Petrogenesis of Late Jurassic Qianlishan granites and mafic dykes, Southeast China: implications for a back-arc extension setting

2006 ◽  
Vol 143 (4) ◽  
pp. 457-474 ◽  
Author(s):  
YAO-HUI JIANG ◽  
SHAO-YONG JIANG ◽  
KUI-DONG ZHAO ◽  
HONG-FEI LING
Keyword(s):  
Lithospheric Mantle ◽  
Source Region ◽  
Biotite Granite ◽  
Granitic Rocks ◽  
Trace Element Geochemistry ◽  
Southeast China ◽  
Mafic Dykes ◽  
Late Mesozoic ◽  
Back Arc ◽  
Extensional Setting

A late Mesozoic belt of volcanic-intrusive complexes occurs in Southeast China. The Qianlishan granites are distributed in the northwest of the belt. The pluton is composed of porphyritic biotite granite (153 Ma) and equigranular biotite granite (151 Ma) and was intruded by granite-porphyry dykes (144 Ma) and mafic dykes such as lamprophyre and diabase (142 Ma). The granitic rocks, consisting mainly of K-feldspar, plagioclase, quartz and Fe-rich biotite, have SiO2 contents of 72.9–76.9%, and are enriched in alkalis, rare earth elements (REE), high field strength elements (HFSE) and Ga with high Ga/Al ratios, but depleted in Ba, Sr and transition metals. Trace-element geochemistry and Sr–Nd isotope systematics further imply that the Qianlishan granitic magmas were most probably derived by partial melting of Palaeo- to Mesoproterozoic metamorphic lower-crustal rocks that had been granulitized during an earlier thermal event. These features suggest an A-type affinity. The Qianlishan lamprophyre and neighbouring coeval mafic dykes (SiO2 = 47.9–53.8 wt%) have high MgO and compatible element contents. These rocks also have high K2O contents and are enriched in alkalis, light REE, large ion lithophile elements, and depleted in HFSE. They have low initial εNd values and relatively high initial 87Sr/86Sr ratios. We suggest a subduction-modified refractory lithospheric mantle (phlogopite-bearing harzburgite or lherzolite) for these high-Mg potassic magmas. The Qianlishan diabases (SiO2 = 48.4–48.7 wt%) are alkaline and have high TiO2 and total Fe2O3 contents, together with the positive initial εNd value, suggesting derivation from fertile asthenopheric mantle (phlogopite-bearing lherzolite). A back-arc extensional setting, related to subduction of the Palaeo-Pacific plate, is favoured to explain the petrogenesis of the Qianlishan granites and associated mafic dykes. Between 180 and 160 Ma, Southeast China was a continental arc, forming the 180–160 Ma plutons of the late Mesozoic volcanic-intrusive complex belt, and the lower-crust was granulitized. Since 160 Ma the northwestern belt has been in a back-arc extensional setting as a consequence of slab roll-back, resulting in the lithosphere thinning and an influx of asthenophere. The upwelling asthenosphere, on the one hand, induced the local lithospheric mantle to melt partially, forming high-Mg potassic magmas, and on the other hand it underwent decompression melting itself to form alkaline diabase magma. Pulsatory injection of such high-temperature magmas into the granulitized crustal source region induced them to partially melt and generate the A-type magmas of the Qianlishan granitic rocks.

scholarly journals Geochemical and Sr-Nd-Pb-Hf Isotopic Characteristics of Muchen Pluton in Southeast China, Constrain the Petrogenesis of Alkaline A-Type Magma

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 80
Author(s):  
Haiyang Yan ◽  
Fangyue Wang ◽  
Hai-Ou Gu ◽  
He Sun ◽  
Can Ge
Keyword(s):  
Early Cretaceous ◽  
Lithospheric Mantle ◽  
Magma Ascent ◽  
Geodynamic Setting ◽  
Southeast China ◽  
Geochemical Properties ◽  
Arc Setting ◽  
Back Arc ◽  
T Values

We present comprehensive petrological, major-trace element, in situ zircon U-Pb dating and Sr-Nd-Pb isotopic data for Muchen granitoid (western Zhejiang Province, Southeast China), to constrain the petrogenesis of alkaline A-type granites and the geodynamic setting of Southeast China in the Early Cretaceous. The Early Cretaceous Muchen quartz monzonite yielded zircon U-Pb crystallization ages of 111.3 ± 0.7 Ma and is metaluminous to weakly peraluminous with SiO2 contents ranging from 59 to 69 wt.%, and can be classified as alkaline A-type granitoid. The quartz monzonites have low (87Sr/86Sr)i values (0.7052 to 0.7061) and high εNd(t) values (−2.6 to −2.0), similar to nearby coeval mafic rocks that have been proposed to be derived from the enriched lithospheric mantle. The high Nb/Ta ratios (16.7 to 30.1, average 21.8) and low Nb/U ratios (as low as 3.5) indicate the involvement of slab-derived melt and fluids in this mantle. These geochemical properties of the Muchen quartz monzonites indicated that they might be from a phlogopite-bearing and rutile-rich subduction-modified subcontinental lithospheric mantle, and underwent strong fractional crystallization of olivine + orthopyroxene + plagioclase during magma ascent. The low Mg# values of these alkaline rocks (<30 mostly) may indicate a low-pressure source in a back-arc setting. The early Cretaceous alkaline granitoids in Southeast China are related to the continental back-arc setting caused by deep angle subduction of the paleo-Pacific plate.

scholarly journals Paleoproterozoic Adakitic Rocks in Qingchengzi District, Northeastern Jiao-Liao-Ji Belt: Implications for Petrogenesis and Tectonism

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 684
Author(s):  
Jian Li ◽  
Hanlun Liu ◽  
Keyong Wang ◽  
Wenyan Cai
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Biotite Granite ◽  
Granitic Rocks ◽  
Geochemical Data ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Magmatic Rocks

Herein, zircon U-Pb geochronology, Lu-Hf isotopes, and whole-rock major and trace element geochemistry are presented for two Palaeoproterozoic granitic rocks in Qingchengzi district, northeastern Jiao-Liao-Ji Belt (JLJB). These new geochronological and geochemical data provide reference clues for exploring the petrogenesis and tectonic setting of Paleoproterozoic magmatic rocks in the Qingchengzi district, which further constrain the tectonic nature of the JLJB. Our zircon U-Pb dating denotes that the Paleoproterozoic magmatic events in the Qingchengzi district were emplaced at ~2163 Ma and ~1854 Ma, represented by granite porphyry and biotite granite, respectively. Geochemically, these Palaeoproterozoic rocks are characterized by high Sr (760–842 ppm), SiO2 (69.72–70.89 wt.%), and Al2O3 (15.53–16.78 wt.%) contents, low Y (2.1–9.0 ppm) and Yb (0.25–0.80 ppm) contents, which indicate an adakite affinity. Combined with Hf isotopic composition (εHf(t) = −1.5~+4.8; TDM2 = 3109~2560 Ma), we believe that the Paleoproterozoic adakitic magma originated from partial melting of the thickened lower crust material in the Meso-Neoarchean. Moreover, these rocks are enriched in light rare earth elements and large ion lithophilic elements (e.g., K, Rb, and Cs), and depleted in heavy rare earth elements and high field strength elements (e.g., Nb and Ta). These features are similar to magmatic rocks formed in an arc environment (either island arc or active continental margin) and are not consistent with an intraplate/intracontinental environment. According to this study and previous research results, we conclude that the arc–continent collision model is conducive to the Paleoproterozoic tectonic attribute of the JLJB, and the oceanic crust subduction between the Namgrim and Longgang blocks may have induced the widespread occurrence of magmatic events in the region.

Geochronological, geochemical and Sr–Nd–Hf isotopic constraints on petrogenesis of Late Mesozoic gabbro–granite complexes on the southeast coast of Fujian, South China: insights into a depleted mantle source region and crust–mantle interactions

2011 ◽  
Vol 149 (3) ◽  
pp. 459-482 ◽  
Author(s):  
ZHEN LI ◽  
JIAN-SHENG QIU ◽  
XI-SHENG XU
Keyword(s):  
South China ◽  
Mantle Source ◽  
Large Scale ◽  
Genetic Relationships ◽  
Source Region ◽  
Granitic Rocks ◽  
Late Mesozoic ◽  
Isotopic Compositions ◽  
Southeast Coast ◽  
Depleted Mantle

AbstractThe Quanzhou (QZ) and Huacuo (HC) gabbro–granite complexes on the southeast coast of Fujian, South China, are important components of a Late Mesozoic calc-alkaline volcanic–plutonic belt in the region. The complexes provide an excellent opportunity to investigate the genetic relationships between acid and basic magmas, and their interactions within the intrusive environment. The complexes are composed mainly of monzogranite and biotite granodiorite in the QZ complex, and biotite granite in the HC complex, with lesser amounts of hornblende gabbro. Zircon U–Pb dating provides consistent crystallization ages of 109 ± 1 Ma and 108 ± 1 Ma for the QZ gabbros and monzogranites, and an age of 111 ± 1 Ma for the HC gabbro, which is contemporaneous with the spatially associated HC granites. Both the mafic and felsic intrusions in these complexes are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and are depleted in high-field-strength elements (HFSEs; e.g. Nb and Ta). They show similarly homogeneous Sr–Nd isotopic compositions. All these factors indicate a close genetic relationship between the gabbroic and granitic rocks in the QZ and HC complexes. Although the enriched Sr–Nd isotopic signatures of the QZ and HC gabbros seemingly point to an enriched mantle source (EM-1), they have highly variable zircon Hf isotopic compositions, with εHf(t) values ranging from negative to positive (specifically –4.6 to +6.1 for the QZ gabbros and –4.8 to +11.6 for the HC gabbros). We interpret the parental basic magmas of these gabbros to have received contributions from a depleted mantle source and crustal components. Contributions from such a depleted mantle source resulted in the growth of juvenile basaltic lower crust, the partial melting of which generated the parental felsic magmas of the QZ and HC complexes. Furthermore, based on a synthesis of petrography, geochronology, elemental and isotopic geochemistry and tectonics, we propose that break-off and rollback of the Late Mesozoic subducted Palaeo-Pacific Plate triggered the upwelling of asthenospheric mantle below the coastal area of the South China Block, which induced extension of the overlying continental lithosphere, and finally initiated the large-scale Late Yanshanian magmatism in the study area.

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

scholarly journals Major-trace element and Sr-Nd isotope compositions of mafic dykes of the Singhbhum Craton: Insights into evolution of the lithospheric mantle

Lithos ◽  
2021 ◽  
Vol 382-383 ◽  
pp. 105959
Author(s):  
Om Prakash Pandey ◽  
Klaus Mezger ◽  
Dewashish Upadhyay ◽  
Debajyoti Paul ◽  
Ajay Kumar Singh ◽  
...  
Keyword(s):  
Trace Element ◽  
Lithospheric Mantle ◽  
Nd Isotope ◽  
Mafic Dykes ◽  
Singhbhum Craton

scholarly journals Major and trace-element geochemistry of Late Cretaceous clastic rocks in the Jitai Basin, southeast China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kai Yan ◽  
Chun-lian Wang ◽  
Steffen Mischke ◽  
Jiu-yi Wang ◽  
Li-jian Shen ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Brackish Water ◽  
Inductively Coupled Plasma ◽  
Salt Water ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Humid Climate ◽  
Southeast China ◽  
Clastic Rocks ◽  
Wide Range

AbstractMajor, trace and rare earth element (REE) geochemistry of the late Cretaceous lower Zhoutian Formation from the Jitai Basin of Southeast China were measured by inductively coupled plasma mass spectrometry (ICP-MS) analysis to infer the provenance of the sediments and to reconstruct the palaeoenvironment and palaeoclimate. The wide range of Sr/Cu ratios point to a fluctuating palaeoclimate, and the negative correlation between the FeO/MnO and Al2O3/MgO ratios and the Sr/Cu ratio indicates that the late Cretaceous climate during the lower Zhoutian Formation in the Jitai Basin can be divided into two parts. The lower part experienced two cooling periods, whilst the upper part was dominated by warm-humid climate. Mostly corresponding trends of the B/Ga, Sr/Ba and Sr/Cu ratios show that the salinity changed consistently with the late Cretaceous climate during the lower Zhoutian Formation in the Jitai Basin. During the lower part, the salinity changed from salt water to fresh/brackish water. In the upper part, water was mainly fresh/brackish, and there were many changes from fresh/brackish water to salt water. The relatively stable Ni/Co, V/Cr, V/(V + Ni) and Ce/Ce* data indicate a long period of oxic conditions. The La-Th-Sc, Th-Sc-Zr/10 and La/Th-Hf data of the silt- and sandstones of the lower Zhoutian Formation show that its provenance was mainly a mixture of felsic upper crust sediments and older sedimentary rocks.

scholarly journals Geochronology, Geochemistry, and Pb–Hf Isotopic Composition of Mineralization-Related Magmatic Rocks in the Erdaohezi Pb–Zn Polymetallic Deposit, Great Xing’an Range, Northeast China

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 274
Author(s):  
Zhitao Xu ◽  
Jinggui Sun ◽  
Xiaolong Liang ◽  
Zhikai Xu ◽  
Xiaolei Chu
Keyword(s):  
Lower Crust ◽  
Western Slope ◽  
Quartz Porphyry ◽  
Late Mesozoic ◽  
Hypabyssal Intrusions ◽  
Polymetallic Mineralization ◽  
Great Xing’An Range ◽  
Hf Isotopic Composition ◽  
Back Arc ◽  
T Values

Late Mesozoic intermediate–felsic volcanics and hypabyssal intrusions are common across the western slope of the Great Xing’an Range (GXAR). Spatiotemporally, these hypabyssal intrusions are closely associated with epithermal Pb–Zn polymetallic deposits. However, few studies have investigated the petrogenesis, contributions and constraints of these Pb–Zn polymetallic mineralization-related intrusions. Therefore, we examine the representative Erdaohezi deposit and show that these mineralization-related hypabyssal intrusions are composed of quartz porphyry and andesite porphyry with concordant zircon U–Pb ages of 160.3 ± 1.4 Ma and 133.9 ± 0.9 Ma, respectively. These intrusions are peraluminous and high-K calc-alkaline or shoshonitic with high Na2O + K2O contents, enrichment in large ion lithophile elements (LILEs; e.g., Rb, Th, and U), and depletion in high field strength elements (HFSEs; e.g., Nb, Ta, Zr, and Hf), similar to continental arc intrusions. The zircon εHf(t) values range from 3.1 to 8.0, and the 176Hf/177Hf values range from 0.282780 to 0.282886, with Hf-based Mesoproterozoic TDM2 ages. No differences exist in the Pb isotope ratios among the quartz porphyry, andesite porphyry and ore body sulfide minerals. Detailed elemental and isotopic data imply that the quartz porphyry originated from a mixture of lower crust and newly underplated basaltic crust, while the andesite porphyry formed from the partial melting of Mesoproterozoic lower crust with the minor input of mantle materials. Furthermore, a magmatic–hydrothermal origin is favored for the Pb–Zn polymetallic mineralization in the Erdaohezi deposit. Integrating new and published tectonic evolution data, we suggest that the polymetallic mineralization-related magmatism in the Erdaohezi deposit occurred in a back-arc extensional environment at ~133 Ma in response to the rollback of the Paleo-Pacific Plate.

scholarly journals Identifikasi Keterdapatan Mineral Radioaktif pada Urat-Urat Magnetit di Daerah Ella Ilir, Melawi, Kalimantan Barat

EKSPLORIUM ◽  
2019 ◽  
Vol 40 (1) ◽  
pp. 33
Author(s):  
Ngadenin Ngadenin ◽  
Frederikus Dian Indrastomo ◽  
Widodo Widodo ◽  
Kurnia Setiawan Widana
Keyword(s):  
Iron Ore ◽  
Biotite Granite ◽  
Ore Deposits ◽  
Geological Mapping ◽  
Granitic Rocks ◽  
Metamorphic Rocks ◽  
West Kalimantan ◽  
The North ◽  
Iron Ore Deposits ◽  
Radioactive Minerals

ABSTRAKElla Ilir secara administratif terletak di Kabupaten Melawi, Kalimantan Barat. Geologi regional daerah Ella Ilir tersusun atas batuan malihan berumur Trias–Karbon yang diterobos oleh batuan granitik berumur Yura dan Kapur. Keterdapatan mineral radioaktif di daerah tersebut terindikasi dari radioaktivitas urat-urat magnetit pada batuan malihan berumur Trias–Karbon dengan kisaran nilai 1.000 c/s hingga 15.000 c/s. Tujuan dari penelitian ini adalah menentukan jenis cebakan mineral bijih dan mengidentifikasi keterdapatan mineral radioaktif pada urat-urat bijih magnetit di daerah Ella Ilir. Metode yang digunakan adalah pemetaan geologi, pengukuran radioaktivitas, analisis kadar uranium, dan analisis mineragrafi beberapa sampel urat bijih magnetit. Litologi daerah penelitian tersusun oleh kuarsit biotit, metatuf, metabatulanau, metapelit, granit biotit, dan riolit. Sesar sinistral barat-timur dan sesar dekstral utara-selatan merupakan struktur sesar yang berkembang di daerah ini. Komposisi mineral urat-urat magnetit terdiri dari mineral-mineral bijih besi, sulfida, dan radioaktif. Mineral bijih besi terdiri dari magnetit, hematit, dan gutit. Mineral sulfida terdiri dari pirit, pirhotit, dan molibdenit sedangkan mineral radioaktif terdiri dari uraninit dan gumit. Keterdapatan urat-urat bijih magnetit dikontrol oleh litologi dan struktur geologi. Urat-urat magnetit pada metabatulanau berukuran tebal (1,5–5 m), mengisi rekahan-rekahan yang terdapat di sekitar zona sesar. Sementara itu, urat-urat magnetit pada metapelit berukuran tipis (milimetrik–sentimetrik), mengisi rekahan-rekahan yang sejajar dengan bidang sekistositas. Cebakan mineral bijih di daerah penelitian adalah cebakan bijih besi atau cebakan bijih magnetit berbentuk urat karena proses hidrotermal magmatik.ABSTRACTElla Ilir administratively located in Melawi Regency, West Kalimantan. Regional geology of Ella Ilir area is composed of metamorphic rocks in Triassic–Carboniferous age which are intruded by Jurassic and Cretaceous granitic rocks. Radioactive minerals occurences in the area are indicated by magnetite veins radioactivities on Triassic to Carboniferous metamorphic rocks whose values range from 1,000 c/s to 15,000 c/s. Goal of the study is to determine the type of ore mineral deposits and to identify the presence of radioactive mineral in magnetite veins in Ella Ilir area. The methods used are geological mapping, radioactivity measurements, analysis on uranium grades, and mineragraphy analysis of severe magnetite veins samples. Lithologies of the study area are composed by biotite quartzite, metatuff, metasilt, metapellite, biotite granite, and ryolite. The east-west sinistral fault and the north-south dextral fault are the developed fault structures in this area. Mineral composition of magnetite veins are consists of iron ore, sulfide, and radioactive minerals. Iron ore mineral consists of magnetite, hematit, and goetite. Sulfide minerals consist of pyrite, pirhotite, and molybdenite, while radioactive minerals consist of uraninite and gummite. The occurences of magnetite veins are controlled by lithology and geological structures. The magnetite veins in metasilt are thick (1.5–5 m), filled the fractures in the fault zone. Meanwhile, the magnetite veins in metapellite are thinner (milimetric–centimetric), filled the fractures that are parallel to the schistocity. The ore deposits in the study area are iron ore deposits or magnetite ore deposits formed by magmatic hydrothermal processes. 

scholarly journals Himalayan and Trans Himalayan granitic rocks in and adjacent to Nepal and their mineral potential

1981 ◽  
Vol 1 (1) ◽  
Author(s):  
A. H. G. Mitchell
Keyword(s):  
Root Zone ◽  
Porphyry Copper ◽  
Tectonic Setting ◽  
Granitic Rocks ◽  
Main Central Thrust ◽  
Southern Tibet ◽  
Late Mesozoic ◽  
The North ◽  
Augen Gneiss ◽  
Host Rocks

Granitic rocks occupying eight distinct tectonic settings can be recognized in the Himalayas and   Transhimalayas.  In the Lower Himalayas geographical belt a few plutons of two-mica granite intrude the lowest unit of the Nawakot Complex or Midland Group. More extensive are sheet- like lies of augen gneiss intrusive within a possibly thrust bounded succession carbonates and graphitic schists beneath the Main Central Thrust to the north. The most abundant granites in the Lower Himalayas are the two- mica cordierite- bearing granite within klippen; minor tin and tungsten mineralization is associated with these plutons, which are of late Cambrian age. Within the Higher Himalayas above the Main Central Thrust, the ‘Central Crystallines’ or Central Gneisses include pegmatites and pegmatitic granites intrusive into gneisses of probable early Proterozoic age; these have same potential for ruby, sapphire, aquamarine and possibly spodumene. Further north within the Higher Himalayan succession a southern belt of anatectic two- mica granites and leucogranites of mid-Tertiary age is favorable for tin, tungsten and uranium mineralization; a northern belt of granites or gneisses is of uncertain age and origin. North of the Indus Suture in the Transhimalayas extensive batholiths of hornblende granodiorite representing the root zone of a late Mesozoic to early Eocene volcanic arc are associated with porphyry copper deposits. Further north in southern Tibet the tectonic, setting for reported granitic bodies of  Tertiary  age  is  uncertain; their location suggests that they could be favorable host rocks for tin, uranium and porphyry molybdenum mineralization.

Sign in / Sign up

Export Citation Format

Share Document