scholarly journals Metamorphic Evolution of Garnet-Bearing Ultramafic Rocks in the Hujialin Area, Sulu Ultrahigh-Pressure Orogenic Belt, Eastern China

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 225
Author(s):  
Zeli Wang ◽  
Shukai Zhang ◽  
Xu-Ping Li ◽  
Songjie Wang ◽  
Dan Wang ◽  
...  
Keyword(s):  
Mineral Assemblage ◽  
Eastern China ◽  
Stage Iv ◽  
Mineral Chemistry ◽  
Orogenic Belt ◽  
Ultrahigh Pressure ◽  
Retrograde Metamorphism ◽  
Metamorphic Evolution ◽  
The North ◽  
Convex Upward

The Rizhao Hujialin area is located in the central Sulu ultrahigh-pressure orogenic belt, where garnet clinopyroxenite is exposed in the upper part of an ultramafic rock complex and serpentinized dunite is exposed in its lower part. Based on textural criteria, the garnet clinopyroxenites were divided into three types: Equigranular garnet, porphyroclastic garnet, and megacrystic garnet pyroxenites. The garnet clinopyroxenites have convex-upward chondrite-normalized rare earth element patterns, large positive Pb anomalies, and depletion of high-field-strength elements (e.g., Nb, Zr, and Ti), suggesting a mantle source protolith overprinted by fluid metasomatism. Petrographic, mineral chemistry, phase equilibrium modeling, and zircon U–Pb geochronology data show that the evolutionary stages of the Hujialin garnet clinopyroxenites were as follows: Stage I: formation of the magmatic protoliths; stage II: formation of megacrystic garnet pyroxenite accompanying subduction; stage III: formation of porphyroclastic or equigranular garnet clinopyroxenite with a mineral assemblage of garnet + clinopyroxene + ilmenite + humite accompanying initial exhumation at ~215.0 ± 5.7 Ma; stage IV = progressive cooling and decompression associated with the crystallization of water-bearing minerals such as clinochlore and pargasite at 206 Ma; and Stage V = late epidote amphibolite-facies retrograde metamorphism producing a mineral assemblage of garnet + clinopyroxene + amphibole + chlorite + epidote + ilmenite at ~180–174 Ma associated with fluid activity in shear–tensional fractures and/or pores. The P-T conditions of the peak metamorphism were estimated at 4.5 ± 0.5 GPa and 800 ± 50 °C. Retrograde metamorphism recorded conditions of 1.0 GPa and 710 ± 30 °C during the exhumation and cooling process. The mineral transformation from early high-Al clinopyroxene to garnet and to late diopside records the general metamorphic evolution during subduction and exhumation, respectively. One zircon U–Pb analysis presents the Palaeoproterozoic age of 1817 ± 40 Ma, which is coeval with widespread magmatic and metamorphic events in the North China Craton.

Late Jurassic, high Ba–Sr Linglong granites in the Jiaodong Peninsula, East China: lower crustal melting products in the eastern North China Craton

2017 ◽  
Vol 155 (5) ◽  
pp. 1040-1062 ◽  
Author(s):  
LI-QIANG YANG ◽  
YILDIRIM DILEK ◽  
ZHONG-LIANG WANG ◽  
ROBERTO F. WEINBERG ◽  
YUE LIU
Keyword(s):  
North China Craton ◽  
Late Jurassic ◽  
North China ◽  
Eastern China ◽  
Ultrahigh Pressure ◽  
Granitic Rocks ◽  
Crustal Melting ◽  
Heavy Rare Earth Element ◽  
The North ◽  
Lower Crustal

AbstractThe Jurassic Linglong granites, intrusive into the North China Craton (NCC) in eastern China, provide a critical record of the first major episode of lithospheric-scale extension and magmatism in NE China during Mesozoic time. Our U–Pb zircon dating reveals that the Linglong granites were emplaced during 161–158 Ma, shortly after the inception of a shallow subduction of the Palaeo-Pacific plate beneath East Asia during Middle Jurassic time. These granites have high alkali contents (K2O + Na2O = 8–9 wt%), low MgO and Mg no. values and variable Cr–Ni abundances. Their relatively high Ba and Sr concentrations, relatively low heavy rare Earth element (HREE) and strongly fractionated REE patterns characterize them as high Ba–Sr granites. The negative whole-rock εNd(t) values ranging from −22.4 to −10.9 and wide-ranging zircon εHf(t) values of −39.1 to −1.5 suggest that magmas of the Linglong granites were produced by partial melting of a garnet-amphibolite-bearing lower crust of the Jiaobei Terrane and by re-melting of the Triassic ultrahigh-pressure (UHP) metamorphic rocks and alkaline suites of the Sulu Terrane. The occurrence in the granitic rocks of inherited zircons of the Neoarchaean, Palaeoproterozoic, Neoproterozoic, Palaeozoic and Triassic ages suggests that magmas of the Linglong granites interacted with the ancient crust in these terranes during their ascent. Asthenospheric upwelling, induced by the steepening and rapid rollback of the Palaeo-Pacific slab during Late Jurassic time, provided the heat source for the inferred lower crustal melting. Trench migration and thermal weakening of the crust caused extensional deformation and thinning in the eastern part of the NCC.

Petrology of low-temperature, ultrahigh-pressure marbles and interlayered coesite eclogites near Sanqingge, Sulu terrane, eastern China

2009 ◽  
Vol 73 (2) ◽  
pp. 307-332 ◽  
Author(s):  
Yong-Feng Zhu ◽  
H.-J. Massonne ◽  
Men-Fan Zhu
Keyword(s):  
Eastern China ◽  
Stage Iv ◽  
Stage I ◽  
Ultrahigh Pressure ◽  
Maximum Pressure ◽  
Crustal Material ◽  
Water Influx ◽  
Subduction Setting ◽  
Sedimentary Carbonates ◽  
The Village

AbstractMarbles and interlayered coesite-bearing eclogites near the village ofSanqingge in the Sulu ultrahighpressure (UHP) terrane ofeastern China were studied to estimate their P-T evolution. Using garnet, omphacite and phengite as geothermobarometers, the coesite eclogites are calculated to have experienced P-T conditions of3.4 –3.7 GPa and ~600ºC (stage I), followed by decompression and a slight temperature decrease to 2.7–3.2 GPa and 520–560ºC respectively (stage II) and later to 2.6–2.8 GPa and ~500ºC (stage III). No water influx affected the eclogites until reaching amphibolite facies conditions of 0.5–1.3 Gpa and 595–685ºC (stage IV). As we interpret the occasional appearance ofcalcite with magnesite relics in the core as a reaction ofUHP dolomite and magnesite with Ca-rich fluids at stage IV to form CaCO3, the calculated pressure for stage I could be the maximum pressure experienced by these rocks. Thus, the crustal material ofthe Sanqingge quarry, originally sedimentary carbonates (now marbles) and interstratified basic tuffs (now eclogites), has been buried to a depth of ≥ 120 km at ~600ºC. This burial occurred in a subduction setting along a very low geotherm of 5–6ºC/km. The exhumation possibly occurred in the environment ofa subduction channel.

Significance of allanite-(Ce) in granitic gneisses from the ultrahigh-pressure metamorphic terrane, Dabie Shan, central China

1999 ◽  
Vol 63 (4) ◽  
pp. 579-586 ◽  
Author(s):  
Xiaochun Liu ◽  
Shuwen Dong ◽  
Huaimin Xue ◽  
Jianxiong Zhou
Keyword(s):  
Large Scale ◽  
Mineral Chemistry ◽  
Central China ◽  
Ultrahigh Pressure ◽  
Chemical Compositions ◽  
Retrograde Metamorphism ◽  
Dabie Shan ◽  
Igneous Origin ◽  
Accessory Phase ◽  
Metamorphic Terrane

AbstractA recent study of granitic gneisses in the ultrahigh-pressure (UHP) metamorphic terrane from Dabie Shan, central China reveals that allanite-(Ce) is a widespread REE-bearing accessory phase. The microprobe analyses show that allanites-(Ce) have nearly uniform chemical compositions, with total REE contents ranging from 23 to 28 wt.% and a La/Ce ratio of 0.57–0.73. All allanites-(Ce) are replaced or rimmed by epidotes and commonly form a relatively REE-poor rim near the interfaces. The textural relations and mineral chemistry suggest that allanite-(Ce) crystallized prior to metamorphism and therefore was of igneous origin, whereas the surrounding epidote was the product of metamorphism. Granitic gneiss, composed chiefly of sodic plagioclase, microcline and quartz with minor amounts of Mn-rich garnet, biotite, low Si phengitic mica, epidote, chlorite and sometimes amphibole, was formed at 495°C and ∼5 kbar, corresponding to the retrograde metamorphism of UHP rocks. Accordingly, it is believed that granitic gneisses have not experienced UHP metamorphism. This implies that a large scale tectonic juxtaposition developed before the epidote-amphibolite facies retrograde metamorphism of UHP rocks during the late continental collision in Dabie Shan.

Texturally Controlled U–Th–Pb Monazite Geochronology Reveals Paleoproterozoic UHT Metamorphic Evolution in the Khondalite Belt, North China Craton

2020 ◽  
Vol 61 (1) ◽  
Author(s):  
Shujuan Jiao ◽  
Ian C W Fitzsimons ◽  
Jian-Wei Zi ◽  
Noreen J Evans ◽  
Brad J Mcdonald ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Mineral Chemistry ◽  
Matrix Group ◽  
Metamorphic Evolution ◽  
The North ◽  
Group 5 ◽  
Group 2 ◽  
Uht Metamorphism ◽  
Khondalite Belt

Abstract Sapphirine-bearing UHT granulites from the Dongpo locality in the Khondalite Belt of the North China Craton have been comprehensively characterized in terms of petrology, mineral chemistry, metamorphic evolution and zircon geochronology. However, the precise timing of the peak-UHT metamorphism and other key stages in the P–T–t evolution remain controversial due to the complexity of multiple metamorphic overprints and the lack of petrographic context for zircon age data. In this study, monazite from four samples of the Dongpo granulite are divided into six groups based on chemical composition and textural context, and dated (in-situ SHRIMP and LA–ICP–MS U–Pb). An age population of 1·91–1·88 Ga was obtained from high-Y cores of monazite inclusions in garnet (Group 1) and on grains in the rock matrix (Group 2). The maximum age of c.1·91 Ga is interpreted as the minimum timing for prograde metamorphism before UHT metamorphism (M1). An age population of 1·90–1·85 Ga was obtained from low-Y domains of monazite inclusions (Group 3) and of matrix grains (Group 4). Combined with previous zircon dating results, the age population from low-Y Mnz constrains the timing and duration of the UHT metamorphism to 1·90–1·85 Ga and 50 (±15) million years, respectively. The large (50 m.y.) age spread is interpreted to reflect continuous monazite formation, and it is consistent with the slow post-peak near-isobaric cooling stage (M2). An age of c.1·86 Ga was obtained from monazite in textural contact with sapphirine/spinel + plagioclase intergrowths (Group 5), which is interpreted as the timing of the subsequent decompression–heating stage (M3). The younger age clusters at c.1·80 and 1·77 Ga, obtained from Th-rich monazite rims (Group 6) and one single Th-depleted monazite in textural contact with matrix biotite, respectively, indicate dissolution–reprecipitation and new monazite growth from fluid released by crystallizing anatectic melt during retrogression. These results, along with the previous 1·93–1·91 Ga data for UHT metamorphism, suggest that there was a very long-lived Paleoproterozoic UHT metamorphism (1·93–1·85 Ga) in the Khondalite Belt of the North China Craton. This supports the large hot orogeny model for the generation of Paleoproterozoic UHT metamorphism in the Khondalite Belt during the amalgamation of the Nuna supercontinent.

Petrogenesis and tectonic implications of A-type granites in the Dabie orogenic belt, China: geochronological and geochemical constraints

2009 ◽  
Vol 146 (5) ◽  
pp. 638-651 ◽  
Author(s):  
LING CHEN ◽  
CHANG-QIAN MA ◽  
ZHEN-BING SHE ◽  
ROGER MASON ◽  
JIN-YANG ZHANG ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Eastern China ◽  
Volcanic Rocks ◽  
Orogenic Belt ◽  
The Body ◽  
Geochemical Data ◽  
Late Mesozoic ◽  
The North ◽  
Dabie Orogenic Belt ◽  
Type Granite

AbstractThe Dabie orogenic belt is characterized by the presence of large volumes of intrusive and volcanic rocks that formed in Late Mesozoic times. Most of the intrusive bodies are I-type granites but it is still unclear whether there are contemporary A-type granites. Here, we report the first unambiguous discovery of A-type granite from Baiyashan in the North Dabie tectonic belt. The crystallization age of the body has been fixed as 120.4 ± 1.2 Ma using U–Pb analysis of zircons by LA-ICPMS. The Baiyashan granite is enriched in Si, K, Na, Rb and REE, has elevated FeOtot/(FeOtot + MgO) and Ga/Al ratios, and is depleted in Mg, Ca, Mn, Ba, Sr, P and Ti. The REE composition shows highly fractionated patterns with (La/Yb)N = 6.95–16.68 and Eu*/Eu = 0.33–0.59. Its crystallization age, field relationships, petrographic and geochemical data show beyond doubt that the Baiyashan granite is an Early Cretaceous A-type granite. Sr–Nd isotope systematics are characterized by a high ISr of 0.708–0.714 and a low ɛNd of −7.5 to −19.4, with TDM2 = 1.5–2.5 Ga, and these data indicate that the magmas were dominantly sourced from partial melting of middle to lower crustal intermediate-felsic igneous rocks and mingling with mafic to intermediate magmas, during rift-related magmatism associated with subduction of the Palaeo-Pacific Plate beneath Eastern China in Early Cretaceous times.

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