English Intern
Lehrstuhl für Geodynamik und Geomaterialforschung

Geodynamik

Laufende Projekte zum Thema Geodynamik

  • Prof. Dr. Ulrich Schüssler
  • Dr. Friedhelm Henjes-Kunst (Federal Institute for Geosciences and Natural Resources Germany)
  • PD Dr. Nikola Koglin (Federal Institute for Geosciences and Natural Resources Germany)

Project duration: since 2016

Supported, in part, by the German Research Foundation (DFG)

Summary:

The project is carried out in the context of the German Antarctic Northern Victoria Land Expeditions (GANOVEX) program of the Federal Institute for Geosciences and Natural Resources, Germany. Aim of this program is to unravel the geodynamic history of Northern Victoria Land and the neighbouring Oates Land. The area is characterized by the late pan-African Ross Orogeny of Upper Cambrian – Lower Ordovician age, which led to the accretion of a former island arc (Bowers Terrane) and a former flysch trough (Robertson Bay Terrane) to the ancient active continental margin (Wilson Terrane) of the East-Antarctic craton.The current project deals with the Hornbende Bluffs gabbroic intrusion of Lower Devonian age (411 +- 7 Ma), which clearly postdates the late pan-African Ross Orogeny and related Granite Harbour Intrusives (c. between 500 and 470 Ma). The gabbro may be interpreted as an early precursor of the Admiralty Intrusives of Middle and Upper Devonian age. In opposite to the Admiralty Intrusives, which are limited to the Bowers and the Robertson Bay Terrane, the Hornblende Bluffs gabbro is located within the Wilson Terrane. Magma origin and the position of this gabbro within the regional geotectonic evolution are subject of the investigation.

Project duration: since 2013

Supported, in part, by the Faculty for Philosophy, Univ. Würzburg

Summary:

A general interpretation of the geodynamic history of the Saxothuringian Zone within the Variscan orogeny is still suffering under the lack of enough geochemical and age data of protoliths. The aim of the current project is to fill this gap particulary for the different nappe units of the Münchberg Massifin NE Bavaria, for the surrounding Palaeozoic rock sequences of the Frankenwald area, but also for the Frankenberger Zwischengebirge in Saxony, which may be interpreted as a continuation of the Münchberg Massif to the NE.

The Münchberg Massif from top to bottom consists of four major units: Hangend-Serie, Liegend-Serie, Randamphibolit-Serie and Prasinit-Phyllit-Serie,which show an inverted metamorphic gradient of eclogite- to amphibolite-facies (top) to greenschist-facies (bottom) and are separated from each other by thrust faults. New geochemical and U-Pb zircon data indicate that the four units host metasedimentary and meta-igneous rocks, which were formed at different time and in distinct geotectonic settings during the evolution of the Saxothuringian terrane between 550 and 370 Ma. Mafic and felsic protoliths of the Hangend-Serie result from a bimodal magmatism in an evolved oceanic to continental magmatic arc setting at about 550 Ma. These rocks represent relics of the Cadomian magmatic arc, which formed a cordillera at the northern margin of Gondwana during the Neoproterozoic. The Liegend-Serie hosts slivers of granitic orthogneisses, emplaced during magmaticevents at c. 505 and 480 Ma, and Early Palaeozoic paragneisses, with our samples deposited at ≤483 Ma. Ortho- and paragneisses were affected by an amphibolite-facies metamorphic overprint at c. 380Ma. Granite emplacement and sediment deposition can be related to the separation of the Avalonia microterrane from the northern Gondwana margin. Amphibolite protoliths of the Randamphibolit-Serie emplaced at c. 400 Ma. They show NMORB to E-MORB signatures, pointing to their formation along an oceanic spreading centre within the Rheic ocean. Mafic igneous rocks in the Prasinit-Phyllit-Serie emplaced at nearly the same time (407–401 Ma), but their calc-alkaline to tholeiitic character rather suggests formation in an intra-oceanic island arc/back arc system. This convergent margin lasted for about 30Ma until the Late Devonian, as is suggested by a maximumdeposition age of 371 Ma of associated phyllites, and by metamorphic Ar-Ar ages of 374–368Ma. The timing of the different magmatic and sedimentary events in the Münchberg Massif and their plate tectonic settings are similar to those estimated for other Variscan nappe complexes throughout Europe, comprising the French Massif Central and NW Spain. This similarity indicates that the Münchberg Massif forms part of an European-wide suture zone, along which rock units of different origin were assembled in a complex way during the Variscan Orogeny.

Stratigraphically well-defined volcanic rocks in Palaeozoic volcano-sedimentary units of the Frankenwald area (Saxothuringian Zone, Variscan Orogen) were sampled for geochemical characterisation and U–Pb zircon dating. The oldest rock suite comprises quartz keratophyre,brecciated keratophyre, quartz keratophyre tuff and basalt, formed in Upper Cambrian to Tremadocian time (c. 497–478 Ma). Basaltic volcanism continued until the Silurian. Quartz keratophyre shows post-collisional calc-alkaline signature, the Ordovician–Silurian basalt has alkaline signaturetypical of continental rift environments. The combined datasets provide evidence of Cambro-Ordovician bimodal volcanism and successive rifting until the Silurian. This evolution very likely resulted from break-up of the northern Gondwana margin, as recorded in many terranes throughout Europe. The position at the northern Gondwana margin is supported by detrital zircon grains in some tuffs,with typical Gondwana-derived age spectra mostly recording ages of 550–750 Ma and minor age populations of 950–1100 and 1700–2700 Ma. The absence of N-MORB basalt in the Frankenwald area points to a retarded breakoff of the Saxothuringian terrane along a continental rift system from Uppermost Cambrian to Middle Silurian time. Geochemical data for a second suite of Upper Devonianbasalt provide evidence of emplacement in a hot spot related ocean-island setting south of the Rheic Ocean. Our results also require partial revision of the lithostratigraphy of the Frankenwald area. The basal volcanic unit of the Randschiefer Formation yielded a Tremadocian age and, therefore, should be attributed to the Vogtendorf Formation. Keratophyre of the Vogtendorf Formation, previouslyassigned to the Tremadoc, is most likely of Upper Devonian age.

Publications:

Höhn, S., Koglin, N., Klopf, L., Schüssler, U., Tragelehn, H., Frimmel, H.E., Zeh, A. and Brätz, H., 2018. Geochronology, stratigraphy and geochemistry of Cambro-Ordovician, Silurian and Devonian volcanic rocks of the Saxothuringian Zone in NE Bavaria (Germany)—new constraints for Gondwana break up and ocean–island magmatism. International Journal of Earth Sciences, 107(1), pp.359-377.

Koglin, N., Zeh, A., Franz, G., Schüssler, U., Glodny, J., Gerdes, A. and Brätz, H., 2018. From Cadomian magmatic arc to Rheic ocean closure: the geochronological-geochemical record of nappe protoliths of the Münchberg Massif, NE Bavaria (Germany). Gondwana Research, 55, pp.135-152.

Project duration: since 2004

Summary:

The Devonian to Permian Variscan Orogeny peaked in the collision of Gondwana with Laurentia, following subduction and the incorporation of continental fragments (terranes). During the late stage of this orogeny and lasting from the Late Carboniferous to the Permian, continental basins of different size formed into which the erosional debris of the orogen was deposited, accompanied by magmatism. The development of the Variscan orogen as a whole is characterized by repeated phases of magmatism. The igneous and sedimentary rocks of the North German Basin have already been investigated in detail. However, for the internal Variscan basins south of the Harz Mountains, a corresponding synopsis is not available.

This project aims at a regional comparison of the igneous rocks of the late Variscan sedimentary basins in the central and southern parts of Germany. Most of the magmatic rocks in these basins belong to the calc-alkaline series and are K2O-rich. Trace element patterns indicate derivation from partial melting of the upper mantle, which previously had been metasomatically altered by subduction. Intrusion of these basic magmas into the lower continental crust led to heat transfer and generation of partially acidic melts by magmatic underplating as well as to different degrees of magma mixing. In combination with geochronological data the development of the magmatism is being compared between the individual basins and its temporal evolution assessed.

Publications:

von Seckendorff V, Timmermann MJ, Kramer W, Wrobel P (2004a) New 40Ar/39Ar ages and geochemistry of Late Carboniferous-Early Permian lamprophyres and related volcanic rocks in the Saxothuringian Zone of the Variscan orogen, Germany. – In: Wilson M, Neumann E-R, Davies GR, Timmermann MJ, Heeremans M, Larsen BT (eds): Permo-Carboniferous magmatism and rifting in Europe. Geological Society, London, Special Publications 223: 335–359

von Seckendorff V, Arz C, Lorenz V (2004b) Magmatism of the late Variscan intermontane Saar-Nahe Basin (Germany): a review. – In: Wilson M, Neumann E-R, Davies GR, Timmermann MJ, Heeremans M, Larsen BT (eds): Permo-Carboniferous magmatism and rifting in Europe. Geological Society, London, Special Publications 223: 361–391

Ulrych J, Pesek J, Stepankova-Svobodova J, Bosak P, Lloyd FE, von Seckendorff V, Lang M, Novak JK (2006) Permo-Carboniferous volcanism in late Variscan continental basins of the Bohemian Massif (Czech Republic): geochemical characteristic. Chemie der Erde Geochemistry 66:37–56

Seckendorff V von (2012) Der Magmatismus in und zwischen den spätvariscischen permokarbonen Sedimentbecken in Deutschland. – In: Deutsche Stratigraphische Kommission (Hrsg.; Koordination und Redaktion: H. Lützner, G. Kowalczyk für die Subkommission Perm-Trias): Stratigraphie von Deutschland X. Rotliegend. Teil I: Innervariscische Becken. – Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften 61: 743–860

Project duration: since 2001

Supported, at times, by the German Research Foundation (DFG)

Summary:

The primary motivationof this project is to delineate the geodynamic history and significance of the Mid-German Crystalline Zone during the Variscan Orogeny. To achieve this aim a combination of petrological, structural, geochemical and geochronological investigations were undertaken during the last years. The Mid-German Crystalline Zone (MGCZ) consists of various basement complexes that are exposed, from SW to NE, in the Rhineland-Palatinate and the Odenwald, Spessart, Ruhla and Kyffhäuser crystalline basement areas. The basement of the MGCZ can be characterized by (i) Variscan magmatic arc rocks and associated sediments as old as Cambrian/Ordovician that are typically metamorphosed at granulate-facies conditions and (ii) Silurian to Early Devonian orthogneisses with mainly calc-alkaline compositions that occur together with medium-pressure metasedimentary rochs that were deposited during the Ordovician and Silurian. Eclogate-facies high-pressure metabasic rocks, which were discovered by Will and Schmädicke (2001), are locally exposed in the orthogneisses. In addition, pre-Variscan granulites occur in the western Odenwald crystalline basement (Will et al. 2017). The MGCZ is part of a much larger suture zone that extends from Mexico to Turkey and formed during the late Variscan closure of the Rheic Ocean that had previously separated Gondwana from Laurussia (i.e. Baltica, Laurentia and Avalonia). The MGCZ is a composite terrane with Palaeozoic sediments of distinct Gondwana/peri-Gondwana and Baltica affinities.

Publications:

Will, T.M. (2001): Paleostress-tensor analysis of late deformation events in the odenwald Crystalline Complex and comparison with other units of the Mid-German Crystalline Rise, Germany. Mineralogy and Petrology, 72, 229-247.

Will, T.M., Schmädicke, E. (2001): A first report of retrogressed eclogites in the Odenwald Crystalline Complex: evidence for high-pressure metamorphism in the Mid-German Crystalline Rise, Germany. Lithos, 59, 109-125.

Will, T.M., Schmädicke, E. (2003): Isobaric cooling and counter-clockwise P-T paths in the Variscan Odenwald Crystalline Complex, Germany. Journal of Metamorphic Geology, 21, 469-480.

Zeh, A., Gerdes, A., Will, T.M., Millar, I.L. (2005): Provenance and magmatic-metamorphic evolution of a Variscan island-arc complex: Constraints from U-Pb dating, petrology, and geospeedometry of the Kyffhäuser Crystalline Complex, Central Germany. Journal of Petrology, 32, 1393-1420.

Zeh, A., Will, T.M., (2010): The Mid-German Crystalline Rise. - In: Linnemann, U., Romer, R.L. (eds.), Pre-Mesozoic geology of Saxo-Thuringia - From the Cadomian active margin to the Variscan orogen. Schweizerbart, Stuttgart, 195-220.

Schmädicke, E., Gose, J., Will, T.M. (2010): High-temperature metamorphism of garnet-bearing ultramafic rocks from the Saxonian Granulite Core Complex, Germany. Journal of Metamorphic Geology, 28,489-508.

Will, TM, Lee S-H, Schmädicke E, Frimmel HE, Okrusch M (2015) Variscan terrane boundaries in the Odenwald-Spessart basement, Mid-German Crystalline Zone: new evidence from ocean ridge, intraplate and arc-derived metabasaltic rocks. Lithos 220-223: 23-42

Will TM, Schulz B, Schmädicke E (2017) The timing of metamorphism in the Odenwald-Spessart basement, Mid-German Crystalline Zone. International Journal of Earth Sciences 106: 1631-1649

Will TM, Schmädicke E, Ling XX, Li XH, Li QL (2018) New evidence for an old idea: Geochronological constraints for a paired metamorphic belt in the Central European Variscides. Lithos 302-303: 278-297.

Project duration: since 2015

Supported by the German Research Foundation (DFG)

Summary:

his project is the result of work carried out within the DFG-funded SPP 1375 South Atlantic margin processes and links with onshore evolution. There, we could demonstrate (i) that the main Pan-African collisional suture lies in South America and, (ii) that the South Atlantic did not open along this suture but followed the long axis of a Neoproterozoic back-arc basin, located to the east of the suture. Remnants of this back-arc basin occur on both sides of the modern South Atlantic, including the allochthonous Cuchilla Dionisio Terrane in eastern Uruguay. Many workers agree that this terrane is exotic to South America and may represent a splinter of the Kalahari Craton. However, its connection with and continuation into SW Africa remains controversial and different links have been proposed: (1) the Angola Block, (2) the Coastal Terrane of the Kaoko Belt in NW Namibia, (3) the Marmora Terrane of the Gariep Belt and, (4) the Malmesbury Terrane in the Saldania Belt in South Africa. Each link has a different implication for the palaeogeographic reconstruction of Rodinia and the amalgamation of SW Gondwana. In this project we plan to determine the tectonothermal history of the Cuchilla Dionisio Terrane and compare it with that of its possible counterparts on the other side of the South Atlantic. This requires a thorough knowledge of themetamorphic and magmatic evolution of the respective terranes, which, at present, is only available at a reconnaissance level for the Cuchilla Dionisio Terrane. Therefore, we aim at resolving (i) the pressure-temperature conditions and paths experienced by high- and medium-grade metasedimentary and metavolcanic rocks, (ii) the tectonic settings in which the metamorphic events occurred and, (iii) the tectonic environments in which the pre-metamorphic magmatic protoliths of the Cuchilla Dionisio Terrane formed. By reconciling the expected results with known information on the geological evolution of SW Gondwana we expect to be able to identify the continuation of the Cuchilla Dionisio Terrane into SW Africa and also its most plausible position during Rodinia dispersion and SW Gondwana assembly. The results are likely to be significant for reconstructing the configuration of the assembled Rodinia supercontinent and the palaeogeographic positions of the various cratonic blocks of Rodinia and SW Gondwana during the Neoproterozoic.

Publications:

Pamoukaghlián K, Gaucher C, Frei R, Poiré DG, Chemale F, Frei D, Will TM (2017) U-Pb age constraints for the La Tuna Granite and Montevideo Formation (Paleoproterozoic, Uruguay): unravelling the structure of the Río de la Plata Craton. Journal of South American Earth Sciences 79: 443-458

Will TM, Gaucher C, Ling XX, Li XH, Li QL, Frimmel HE (2019) Neoproterozoic magmatic and metamorphic events in the exotic Cuchilla Dionisio Terrane, Uruguay, and possible correlations across the South Atlantic. Precambrian Research 320: 303-322.

Abgeschlossene Projekte zum Thema Geodynamik

  • Prof. Dr. Hartwig E. Frimmel
  • Prof. Dr. Divya Prakash (Banaras Hindu University)
  • PD Dr. Nikola Koglin (BGR)
  • Prof. Dr. Armin Zeh (KIT)
  • Dr. Suparna Tewari (Banaras Hindu University)

Project duration: 2012 - 2015

Supported by the German Research Foundation (DFG) and the German Academic Exchange Service (DAAD)

Summary:

The aim of the project was to compare ultrahigh-temperature (UHT) metamorphic rocks from various tectonic units of the South Indian Shield with regard to their pressure-temperature evolution in order to obtain information on the likely causes of the extreme conditions of metamorphism there. To this effect, metapelitic gneisses and granulites from three larger geological units were studied: from the Eastern Ghats Belt, the Eastern Dharwar Craton, and the Madurai Block. Based on microtextural observations to aid in the reconstruction of mineral reactions, conventional geothermobarometric calculations and the modelling of pseudosections, P-T paths around the various peak metamorphic events were reconstructed for all three areas. They are all similar with T-convex forms, which point at isothermal decompression after the metamorphic peak. This is explained by crustal thickening following continent-continent collision. Existing and newly acquired geochronological data indicate UHT metamorphism to have occurred at different times in the various units. In the Eastern Dharwar Craton UHT metamorphism was late Archaean (2604 Ma), in the Eastern Ghats Belts Mesoproterozoic (1130-930 Ma) and in the Madurai Block late Neoproterozoic (550-543 Ma). The latter two events can be explained by the formation of the supercontinents Rodinia and Gondwana, respectively. Similar P-T paths at different times in different, spatially unrelated geological units suggest that the tectonic interpretation presented in this study for UHT metamorphism might be the rule rather than exception. Our new results support the hypothesis that UHT metamorphism is caused by radiogenic heat production in thickened continental crust below an orogeny-induced continental plateau. Thus our results provide a useful contribution towards the long-standing debate on the causes of extreme, UHT metamorphism.

Publications:

Prakash, D., Yadav, R., Tewari, S., Frimmel, H.E., Koglin, N., Sachan, H., Yadav M., 2018, Geochronology and phase equilibria modeling of ultra-high temperature sapphirine+quartz-bearing granulite at Usilampatti, Madurai block, southern India. Geological Journal 53, 139-158.

Prakash, D., Chandra Singh, P., Tewari, S., Joshi, M., Frimmel, H.E., M., Hokada, T., Rakotonandrasana, T., 2017, Petrology, pseudosection modelling and U-Pb geochronology of silica-deficient Mg-Al granulites from the Jagtiyal section of Karimnagar granulite terrane, northeastern Dharwar Craton, India. Precambrian Research 299, 177-194.

Prakash, D., Deepak, Chandra Singh, P., Singh, C.K., Arima, M., Frimmel, H.E., 2015, Reaction textures and metamorphic evolution of sapphirine–spinel-bearing and associated granulites from Diguva Sonaba, Eastern Ghats Mobile Belt, India. Geological Magazine 152, 316-340.

  • Prof. em. Dr. Martin Okrusch
  • Prof. Naveen Chaudhri
  • Prof. Parampreet Kaur (Panjab Univ., Chandrigarh, India)
  • PD Dr. Armin Zeh (KIT)
  • Dr. Axel Gerdes (Univ. Frankfurt)
  • (Univ. Frankfurt/Main)
  • Prof. em. Dr. Alfred Kröner (Univ. Mainz)
  • Prof. Dr. Alfred W. Hofmann
  • Ingrid Radczek (MPI Chemie, Mainz)
  • PD Dr. Jürgen Köpke
  • Dr. Anette Schimrosczyk (Univ. Hannover)
  • Prof. Dr. Lukas P. Baumgartner
  • Dr. Susanne Skora (Univ. Lausanne, Switzerland)

Project duration: 2001 - 2013

Supported by the German Research Foundation (DFG) and the German Academic Exchange Service (DAAD)

Summary:

The NE-SW trending Proterozoic Khetri Complex is part of the 800 km long Aravalli Orogen, forming an important constituent of the Indian Plate. The complex consists predominantly of metasedimentary sequences that were intruded by a 1822 Ma old, subduction-related I-type granite and several 1711-1660 Ma old, extension-related A-type granites. These underwent pervasive albitization due to a Na-metasomatic event of regional extent. During our long-lasting cooperation with the Indian colleagues, we contributed a wealth of bulk rock and mineral analyses that helped to constrain the geochemical character and petrological evolution of these granites. Zircon ages and Nd-isotope data were determined at Mainz and oxygen isotope data at Lausanne.In 2009 we started a companion research project on the petrology. geochemistry and geochronology of the metamorphic sequences with the goal to reconstruct the P-T evolution of the Khetri metamorphics, using conventional geothermobarometry and calculated pseudosections. In the Frankfurt isotope laboratory, in-situ U-Pb and Lu-Hf isotope analyses on zircons and monazites are performed, using laser-ablation multicollector ICP-MS. The first results obtained on detrital zircons in a quartzite sample provided a comprehensive overview on the source areas of the (meta-)sedimentary sequences, with ages ranging between 3700 and 1700 Ma. Interestingly, the age of the youngest zircons overlaps - within limits of error - with the oldest intrusion age of the A-type granites. Although field evidence is somewhat ambiguous, it is clear that the granites form the crystalline basement, on which the protoliths of the metasedimentary sequence were deposited well after 1700 Ma. Judging from an in-situ U-Pb date on monazite, the metamorphic overprint took place much later, about 900 Ma ago.

Publications:

Kaur, P.; Chaudhri, N.; Hofmann, A.W.; Raczek, I.; Okrusch, M. (2013): Geochemistry and Sm-Nd geochronology of the metasomatised mafic rocks in the Khetri complex, Rajasthan, NW India: Evidence of an Early Cryogenian metasomatic event in the northern Aravalli orogeny. Journal of Asian Earth Sciences 62, 401-413.

Kaur, P.; Zeh, A.; Chaudhri, N.; Gerdes, A.; Okrusch, M. (2013): Nature of magmatism and sedimentation at a Columbia active margin: Insights from combined U-Pb und Lu-Hf isotope data of detrital zircons from NW India. Gondwana Research 23, 1040-1052.

Kaur, P., Chaudhri, N., Hofmann, A.W., Radczek, I., Okrusch, M., Skora, S., Baumgartner, L. (2012): Two stage, extreme albitisation of A-type granites from NE Rajasthan, India. Journal of Petrology, 53, 919-948.

Kaur, P., Chaudhri, N., Radzek, I., Kröner, A., Hofmann, A.W., Okrusch, M. (2011): Zircon ages of late Paleoproterozoic (ca. 1.72-.70) Ga) extension-related granitoids in NE Rajasthan, India: Regional and tectonic significance. Gondwana Research, 19, 1040-1053.

Kaur, P., Zeh, A., Chaudhri, N., Gerdes, A., Okrusch, M., (2011): Archean to Paleoproterozoic crustal evolution of the Aravalli mountain range, NW India, and its hinterland: The U-Pb and Hf isotope record of detrital zircons. Precambrian Research, 187, 155-164.

Kaur, P., Chaudhri, N., Okrusch, M., Koepke, J. (2006): Paleoproterozoic A-type felsic magmatism in the Khetri Copper Belt, Rajasthan, northwestern India: petrologic and tectonic implications. Mineralogy and Petrology, 87, 81-122.

Chaudhri, N., Kaur, P., Okrusch, M., Schimrosczyk, A. (2003): Charaterization of the Dabla granitoids, North Khetri Copper Belt, Rajasthan, India: evidence of bimodal anorogenic felsic magmatism. Gondwana Research, 6, 879-895.

Project duration: 1998 - 2010

Supported by the German Research Foundation (DFG)

Summary:

The main aim of this long-running project has been to integrate metamorphic petrological, geochronological and structural data to decipher the exhumation history and mechanisms of subduction-related high- and medium-pressure rocks associated with the Cenozoic Hellenic subduction system in the eastern Mediterranean. The main results obtained so far are summarized below. The Cenozoic history of the retreating Hellenic subduction involves subduction, accretion, arc magmatism, exhumation, normal faulting and large-scale continent extension from about 60 Ma until the present day. Ages for high-pressure metamorphism in the central Aegean Sea region range fromabout 53 Ma in the north to 25-20 Ma in Crete in the south, equivalent to a decrease in age down-section. Younging of high-pressure metamorphism in a southerly direction reflects the southward retreat of the Hellenic subduction zone. The shape of pressure-temperature-time paths of high-pressure rocks is remarkably similar across all tectonic units, suggesting a steady-state thermal profile of the subduction system and persistence of deformation and exhumation stiles. The high-pressure metamorphic events were caused by the underthrusting of fragments of continental crust that were superimposed on slab retreat. Most of the exhumation of high-pressure units occurred in extrusion wedges during ongoing subduction and overall lithospheric convergence. At 23-19-Ma large-scale lithospheric extension commenced, causing metamorphic core complexes and the opening of the Aegean Sea basin. This extensional stage caused limited exhumation at the margins of the Aegean Sea but accomplished the major part of the exhumation of 21-16 Ma old high-grade rocks in the central Aegean. The age pattern of extensional faults, as well as contoured maps of apatite and zircon fission-track cooling ages, do not show a simple southward progression but reflect fluctuations in regional partitioning of extensional deformation and related exhumation from 23-19 Ma to the Recent. The data support a temporal link between trapping of the subducted slab over the 660 km discontinuity and large-scale extension causing the opening of the Aegean Sea basin.

Publications:

Ring, U., Glodny, J., Will, T.M., Thompson, S.N. (2010): The retreating Hellenic subduction system: high-pressure metamorphism, exhumation, normal faulting and large-scale extension. Annual Review of Earth and Planetary Sciences, 38, 45-76.

Thompson, S.N., Ring, U., Brichau, S.,Glodny, J., Will, T.M. (2009): Timing and nature of formation of the Ios metamorphic core complex, southern Cyclades, Greece. - In: Ring, U., Wernicke, B. (eds.), Extending a continent: architecture, rheology and heat budget. Geological Society of London Special Publication, 321, 139-167.

Ring, U., Glodny, J., Will, T.M., Thompson, S.N. (2007): Crustal shortening versus crustal extension on Evia Island, Aegean Sea, Greece. Journal of the Geological Society of London, 164, 637-652.

Schmädicke, E., Will, T.M. (2003): Pressure-temperature evolutionof blueschist-facies rocks from the island of Sifnos, Greece, and constraints on exhumation processes. Journal of Metamorphic Geology, 21,799-811.

Will, T.M., Okrusch, M., Schmädicke, E., Chen, G. (1998): Phase relations in the greenschist-blueschist-amphibolite-eclogite facies in the system Na2O-CaO-FeO-MgO-Al2O3-SiO2-H2O (NCFMASH), with applications to the PT-evolution of metamorphic rocks from Samos, Greece. Contributions to Mineralogy and Petrology, 132, 85-102.

  • Prof. Dr. Ulrich Schüßler
  • Dr. Friedhelm Henjes-Kunst (Fed. Inst. for Geosci. and Natural Resources Germany (BGR)
  • Prof. Dr. Bernhard Schulz (TU Freiberg)
  • Prof. Dr. Franco Talarico (University Siena)

Project duration: 1998 - 2013

Supported in part by the German Research Foundation and the expedition program of the Federal Institute for Geosciences and Natural Resources Germany (BGR)

Summary:

In the frame of the German Antarctic North Victorialand Expedition (GANOVEX) program of the Federal Institute for Geosciences and Natural Resources Germany, the northern end of the Transantarctic Mountains along the Pacific coast of North Victorialand and Oates Land, and particularly the northern end of the Wilson Terrane, westernmost terrane of the Ross orogenic belt, was visited during GANOVEX V and VII in 1988/98 and 1992/93. It was the first systematic geological reconnaissance in that area (apart from a New Zealand dog-sledge expedition in 1968). Beside basic geological work like mapping and sampling, the project focused on the tectono-metamorphic evolution of this area and an elucidation of the pressure-temperature-time paths of different metamorphic units.

Publications:

SCHÜSSLER, U., SKINNER, D.N.B., ROLAND, N.W., (1993): Subduction-related Mafic to Intermediate Plutonism in the Northwestern Wilson Terrane, North Victoria Land and Oates Coast, Antarctica. Geologisches Jahrbuch, Reihe E 47: 389-417.

SCHÜSSLER, U., HENJES-KUNST, F. (1994): Petrographical and Geochronological Investigations on a Garnet-Tourmaline Pegmatite from Ringgold Knoll, Oates Coast, Antarctica. Chemie der Erde, 54: 297-318.

SCHÜSSLER, U. (1996): Metamorphic Rocks in the Northern Wilson Terrane, Oates Coast, Antarctica. Geologisches Jahrbuch, Reihe B 89: 247-269.

ROLAND, N.W., ADAMS, C.J., FLÖTTMANN, T., KLEINSCHMIDT, G., OLESCH, M., SCHÜSSLER, U., SKINNER, D.N.B., WÖRNER, G. (1996): Geological Map of the Suvorov Glacier Quadrangle, Victoria Land, Antarctica, 1:250000. - In: PERTUSATI, P.C. & TESSENSOHN, F. (eds.): German-Italian Geological Antarctic Map Program (GIGAMAP), Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover.

SCHÜSSLER, U., FENN, G., FLÖTTMANN, T., KLEINSCHMIDT, G., OLESCH, M., ROLAND, N.W., SCHUBERT, W., SKINNER, D.N.B. (1999): Geological Map of the Pomerantz Tableland Quadrangle, Victoria Land, Antarctica, 1:250000. - In: PERTUSATI, P.C. & TESSENSOHN, F. (eds.): German-Italian Geological Antarctic Map Program (GIGAMAP), Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover.

SCHÜSSLER, U., BRÖCKER, M., HENJES-KUNST, F., WILL, T. (1999): P-T-t evolution of the Wilson Terrane metamorphic basement at the Oates Coast, Antarctica. Precambrian Research, 93: 235-258.

ROLAND, N.W., ADAMS, C.J., FLÖTTMANN, T., KLEINSCHMIDT, G., OLESCH, M., PERTUSATI, P.C., SCHÜSSLER, U., SKINNER, D.N.B., HENJES-KUNST, F. (2001): Geological Map of the Matusevich Glacier Quadrangle, Victoria Land, Antarctica, 1:250000. - In: PERTUSATI, P.C. & TESSENSOHN, F. (eds.): German-Italian Geological Antarctic Map Program (GIGAMAP), Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover.

HENJES-KUNST, F., SCHÜSSLER, U. (2003): Metasedimentary units of the Cambro-Ordovician Ross Orogen in northern Victoria Land and Oates Land: implications for their provenance and geotectonic setting from geochemical and Nd-Sr isotope data. Terra Antartica.10: 105-128.

SCHÜSSLER, U., HENJES-KUNST, F., TALARICO, F., FLÖTTMANN, T. (2004): High-grade crystalline basement of the northwestern Wilson Terrane at Oates Coast: new petrological and geochronological data and implications for its tectonometamorphic evolution. Terra Antartica, 11: 15-34.

SCHULZ, B., SCHÜSSLER, U. (2013): Electron-microprobe monazite dating in Early-Paleozoic high-grade gneisses as a completion of U-Pb isotope ages (Wilson Terrane, Antarctica). Lithos, 175/176, 178-192.

Project duration: 2005 - 2008

Supported by the German Research Foundation (DFG)

Summary:

The overall aims of this project were to distinguish different crustal components in the Shackleton Range, East Antarctica, to infer their source, age and tectonic evolution and to document how the individual basement components are related to other terranes of the East Antarctic Craton, and wether they provide evidence for supercontinental formation during the Meso- and/or Neoproterozoic/Cambrian. Towards these aims it was intended to:1. determine the pressure-temperature conditions of various rock types, 2. characterize the geochemical signature of (predominantly) mafic igneous rocks via major, minor, trace and rare earth element geochemistry, 3. ascertain the source region (juvenile mantle, reworked crust, tectonic affinities of metabasic rocks) of felsic and mafic orthogneisses through whole rock isotope and Lu-Hf in-situ zircon analyses, 4. establish the timing of various tectonothermal events by combined U-Pb and Lu-Hf zircon isotope analysis, grt-whole rock Sm-Nd and Ar-Ar dating.With the help of detailed geochronological analysis, combined with Hf isotope data on single zircon domains, numerous lithogeochemical and bulk rock isotopic (Sr, Nd, Pb isotopes) as well as mineral-chemical analyses for thermobarometric calculations, three different terranes could be identified within the Shackleton Range. For each of these terranes, a series of distinct magmatic and metamorphic events could be recognized and the likely tectonic setting for these events reconstructed.

Publications:

Schmädicke, E., Will, T.M. (2006): First evidence of eclogite-facies metamorphism in the Shackleton Range, Antarctica: Tracer of a suture between East and West Gondwana? Geology, 34, 133-136.

Will, T.M., Frimmel, H.E., Zeh, A., Le Roux, P., Schmädicke, E. (2010): Tectonic and crustal evolution of the Shackleton Range, East Antarctica: geochemical and isotope constraints. Precambrian Research, 180, 85-112.

Will, T.M., Zeh, A., Gerdes, A., Frimmel, H.E., Millar, I.L., Schmädicke, E. (2009): Palaeoproterozoic to Palaeozoic magmatic and metamorphic events in the Shackleton Range, East Antarctica: Constraints from zircon and monazite dating, and implications for the amalgamation of Gondwana. Precambrian Research, 172, 25-45.

Zeh, A., Gerdes, A., Will, T.M., Frimmel, H.E. (2010): Hafnium isotope homogenisation in metasedimentary rocks under amphibolite-facies conditions (>650°C): examples from the Shackleton Range (Antarctica). Geochimica et Cosmochimica Acta, 74, 4740-4758.

Project duration: 2009 - 2017

Supported by the German Research Foundation (DFG)

Summary:

The aim of the project was to reconstruct the mode of opening of the South Atlantic. Using the Mesozoic structures as a reference frame it was tested whether the break-up of southwestern Gondwana followed pre-existing older lithospheric structures. Several different tectonic scenarios appear possible: (i) the South Atlantic opened along Pan-African suture zones that had formed between the southern African continental cratonic blocks and the South American Rio de la Plata Craton during the assembly of Gondwana, i.e. within a former subduction and continental collision zone, (ii) break-up may have commenced along a former back-arc along the western margin of the Kalahari palaeocontinent along a thermally and rheologically softened crustal domain or, (iii) it may turn out that inherited lithospheric anisotropies did not play any significant role for the initiation and location of Mesozoic continental rifting.

In order to achieve the set goal, the kinematic evolution of the Mesozoic structures associated with the South Atlantic opening was determined first. This served as a reference frame for comparison with the structural-kinematic history of pre-rift structures, which had to be inferred from field observations. Integral to the study was the reconstruction of the orientations (and their change) of the palaeostress fields that produced the Mesozoic and pre-Mesozoic structures. This was done with an algorithm developed by the T. Will that uses robust regression techniques, which are capable of detecting outliers, to calculate geologically meaningful palaeostress orientations (i.e. the reduced stress tensor) from field data. This structural-kinematic study was augmented by petrological and geochemical investigations on selected samples. In addition, the study demonstrate whether pre-Mesozoic structures influenced rift-related magma emplacement. Furthermore, an effort was made to directly date the age of movement along the major fault and shear zones using the Ar-Ar isotope systems.

Publications:

Will, T., Frimmel, H.E., 2018, Where does a continent prefer to break up? Lessons from the South Atlantic margins. Gondwana Research 53, 9-19.

Will, T., Frimmel, H.E., Pfänder, J., 2016, Möwe Bay dykes, northwestern Namibia: Geochemical and geochronological evidence for different mantle source regions during the Cretaceous opening of the South Atlantic. Chemical Geology, 444, 141-157.

Will, T., Frimmel, H.E., Gaucher, C., Bossi, J., 2014, Geochemical and isotope evidence for initiation of Cretaceous South Atlantic opening along a former Neoproterozoic back-arc basin — Implications for the location of the main Pan-African suture in south west Gondwana. Lithos 202-203, 363-381.

Frimmel, H.E., Basei, M.A.S., Correa, V.X., Mbangula, N., 2013, A new lithostratigraphic subdivision and geodynamic model for the Pan-African western Saldania Belt, South Africa. Precambrian Research 231, 218-235.

Will, T., Frimmel, H.E., 2013, The influence of inherited structures on dyke emplacement during Gondwana break-up in southwestern Africa. Journal of Geology 121, 455-474.

Frimmel, H.E., Basei, M.S., Gaucher, C., 2011, Neoproterozoic geodynamic evolution of SW-Gondwana: a southern African perspective. International Journal of Earth Sciences, 100, 323-354.

Will, T.M., Miller, R.McG., Frimmel, H.E., 2009, Orogenic tectono-thermal evolution. Neoproterozoic to Early Palaeozoic evolution of Southwestern Africa: In Gaucher, C., Sial, A.N., Halverson, G.P., Frimmel, H.E. (eds.), Neoproterozoic-Cambrian Tectonics, Global Change and Evolution: a Focus on Southwestern Gondwana, Developments in Precambrian Geology, Elsevier, Amsterdam, v. 16, p. 205-218.

Miller, R.McG., Frimmel, H.E., Will, T.M., 2009, Geodynamic synthesis of the Damara Orogen sensu lato. Neoproterozoic to Early Palaeozoic evolution of Southwestern Africa. In Gaucher, C., Sial, A.N., Halverson, G.P., Frimmel, H.E. (eds.), Neoproterozoic-Cambrian Tectonics, Global Change and Evolution: a Focus on Southwestern Gondwana, Developments in Precambrian Geology, Elsevier, Amsterdam, v. 16, p. 231-235.

 

Project duration: 2007 - 2010

Supported by the German Research Foundation (DFG)

Summary:

In many oceanic core complexes plagioclase-free, spinel-bearing mantle peridotite occurs directly on the seafloor. Peridotite samples collected on ODP leg 153 are variably serpentinised (50-100%) and are strongly depleted in light rare earth and other trace elements, indicating that they experienced some 10-20% melt loss. The genesis of this rock type on the ocean floor has remained highly speculative in spite of its enormous significance for our understanding of oceanic tectonic processes. The presence of spinel requires equilibration pressures of at least 8 kbar at 950°C. Significantly higher pressures in the excess of 20 kbar are however possible. This implies an exhumation of the spinel peridotite from depths between 25 and possibly more than 70 km, which is in strong contrast to the 4 to 7 km of exhumation that have been suggested previously (Karson & Lawrence 1997). Geothermobarometric techniques will be applied to these rocks to infer their equilibration depth and their pressure-temperature evolution. Ar-Ar age dating will be used in an attempt to put constraints on the exhumation rate and cooling history of these rocks. The timing of the partial melting event that is responsible for the residual chemical character of the peridotite is debated. It could have occurred during recent uplift or, as suggested by Brandon et al. (2000), in Proterozoic times, which, however, has been strongly questioned by Alard et al. (2005). In order to resolve this controversy and to determine the timing of partial melting it is planned to carry out a Sm-Nd, Rb-Sr and Pb isotope study. The overall goal is to distinguish between different lithospheric components and to constrain the age of the source for the protoliths. With such new data and, together with the inferred PT-evolution, we aim to assign the source and tectonic evolution of these rocks to Proterozoic and/or recent magmatic and tectonometamorphic events. Ultimately, the expected results will improve our understanding of abyssal peridotite whose origin is inconsistent with current partial melting in the global ridge system of modern Earth.

Publications:

Will, T.M., Schmädicke, E., Frimmel, H.E. (2010): Deep solid-state equilibration and deep melting of abyssal peridotite from the slow-spreading Mid-Atlantic Ridge at the Kane Transform area (MARK), 23°N, ODP leg 153. Mineralogy and Petrology, 100, 185-200.

Schmädicke E, Gose J, Will TM (2011) Heterogeneous mantle underneath the North Atlantic: Evidence from water in orthopyroxene, mineral composition and equilibrium conditions of spinel peridotite from different locations at the Mid-Atlantic Ridge. Lithos 125: 308-320.

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