caa a22 4500 465791611 CHVBK 20180323112026.0 cr unu---uuuuu 170327e19900901xx s 000 0 eng 10.1007/BF00286830 doi (NATIONALLICENCE)springer-10.1007/BF00286830 Rare earth element geochemistry of Thetford Mines ophiolite complex, Northern Appalachians, Canada [Elektronische Daten] [Luc Harnois, Jacques Trottier, Maurice Morency] The Thetford Mines complex is a complete ophiolite which is part of an ultramafic-mafic belt within Québec Appalachians. These allochtonous bodies were emplaced during the Early Ordovician. The Thetford Mines complex comprises a lower unit of metamorphic harzburgite (in which tabular, dyke-like, dunitic bodies occur) overlain successively by ultramafic cumulates, mafic cumulates, ophitic gabbros, diabase sills and dykes, and basaltic volcanic rocks. Field evidence, petrography and chemical data indicate that the tabular dunitic bodies formed when fractures in the metamorphic harzburgite (which constituted the floor of the magma chamber) filled with early cumulates (i.e., olivine±chromite). Representative rocks from all units were analyzed for major and rare earth elements (REE). Metamorphic harzburgite samples from Thetford Mines complex have U-shaped chondrite-normalized REE patterns. Pyroxenites and wehrlites of the cumulate sequence are all strongly light-REE depleted and have heavy REE ranging from 0.4 to 1.5 times chondrite. REE data from ultramafic and volcanic rocks of Thetford Mines complex and geochemical modelling indicate that the metamorphic harzburgite has the chemical characteristics of depleted upper mantle residues with U-shaped patterns, and that the ultramafic cumulates crystallized from magmas having different La/Yb ratios. Springer-Verlag, 1990 Harnois Luc GEOTERAP, Université du Québec à Montréal, PO Box 8888, Station A, H3C 3P8, Montréal, Québec, Canada aut Trottier Jacques Groupe Minier Morisco, 800 West, Boulevard René-Lévesque (Room 450), H3B 1X9, Montréal, Québec, Canada aut Morency Maurice Departement des Sciences de la Terre, Université du Québec à Montréal, PO Box 8888, Station A, H3C 3P8, Montréal, Québec, Canada aut Contributions to Mineralogy and Petrology Springer-Verlag 105/4(1990-09-01), 433-445 0010-7999 105:4<433 1990 105 410 https://doi.org/10.1007/BF00286830 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00286830 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Harnois Luc GEOTERAP, Université du Québec à Montréal, PO Box 8888, Station A, H3C 3P8, Montréal, Québec, Canada aut NATIONALLICENCE 700 1- Trottier Jacques Groupe Minier Morisco, 800 West, Boulevard René-Lévesque (Room 450), H3B 1X9, Montréal, Québec, Canada aut NATIONALLICENCE 700 1- Morency Maurice Departement des Sciences de la Terre, Université du Québec à Montréal, PO Box 8888, Station A, H3C 3P8, Montréal, Québec, Canada aut NATIONALLICENCE 773 0- Contributions to Mineralogy and Petrology Springer-Verlag 105/4(1990-09-01), 433-445 0010-7999 105:4<433 1990 105 410 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer