@article{RoetzlerTimmerman2020, author = {R{\"o}tzler, Jochen and Timmerman, Martin Jan}, title = {Geochronological and petrological constraints from the evolution in the Saxon Granulite Massif, Germany, on the Variscan continental collision orogeny}, series = {Journal of metamorphic geology}, volume = {39}, journal = {Journal of metamorphic geology}, number = {1}, publisher = {Wiley}, address = {Hoboken}, issn = {0263-4929}, doi = {10.1111/jmg.12559}, pages = {3 -- 38}, year = {2020}, abstract = {Controversy over the plate tectonic affinity and evolution of the Saxon granulites in a two- or multi-plate setting during inter- or intracontinental collision makes the Saxon Granulite Massif a key area for the understanding of the Palaeozoic Variscan orogeny. The massif is a large dome structure in which tectonic slivers of metapelite and metaophiolite units occur along a shear zone separating a diapir-like body of high-Pgranulite below from low-Pmetasedimentary rocks above. Each of the upper structural units records a different metamorphic evolution until its assembly with the exhuming granulite body. New age and petrologic data suggest that the metaophiolites developed from early Cambrian protoliths during high-Pamphibolite facies metamorphism in the mid- to late-Devonian and thermal overprinting by the exhuming hot granulite body in the early Carboniferous. A correlation of new Ar-Ar biotite ages with publishedP-T-tdata for the granulites implies that exhumation and cooling of the granulite body occurred at average rates of similar to 8 mm/year and similar to 80 degrees C/Ma, with a drop in exhumation rate from similar to 20 to similar to 2.5 mm/year and a slight rise in cooling rate between early and late stages of exhumation. A time lag ofc. 2 Ma between cooling through the closure temperatures for argon diffusion in hornblende and biotite indicates a cooling rate of 90 degrees C/Ma when all units had assembled into the massif. A two-plate model of the Variscan orogeny in which the above evolution is related to a short-lived intra-Gondwana subduction zone conflicts with the oceanic affinity of the metaophiolites and the timescale ofc. 50 Ma for the metamorphism. Alternative models focusing on the internal Variscan belt assume distinctly different material paths through the lower or upper crust for strikingly similar granulite massifs. An earlier proposed model of bilateral subduction below the internal Variscan belt may solve this problem.}, language = {en} } @article{EnnisMeereTimmermanetal.2015, author = {Ennis, Meg and Meere, Patrick A. and Timmerman, Martin Jan and Sudo, Masafumi}, title = {Post-Acadian sediment recycling in the Devonian Old Red Sandstone of Southern Ireland}, series = {Gondwana research : international geoscience journal ; official journal of the International Association for Gondwana Research}, volume = {28}, journal = {Gondwana research : international geoscience journal ; official journal of the International Association for Gondwana Research}, number = {4}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1342-937X}, doi = {10.1016/j.gr.2014.10.007}, pages = {1415 -- 1433}, year = {2015}, abstract = {The Upper Devonian Munster Basin of southern Ireland has traditionally been viewed as a post-orogenic molasse deposit that was sourced from the Caledonides of central Ireland and subsequently deformed by the end Carboniferous Variscan orogenic event. The basin fill is composed of super-mature quartz arenite sandstone that clearly represents a second cycle of deposition. The source of this detritus is now recognized as Lower Devonian Dingle Basin red bed sequences to the north. This genetic link is based on the degree of similarity in the detrital mica chemistry in both of these units; micas plot in identical fields and define the same trends. In addition, the two sequences show increased textural and chemical maturity up-sequence and define indistinguishable Ar-40/Ar-39 age ranges for the detrital mica grains. Partial resetting of the Ar ages can be attributed to elevated heat flow in the region caused by Munster Basin extension and subsequent Variscan deformation. The combined evidence from southwest Ireland therefore points to a Caledonian or possibly Taconian primary source area that initially shed detritus into the Lower Devonian Dingle Basin which was subsequently recycled into the Upper Devonian Munster Basin following mid-Devonian Acadian basin inversion. (C) 2014 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.}, language = {en} }