91 results on '"Thomas, Bader"'
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2. Petrology of UHP eclogite-facies felsic schist in the Western Tianshan subduction zone, China
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Lijuan Zhang, Lifei Zhang, Ning Qi, and Thomas Bader
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quartz ,felsic schist ,UHP metamorphism ,exhumation ,deformation ,Science - Abstract
Although quartzo-feldspathic metasedimentary rocks are widespread in high pressure-ultrahigh pressure (HP-UHP) metamorphic belts worldwide, their petrogenesis and metamorphic evolution is poorly understood. We discovered an UHP eclogite-facies felsic schist in the Western Tianshan metamorphic belt, China. Petrological observations and phase equilibria modeling both indicate the felsic schist experienced UHP metamorphism in the coesite stability field. In particular, it experienced prograde metamorphism at 21–24 kbar, 445°C–470°C, a pressure peak at 25–28 kbar and 490°C–525°C, and eventually heating with decompression to 20 kbar and 560°C. The obtained clockwise P-T path was consistent with those of other lithologies (eclogite and pelitic schist) from the same belt, which provides new evidence for the coherent exhumation of the UHP unit of the Western Tianshan metamorphic belt. The final uplift of the Western Tianshan oceanic crust to the surface is attributed to fluid activity and late tectonic deformation.
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- 2023
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3. Metamorphic PT path, U-Pb zircon dating and tectonic implications of High-pressure Pelitic Granulites from the Kharta region, Southern Tibet, China
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Lifei Zhang, Qingyun Li, Guibin Zhang, Chenguang Wu, Thomas Bader, Yang Wang, and Xu Chu
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Grossular ,Metamorphic rock ,Geochemistry ,Geology ,engineering.material ,Granulite ,visual_art ,visual_art.visual_art_medium ,engineering ,Eclogite ,Sillimanite ,Biotite ,Zircon ,Gneiss - Abstract
HP pelitic granulites associated with eclogites from the Kharta Gneiss are found in the Thongmon area, central Himalaya, which provides significant constraints for the tectonic evolution of the Himalayan orogeny. Three generations of garnets are identified in pelitic granulites (DR15P15). The first generation of garnet is core sections of euhedral to subhedral porphyroblasts (Grt-I core) followed by growth of Grt-I mantle during the heating stage. The third generation of garnet is represented by thin rims of Grt-I and small grains (Grt-II) in the matrix, which likely nucleated and grew in response to peritectic reaction during exhumation. Petrographic evidence and P–T pseudosection calculation reveal a four-stages metamorphic evolution: 1) a prograde metamorphic stage (M1) represented by Grt-I core and its mineral inclusions rutile, ilmenite and quartz with metamorphic conditions of 740–760 °C and 13–16 kbar; 2) a near isobaric heating stage with slightly decompression to HP granulite-facies (M2, 820–840 °C, 13–14 kbar) indicated by the composition of Grt-I mantle and the increase of Zr concentrations of rutile in it; 3) a heating decompression stage (M3) supported by a decrease in grossular content in the Grt-I rim and higher XAn in plagioclase, yielding T > 860 °C and P = 10–11 kbar in the sillimanite stability field; 4) a final decompression stage followed by cooling (M4, T ~ 800 °C and P = 6–8 kbar) indicated by biotite replacing sillimanite and lower Ti content in biotite in the matrix. Based on the zircon trace element geochemistry, zircon inclusions, and the REE partitioning between garnet and zircon, the metamorphic zircon rims with middle Miocene age (16–13 Ma) probably grew during Grt-I rim/Grt-II formation at granulite facies stage (M3). The P–T history of the pelitic granulites of the Kharta Gneiss indicates that they were subducted beneath the Asian plate and exhumed to middle-lower crustal depths prior to 14–13 Ma due to the activity of STDS.
- Published
- 2022
4. Raman geobarometry of quartz inclusions in eclogitic garnet constrains the metamorphic evolution and exhumation of the Sumdo oceanic slab in Tibet
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Xiaoyu Liu, Tian Qiu, Tingting Shen, Thomas Bader, Cong Zhang, and Zhenqun Xiang
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Subduction ,Oceanic crust ,Metamorphic rock ,Slab ,Geology ,Eclogite ,Petrology ,Quartz ,Mantle (geology) ,Terrane - Abstract
Due to the high density at mantle depths, subducted oceanic crust rarely exhumes to the surface of Earth, making it challenging to determine the evolution and dynamic behavior of oceanic crust. The Sumdo eclogite-bearing metamorphic belt, located between the north and south Lhasa terranes in Tibet, is a natural laboratory for studying the metamorphic evolution of oceanic eclogites. We combined phase equilibrium modeling with detailed petrological investigations for the newly discovered Xilang eclogite from this belt and obtained near-peak metamorphic conditions of 539 °C at 1.84 GPa and a steep exhumation P–T path. These values are much lower than published for the other areas of this belt. Quartz inclusions sealed in garnet from high-pressure rocks are known to preserve residual pressures during exhumation, which can be used to reexamine the peak metamorphic conditions of eclogites in the Sumdo metamorphic belt. We analyzed quartz from three different areas in the belt, including Xilang, Jilang, and Xindaduo, with laser Raman micro spectroscopy. Xilang eclogite preserved the highest residual pressure of 0.53 ± 0.07 GPa in the quartz stability field. A systematic comparison of the residual pressures of different eclogites revealed that not only the peak metamorphic conditions but also the exhumation rate of the host rocks controlled the residual pressure. Hence, the Xilang eclogite may record lower peak P–T conditions, because it exhumed differently than the eclogites from the other areas in the Sumdo metamorphic belt. Combined with numerical modeling, the residual pressures obtained by Raman spectroscopy may be a new way to compare the metamorphic conditions of eclogites and to obtain geochronological information in addition to isotopic investigations.
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- 2022
5. Tectonothermal transition from continental collision to post‐collision: Insights from eclogites overprinted in the ultrahigh‐temperature granulite facies (Yadong region, central Himalaya)
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Chenguang Wu, Lifei Zhang, Qingyun Li, Thomas Bader, Yang Wang, and Bin Fu
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Geochemistry and Petrology ,Geology - Published
- 2022
6. Massive abiotic methane production in eclogite during cold subduction
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Lijuan Zhang, Lifei Zhang, Ming Tang, Xiao Wang, Renbiao Tao, Cheng Xu, and Thomas Bader
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Multidisciplinary - Abstract
Methane (CH4) is a critical but overlooked component in the study of the deep carbon cycle. Abiotic CH4 produced by serpentinization of ultramafic rocks has received extensive attention, but its formation and flux in mafic rocks during subduction remain poorly understood. Here, we report massive CH4-rich fluid inclusions in well-zoned garnet from eclogites in Western Tianshan, China. Petrological characteristics and carbon–hydrogen isotopic compositions confirm the abiotic origin of this CH4. Reconstructed P–T–fO2–fluid trajectories and Deep Earth Water modeling imply that massive abiotic CH4 was generated during cold subduction at depths of 50–120 km, whereas CO2 was produced during exhumation. The massive production of abiotic CH4 in eclogites may result from multiple mechanisms during prograde high pressure-ultrahigh pressure metamorphism. Our flux calculation proposes that abiotic CH4 that has been formed in HP-UHP eclogites in cold subduction zones may represent one of the largest, yet overlooked, sources of abiotic CH4 on Earth.
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- 2022
7. Lift-and-drop: crossing boundaries in a multi-display environment by Airlift.
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Thomas Bader, Astrid Heck, and Jürgen Beyerer
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- 2010
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8. Lift-and-Drop - Lückenlose Interaktion über Displaygrenzen hinweg.
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Thomas Bader and Astrid Heck
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- 2010
9. Multimodal integration of natural gaze behavior for intention recognition during object manipulation.
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Thomas Bader, Matthias Vogelgesang, and Edmund Klaus
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- 2009
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10. Fast Invariant Contour-Based Classification of Hand Symbols for HCI.
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Thomas Bader, René Räpple, and Jürgen Beyerer
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- 2009
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11. Model-based Motion Estimation of Elastic Surfaces for Minimally Invasive Cardiac Surgery.
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Thomas Bader, Alexander Wiedemann, Kathrin Roberts, and Uwe D. Hanebeck
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- 2007
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12. Cold subduction recorded by the 1.9 Ga Salma eclogite in Belomorian Province (Russia)
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Xiaoli Li, Lifei Zhang, Chunjing Wei, Thomas Bader, and Jinghui Guo
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Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) - Published
- 2023
13. The metamorphic PT history of Precambrian Belomorian eclogites (Shirokaya Salma), Russia
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Thomas Bader, Lifei Zhang, and Xiaoli Li
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Precambrian ,Geochemistry and Petrology ,Metamorphic rock ,Geochemistry ,Geology ,Eclogite - Published
- 2020
14. Impact of cigarette smoke on physical‐chemical and molecular proprieties of human skin in an ex vivo model
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Florine Eudier, Giuseppe Percoco, Angela Patatian, Michel Grisel, Géraldine Savary, Thomas Bader, Elian Lati, Philippe Benech, Céline Picard, Unité de Recherche en Chimie Organique et Macromoléculaire (URCOM), Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), Institut de neurophysiopathologie (INP), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
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0301 basic medicine ,Chemical Phenomena ,surface physico-chemistry ,Human skin ,Dermatology ,In Vitro Techniques ,Biochemistry ,Skin Aging ,030207 dermatology & venereal diseases ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Downregulation and upregulation ,Skin Physiological Phenomena ,Smoke ,Humans ,Molecular Biology ,transcriptomic analysis ,Skin ,[SDV.EE.SANT]Life Sciences [q-bio]/Ecology, environment/Health ,Transepidermal water loss ,integumentary system ,Epidermis (botany) ,cigarette smoke ,mitochondrial alterations ,Tobacco Products ,Malondialdehyde ,3. Good health ,030104 developmental biology ,chemistry ,[SDV.TOX]Life Sciences [q-bio]/Toxicology ,[SDE]Environmental Sciences ,skin exposome ,Biophysics ,[SDV.MHEP.DERM]Life Sciences [q-bio]/Human health and pathology/Dermatology ,Ex vivo ,Immunostaining - Abstract
International audience; This is a study about the skin aging exposome, focusing on the effect of cigarette smoke.Human living skin explants (HSE) were exposed to cigarette smoke (CS) of two cigarettes for 2 hours using a custom-made exposure chamber, the Pollubox®. Effects on the surface physico-chemistry and molecular properties of the skin were analyzed and reported for the first time. To this end, transcriptomic study followed by immunohistochemistry, malondialdehyde dosage (MDA) and surface physio-chemistry data (surface free energy determination, TEWL, skin pH and FTIR spectroscopy of the explant) were collected from non-treated and treated HSE.Results showed a decrease of the total surface free energy of the treated HSE. This decrease reflected higher interactions with polar compounds from the environment and consequently a decrease of the surface hydrophobicity. Additionally, an increase of TEWL and skin pH was observed after treatment. The transcriptomic analysis showed downregulation of mitochondrial genes (PON2-NDUFA4L2-ATP1A1-ALDH2-PRODH) combined with an increase of MDA in CS-treated HSE. CS-induced oxidation of lipids at HSE surface alters the skin barrier: interactions with polar products are enhanced and the lipid chain packing at the surface is modified. Consequently, skin permeability could increase which correlated with repression of CA9 and AQP1 genes. Beside activation of AHR-NRF2 pathway in CS-exposed HSE, our results suggested that mitochondrial functions were strongly impacted and oxidized lipids failed to be eliminated promoting skin barrier alteration. A mitophagy activity was suggested through the confirmation of PINK1 accumulation in the epidermis by immunostaining.
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- 2020
15. Correction to: Melting of carbonated pelite at 5.5–15.5 GPa: implications for the origin of alkali‑rich carbonatites and the deep water and carbon cycles
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Xueqian Chen, Meili Wang, Toru Inoue, Qiong Liu, Lifei Zhang, and Thomas Bader
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Geophysics ,Geochemistry and Petrology - Published
- 2022
16. High‐P granulites of the Songshugou area (Qinling Orogen, east‐central China): Petrography, phase relations, and U/Pb zircon geochronology
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Thomas Bader, Bin Xia, Lifei Zhang, Leander Franz, Qingyun Li, Xiaowei Li, and Christian de Capitani
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010504 meteorology & atmospheric sciences ,Metamorphic rock ,Geochemistry ,Geology ,010502 geochemistry & geophysics ,Granulite ,01 natural sciences ,Kyanite ,Continental arc ,Geochemistry and Petrology ,visual_art ,visual_art.visual_art_medium ,Eclogite ,Mafic ,Metamorphic facies ,0105 earth and related environmental sciences ,Zircon - Abstract
High-pressure (HP) granulites provide telling records of mineral reactions at upper mantle to lower crustal levels and key information on the fate of material in subduction systems. The latter especially applies when they abut eclogite and mantle dunite because such rock associations are crucial for understanding the incompletely known processes at the interface of converging plates. A continental arc, active c. 520-395 Ma ago, formed an enigmatic example of such a rock association in the Songshugou area, Qinling Orogen. To unravel the juxtaposition of the distinct rocks, this study combines petrography, phase equilibria modelling, conventional thermobarometry, and zircon U-Th-Pb-Ti-REE analysis. Two mafic HP granulites, which contain the mineral assemblages garnet-clinopyroxene-plagioclase-rutile-mesoperthite-quartz and garnet-clinopyroxene-plagioclase-rutile, experienced peak metamorphic conditions of ≤1.4 GPa, 860°C and ~1.3 GPa, ≥910°C, respectively. During decompression and cooling, at 489 ± 4 Ma, amphibole lamellae unmixed from a clinopyroxene solid solution and orthopyroxene in part replaced garnet. A felsic HP granulite shows equilibration of garnet, perthite, antiperthite, kyanite, quartz, and rutile at 810-860°C, ~1.2 GPa, sillimanite growth during decompression, and upper amphibolite facies cooling at 510 ± 4 Ma. Though the thermobarometric data are just within the methodological errors, the U/Pb zircon ages imply the HP granulites did not evolve coherently. The HP granulites either represent foundered lower arc crust or originated from subduction erosion because their geochemistry is indistinguishable from that of the hanging-wall plate. Published and new pressure-temperature-time-deformation paths converge at ~710°C, ~0.9 GPa, and ≲470 Ma, implying exhumation tectonics juxtaposed the HP granulites with a melange of eclogite and mantle dunite at lower crustal levels. This study highlights that lower arc crust can comprise material of diverse evolution.
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- 2020
17. Melting of carbonated pelite at 5.5–15.5 GPa: implications for the origin of alkali-rich carbonatites and the deep water and carbon cycles
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Xueqian Chen, Meili Wang, Toru Inoue, Qiong Liu, Lifei Zhang, and Thomas Bader
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Geophysics ,Geochemistry and Petrology - Published
- 2021
18. The metamorphic evolution of Salma-type eclogite in Russia: Constraints from zircon/titanite dating and phase equilibria modeling
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Chunjing Wei, Thomas Bader, Huanglu Yu, Lifei Zhang, Lijuan Zhang, Jinghui Guo, Yunfei Qi, and Xiaoli Li
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010504 meteorology & atmospheric sciences ,Geochemistry ,Metamorphism ,Geology ,engineering.material ,010502 geochemistry & geophysics ,Granulite ,01 natural sciences ,Geochemistry and Petrology ,Titanite ,Facies ,engineering ,Eclogite ,Metamorphic facies ,0105 earth and related environmental sciences ,Zircon ,Gneiss - Abstract
Combined geochronology with phase equilibria modeling, the P-T-t evolution of metamorphic rocks can be deciphered. Four different representative samples, including retrogressed eclogite, garnetite, paragneiss and tonalite–trondhjemite–granodiorite (TTG) gneiss have been selected for detailed petrography and U/Pb dating from the Belomorian Eclogite Province in Russia. Zircon cores yield Archean ages for the protoliths of these samples. Zircon rims of the TTG gneiss have recorded Neoarchean anataxis at ca 2.73 Ga, whereas 1.91–1.92 Ga zircon rims of the garnetite and the paragneiss have dated high-pressure granulite facies metamorphism. Titanite in the retrogressed eclogite has recorded amphibolite facies retrogression at ca 1.86 Ga. Phase equilibria modelings for retrogressed eclogite, garnetite, and paragneiss define P-T conditions of 17–18 kbar/below 790 °C for the peak eclogite facies metamorphism, 11–12 kbar/870–900 °C for the high-pressure granulite facies metamorphism, and 8–10 kbar/650–710 °C for titanite’s stability which corresponds to the amphibolite facies metamorphism. A clockwise P-T path is inferred for the Salma-type eclogite, which is characterized by thermal relaxation from the peak eclogite facies to the high-pressure granulite facies, and nearly isobaric cooling from the high-pressure granulite facies to the amphibolite facies.
- Published
- 2019
19. Is the Songshugou Complex, Qinling Belt, China, an Eclogite Facies Neoproterozoic Ophiolite?
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Lifei Zhang, Thomas Bader, and Xiaowei Li
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020209 energy ,Continental crust ,Metamorphic rock ,Geochemistry ,02 engineering and technology ,010502 geochemistry & geophysics ,Ophiolite ,01 natural sciences ,Ultramafic rock ,0202 electrical engineering, electronic engineering, information engineering ,General Earth and Planetary Sciences ,Eclogite ,Mafic ,Protolith ,Geology ,Metamorphic facies ,0105 earth and related environmental sciences - Abstract
Ophiolites play a key role in understanding subduction-accretion-collision processes. Herein, we discuss origin and metamorphic evolution of an enigmatic, Neoproterozoic ophiolite candidate—the mafic-ultramafic Songshugou Complex, Qinling belt, China—summarizing published thermobarometry, U/Pb geochronology, and geochemistry and presenting new phase equilibrium modeling. Garnet, rarely preserved in amphibolites of the Songshugou Complex, has prograde zoning and low-pyrope cores [Alm54−71 (Grs+And)25−30Prp1−6Sps5−12]. It formed at quartz eclogite facies conditions of 1.93–2.54 GPa, 462–542 °C. During exhumation, garnet first was mantled by plagioclase-rich coronas at about 0.7–1.2 GPa, 660–710 °C. During an isothermal uplift to 0.5–0.8 GPa, these coronas evolved widely into σ-shaped aggregates and eventually into whitish ribbons oriented with a steeply southwest dipping mineral stretching lineation. The exhumation into middle-upper crustal levels proceeded till the Late Devonian. The oceanic protoliths of the eclogites were emplaced into continental crust in the Neoproterozoic and dragged into a subduction zone in North Qinling in the Cambrian. The ultramafic rocks of the Songshugou Complex were not subducted with the mafic rocks in a coherent block given the absence of garnet but ubiquitous occurrence of spinel implies a P maximum of ≈1.7 GPa. Rather, mafic and ultramafic rocks belonged to downgoing and overriding plate, respectively. They were juxtaposed at 0.8–1.7 GPa at Early Ordovician time.
- Published
- 2019
20. The Exhumation of Subducted Oceanic‐Derived Eclogites: Insights From Phase Equilibrium and Thermomechanical Modeling
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Yang Wang, Thomas Bader, Zhong-Hai Li, Qingyun Li, and Lifei Zhang
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Geophysics ,Subduction ,Geochemistry and Petrology ,Phase equilibrium ,Eclogite ,Petrology ,Gloss (optics) ,Geology - Published
- 2019
21. Petrology and zircon U–Pb dating of well‐preserved eclogites from the Thongmön area in central Himalaya and their tectonic implications
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Thomas Bader, Huanglu Yu, Lifei Zhang, Bin Fu, and Qingyun Li
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Tectonics ,010504 meteorology & atmospheric sciences ,Geochemistry and Petrology ,Geology ,Eclogite ,010502 geochemistry & geophysics ,Petrology ,01 natural sciences ,0105 earth and related environmental sciences ,Zircon - Published
- 2018
22. 2nd workshop on eye gaze in intelligent human machine interaction.
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Yukiko I. Nakano, Cristina Conati, and Thomas Bader
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- 2011
- Full Text
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23. Metamorphic Evolution and Exhumation Processes of the Newly Discovered Xilang Eclogite in Tibet—constraints from Phase Equilibrium Modeling and Raman Microspectroscopy
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Cong Zhang, Thomas Bader, Herman van Roermund, and Jingsui Yang
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- 2020
24. The early exhumation history of the Western Tianshan UHP metamorphic belt, China: New constraints from titanite U-Pb geochronology and thermobarometry
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Lijuan Zhang, Lifei Zhang, Xu Chu, Xiaoli Li, Jin-Xue Du, Bin Fu, and Thomas Bader
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010504 meteorology & atmospheric sciences ,Metamorphic rock ,Foundation (engineering) ,Geochemistry ,Geology ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Geochemistry and Petrology ,Geochronology ,Titanite ,engineering ,Eclogite ,China ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Zircon - Abstract
the National Natural Science Foundation, Grant/Award Number: 41330210, 41702052; China Postdoctoral Science Foundation Funded Project, Grant/Award Number: 8201400768
- Published
- 2018
25. The metamorphic evolution and tectonic significance of the Sumdo HP–UHP metamorphic terrane, central-south Lhasa Block, Tibet
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Thomas Bader, Herman L.M. van Roermund, Tian Qiu, Tingting Shen, Jingsui Yang, Peng Li, and Cong Zhang
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010504 meteorology & atmospheric sciences ,Subduction ,Geochemistry ,Metamorphism ,Geology ,Ocean Engineering ,010502 geochemistry & geophysics ,Tethys Ocean ,01 natural sciences ,Oceanic crust ,Suture (geology) ,Eclogite ,Metamorphic facies ,0105 earth and related environmental sciences ,Water Science and Technology ,Terrane - Abstract
The Lhasa terrane, forming one of the main tectonic components of the Himalayan–Tibetan orogen, has received a lot of attention as it records multiple episodes of plate spreading, subduction and collision within the realm of the Paleo-Tethys Ocean. A review of the mineralogical, petrological, geochemical and geochronological data of eclogites, associated blueschists and garnet-bearing mica schists from the Sumdo high- and ultrahigh-pressure metamorphic (HP/UHP) complex in the central/southern part of the Lhasa terrane, is present here so that the origin and tectono-metamorphic evolution of this important suture can be deduced. By re-evaluating the original published P–T conditions for the metamorphic rocks of the Sumdo Complex, we consider that the Sumdo Complex has experienced low temperature HP/UHP metamorphic conditions, characteristic of fast subduction (and exhumation) in a typical oceanic subduction zone setting. The original wide spread in the maximal peak P–T conditions could be reduced in size due to thus far unknown inconsistencies in the usage of applied geothermobarometric techniques. The remaining spread in the maximal P–T conditions (c. 200°C/10 kbar) of the HP/UHP regions can be explained by a mechanism that the rocks from individual tectonic slices were subducted to different depths and followed by juxtaposition on their way back to the surface. A re-consideration of the isotopic ages of eclogites from the Sumdo Complex demonstrates that the opening of the Paleo-Tethys Ocean, located in between the two major components of the Lhasa terrane, was initiated prior to c. 280 Ma and the eclogite facies metamorphism is likely to be of late Permian (c. 260 Ma) to early Triassic age (245–225 Ma), recording different ages of subduction from individual slices of the oceanic crust. The closure of the Paleo-Tethys Ocean resulted, no earlier than 210 Ma, in the final collision between the northern and southern Lhasa blocks. This final collision event may have been triggered by the initial subduction of the Bangong–Nujiang Tethys Ocean in the north.
- Published
- 2018
26. Elemental and isotopic (C, O, Sr, Nd) compositions of Late Paleozoic carbonated eclogite and marble from the SW Tianshan UHP belt, NW China: Implications for deep carbon cycle
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Lifei Zhang, Zeng Lü, Thomas Bader, and Jianjiang Zhu
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Basalt ,010504 meteorology & atmospheric sciences ,Metamorphic rock ,Geochemistry ,Metamorphism ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,chemistry.chemical_compound ,chemistry ,Isotopes of carbon ,Carbonate ,Eclogite ,Protolith ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
Subduction zones are important for understanding of the global carbon cycle from the surface to deep part of the mantle. The processes involved the metamorphism of carbonate-bearing rocks largely control the fate of carbon and contribute to local carbon isotopic heterogeneities of the mantle. In this study, we present petrological and geochemical results for marbles and carbonated eclogites in the Southwestern Tianshan UHP belt, NW China. Marbles are interlayered with coesite-bearing pelitic schists, and have Sr-Nd isotopic values (eNd (T=320Ma) = −3.7 to −8.9, 87Sr/86Sr (i) = 0.7084–0.7089), typical of marine carbonates. The marbles have dispersed low δ18OVSMOW values (ranging from 14 to 29‰) and unaffected carbon isotope (δ13CVPDB = −0.2–3.6‰), possibly due to infiltration of external H2O-rich fluids. Recycling of these marbles into mantle may play a key role in the carbon budget and contributed to the mantle carbon isotope heterogeneity. The carbonated eclogites have high Sr isotopic compositions (87Sr/86Sr (i) = 0.7077–0.7082) and positive eNd (T = 320 Ma) values (from 7.6 to 8.2), indicative of strong seafloor alteration of their protolith. The carbonates in the carbonated eclogites are mainly dolomite (Fe# = 12–43, Fe# = Fe2+/(Fe2+ + Mg)) that were added into oceanic basalts during seafloor alteration and experienced calcite – dolomite – magnesite transformation during the subduction metamorphic process. The uniformly low δ18O values (∼11.44‰) of carbonates in the carbontaed eclogites can be explained by closed-system equilibrium between carbonate and silicate minerals. The low δ13C values (from −3.3 to −7.7‰) of the carbonated eclogites most likely reflect contribution from organic carbon. Recycling of these carbonated eclogites with C isotope similar to typical mantle reservoirs into mantle may have little effect on the mantle carbon isotope heterogeneity.
- Published
- 2018
27. Petrological Investigations and Zircon U-Pb Dating of High Pressure Felsic Granulites from the Yushugou Complex, South Tianshan, China
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Zeng Lü, Thomas Bader, Lifei Zhang, Bin Xia, Lu Zhang, and Jianjiang Zhu
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Felsic ,010504 meteorology & atmospheric sciences ,High pressure ,Geochemistry ,Geology ,010502 geochemistry & geophysics ,China ,Granulite ,01 natural sciences ,0105 earth and related environmental sciences ,Zircon - Published
- 2018
28. Teamarbeit am Digitalen Lagetisch mit Fovea-Tablett®.
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Elisabeth Peinsipp-Byma, Ralf Eck, Thomas Bader, and Jürgen Geisler
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- 2007
29. Masitinib combined with standard gemcitabine chemotherapy: in vitro and in vivo studies in human pancreatic tumour cell lines and ectopic mouse model.
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Martine Humbert, Nathalie Castéran, Sébastien Letard, Katia Hanssens, Juan Iovanna, Pascal Finetti, François Bertucci, Thomas Bader, Colin D Mansfield, Alain Moussy, Olivier Hermine, and Patrice Dubreuil
- Subjects
Medicine ,Science - Abstract
BackgroundTyrosine kinases are attractive targets for pancreatic cancer therapy because several are over-expressed, including PDGFRalpha/beta, FAK, Src and Lyn. A critical role of mast cells in the development of pancreatic cancer has also been reported. Masitinib is a tyrosine kinase inhibitor that selectively targets c-Kit, PDGFRalpha/beta, Lyn, and to a lesser extent the FAK pathway, without inhibiting kinases of known toxicities. Masitinib is particularly efficient in controlling the proliferation, differentiation and degranulation of mast cells. This study evaluates the therapeutic potential of masitinib in pancreatic cancer, as a single agent and in combination with gemcitabine.Methodology/findingsProof-of-concept studies were performed in vitro on human pancreatic tumour cell lines and then in vivo using a mouse model of human pancreatic cancer. Molecular mechanisms were investigated via gene expression profiling. Masitinib as a single agent had no significant antiproliferative activity while the masitinib/gemcitabine combination showed synergy in vitro on proliferation of gemcitabine-refractory cell lines Mia Paca2 and Panc1, and to a lesser extent in vivo on Mia Paca2 cell tumour growth. Specifically, masitinib at 10 microM strongly sensitised Mia Paca2 cells to gemcitabine (>400-fold reduction in IC(50)); and moderately sensitised Panc1 cells (10-fold reduction). Transcriptional analysis identified the Wnt/beta-catenin signalling pathway as down-regulated in the cell lines resensitised by the masitinib/gemcitabine combination.ConclusionsThese data establish proof-of-concept that masitinib can sensitise gemcitabine-refractory pancreatic cancer cell lines and warrant further in vivo investigation. Indeed, such an effect has been recently observed in a phase 2 clinical study of patients with pancreatic cancer who received a masitinib/gemcitabine combination.
- Published
- 2010
- Full Text
- View/download PDF
30. Laboratory for Process Research – Ten Years of Successful Partnership between University of Zurich and the Pharmaceutical Industry
- Author
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Thomas Bader
- Subjects
Api synthesis ,Gmp facility in university environment ,Joint venture ,Process research and development ,Training in industrial process chemistry ,Chemistry ,QD1-999 - Abstract
In 1996, the Laboratory for Process research (Labor für Prozessforschung = LPF) was founded as a collaboration between the University of Zurich and the pharmaceutical industry. This joint venture is based on the concept of providing a professional training platform in industrial process chemistry for Ph.D. graduates and performing highly sophisticated process research and development at the same time. The well-equipped LPF facilities, approved by swissmedic, operate according to the standards of Good manufacturing Practice (GmP). Chemical processes for manufacturing of active pharmaceutical ingredients (API) are developed from bench to production under GMP compliance. A large number of projects were successfully developed in the last decade, for which production was carried out at the LPF and/or after transfer of the whole technology to customers or contract manufacturers worldwide. In the course of these projects, the development of numerous innovative reactions and routes has resulted in several patents.
- Published
- 2006
- Full Text
- View/download PDF
31. Quartz and orthopyroxene exsolution lamellae in clinopyroxene and the metamorphicP-Tpath of Belomorian eclogites
- Author
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Lifei Zhang, Chunjing Wei, Alexander I. Slabunov, Xiaoli Li, and Thomas Bader
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Mineral ,010504 meteorology & atmospheric sciences ,Metamorphic rock ,Geochemistry ,Metamorphism ,Geology ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Geochemistry and Petrology ,engineering ,Plagioclase ,Omphacite ,Eclogite ,Quartz ,Amphibole ,0105 earth and related environmental sciences - Abstract
The Shirokaya Salma eclogite-bearing complex is located in the Archean-Paleoproterozoic Belomorian Province (Russia). Its eclogites and eclogitic rocks show multiple clinopyroxene breakdown textures, characterized by quartz-amphibole, orthopyroxene, and plagioclase lamellae. Representative samples, a fresh eclogite, two partly retrograded eclogites, and a strongly retrograded eclogitic rock, were collected for this study. Two distinct mineral assemblages – (1) omphacite+garnet+quartz+rutile±amphibole and (2) clinopyroxene+garnet+amphibole+plagioclase +quartz+rutile+ilmenite±orthopyroxene – are described. Based on phase equilibria modelling, these assemblages correspond to the eclogite- and granulite-facies metamorphism that occurred at 16-18 kbar, 750-800 °C and 11-15 kbar, 820-850 °C, respectively. The quartz-amphibole lamellae in clinopyroxene formed during retrogression with water ingress, but do not imply UHP metamorphism. The superfine orthopyroxene lamellae developed due to breakdown of an antecedent clinopyroxene (omphacite) during retrogression that was triggered by decompression from the peak of metamorphism, while the coarser orthopyroxene grains and rods formed afterwards. The P-T path reconstructed for the Shirokaya Salma eclogites is comparable to that of the adjacent 1.9 Ga Uzkaya Salma eclogite (Belomorian Province), and those of several other Paleoproterozoic high-grade metamorphic terranes worldwide, facts allowing us to debate the exact timing of eclogite-facies metamorphism in the Belomorian Province. This article is protected by copyright. All rights reserved.
- Published
- 2017
32. Phase relations and formation of K-bearing Al-10 Å phase in the MORB+H2O system: Implications for H2O- and K-cycles in subduction zones
- Author
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Renbiao Tao, Thomas Bader, Xi Liu, Lifei Zhang, and Yingwei Fei
- Subjects
Peridotite ,010504 meteorology & atmospheric sciences ,Lawsonite ,Subduction ,Muscovite ,Analytical chemistry ,Geochemistry ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,Geophysics ,Geochemistry and Petrology ,Ultramafic rock ,engineering ,Phlogopite ,Mafic ,Geology ,0105 earth and related environmental sciences - Abstract
The potassium (K) and water (H 2 O) cycles in subduction zones are predominately controlled by the stability of K- and H 2 O-bearing minerals, such as K-mica, lawsonite, and dense hydrous magnesium silicates (DHMS). K-micas (muscovite or phlogopite) are the principal H 2 O and K hosts in subduction zones and Earth’s upper mantle and play a significant role in the deep H 2 O and K cycles. The Mg-10 A phase, normally appearing in hydrated peridotite in high-pressure experiments, has been considered as an important water-carrier in subducted hydrated peridotite. In this study, we found a K-bearing Al-10 A phase in the MORB+H 2 O system (hydrated basalt) at high pressures according to X-ray diffraction and stoichiometry. We experimentally constrained its stability field at high pressure. By considering newly and previously documented compositions of the 10 A phase and micas, we confirmed a continuous solid solution or mixed layering between the 10 A phase and K-mica at the interlayer site, suggesting that the K cycle and the H 2 O cycle in subduction zones are coupled. From the discussion of the effect of f H 2 O on stability of the Al-10 A phase, we conclude that a cold subduction zone can host and carry more bulk H 2 O and K into Earth’s deep mantle than a hot one. This work expands the stability regions of the 10 A phase from the ultramafic system (Mg-10 A phase) to the mafic system (Al-10 A phase), and emphasizes the significance of the 10 A phase for the deep H 2 O and K cycle in subduction zone.
- Published
- 2017
33. Neoarchean-Paleoproterozoic granulite-facies metamorphism in Uzkaya Salma eclogite-bearing mélange, Belomorian Province (Russia)
- Author
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Xiaoli Li, Alexander I. Slabunov, Thomas Bader, Chunjing Wei, and Lifei Zhang
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010504 meteorology & atmospheric sciences ,Metamorphic rock ,Geochemistry ,Metamorphism ,Geology ,Epidote ,engineering.material ,010502 geochemistry & geophysics ,Granulite ,01 natural sciences ,Geochemistry and Petrology ,engineering ,Eclogite ,Omphacite ,Petrology ,0105 earth and related environmental sciences ,Gneiss ,Zircon - Abstract
A TTG gneiss of Uzkaya Salma, Belomorian Province and retrogressed eclogites embedded in it have been thoroughly analyzed. The gneiss is made of plagioclase, K-feldspar, biotite, and quartz with accessory epidote, chlorite, titanite and zircon. The retrogressed eclogite is featured by garnet, clinopyroxene, plagioclase, amphibole, and quartz with subordinate orthopyroxene, muscovite, epidote, and melt phase exhibiting a typical symplectic texture. Diversity of compositional zonation in garnets depends on different garnet diameters and is related to ion diffusion between garnet and clinopyroxene/amphibole during retrogression. Clinopyroxene is mostly diopside, although a few Jd-enriched varieties (Na-rich clinopyroxene) have been found at some sites, indicating an omphacite precursor. Plagioclase formed in both symplectites and aggregates displays a wide compositional range, revealing alteration at certain PT conditions. K-bearing ternary feldspar casually occurs in association with muscovite, zoisite/epidote, and melt phase, denoting a partial melting product. Phase equilibria modeling, combined with mineralogical constrains yielded a clock-wise PT path with peak conditions of P ≥ 17–18 kbar, T = 700–750 °C, followed by granulite-facies at P = 13–15 kbar, T = 800–850 °C, and, eventually into the (upper) amphibolite-facies of T ≤ 700–750 °C at lower pressures. A geothermal gradient of ∼12–13 °C/km is inferred accordingly, rather common for the Belomorian eclogites and some other eclogite/high-pressure granulite belts (EHPG) on Earth. Zircon U-Pb dating shows that the TTG gneiss formed at 2.73–2.74 Ga, while the protolith of the eclogites may have experienced magmatism/anatexis at ≥2.77 Ga. There is no implication of any Archean eclogite-facies metamorphism in this work. Nevertheless, a granulite-facies metamorphism, featured by a diopside + plagioclase + amphibole ± garnet, orthopyroxene assemblage, has been determined at 2.7 Ga that also superimposed the host gneiss. Afterwards, due to regional plume activities, repeated thermal events of granulite-facies metamorphism, occurred at least locally at 2.4–2.5 Ga. An eclogite-facies metamorphism at 1.9–2.0 Ga was dated only that corresponds to the Lapland-Kola orogeny. Further retrogression into the (upper) amphibolite-facies was documented at 1.8 Ga. The proposed metamorphic PT path corresponds to the late Paleoproterozoic eclogite-facies event, while before that, only (repeated) granulite-facies metamorphism has been recorded by zircons.
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- 2017
34. The metamorphic evolution of Paleoproterozoic eclogites in Kuru-Vaara, northern Belomorian Province, Russia: Constraints from P-T pseudosections and zircon dating
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Lifei Zhang, Chunjing Wei, Thomas Bader, Fenglin Liu, A. I. Slabunov, and Xiaoli Li
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010504 meteorology & atmospheric sciences ,Geochemistry ,Metamorphism ,Geology ,engineering.material ,010502 geochemistry & geophysics ,Granulite ,01 natural sciences ,Kyanite ,Geochemistry and Petrology ,visual_art ,Facies ,visual_art.visual_art_medium ,engineering ,Omphacite ,Eclogite ,Petrology ,Metamorphic facies ,0105 earth and related environmental sciences ,Zircon - Abstract
The rare occurrence of Precambrian eclogite has been used to argue when plate tectonics initiated. Well-preserved kyanite-bearing eclogites were collected in the Kuru-Vaara quarry, northern Belomorian Province, Fennoscandian Shield. Textural observations and phase equilibria modeling were applied to constrain their P-T evolution. The eclogite is characterized by the peak pressure assemblage garnet + omphacite + kyanite + amphibole + quartz. The garnet has inclusions of zoisite, omphacite and kyanite. This omphacite with high jadeite (up to 33 mol%) and 5% Ca-Eskola content bears oriented rods of quartz, amphibole, and rutile. Omphacite was replaced by diopside + plagioclase ± orthopyroxene symplectites and garnet surrounded by plagioclase coronas. Kyanite was mantled by the assemblage sapphirine + spinel + plagioclase ± scapolite. The symplectites of diopside + plagioclase ± orthopyroxene are further replaced by amphibole. P-T estimates of peak eclogite facies conditions are c. 18–20 kbar and 720–820 °C. The granulite facies assemblages formed at c. 11–13 kbar and 870–915 °C. Zircon U-Pb dating reveals the protolith ages of 2802–2929 Ma for the eclogites. The c. 1896 Ma zircon ages correspond to the time of prograde metamorphism in eclogite facies. The age of 1885 ± 7 Ma for a corundum-bearing mica pegmatite vein that intruded into the eclogites reflects the infiltration of fluid at amphibolite facies conditions. Thus, the Kuru-Vaara eclogite was metamorphosed during the Paleoproterozoic, not the Archean. The P-T path of Kuru-Vaara eclogites was characterized by eclogite facies metamorphism overprinted by granulite facies and retrograde amphibolite facies metamorphism within c. 10 Ma. This process reflects the fast exhumation of the eclogites. The increase in temperature from eclogite to granulite facies in the HT-UHT domain suggests a hot Precambrian tectonic environment.
- Published
- 2017
35. Modeling of wood under combination of normal stresses with rolling shear stress
- Author
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Shaheda Bakter, Thomas Bader, and Erik Serrano
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Trävetenskap ,Husbyggnad ,Wood Science ,Building Technologies - Published
- 2019
36. Nb–Ta mobility and fractionation during exhumation of UHP eclogite from southwestern Tianshan, China
- Author
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Lifei Zhang, Zeng Lü, Thomas Bader, Lijuan Zhang, and Zhen-Yu Chen
- Subjects
010504 meteorology & atmospheric sciences ,Lawsonite ,Metamorphic rock ,Geochemistry ,Metamorphism ,Geology ,Subduction zone metamorphism ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Rutile ,Titanite ,engineering ,Eclogite ,Vein (geology) ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
In order to study the behavior of high field strength elements (HFSE) during retrograde overprint of ultrahigh-pressure (UHP) eclogites, analysis of Nb and Ta concentrations was carried out on bulk rock, rutile (in both veins and host rocks) and titanite in the host eclogite. The studied samples were collected from the UHP metamorphic belt of southwestern Tianshan, China. Petrographic observation and phase equilibria modeling show that the host eclogites have experienced UHP metamorphism and the rutile-bearing veins are thought to be originated from an internal fluid source, probably by lawsonite dehydration during exhumation. The presence of vein rutile indicates HFSE could be mobilized from host eclogites to veins, which is probably facilitated by complexation with dissolved Na–Al silicates and fluorine-rich fluids. Changes in fluid composition (e.g., F−1, X(CO2)) may trigger the precipitation of rutile. Rutile/fluid partitioning may be the key to fractionating Nb and Ta, with preference for Ta in the fluid, resulting in Nb/Ta ratio of rutile in the veins lower than that in the host eclogite. Besides, the transformation of rutile into titanite also might be an effective mechanism for fractionating Nb from Ta, resulting in the intra-grain Nb–Ta zonations in vein rutile. The Nb–Ta mobility and fractionation can happen during exhumation of the UHP eclogite, which should be very important for understanding the behavior of HFSE in subduction zone metamorphism.
- Published
- 2016
37. 1.9 Ga eclogite from the Archean-Paleoproterozoic Belomorian Province, Russia
- Author
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Xiaoli Li, Huanglu Yu, Thomas Bader, Lifei Zhang, and Chunjing Wei
- Subjects
Multidisciplinary ,010504 meteorology & atmospheric sciences ,Archean ,Geochemistry ,Eclogite ,010502 geochemistry & geophysics ,01 natural sciences ,Geology ,0105 earth and related environmental sciences - Published
- 2017
38. Late Palaeozoic40Ar/39Ar ages of the HP-LT metamorphic rocks from the Kekesu Valley, Chinese southwestern Tianshan: new constraints on exhumation tectonics
- Author
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Thomas Bader, Tingting Shen, Lifei Zhang, Nengsong Chen, and Bin Xia
- Subjects
geography ,Plateau ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Glaucophane ,Metamorphic rock ,Schist ,Geochemistry ,Geology ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Phengite ,Tectonics ,High pressure ,engineering ,Mica ,0105 earth and related environmental sciences - Abstract
Although numerous ages have been obtained for the Chinese southwestern Tianshan high pressure/ultrahigh pressure-low temperature (HP/UHP-LT) metamorphic belt in the past two decades, its exhumation history is still controversial. The poor age constraint was related to the appealing low metamorphic temperatures and excess Ar commonly present under HP/UHP conditions. This study aims to provide new age constraints on the orogen’s exhumation by obtaining 40Ar/39Ar mica ages using the conventional step-heating technique, with emphasis on the avoidance of excess Ar contamination. From a cross section along the Kekesu Valley, four samples, three from the HP-LT metamorphic belt (TK050, TK051, and TK081) and one from the southern margin of the low pressure metamorphic belt (TK097), were selected for 40Ar/39Ar dating. Phengites from garnet glaucophane schist TK050 and the surrounding rock garnet phengite schist TK051 yield comparable plateau ages of 321.4 ± 1.6 and 318.6 ± 1.6 Ma, respectively, while epidot...
- Published
- 2015
39. Evidence for crustal contamination in intra-continental OIB-like basalts from West Qinling, central China: A Re–Os perspective
- Author
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Thomas Bader, Mark Scheltens, Xuehui Yu, Xiong-Fei Huang, Jie Li, Xiao-Wei Li, Zhenyu Chen, Xuanxue Mo, and Ji-Feng Xu
- Subjects
Peridotite ,Basalt ,geography ,geography.geographical_feature_category ,Radiogenic nuclide ,Fractional crystallization (geology) ,Continental crust ,Geochemistry ,Partial melting ,Geology ,Crust ,Volcanic rock ,Earth-Surface Processes - Abstract
The magnitude of crustal contamination in intra-continental OIB-like basalts is commonly difficult to assess in terms of major, trace-element and Pb–Sr–Nd isotopes. However, the Re–Os isotope system is a very sensitive tracer of the crustal component during formation of basaltic rocks. Here we report new Sr–Nd–Pb–Os geochemical and isotopic data from the Cretaceous Duofutun Volcanic Rocks (DVRs) of West Qinling, central China. The DVRs exhibit low Os abundances (4.46–42.02 ppt) with Re abundances ranging from 45.58 to 812.98 ppt, variably high Re/Os (3–126), and high initial 187Os/188Os ratios (0.2112–0.6784). We propose that the degree of partial melting is responsible for the first-order control on the variation of Os concentrations. Even the least radiogenic sample still possesses a higher initial 187Os/188Os ratio than the primitive upper mantle, implying a non-negligible contribution from high Re/Os and 187Os/188Os reservoir(s). Both the crust and pyroxenite-rich mantle are reliable candidates, but the latter cannot be reconciled with the Os mass balance between pyroxenite and ambient peridotite. Hence, we contend that these rocks were contaminated by crustal materials en route to the surface. Assimilation/fractional crystallization modeling manifests the observed isotopic variations can be produced by minor assimilation of the Proterozoic mafic lower crust. In addition, the intra-continental OIB-like basalts show a relatively wider range of 187Os/188Os ratios in comparison with MORB and OIB, confirming the continental crust can have a higher concentration of radioactive Os, which is induced by time-integrated growth.
- Published
- 2015
40. Petrology, geochemistry and geochronology of the magmatic suite from the Jianzha Complex, central China: Petrogenesis and geodynamic implications
- Author
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Xuanxue Mo, Thomas Bader, Xiong-Fei Huang, Xiaowei Li, Guochen Dong, Mark Scheltens, and Xuehui Yu
- Subjects
Fractional crystallization (geology) ,Olivine ,Gabbro ,Geochemistry ,Geology ,engineering.material ,Diorite ,Ultramafic rock ,engineering ,Mafic ,Petrology ,Earth-Surface Processes ,Hornblende ,Zircon - Abstract
The intermediate–mafic–ultramafic rocks in the Jianzha Complex (JZC) at the northern margin of the West Qinling Orogenic Belt have been interpreted to be a part of an ophiolite suite. In this study, we present new geochronological, petrological, geochemical and Sr–Nd–Hf isotopic data and provide a different interpretation. The JZC is composed of dunite, wehrlite, olivine clinopyroxenite, olivine gabbro, gabbro, and pyroxene diorite. The suite shows characteristics of Alaskan-type complexes, including (1) the low CaO concentrations in olivine; (2) evidence of crystal accumulation; (3) high calcic composition of clinopyroxene; and (4) negative correlation between FeOtot and Cr2O3 of spinels. Hornblende and phlogopite are ubiquitous in the wehrlites, but minor orthopyroxene is also present. Hornblende and biotite are abundant late crystallized phases in the gabbros and diorites. The two pyroxene-bearing diorite samples from JZC yield zircon U–Pb ages of 245.7 ± 1.3 Ma and 241.8 ± 1.3 Ma. The mafic and ultramafic rocks display slightly enriched LREE patterns. The wehrlites display moderate to weak negative Eu anomalies (0.74–0.94), whereas the olivine gabbros and gabbros have pronounced positive Eu anomalies. Diorites show slight LREE enrichment, with (La/Yb)N ratios ranging from 4.42 to 7.79, and moderate to weak negative Eu anomalies (Eu/Eu∗ = 0.64–0.86). The mafic and ultramafic rocks from this suite are characterized by negative Nb–Ta–Zr anomalies as well as positive Pb anomalies. Diorites show pronounced negative Ba, Nb–Ta and Ti spikes, and typical Th–U, K and Pb peaks. Combined with petrographic observations and chemical variations, we suggest that the magmatism was dominantly controlled by fractional crystallization and crystal accumulation, with limited crustal contamination. The arc-affinity signature and weekly negative to moderately positive eNd(t) values (−2.3 to 1.2) suggest that these rocks may have been generated by partial melting of the juvenile sub-continental lithospheric mantle that was metasomatized previously by slab-derived fluids. The lithologies in the JZC are related in space and time and originated from a common parental magma. Geochemical modeling suggests that their primitive parental magma had a basaltic composition. The ultramafic rocks were generated through olivine accumulation, and variable degrees of fractional crystallization with minor crustal contamination produced the diorites. The data presented here suggest that the subduction in West Qinling did not cease before the early stage of the Middle Triassic (∼242 Ma), a back-arc developed in the northern part of West Qinling during this period, and the JZC formed within the incipient back-arc.
- Published
- 2014
41. Metamorphic evolution of ultrahigh-pressure rocks from Chinese southwestern Tianshan and a possible indicator of UHP metamorphism using garnet composition in low-T eclogites
- Author
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Tingting Shen, Lifei Zhang, Jin-Xue Du, and Thomas Bader
- Subjects
Grossular ,Lawsonite ,Metamorphic rock ,Geochemistry ,Metamorphism ,Geology ,engineering.material ,Pyrope ,visual_art ,Coesite ,visual_art.visual_art_medium ,engineering ,Eclogite ,Metamorphic facies ,Earth-Surface Processes - Abstract
How to identify ultrahigh-pressure (UH P ) metamorphism in the absence of coesite is a key problem to gain the correct P–T history for an orogenic belt. In this study, garnet composition combined with the pseudosection approach was used to identify ultrahigh-pressure metamorphism and to determine P–T paths for eclogites and metapelites from Chinese southwestern Tianshan. Porphyroblastic garnets from both eclogites and metapelites develop pronounced chemical core-rim textures: the relatively homogeneous core with low pyrope [Prp; Mg/(Ca + Mn + Mg + Fe 2+ ) × 100] and grossular [Grs; Ca/(Ca + Mn + Mg + Fe 2+ ) × 100] content is overgrown by a thin rim with sharply increased Prp and Grs. Phase equilibria modeling indicates that the ultrahigh-pressure rocks have undergone a clockwise P–T path characterized by heating during early exhumation with peak P–T at 31–33 kbar and 490–520 °C. The P–T pseudosections for eclogites show that isopleths of Prp and Grs strongly depend on temperature and pressure, respectively, especially in the stability fields of glaucophane–lawsonite-bearing eclogite facies assemblages. This indicates that garnet composition provides robust thermobarometric constraints. Consequently, we propose a Prp–Grs diagram which is subdivided into a high-pressure region and an ultrahigh-pressure region by the quartz–coesite–transition curve. Those garnet compositions which fall into the ultrahigh-pressure region are regarded to have experienced ultrahigh-pressure metamorphism. This approach is expected to be a useful tool to qualitatively identify ultrahigh-pressure metamorphism for glaucophane–lawsonite-bearing eclogites and its particular strength is the quick examination of large datasets comprising samples with similar bulk composition. Using this method, garnet compositions of eclogites and mafic blueschists from Chinese southwestern Tianshan and lawsonite eclogites worldwide are plotted in the Prp–Grs diagram and several possible ultrahigh-pressure eclogite occurrences are newly identified.
- Published
- 2014
42. A new P-T-t path of eclogites from Chinese southwestern Tianshan: constraints from P-T pseudosections and Sm-Nd isochron dating
- Author
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Xiao-Jie Shen, Jin-Xue Du, Lifei Zhang, and Thomas Bader
- Subjects
Isochron ,Isochron dating ,Lawsonite ,Geochemistry and Petrology ,Oceanic crust ,Geochemistry ,Metamorphism ,Geology ,Eclogite ,Petrology ,Closure temperature ,Metamorphic facies - Abstract
The southwestern Tianshan orogenic belt hosts one of the Earth’s rare occurrences of ultrahigh-pressure (UHP) metamorphic rocks derived from subducted oceanic crust. To address its poorly constrained and controversial P-T-t evolution, for this study, three representative samples, two paragonite-epidote eclogites (H505-26 and H76-10) and one glaucophane-phengite eclogite (H711-1) are selected, and Sm-Nd geochronology and detailed phase equilibria modeling are combined. Garnet porphyroblasts from the three studied eclogites have well-preserved growth zoning with rim-ward increasing pyrope and decreasing spessartine contents. Phase equilibria modeling reveals that the investigated garnets grew in the lawsonite eclogite facies; in eclogite H505-26 during heating and burial, and in eclogites H76-10 and H711-1 during heating and decompression. Temperatures of 460–590 °C derived for the three eclogites are below the closure temperature of the Sm-Nd system, and, thus, the garnet-omphacite-whole rock Sm-Nd isochron ages have the potential to reflect garnet growth, i.e., eclogite facies metamorphism. The three eclogites yield consistent Sm-Nd isochron ages of 309 ± 4.6 Ma (H505-26), 306 ± 15 Ma (H76-10) and 305 ± 11 Ma (H711-1), reflecting HP eclogite facies metamorphism. Based on the new geochronology, detailed investigation of phase equilibria and published data, a clockwise P-T-t path with post- P max heating – decompression, subsequent isothermal decompression and final cooling – decompression is predicted for the eclogites from Chinese southwestern Tianshan. We propose, subduction of the South Tianshan paleo-ocean began before 346 Ma, the eclogite facies prograde metamorphism of the subducting oceanic crust occurred at 346–333 Ma, peak eclogite facies metamorphism at 320–305 Ma, and buoyancy-driven exhumation of the oceanic crust at 296–226 Ma.
- Published
- 2014
43. The tectonic evolution of the Tianshan Orogenic Belt: Evidence from U–Pb dating of detrital zircons from the Chinese southwestern Tianshan accretionary mélange
- Author
-
Thomas Bader, Bin Xia, Yang Xia, and Lifei Zhang
- Subjects
geography ,Provenance ,geography.geographical_feature_category ,Geochemistry ,Geology ,Orogeny ,Continental arc ,Craton ,Precambrian ,Rodinia ,Petrology ,Terrane ,Zircon - Abstract
The Tianshan Orogenic Belt, which is located in the southwestern part of the Central Asian Orogenic Belt (CAOB), is an important component in the reconstruction of the tectonic evolution of the CAOB. In order to examine the evolution of the Tianshan Orogenic Belt, we performed detrital zircon U–Pb dating analyses of sediments from the accretionary melange from Chinese southwestern Tianshan in this study. A total of 542 analyzed spots on 541 zircon grains from five samples yield Paleoarchean to Devonian ages. The major age groups are 2520–2400 Ma, 1890–1600 Ma, 1168–651 Ma, and 490–390 Ma. Provenance analysis indicates that, the Precambrian detrital zircons were probably mainly derived from the paleo-Kazakhstan continent formed before the Early Silurian by amalgamation of the Kazakhstan–Yili microplate, the Chinese central Tianshan terrane and the Kyrgyz North and Middle Tianshan blocks, while detrital zircons with Paleozoic ages mainly from igneous rocks of the continental arc generated by the northward subduction of the south Tianshan paleocean. The age data correspond to four tectono-thermal events that took place in these small blocks, i.e., the continental nucleus growth during the Late Neoarchean–early Paleoproterozoic (~ 2.5 Ga), the evolution of the supercontinents Columbia (2.1–1.6 Ga) and Rodinia (1.3–0.57 Ga), and the arc magmatism related with the Phanerozoic orogeny. The Precambrian zircons show a similar age pattern as the Tarim and the Cathaysia cratons and the Eastern India–Eastern Antarctica block but differ from those of Siberia distinctly. Therefore, the Tianshan region blocks and the Kazakhstan–Yili microplate have a close affinity to the eastern paleo-Gondwana fragments, but were not derived from the Siberia craton as proposed by some previous researchers. These blocks were likely generated by rifting accompanying Rodinia break-up in late Precambrian times. The youngest ages of the detrital zircons from the subduction melange show a maximum depositional age of ca. 390 Ma. It is coeval with the end of an earlier arc magmatic pulse (440–390 Ma) but a bit older than a younger one at 360–320 Ma and nearly 70–80 Ma older than the HP–UHP metamorphism in the subduction zone (320–310 Ma).
- Published
- 2014
44. Zircon U–Pb ages and Hf isotopic analyses of migmatite from the ‘paired metamorphic belt’ in Chinese SW Tianshan: Constraints on partial melting associated with orogeny
- Author
-
Lifei Zhang, Bin Xia, and Thomas Bader
- Subjects
Continental collision ,Geochemistry and Petrology ,Partial melting ,Geochemistry ,Metamorphism ,Geology ,Anatexis ,Granulite ,Migmatite ,Continental arc ,Zircon - Abstract
A paired metamorphic belt with ubiquitous migmatites and rare granulites in its high dT/dP part formed due to oceanic subduction in Chinese southwestern (SW) Tianshan. Although several geochronological studies have addressed it in recent years, the exact timing of the high-grade metamorphism and partial melting is still controversial. For this study, we selected nine samples obtained from three valleys transecting the SW Tianshan Migmatite Complex for U–Pb geochronology and Lu–Hf isotope analysis to provide constraints on partial melting and the mid-crustal evolution during oceanic subduction and subsequent continental collision. On the basis of internal morphology, Th/U ratios and REE patterns, three types of zircons are discriminated. Dating them reveals five age groups: (1) Inherited zircons either are detrital, with ages scattering from 432 Ma to 3261 Ma, or yield ages concentrated at 406–410 Ma reflecting Early Devonian magmatism; (2) Recrystallized zircon has been transformed from pre-existing zircon under subsolidus conditions at ~ 400 Ma and ~ 360 Ma; (3) Metamorphic rims have grown on zircons at ~ 400 Ma, ~ 290 Ma and ~ 270 Ma, corresponding to three phases of anatexis. The partial melting phase at ~ 400 Ma is probably related to the emplacement of voluminous mafic to felsic magmas in a continental arc region above the subduction zone consuming the South Tianshan Paleo-Ocean that triggered the most extensive regional-scale thermal event. However, the two subsequent partial melting phases at ~ 290 Ma and ~ 270 Ma representing post-collisional stages were not penetrative. P–T conditions of the studied migmatites estimated by Hb–Pl thermobarometry and Ti-in-zircon thermometry are 682–763 °C, 4.7–8.0 kbar; together with composite Kfs + Q + Pl, Kfs + Q and Kfs + Q + Ab inclusions representing entrapped melt and Kfs inclusions with Ab exsolution lamellae in zircon rims, the P–T estimates support the occurrence of anatexis. Zircon Lu–Hf isotope analysis indicates that zircon rims formed under high-grade metamorphic conditions and during partial melting by dissolution–precipitation of pre-existing zircons in a close system. Zircon two-stage Hf model ages constrain the development of the protoliths of the migmatites at four major crustal formation periods (~ 1871 Ma, 1368–1426 Ma, 1099–1276 Ma and 743 Ma). Combined with previous researches in this area, we conclude that the main crustal formation of the Yili and Central Tianshan Plates has mostly occurred in Proterozoic times, but not or only subordinately during the Archean.
- Published
- 2014
45. The effect of water activity on calculated phase equilibria and garnet isopleth thermobarometry of granulites, with particular reference to Tongbai (east-central China)
- Author
-
Christian de Capitani, Thomas Bader, Lifei Zhang, and Leander Franz
- Subjects
Siderite ,chemistry.chemical_compound ,Felsic ,chemistry ,Geochemistry and Petrology ,Metamorphic rock ,Geochemistry ,Fluid inclusions ,Mafic ,Granulite ,Mantle (geology) ,Geology ,Magnesite - Abstract
Granulites form at low water activities whose exact value is often unknown. This complicates the calculation of equilibrium assemblage phase diagrams and metamorphic pressure ( P ) and temperature ( T ) conditions by isopleth thermobarometry, because the fluid characteristics distinctly affect the results. To evaluate the significance of this influence, granulites from Tongbai, east-central China are investigated in this study; equilibrium-assemblage calculations and multiequilibrium calculations are combined with fluid-inclusion studies to determine peak metamorphic P - T conditions together with water activities. Calculations using the Theriak/Domino and the TWQ programs on a felsic and two mafic granulites yield P - T conditions of 750–805°C at 0.75–0.93 GPa and water activities of 0.10–0.65 for the equilibration of the mineral assemblages. Armored relics of Zn-rich Fe-Mg-spinel included in garnet of the felsic granulite point to an earlier metamorphic stage at lower pressures on the same P - T loop. Garnet porphyroblasts from two samples contain primary fluid inclusions comprising vapor and daughter crystals. Using a Raman probe, CO 2 and magnesite were identified in fluid inclusions of the felsic granulite while one mafic granulite yielded fluid inclusions with CO 2 dominating besides CH 4 , H 2 O, graphite and siderite. The carbonic fluid is consistent with the implied low water activities. Possible CO 2 -sources are fluids from marbles associated with the granulites and fluids or magmas from the mantle. Equilibrium assemblage calculations reveal a distinct influence of the water activity on both the stability of considered phases and the location of compositional isopleths of the rock-forming minerals. We demonstrate that an estimate of the water activity using the Theriak/Domino and the TWQ programs in combination with Raman spectroscopy is essential to perform accurate thermobarometry in granulites.
- Published
- 2014
46. Metamorphic evolution of relict lawsonite-bearing eclogites from the (U) HP metamorphic belt in the Chinese southwestern Tianshan
- Author
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Thomas Bader, Z. Y. Chen, Zeng Lü, Jin-Xue Du, and Lijian Zhang
- Subjects
Lawsonite ,Metamorphic rock ,Glaucophane ,Geochemistry ,Geology ,Epidote ,engineering.material ,Paragonite ,Geochemistry and Petrology ,engineering ,Eclogite ,Omphacite ,Metamorphic facies - Abstract
In the Chinese southwestern Tianshan (U)HP belt, former lawsonite presence has been predicted for many (U)HP metamorphic eclogites, but only a very few lawsonite grains have been found so far. We discovered armoured lawsonite relicts included in quartz, which, on its part, is enclosed in porphyroblastic garnet in an epidote eclogite H711-14 and a paragonite eclogite H711-29. H711-14 is mainly composed of garnet, omphacite, epidote and titanite, with minor quartz, paragonite and secondary barroisite and glaucophane. Coarse-grained titanite occasionally occurs in millimetre-wide veins in equilibrium with epidote and omphacite, and relict rutile is only preserved as inclusions in matrix titanite and garnet. H711-29 shows the mineral assemblage of garnet, omphacite, glaucophane, paragonite, quartz, dolomite, rutile and minor epidote. Dolomite and rutile are commonly rimed by secondary calcite and titanite respectively. Porphyroblastic garnet in both eclogites is compositionally zoned and exhibits an inclusion-rich core overgrown by an inclusion-poor rim. Phase equilibria modelling predicts that garnet cores formed at the P-peak (490–505 °C and 23–25.5 kbar) and coexisted with the lawsonite eclogite facies assemblage of omphacite + glaucophane + lawsonite + quartz. Garnet rims (550–570 °C and ~20 kbar) grew subsequently during a post-peak epidote eclogite facies metamorphism and coexisted with omphacite + quartz ± glaucophane ± epidote ± paragonite. The results confirm the former presence of a cold subduction zone environment in the Chinese southwestern Tianshan. The P–T evolution of the eclogites is characterized by a clockwise P–T path with a heating stage during early exhumation (thermal relaxation). The preservation of lawsonite in these eclogites is attributed to isolation from the matrix by quartz and rigid garnet, which should be considered as a new type of lawsonite preservation in eclogites. The complete rutile–titanite transition in H711-14 took place in the epidote eclogite facies stage in the presence of an extremely CO2-poor fluid with X(CO2) [CO2/(CO2 + H2O) in the fluid] 0.01) in the coexisting fluid at the epidote eclogite facies stage.
- Published
- 2014
47. The Metamorphic Evolution and Tectonic Significance of the Eclogite in the Sumdo Complex, Tibet, China
- Author
-
Jingsui Yang, Thomas Bader, Herman L.M. van Roermund, and Cong Zhang
- Subjects
Tectonics ,Metamorphic rock ,Geochemistry ,Geology ,Eclogite ,China - Published
- 2019
48. Petrology and U–Pb zircon dating of coesite-bearing metapelite from the Kebuerte Valley, western Tianshan, China
- Author
-
Lifei Zhang, Zuolin Tian, Xin Yang, and Thomas Bader
- Subjects
Geothermobarometry ,Schist ,Geochemistry ,Geology ,engineering.material ,Phengite ,Paragonite ,Coesite ,engineering ,Chloritoid ,Eclogite ,Petrology ,Earth-Surface Processes ,Zircon - Abstract
This paper deals with the petrology and U–Pb dating of coesite-bearing garnet–phengite schist from the Kebuerte Valley, Chinese western Tianshan. It mainly consists of porphyroblastic garnet, phengite, quartz and chlorite with minor amounts of paragonite, albite, zoisite and chloritoid. The well preserved coesite inclusions (∼100 μm) in garnet are encircled by a narrow rim of quartz. They were identified by optical microscopy and confirmed by Raman spectroscopy. Using the computer program THERMOCALC, the peak metamorphic conditions of 29 kbar and 565 °C were obtained via garnet isopleth geothermobarometry. The predicted UHP peak mineral assemblage comprises garnet + jadeite + lawsonite + carpholite + coesite + phengite. The metapelite records prograde quartz–eclogite-facies metamorphism, UHP coesite–eclogite-facies peak metamorphism, and a late greenschist-facies overprint. Phase equilibrium modeling predicts that garnet mainly grew in the mineral assemblages garnet + jadeite + lawsonite + chloritoid + glaucophane + quartz + phengite and garnet + jadeite + lawsonite + carpholite + glaucophane + quartz + phengite. SHRIMP U–Pb zircon dating of the coesite-bearing metapelite yielded the peak metamorphic age 320.4 ± 3.7 Ma. For the first time, age data of coesite-bearing UHP metapelite from the Chinese western Tianshan are presented in this paper. They are in accord with published ages obtained from eclogite from other localities in the Chinese western Tianshan and the Kyrgyz South Tianshan and therefore prove a widespread occurrence of UHP metamorphism.
- Published
- 2013
49. The heart of China revisited, I. Proterozoic tectonics of the Qin mountains in the core of supercontinent Rodinia
- Author
-
Zhao Yang, Honglin Yuan, Leander Franz, Thomas Bader, Mandy Hofmann, Ulf Linnemann, and Lothar Ratschbacher
- Subjects
geography ,geography.geographical_feature_category ,Accretionary wedge ,Proterozoic ,Continental crust ,Supercontinent ,Paleontology ,Craton ,Geophysics ,Basement (geology) ,Geochemistry and Petrology ,Passive margin ,Rodinia ,Geology - Abstract
[1] The Qinling-Dabie orogenic collage, central China, constitutes the geographic, geologic, and cultural heart of China; it plays a key role in understanding the amalgamation and breakup of the Rodinia supercontinent and the subduction and exhumation of continental crust under ultrahigh-pressure conditions. Herein, we investigate the Proterozoic evolution of the Qinling-Dabie orogenic collage and surrounding segments of the bounding South China craton (SCC) and North China craton (NCC), employing published and new U/Th–Pb geochronology. The Kongling, Hong'an-Dabie, and Douling-Foping complexes constitute the nucleus of the Yangtze block, recording a common ~2.0 Ga orogenic event that integrated the Yangtze block into the supercontinent Columbia. The ~1.10–0.95 Ga Miaowan “ophiolite”-Shennongjia arc association of the Huangling dome-Shennongjia massif seems to have split and reassembled that nucleus. It formed earlier than or contemporaneously with the Sibao orogeny along the southeastern margin of the Yangtze block. The ~0.95–0.80 Ga Mian-Lue complex comprises an oceanic accretionary wedge that formed outboard of an associated fore-arc-arc system represented by the Bikou-Hannan-Micangshan massifs along the north(western) margin of the Yangtze block. The Qinling complex, currently sandwiched between the SCC and NCC, lacks pre-Mesoproterozoic cratonal basement, and its igneous rocks intruded a ~1.7–1.0 Ga old clastic wedge that incorporates meta-basites; it might have been part of the extended passive margin of East Antarctica and/or Australia. Neoproterozoic Qinling-complex magmatism spanned ~260 Myr and evolved from partial melting of the thick clastic sequence over an arc to a rift setting; most Qinling-complex paragneisses are erosional products of these igneous rocks. The ~1.0–0.85 Ga Qinling-complex magmatism formed independently from that along the north(west)ern Yangtze-block margin, but its ~0.8–0.7 Ga magmatism, peaking at ~750 Ma, is widespread throughout the Yangtze block; this suggests post- ~ 825 Ma accretion of the Qinling complex to the Yangtze block. The Daba and Wudang Shan, Douling, and Hong'an-Dabie areas of the northern Yangtze block are dominated by ~0.8–0.6 Ga bimodal continental-rift igneous rocks; in accordance with similar ages in the Qinling complex and the entire SCC, continental rifting appears to have been most active at ~750 Ma. Our Rodinia scenario suggests that the Qinling-Dabie orogenic collage records the final stages of the assemblage of the core of Rodinia, and this was completed not earlier than ~825 Ma, and its breakup, which was most active at ~750 Ma.
- Published
- 2013
50. Geochemistry and trace element behaviors of eclogite during its exhumation in the Xitieshan terrane, North Qaidam UHP belt, NW China
- Author
-
Lifei Zhang, Shuguang Song, Thomas Bader, Yuxing Lou, and Cong Zhang
- Subjects
Oceanic crust ,Geochemistry ,Trace element ,Geology ,Eclogite ,Mafic ,Petrology ,Protolith ,Metamorphic facies ,Earth-Surface Processes ,Zircon ,Terrane - Abstract
The Xitieshan terrane, located in the central part of the North Qaidam ultrahigh pressure (UHP) metamorphic belt, China, is mainly composed of orthogneiss and paragneiss and a few intercalated eclogite layers and boudins. Based on their bulk-rock TiO 2 -contents, the eclogites can be subdivided into a high-Ti group (TiO 2 > 2%) and a low-Ti group (TiO 2 e Nd ( T ) and restricted I Sr values and therefore provide further evidence for the formation of the protoliths of the eclogites in an oceanic environment. On the other hand, the Sr–Nd isotopes of high-Ti eclogites show mainly positive but also some negative e Nd ( T ) values and relatively broadly distributed I Sr values, indicating minor crustal contamination of the ocean floor basalts. Considering available 750–877 Ma protolith ages preserved in zircon cores, it is inferred that some of the eclogites derived from Neoproterozoic protoliths were emplaced onto the crust far ahead of the Paleozoic deep subduction, while the other eclogites originate from a different oceanic crust, e.g., the Paleo-Qilian ocean, indicating multiple orogenies in the geological history of the Xitieshan terrane, China. Whole-rock and in-situ LA-ICP-MS mineral trace element analyses of eclogites revealed two stages of fluid behavior during retrogression that correspond to the two exhumation stages uncovered by phase equilibrium calculations. The mineral scale trace element distributions and trace element inheritance of newly formed amphibole from its precursors indicate that, at the peak metamorphic stage (M1) and at the earlier (eclogite facies) overprint (M2), the fluid was internally controlled by the rock itself. Within a mafic lens, the amount of water-soluble elements (e.g., Rb, Sr, Ba, U, Pb and LREE), observed in the whole-rock compositions as well as in amphiboles, increases from the core (phengite-bearing eclogite) to the rim (amphibolite) and implies an external fluid source for the amphibolite facies retrogression (M3) which should be helpful for the final exhumation of UHP eclogite.
- Published
- 2013
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