Hoefs, Jochen

[["dc.bibliographiccitation.firstpage","67"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of Petrology"],["dc.bibliographiccitation.lastpage","98"],["dc.bibliographiccitation.volume","53"],["dc.contributor.author","Slaby, Ewa"],["dc.contributor.author","Martin, Herve"],["dc.contributor.author","Hamada, Morihisa"],["dc.contributor.author","Smigielski, Michal"],["dc.contributor.author","Domonik, Andrzej"],["dc.contributor.author","Goetze, Jens"],["dc.contributor.author","Hoefs, Jochen"],["dc.contributor.author","Halas, Stanislaw"],["dc.contributor.author","Simon, Klaus"],["dc.contributor.author","Devidal, Jean-Luc"],["dc.contributor.author","Moyen, Jean-Francois"],["dc.contributor.author","Jayananda, Mudlappa"],["dc.date.accessioned","2018-11-07T09:15:55Z"],["dc.date.available","2018-11-07T09:15:55Z"],["dc.date.issued","2012"],["dc.description.abstract","Growth and regrowth textures, trace element and oxygen isotope compositions, and water content or species have been studied in alkali feldspars from the late Archaean Closepet igneous bodies. Feldspar crystals grew from mixed magmas that are characterized by a high degree of homogenization. The 3D depiction of trace element distribution indicates that the crystallization process was followed by interaction with fluids. The magmatic system involved in feldspar formation shows non-linear dynamics. The interaction with fluids is also deterministic, but in contrast to magmatic crystallization, it shows an increasing persistency in element behaviour. The degree of persistency of the element activities in both processes has been calculated using the Hurst exponent. The recrystallization (regrowth) process induced by fluids proceeded along crystal fractures and cleavages, causing selective enrichment in large ion lithophile elements (light rare earth elements), Pb, Y, and in various water species. It did not change the feldspar oxygen isotope signature. In turn, the incorporation of hydrogen species into feldspar domains reduced Al-O--Al defect densities in the structure, decreasing their luminescence. Water speciation shows persistent behaviour during heating, the process being reversible at least up to 600 degrees C. Carbonate crystals with a mantle isotope signature are associated with the re-equilibrated feldspar domains. The feldspar compositions, the abundance of water species in them and the refractory nature of the residuum after heating, the unchanged oxygen isotopes and the mantle signature of co-precipitated carbonates testify that the observed recrystallization has taken place at temperatures above 600 degrees C with H2O-CO2 fertile, mantle-derived fluids. The paper draws special attention to some methodological aspects of the problem. The multi-method approach used here (major element, trace element and isotope geochemistry, infra-red, cathodoluminescence, 3D depiction of geochemical data and fractal statistics) may help to recognize and separate the various processes throughout the alteration history of the pluton."],["dc.description.sponsorship","IGSci PASci 'Hybrid'; IGSci PASci-CNRS-UMR [6524-LMV]"],["dc.identifier.doi","10.1093/petrology/egr056"],["dc.identifier.isi","000299347800004"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/27815"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","0022-3530"],["dc.title","Evidence in Archaean Alkali Feldspar Megacrysts for High-Temperature Interaction with Mantle Fluids"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1505"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Journal of Petrology"],["dc.bibliographiccitation.lastpage","1527"],["dc.bibliographiccitation.volume","43"],["dc.contributor.author","Xiao, Y. L."],["dc.contributor.author","Hoefs, Jochen"],["dc.contributor.author","van den Kerkhof, A. M."],["dc.contributor.author","Simon, Klaus"],["dc.contributor.author","Fiebig, J."],["dc.contributor.author","Zheng, Y."],["dc.date.accessioned","2018-11-07T10:16:29Z"],["dc.date.available","2018-11-07T10:16:29Z"],["dc.date.issued","2002"],["dc.description.abstract","The Dabie Shan ultrahigh-pressure (UHP) metamorphic terrane is located in the eastern part of the east-west-striking Qinling-Dabie orogenic belt in China. A major mylonitized contact zone of 200-300 m width divides Dabie Shan into the South Dabie Terrane (SDT) and the North Dabie Complex (NDC). Combined investigation of major and trace element geochemistry, fluid inclusions, and oxygen and hydrogen isotopes constrains the fluid history during the metamorphic evolution of the two metamorphic belts, which differ in their fluid and metamorphic evolution. Fluid inclusions in rocks from the SDT are mainly aqueous with varying salinities, whereas those from the NDC are dominated by CO2. Low delta(18)O values in the SDT rocks (-2.8 to 8.6parts per thousand) indicate meteoric water-rock interactions before UHP metamorphism, whereas rocks from the NDC show 'normal' delta(18)O values (6.7-9.0parts per thousand) with no obvious meteoric water-rock signature. Whole-rock rare earth element (REE) contents correlate with oxygen isotope compositions: samples from the SDT have higher REE contents and lower delta(18)O values, whereas samples from the NDC have lower REE contents and higher delta(18)O values. During retrograde metamorphism fluids with different hydrogen isotope compositions interacted with the rocks from the SDT."],["dc.identifier.doi","10.1093/petrology/43.8.1505"],["dc.identifier.isi","000177226600004"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/41048"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","0022-3530"],["dc.title","Fluid evolution during HP and UHP metamorphism in Dabie Shan, China: Constraints from mineral chemistry, fluid inclusions and stable isotopes"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","953"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Mineralium Deposita"],["dc.bibliographiccitation.lastpage","967"],["dc.bibliographiccitation.volume","38"],["dc.contributor.author","Germann, K."],["dc.contributor.author","Luders, V."],["dc.contributor.author","Banks, D. A."],["dc.contributor.author","Simon, Klaus"],["dc.contributor.author","Hoefs, Jochen"],["dc.date.accessioned","2018-11-07T10:34:29Z"],["dc.date.available","2018-11-07T10:34:29Z"],["dc.date.issued","2003"],["dc.description.abstract","Late Variscan vein-type mineralization in the Iberian Pyrite Belt, related to the rejuvenation of pre-existing fractures during late Variscan extensional tectonism, comprises pyrite-chalcopyrite, quartz-galena-sphalerite, quartz-stibnite-arsenopyrite, quartz-pyrite, quartz-cassiterite-scheelite, fluorite-galena-sphalerite-chalcopyrite, and quartz-manganese oxide mineral assemblages. Studies of fluid inclusions in quartz, stibnite, and barite as well as the sulfur isotopic compositions of stibnite, galena, and barite from three occurrences in the central part of the Iberian Pyrite Belt reveal compelling evidence for there having been different sources of sulfur and depositional conditions. Quartz-stibnite mineralization formed at temperatures of about 200 degreesC from fluids which had undergone two-phase separation during ascent. Antimony and sulfide are most probably derived by alteration of a deeper lying, volcanic-hosted massive sulfide mineralization, as indicated by delta(34)S signatures from -1.45 to -2.74parts per thousand. Sub-critical phase separation of the fluid caused extreme fractionation of chlorine isotopes (delta(37)Cl between -1.8 and 3.2parts per thousand), which correlates with a fractionation of the Cl/Br ratios. The source of another high-salinity fluid trapped in inclusions in late-stage quartz from quartz-stibnite veins remains unclear. By contrast, quartz-galena veins derived sulfide (and metals?) by alteration of a sedimentary source, most likely shale-hosted massive sulfides. The delta(34)S values in galena from the two study sites vary between -15.42 and -19.04parts per thousand. Barite which is associated with galena has significantly different delta(34)S values (-0.2 to 6.44parts per thousand) and is assumed to have formed by mixing of the ascending fluids with meteoric water."],["dc.identifier.doi","10.1007/s00126-002-0342-z"],["dc.identifier.isi","000187508300004"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/44882"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0026-4598"],["dc.title","Late Hercynian polymetallic vein-type base-metal mineralization in the Iberian Pyrite Belt: fluid-inclusion and stable-isotope geochemistry (S-O-H-Cl)"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","421"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Contributions to Mineralogy and Petrology"],["dc.bibliographiccitation.lastpage","441"],["dc.bibliographiccitation.volume","152"],["dc.contributor.author","Zhang, Z."],["dc.contributor.author","Xiao, Yilin"],["dc.contributor.author","Hoefs, Jochen"],["dc.contributor.author","Liou, J. G."],["dc.contributor.author","Simon, Klaus"],["dc.date.accessioned","2018-11-07T09:09:25Z"],["dc.date.available","2018-11-07T09:09:25Z"],["dc.date.issued","2006"],["dc.description.abstract","The main hole (MH) of the Chinese Continental Scientific Drilling Project (CCSD) in southern Sulu has penetrated into an ultrahigh-pressure (UHP) metamorphic rock slice which consists of orthogneiss, paragneiss, eclogite, ultramafic rock and minor schist. Recovered eclogites have a UHP metamorphic mineral assemblage of garnet + omphacite + rutile +/- phengite +/- kyanite +/- coesite +/- epidote. Ultramafic rocks contain garnet + olivine + clinopyroxene + orthopyroxene +/- Ti-clinohumite +/- phlogopite. Gneisses and schists contain an amphibolite-facies paragenesis, but their zircons have coesite, garnet, omphacite (or jadeite) and phengite inclusions, indicating that eclogites and gneisses have been subjected to in situ UHP metamorphism. Using available geothermobarometers, P-T estimates of 3.1-4.4 GPa and 678-816 degrees C for eclogites were obtained. If surface outcrops and neighboring shallow drill holes are considered together, we suggest that a huge supracrustal rock slab (> 50 km long x 100 km wide x 5 km deep) was subducted to a depth > 100 km and then exhumed to the surface. The depth interval (0-2,050 m) of the CCSD-MH can be divided into six lithological units. Unit 1 consists of alternating layers of quartz-rich and rutile-rich eclogites, with thin interlayers of gneiss and schist. Eclogites of unit 1 are characterized by Nb, Ta, Sr and Ti depletions, low Mg number and general LREE enrichment. Unit 2 comprises rutile- and ilmenite-rich eclogite and minor \"normal\" eclogite and is characterized by high TiO2, total Fe, V, Co and Sr, and very low SiO2, alkali, Zr, Ba, Nb, Ta and total REE contents, and LREE-depleted REE patterns with slightly positive Eu anomalies. Unit 3 contains ultramafic rock and minor MgO-rich eclogite. Protoliths of UHP rocks from units 1, 2 and 3 represent a layered mafic to ultramafic intrusion at crustal depth. Units 4 and 6 consist of interlayered eclogite and paragneiss; the eclogites are characterized by Th, U, Nb, Ta and Ti depletion and K enrichment and LREE-enriched REE patterns. Paragneisses show Nb, Ta, Sr and Ti depletions and LREE-enriched REE patterns occasionally with slightly negative Eu anomalies, indicating that their protoliths represent metamorphic supracrustal series. Unit 5 consists mainly of orthogneisses, showing distinct Nb, Ta, Sr and Ti depletions, and LREE-enriched REE patterns with pronounced negative Eu anomalies, suggesting granitic protoliths. In conclusion it is proposed that the southern Sulu UHP belt consists of a series of meta-supracrustal rocks, a layered mafic-ultramafic complex and granites."],["dc.identifier.doi","10.1007/s00410-006-0120-5"],["dc.identifier.isi","000240548000002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/26257"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0010-7999"],["dc.title","Ultrahigh pressure metamorphic rocks from the Chinese Continental Scientific Drilling Project: I. Petrology and geochemistry of the main hole (0-2,050 m)"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","18"],["dc.bibliographiccitation.journal","Geochimica et Cosmochimica Acta"],["dc.bibliographiccitation.volume","70"],["dc.contributor.author","Sun, Weidong"],["dc.contributor.author","Xiao, Y. L."],["dc.contributor.author","Hoefs, Jochen"],["dc.contributor.author","Simon, Klaus"],["dc.contributor.author","Zhang, Z. M."],["dc.contributor.author","Li, S. G."],["dc.date.accessioned","2018-11-07T09:28:35Z"],["dc.date.available","2018-11-07T09:28:35Z"],["dc.date.issued","2006"],["dc.format.extent","A629"],["dc.identifier.doi","10.1016/j.gca.2006.06.1167"],["dc.identifier.isi","000241374201504"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30813"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Pergamon-elsevier Science Ltd"],["dc.publisher.place","Oxford"],["dc.relation.conference","16th Annual V M Goldschmidt Conference"],["dc.relation.eventlocation","Melbourne, AUSTRALIA"],["dc.relation.issn","0016-7037"],["dc.title","Nb/Ta fractionation in rutile from eclogites"],["dc.type","conference_abstract"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","797"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Contributions to Mineralogy and Petrology"],["dc.bibliographiccitation.lastpage","819"],["dc.bibliographiccitation.volume","162"],["dc.contributor.author","Xiao, Yilin"],["dc.contributor.author","Hoefs, Jochen"],["dc.contributor.author","Hou, Zhenhui"],["dc.contributor.author","Simon, Klaus"],["dc.contributor.author","Zhang, Z."],["dc.date.accessioned","2018-11-07T08:51:32Z"],["dc.date.available","2018-11-07T08:51:32Z"],["dc.date.issued","2011"],["dc.description.abstract","In order to better understand the role of fluids during subduction and subsequent exhumation, we have investigated whole-rock and mineral chemistry (major and trace elements) and Li, B as well as O, Sr, Nd, Pb isotopes on selected continuous drill-core profiles through contrasting lithological boundaries from the Chinese Continental Scientific Drilling Program (CCSD) in Sulu, China. Four carefully selected sample sets have been chosen to investigate geochemical changes as a result of fluid mobilization during dehydration, peak metamorphism, and exhumation of deeply subducted continental crust. Our data reveal that while O and Sr-Nd-Pb isotopic compositions remain more or less unchanged, significant Li and/or B isotope fractionations occur between different lithologies that are in close contact during various metamorphic stages. Samples that are supposed to represent prograde dehydration as indicated by veins formed at high pressures (HP) are characterized by element patterns of highly fluid-mobile elements in the veins that are complementary to those of the host eclogite. A second sample set represents a UHP metamorphic crustal eclogite that is separated from a garnet peridotite by a thin transitional interface. Garnet peridotite and eclogite are characterized by a > 10% difference in MgO, which, together with the presence of abundant hydroxyl-bearing minerals and compositionally different clinopyroxene grains demonstrate that both rocks have been derived from different sources that have been tectonically juxtaposed during subduction, and that hydrous silicate-rich fluids have been added from the subducting slab to the mantle. Two additional sample sets, comprising retrograde amphibolite and relatively fresh eclogite, demonstrate that besides external fluids, internal fluids can be responsible for the formation of amphibolite. Li and B concentrations and isotopic compositions point to losses and isotopic fractionation during progressive dehydration. On the other hand, fluids with isotopically heavier Li and B are added during retrogression. On a small scale, mantle-derived rocks may be significantly metasomatized by fluids derived from the subducted slab. Our study indicates that during high-grade metamorphism, Li and B may show different patterns of enrichment and of isotopic fractionation."],["dc.identifier.doi","10.1007/s00410-011-0625-4"],["dc.identifier.isi","000294704900008"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/7320"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21955"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0010-7999"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Fluid/rock interaction and mass transfer in continental subduction zones: constraints from trace elements and isotopes (Li, B, O, Sr, Nd, Pb) in UHP rocks from the Chinese Continental Scientific Drilling Program, Sulu, East China"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","4770"],["dc.bibliographiccitation.issue","18"],["dc.bibliographiccitation.journal","Geochimica et Cosmochimica Acta"],["dc.bibliographiccitation.lastpage","4782"],["dc.bibliographiccitation.volume","70"],["dc.contributor.author","Xiao, Yilin"],["dc.contributor.author","Sun, Weidong"],["dc.contributor.author","Hoefs, Jochen"],["dc.contributor.author","Simon, Klaus"],["dc.contributor.author","Zhang, Z."],["dc.contributor.author","Li, Shuguang"],["dc.contributor.author","Hofmann, Albrecht W."],["dc.date.accessioned","2018-11-07T09:15:17Z"],["dc.date.available","2018-11-07T09:15:17Z"],["dc.date.issued","2006"],["dc.description.abstract","The formation of the continental crust (CC) is one of the most important processes in the evolution of the silicate Earth. Exactly how the CC formed is the subject of ongoing debate that focuses on its subchondritic Nb/Ta ratio. Nb and Ta are \"geochemical identical twins,\" so they usually do not fractionate from each other. Here, we show that rutile grains from hydrous rutile-bearing eclogitic layers recovered from drillcores in the Dabie-Sulu ultrahigh pressure terrain have highly variable Nb/Ta values (ranging from 5.4 to 29.1, with an average of 9.8 +/- 0.6), indicating major fractionation of Nb and Ta most likely occurred during blueschist to amphibole-eclogite transformation in the absence of rutile. It is suggested that the released fluids with subchondritic Nb/Ta were transported to, and retained by, hydrous rutile-bearing eclogite in colder regions, resulting in suprachondritic Nb/Ta ratios for drier eclogite in hotter regions. Further dehydration of hydrous rutile-bearing eclogites cannot transfer the fractionated Nb/Ta values to the CC due to the low solubility of Nb and Ta in fluids in the presence of rutile, while dehydration-melting results in a major component of the CC, the tonalite-trondhjemite-granodiorite (TTG) component, which is responsible for the low Nb/Ta of the CC. Consequently, residual eclogites have variable but overall suprachondritic Nb/Ta. (c) 2006 Elsevier Inc. All rights reserved."],["dc.identifier.doi","10.1016/j.gca.2006.07.010"],["dc.identifier.isi","000241001400012"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/27647"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Pergamon-elsevier Science Ltd"],["dc.relation.issn","0016-7037"],["dc.title","Making continental crust through slab melting: Constraints from niobium-tantalum fractionation in UHP metamorphic rutile"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]