UHP impure marbles from the Dabie Mountains: Metamorphic evolution and carbon cycling in continental subduction zones

Liu, Penglei; Wu, Yao; Chen, Yi; Zhang, Junfeng; Zhang, Jin

doi:10.1016/j.lithos.2014.11.018

Cited by 27 publications

(18 citation statements)

References 98 publications

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“…In addition to coesite, some other UHP indicators have also been reported, such as diamond (Xu et al, ; Xu et al, ), magnetite lamellae in olivine (Zhang et al, ), α‐PbO 2 ‐type TiO 2 lamellae in rutile (Wu et al, ), and clinoenstatite exsolution in clinopyroxene (Liu et al, ). Peak P‐T conditions for the Dabie UHP rocks are normally constrained to 3.0–4.5 GPa and 650–750 °C (e.g., Carswell et al, ; Guo et al, ; Liu et al, ; Okay, ; Schmid et al, ; Wei et al, ). A nearly isothermal decompression is commonly envisaged after the peak UHP metamorphism, which was followed by an amphibolite‐ to epidote‐amphibolite‐facies overprint.…”

Section: Geological Setting and Samplingmentioning

confidence: 99%

“…The preservation of such an oxygen isotope signature in these rocks after deep subduction suggests limited fluid activities during UHP metamorphism (Rumble et al, ; Zhang et al, ; Zheng et al, ). During exhumation, the fluid activities became stronger, as recorded by the formation of amphibole and zoisite porphyroblasts (Massonne, ) and the wide occurrence of various eclogite‐facies veins in UHP rocks (e.g., Chen et al, ; Guo et al, ; Liu et al, ; Zhang et al, ; Zheng et al, ). These veins generally consist of various combinations of quartz, kyanite, epidote‐group minerals, garnet, omphacite, phengite, paragonite, rutile, and apatite, most of which were directly precipitated from the circulating aqueous fluids.…”

Section: Geological Setting and Samplingmentioning

confidence: 99%

“…It is believed to have been enclosed by the marbles as dolomite is a rock‐forming mineral in the sample, which is a common feature for those in situ eclogites in the marble. Earlier studies of the impure marbles have led to the discovery of coesite inclusions in dolomite and the derivation of peak P‐T conditions of 4.2 ± 0.32 GPa and 745 ± 65 °C (Liu et al, ). In addition, intergranular coesite has been found in a dolomite‐rich metasedimentary rock from this outcrop (Liu, Massonne, Zhang, et al, ).…”

Section: Geological Setting and Samplingmentioning

confidence: 99%

“…Geochemistry, Geophysics, Geosystems and zoisite porphyroblasts (Massonne, 2012) and the wide occurrence of various eclogite-facies veins in UHP rocks (e.g., Chen et al, 2012;Guo et al, 2012;Liu et al, 2015;Zhang et al, 2008;Zheng et al, 2007). These veins generally consist of various combinations of quartz, kyanite, epidote-group minerals, garnet, omphacite, phengite, paragonite, rutile, and apatite, most of which were directly precipitated from the circulating aqueous fluids.…”

Section: 1029/2019gc008521mentioning

confidence: 99%

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High‐Pressure Fluid‐Rock Interaction and Mass Transfer During Exhumation of Deeply Subducted Rocks: Insights From an Eclogite‐Vein System in the Ultrahigh‐Pressure Terrane of the Dabie Shan, China

Liu

Massonne

Harlov

et al. 2019

Geochem Geophys Geosyst

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A petrological study was performed on an eclogite-vein system from the Dabie ultrahigh-pressure terrane by focusing on high-pressure (HP) fluid-rock interaction and mass transfer during exhumation. The veins comprise mainly garnet and quartz and resulted from a HP leaching process along fractures in the eclogite during exhumation. Relict peak garnet, phengite, and apatite in this rock system were altered by HP fluids forming characteristic compositional zonings. Zoned garnet in the eclogite records an isothermal exhumation from 3.3 GPa and 665-680°C. Partial dissolution of garnet and a back incorporation of Mn-heavy rare earth element (REE)-Y increased the content of these elements in the altered garnet zone in the veins. Altered phengite is characterized by a Ba-rich rim. Fluid-aided alteration reduced the light REE (LREE) contents and produced oriented monazite, calcite, and pyrrhotite inclusions within apatite, reflecting mobilization and redistribution of LREEs, CO 3 2− , Fe, and S between these minerals. The active HP fluid is proposed to have been a Si-Al-Na-Ba-rich aqueous fluid, as indicated by sodic plagioclase rims around various eclogitic minerals and by the altered phengite composition. Mass balance calculations reveal that LREEs, middle REEs, and Zr-Hf-Th-U were added to and Li, large ion lithophile elements, and Ti-Nb were removed from the quartz-garnet veins, requiring a high fluid flux. These findings shed new light on the nature and behavior of HP fluids and highlight their key role in resetting mineral chemistry and mass transfer in subduction zone metamorphic environments. . (2019). High-pressure fluid-rock interaction and mass transfer during exhumation of deeply subducted rocks: insights from an eclogite-vein system in the ultrahigh-pressure terrane of the Dabie The Dabie-Sulu orogenic belt in east-central China is considered to be one of the largest UHP terranes on Earth. This belt resulted from the Triassic continental collision between the North China and South China blocks (Ernst et al., 2007;Li et al., 1993;Zhang et al., 2009). It is separated into the eastern Sulu terrane and the western Dabie terrane by the sinistral Tanlu strike-slip fault. The western part of the Dabie terrane is further truncated by the Shangma fault and known as the Hongan terrane (Figure 1a).Several large-scale EW trending faults divide the Dabie terrane into five major lithotectonic units with different metamorphic histories (Hacker et al., 2000;Zheng et al., 2005). From north to south, these units are (1) the Beihuaiyang greenschist-facies unit made up of low-grade metasedimentary and metaigneous rocks that are overlain by Jurassic-Cretaceous sedimentary and volcanic rocks; (2) the North Dabie high-T granulite-facies unit composed of typical amphibolite-to granulite-facies rocks, migmatitic gneisses, and minor mafic to ultramafic rocks; (3) the Central Dabie medium-T/UHP eclogite-facies unit including abundant orthogneisses and paragneisses that enclose subordinate bodies of coesite-bearing eclogite, pure to imp...

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Section: Geological Setting and Samplingmentioning

confidence: 99%

Section: Geological Setting and Samplingmentioning

confidence: 99%

Section: Geological Setting and Samplingmentioning

confidence: 99%

Section: 1029/2019gc008521mentioning

confidence: 99%

See 2 more Smart Citations

High‐Pressure Fluid‐Rock Interaction and Mass Transfer During Exhumation of Deeply Subducted Rocks: Insights From an Eclogite‐Vein System in the Ultrahigh‐Pressure Terrane of the Dabie Shan, China

Liu

Massonne

Harlov

et al. 2019

Geochem Geophys Geosyst

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“…However, there are multiple examples of coesite preserved in non‐rigid minerals, such as dolomite (e.g. Liu, Massonne, Zhang, Wu, & Jin, ; Liu, Wu, Chen, Zhang, & Jin, ; Mosenfelder, Schertl, Smyth, & Liou, ; Zhang & Liou, ), suggesting that a high internal over‐pressure during decompression is not the only viable explanation for its conservation. Indeed, Parkinson () described a systematic zonal distribution of different types of silica inclusions in garnet, from low‐temperature quartz in the cores outward through a mantle with inverted, partially inverted and pristine coesite to an inclusion‐free rim.…”

Section: Introductionmentioning

confidence: 99%

On the survival of intergranular coesite inUHPeclogite

Wang

Brown

et al. 2017

Journal Metamorphic Geology

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Coesite is typically found as inclusions in rock‐forming or accessory minerals in ultrahigh‐pressure (UHP) metamorphic rocks. Thus, the survival of intergranular coesite in UHP eclogite at Yangkou Bay (Sulu belt, eastern China) is surprising and implies locally “dry” conditions throughout exhumation. The dominant structures in the eclogites at Yangkou are a strong D2 foliation associated with tight‐to‐isoclinal F2 folds that are overprinted by close‐to‐tight F3 folds. The coesite‐bearing eclogites occur as rootless intrafolial isoclinal F1 fold noses wrapped by a composite S1–S2 foliation in interlayered phengite‐bearing quartz‐rich schists. To evaluate controls on the survival of intergranular coesite, we determined the number density of intergranular coesite grains per cm2 in thin section in two samples of coesite eclogite (phengite absent) and three samples of phengite‐bearing coesite eclogite (2–3 vol.% phengite), and measured the amount of water in garnet and omphacite in these samples, and also in two samples of phengite‐bearing quartz eclogite (6–7 vol.% phengite, coesite absent). As coesite decreases in the mode, the amount of primary structural water stored in the whole rock, based on the nominally anhydrous minerals (NAMs), increases from 107/197 ppm H2O in the coesite eclogite to 157–253 ppm H2O in the phengite‐bearing coesite eclogite to 391/444 ppm H2O in the quartz eclogite. In addition, there is molecular water in the NAMs and modal water in phengite. If the primary concentrations reflect differences in water sequestered during the late prograde evolution, the amount of fluid stored in the NAMs at the metamorphic peak was higher outside of the F1 fold noses. During exhumation from UHP conditions, where NAMs became H2O saturated, dehydroxylation would have generated a free fluid phase. Interstitial fluid in a garnet–clinopyroxene matrix at UHP conditions has dihedral angles >60°, so at equilibrium fluid will be trapped in isolated pores. However, outside the F1 fold noses strong D2 deformation likely promoted interconnection of fluid and migration along the developing S2 foliation, enabling conversion of some or all of the intergranular coesite into quartz. By contrast, the eclogite forming the F1 fold noses behaved as independent rigid bodies within the composite S1–S2 foliation of the surrounding phengite‐bearing quartz‐rich schists. Primary structural water concentrations in the coesite eclogite are so low that H2O saturation of the NAMs is unlikely to have occurred. This inherited drier environment in the F1 fold noses was maintained during exhumation by deformation partitioning and strain localization in the schists, and the fold noses remained immune to grain‐scale fluid infiltration from outside allowing coesite to survive. The amount of inherited primary structural water and the effects of strain partitioning are important variables in the survival of coesite during exhumation of deeply subducted continental crust. Evidence of UHP metamorphism may be preserved in similar isolated st...

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Porous Covalent Organic Framework Based Hydrogen‐Bond Nanotrap for the Precise Recognition and Separation of Gold

Qiu

et al. 2023

Angewandte Chemie

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Utilizing weak interactions to effectively recover and separate precious metals in solution is of great importance but the practice remains a challenge. Herein, we report a novel strategy to achieve precise recognition and separation of gold by regulating the hydrogen‐bond (H‐bond) nanotrap within the pore of covalent organic frameworks (COFs). It is found that both COF‐HNU25 and COF‐HNU26 can efficiently capture AuIII with fast kinetics, high selectivity, and uptake capacity. In particular, the COF‐HNU25 with the high density of H‐bond nanotraps exhibits an excellent gold uptake capacity of 1725 mg g−1, which is significantly higher than that (219 mg g−1) of its isostructural COF (COF‐42) without H‐bond nanostrap in the pores. Importantly, the uptake capacity is strongly correlated to the number of H‐bonds between phenolic OH in the COF and [AuCl4]− in water, and multiple H‐bond interactions are the key driving force for the excellent gold recovery and reusability of the adsorbent.

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UHP impure marbles from the Dabie Mountains: Metamorphic evolution and carbon cycling in continental subduction zones

Cited by 27 publications

References 98 publications

High‐Pressure Fluid‐Rock Interaction and Mass Transfer During Exhumation of Deeply Subducted Rocks: Insights From an Eclogite‐Vein System in the Ultrahigh‐Pressure Terrane of the Dabie Shan, China

High‐Pressure Fluid‐Rock Interaction and Mass Transfer During Exhumation of Deeply Subducted Rocks: Insights From an Eclogite‐Vein System in the Ultrahigh‐Pressure Terrane of the Dabie Shan, China

On the survival of intergranular coesite inUHPeclogite

Porous Covalent Organic Framework Based Hydrogen‐Bond Nanotrap for the Precise Recognition and Separation of Gold

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