –1.68 and from –7.88 to –6.64, respectively. The mixing of crustal and mantle melts formed the parental magma of the Late Permian granitoids. This study, combined with previous work, demonstrates the process from subduction to collision of the Jinsha River Paleo‐Tethys Ocean.

Middle–late permian I-type granitoids from the Diaobingshan region in the northern margin of the North China Craton: insight into southward subduction of the Paleo–Asian Ocean

ABSTRACT An integrated study of the petrology, zircon U–Pb geochronology, whole–rock geochemistry, and in situ zircon Hf isotopic compositions of middle–late Permian granitoids from the Diaobingshan region in the northern margin of the North China Craton (NCC) has been implemented, with the aim of investigating their geochronological framework, petrogenesis, and tectonic significance. The studied granitoids are widely distributed on the southern side of the Changchun–Yanji suture zone and comprise mainly monzogranite and syenogranite, with minor quartz monzonite. New zircon U–Pb data measured by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) yield emplacement ages of 262–256 Ma, reflecting middle–late Permian magmatism. Geochemically, the rocks contain 60.53–73.33 wt.% SiO2, 12.60–18.35 wt.% Al2O3, 3.50–8.10 wt.% K2O, 0.18–0.91 wt.% TiO2, and 0.22–1.01 wt.% MgO, and exhibit weakly peraluminous (A/CNK = 0.86–1.01) and high-K calc–alkaline and shoshonitic characteristics, indicating I-type granite affinities. They are also characterized by low Sr and high Yb contents, reflecting low-pressure magma source conditions with residual plagioclase (i.e. amphibolite facies). These granitoids also exhibit geochemical characteristics typical of arc–type magmatic rocks, with enrichment in large ion lithophile elements (LILEs; e.g. Rb, Ba, and K) and light rare earth elements (LREEs), and depletion in high field strength elements (HFSEs; e.g. Nb, Ta, Ti, and P) and heavy rare earth elements (HREEs), indicating that they were formed in a subduction-related setting. Moreover, magmatic zircons from the studied rocks have relatively homogeneous Hf isotopic compositions (εHf(t) = – 1.4 to +15.1) and corresponding two–stage model (TDM2) ages of 1839–348 Ma, indicating that they were generated by partial melting of Paleoproterozoic–Phanerozoic accreted lower crust, with minor contributions of ancient crustal materials. Their geochemical characteristics and specific lithological assemblage, together with the temporal–spatial distribution of Permian granitic magmatism, indicate that the formation of middle–late Permian granitoids in the northern margin of the NCC was related to southward Paleo–Asian oceanic subduction. Data from this and previous studies lead us to favour a double-sided, early–late Permian subduction model, with the Paleo–Asian Ocean closing after the late Permian.

Age and sources of the metasedimrntary rocks of the Tokur terrane in the Mongol-Okhotsk fold belt: results of the U–Pb geoсhronological
 and Lu–Hf isotope studies

This paper presents the results of U–Pb (LA–ICP–MS) and Lu–Hf ­isotope studies of detrital zircons from metasedimentary rocks of the Tokur Terrane. It has been shown that metasedimentary rocks of the Tokur and Ekimchan formations are characterized by similar age peaks of detrital zircons, which indicates a close (or same) age of these formations. The lower age of the sedimentation is determined by the age of the youngest zircons of 326–323 Ma. The upper age boundary is determined of 254–251 Ma, based on the intruded of the Late Permian granitoids. The main sources of zircons in the metasedimentary rocks of the Tokur Terrane are the igneous and metamorphic complexes of the southeast framing of the North Asia Craton. The Tokur Terrane can be considered as a fragment of the Paleozoic accretionary complex, the formation in front of the southeastern margin of the North Asia Craton.

Age and Sources of Metasedimentary Rocks of the Tokur Terrane of the Mongol–Okhotsk Fold Belt: Results of U–Pb and Lu–Hf Isotope Studies

This paper presents the results of U–Pb (LA-ICP-MS) and Lu–Hf isotope studies of detrital zircons from the presumably Permian meta sedimentary rocks of the Tokur terrane. It has been established that the grains of detrital zircons from the meta sedimentary rocks of the Tokur and Ekimchan formations have a similar age distribution, which indicates the similar (or equal) age of these formations. The youngest zircons in these rocks has a U–Pb age of 326–323 Ma, which determines the lower age limit of the protolith of the rocks. The upper age limit of the formations corresponds to 254–251 Ma, which is the age of the Late Permian granitoids intruded into these formations. The main sources of zircon in the meta sedimentary rocks of the Tokur terrane are the igneous and metamorphic massifs of the southeast framing of the North Asian Craton. The Tokur terrane can be considered as a fragment of the Paleozoic accretionary complex, formed near the southeastern margin of the North Asian Craton.

Petrophysical Characteristics of the Intrusive Complexes of Different Age of the Gamow Peninsula (Southwestern Primorye)

The petrophysical data on the granitoids of the Gamow Peninsula are presented and compared with those of the granitoid complexes distributed on the adjacent territory. The physical properties of the Late Permian and Early Jurassic granitoid complexes are considered. Granitoids of different age sharply differ in petrophysical properties. The Late Permian granitoids developed on the Gamow Peninsula have higher density and lower magnetic characteristics relative to the same rocks distributed on the adjacent continental territory. It is established that the petrophysical properties of the Early Jurassic granitoids are similar to those of one phase of the Late Permian granitoids. The simultaneous formation of these complexes is proposed.

Late-paleozoic granitoid complexes of the southwest Primorye: geochemistry, age and typification

The article presents the first data of geochemical studies of the Late Permian granitoids of the Gamov Complex located in the southwestern part of the Voznesenskiy terrane. The purpose of the study was to identify the main geochemical features of the Late Paleozoic granitoids of the southwestern Primorye, which in the future will allow us to draw conclusions about the petrogenesis of these granitoids. Elemental analysis of 20 samples was carried out, conducted statistical and mathematical processing of the data, have been constructed representative diagrams and graphs for this group of rocks. Elemental analysis was performed by atomic emission (ICP-AES) and inductively-coupled-plasma (ICP-MS) mass spectrometry, at the Analytical Center FEGI FEB RAS.

WITHDRAWN: Late Paleozoic-Early Mesozoic magmatic history of central Inner Mongolia, China: Implications for the Tectonic Evolution of the Xingmeng Orogenic Belt, the southeastern segment of the Central Asian Orogenic Belt

Abstract The tectonic setting and location of the southernmost boundary of the Central Asian Orogenic Belt (CAOB) in the Late Paleozoic–Early Mesozoic Era and the history evolution for the Xingmeng Orogenic Belt (XMOB) are sources of debate within the scientific community. This paper presents new geochronological, petrological, and geochemical data for Late Paleozoic–Early Mesozoic intrusions from the Siziwangqi region in the southeastern CAOB and discusses the tectonic setting for that area. Using zircon LA-MC-ICPMS U–Pb dating, intrusions can be broadly grouped as Late Carboniferous amphibolite with an age of 323.1 ± 3.4 Ma; Middle–Late Permian granitoids with ages of 271.3 ± 1.5 Ma, 261.3 ± 3.8 Ma, 260.6 ± 4.8 Ma, 259.9 ± 3.5 Ma, 253.3 ± 4.8 Ma, and 249.6 ± 4.8 Ma; Early Triassic K-feldspar granite with an age of 235.0 ± 1.8 Ma. These studies, by interaction of regional geology, provide new constraints on the tectonic evolution of the southeastern Central Asian Orogenic Belt during the Late Paleozoic–Early Mesozoic, and we predict five stages of tectonic evolution during the Late Paleozoic–Early Mesozoic: (1) the Early Carboniferous–Early Permian (>298 Ma), which is the active continental margin stage and the exit of the back-arc basin during the Late Carboniferous; (2) the Early Permian–Middle Permian (298–271 Ma), where there was continued subduction of Paleo-Asian oceanic lithosphere and the Solonker ophiolite emplacement at the end of Early Permian; (3) the Middle Permian (271–261 Ma), which had continent–continent collision between the Siberian Plate and the North China Craton; (4) the Middle Permian–Middle Triassic (261–235 Ma), which was the collisional orogeny stage with few intermountain basin deposition and the disappearance of marine strata; and (5) Late Triassic (

Petrogenesis and geodynamic setting of Neoproterozoic and Late Paleozoic magmatism in the Manzhouli–Erguna area of Inner Mongolia, China: Geochronological, geochemical and Hf isotopic evidence

U–Pb dating and Hf isotopic analyses of zircons from various granitoids, combined with major and trace element analyses, were undertaken to determine the petrogenesis and geodynamic setting of Neoproterozoic and Late Paleozoic magmatism in the Manzhouli–Erguna area of Inner Mongolia, China. The Neoproterozoic granitoids are mainly biotite monzogranites with zircon U–Pb ages of 894±13Ma and 880±10Ma, and they are characterised by enrichment in large ion lithophile elements (LILEs; e.g., Rb, Ba, K) and light rare earth elements (LREEs), depletion in high field strength elements (HFSEs; e.g., Nb, Ta, Ti) and heavy rare earth elements (HREEs). The Late Devonian granitoids are dominantly syenogranites and mylonitised syenogranites with zircon U–Pb ages of 360±4Ma, and they form a bimodal magmatic association with subordinate gabbroic rocks of the same age. The Late Devonian syenogranites have A-type characteristics including high total alkalis, Zr, Nb, Ce and Y contents, and high FeOt/MgO, Ga/Al and Rb/Sr ratios. The Carboniferous granitoids are mainly tonalites, granodiorites and monzogranites with U–Pb ages varying from 319 to 306Ma, and they show very strong adakitic characteristics such as high La/Yb and Sr/Y ratios but low Y and Yb contents. The Late Permian granitoids are dominated by monzogranites and syenogranites with zircon U–Pb ages ranging between 257 and 251Ma. Isotopically, the εHf(t) values of the Neoproterozoic granitoids range from +4.3 to +8.3, and the two-stage model ages (TDM2) from 1.2 to 1.5Ga. The Late Devonian granitoids are less radiogenic [εHf(t) from +12.0 to +12.8 and TDM2 from 545 to 598Ma] than the Carboniferous [εHf(t) from +6.8 to +9.5 and TDM2 from 722 to 894Ma] and Late Permian granitoids [εHf(t) from +6.1 to +9.4 and TDM2 in the range of 680–895Ma]. These data indicate (1) the Neoproterozoic granitoids may have been generated by melting of a juvenile crust extracted from the mantle during the Mesoproterozoic, probably during or following the final stages of assembly of Rodinia as a result of the collision and amalgamation of Australia and the Tarim Craton; (2) the Late Devonian granitoids may have formed by partial melting of a new mantle-derived juvenile crust in a post-orogenic extensional setting; (3) the Carboniferous granitoids appear to have been produced by melting of garnet-bearing amphibolites within a thickened continental crust during and following the collision of the Songnen and Erguna–Xing’an terranes; and (4) the Late Permian granitoids may have been generated by melting of garnet-free amphibolites within the Neoproterozoic juvenile continental crust, probably in the post-collisional tectonic setting that followed the collision of the North China and Siberian cratons.

Geochemistry and zircon U–Pb ages and Hf isotopic composition of Permian alkali granitoids of the Phan Si Pan zone in northwestern Vietnam

The late Permian granitoids exposed in the Phan Si Pan zone of northwestern Vietnam consist mainly of the Ye Yen Sun metaluminous granites and the Nam Xe–Tam Duong peralkaline granites. Laser ablation inductively coupled plasma mass spectrometry U–Pb zircon analysis reveals that both the granite suites were emplaced from 253Ma to 251Ma. They have a distinctive A-type geochemistry of high 10,000×Ga/Al ratios of 3.0–5.7 and are also characterized by elevated contents of high field strength elements, A/CNK values of 0.85–1.58, negative Eu-anomalies. Magmatic zircons from the granitoids exhibit positive initial ɛHf values ranging from 6.4 to 15.9 and yield single-stage depleted mantle Hf model ages of 257–663Ma. This Hf isotopic feature implies significant contribution of juvenile mantle material to the magmas of the spatially and temporally associated Ye Yen Sun metaluminous and Nam Xe–Tam Duong peralkaline granites.