caa a22 4500 38638455X CHVBK 20180307112054.0 cr unu---uuuuu 161130s1989 xx s 000 0 eng 10.1017/S0263593300014449 doi S0263593300014449 pii (NATIONALLICENCE)cambridge-10.1017/S0263593300014449 Geology, geochemistry and geochronology of a taconic batholith, southwestern Newfoundland [Elektronische Daten] Foliated to massive hornblende and biotite-bearing tonalite, trondhjemite and granodiorite comprise a terrane of batholithic dimensions in southwestern to central Newfoundland. These rocks intrude and include Ordovician ophiolite fragments and metasedimentary rocks of Fleur de Lys type, and are cut by a suite of Silurian gabbro-diorite and norite and Siluro-Devonian (?) granite intrusions. A U/Pb (zircon, sphene) age of 456 ± 3 Ma (2σ) and a K/Ar (hornblende) age of 455 ± 14 Ma (previously reported) for a representative least-deformed tonalite of the Southwest Brook Complex indicate that it crystallised and cooled in Caradoc time. A less precise U/Pb (zircon) age of 428 ± 41 Ma (2σ) is measured for tonalitic Cape Ray Granite in southern Newfoundland. On discrimination diagrams which use Rb, Nb and Y contents to infer tectonic setting, these rocks fall in the field of volcanic arc granites. The occurrence of zircon cores with average ages of 1430 + 18/-17 and 1541 ± 173 Ma (2σ) also indicate that the magmas formed in part by partial melting of Proterozoic crust, or sediments derived from such crust. It is suggested that the tonalitic magmas were generated during the Taconic Orogeny in an arc: continent collision zone at the ancient margin of eastern North America. Tonalitic rocks in western Newfoundland broadly correlative in age and chemistry with the batholith include the Burlington Granodiorite and Hungry Mountain Complex, as well as allochthonous slices of foliated tonalite emplaced over Ordovician platform carbonates W of Grand Lake. Copyright © Royal Society of Edinburgh 1989 Ordovician tonalite nationallicence major nationallicence trace nationallicence REE chemistry nationallicence U/Pb zircon age nationallicence Dunning G. R. Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland, Canada, A1B 3X5. Wilton D. H. C. Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland, Canada, A1B 3X5. Herd R. K. Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, Canada, K1A 0E8. Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 80/2(1989), 159-168 0263-5933 80:2<159 1989 80 TRE https://doi.org/10.1017/S0263593300014449 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0263593300014449 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Dunning G. R. Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland, Canada, A1B 3X5 NATIONALLICENCE 700 1- Wilton D. H. C. Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland, Canada, A1B 3X5 NATIONALLICENCE 700 1- Herd R. K. Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, Canada, K1A 0E8 NATIONALLICENCE 773 0- Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 80/2(1989), 159-168 0263-5933 80:2<159 1989 80 TRE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge