R. M. Tosdal
J. L. Wooden
F.K. Mazdab
R.M. Friedman
A.J. Wainwright
2011
<p><span>Uranium–Pb (zircon) ages are linked with geochemical data for <a title="Learn more about Porphyry from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/porphyry" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/porphyry">porphyry</a> intrusions associated with giant porphyry Cu–Au systems at Oyu Tolgoi to place those rocks within the <a title="Learn more about Petrochemical from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/petrochemical" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/petrochemical">petrochemical</a> framework of <a title="Learn more about Devonian from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/devonian" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/devonian">Devonian</a> and Carboniferous rocks of southern Mongolia. In this part of the Gurvansayhan <a title="Learn more about Terrane from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/terrane" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/terrane">terrane</a> within the Central Asian <a title="Learn more about Orogenic Belt from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/orogenic-belt" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/orogenic-belt">Orogenic Belt</a>, the transition from Devonian tholeiitic marine rocks to unconformably overlying Carboniferous calc-alkaline subaerial to shallow marine volcanic rocks reflects <a title="Learn more about Volcanic Arc from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/volcanic-arc" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/volcanic-arc">volcanic arc</a> thickening and maturation. Radiogenic Nd and Pb <a title="Learn more about Isotopic Composition from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/isotopic-composition" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/isotopic-composition">isotopic compositions</a> (</span><i>ε</i><sub>Nd(t)</sub><span> range from +</span><span> </span><span>3.1 to +</span><span> </span><span>7.5 and </span><sup>206</sup><span>Pb/</span><sup>204</sup><span>Pb values for <a title="Learn more about Feldspar from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/feldspar" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/feldspar">feldspars</a> range from 17.97 to 18.72), as well as low high-field strength element (HFSE) contents of most rocks (mafic rocks typically have <</span><span> </span><span>1.5% TiO</span><sub>2</sub><span>) are consistent with <a title="Learn more about Magma from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/magma" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/magma">magma</a> derivation from depleted mantle in an intra-oceanic volcanic arc. The <a title="Learn more about Late Devonian from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/late-devonian" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/late-devonian">Late Devonian</a> and Carboniferous <a title="Learn more about Felsic Rock from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/felsic-rock" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/felsic-rock">felsic rocks</a> are dominantly medium- to high-K calc-alkaline and characterized by a decrease in Sr/Y ratios through time, with the Carboniferous rocks being more felsic than those of Devonian age. Porphyry Cu–Au related intrusions were emplaced in the Late Devonian during the transition from tholeiitic to calc-alkaline arc <a title="Learn more about Magmatism from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/magmatism" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/magmatism">magmatism</a>. Uranium–Pb (zircon) <a title="Learn more about Geochronology from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/geochronology" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/geochronology">geochronology</a> indicates that the Late Devonian pre- to syn-mineral <a title="Learn more about Quartz from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/quartz" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/quartz">quartz</a> monzodiorite intrusions associated with the porphyry Cu–Au deposits are ~</span><span> </span><span>372</span><span> </span><span>Ma, whereas <a title="Learn more about Granodiorite from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/granodiorite" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/granodiorite">granodiorite</a> intrusions that post-date major shortening and are associated with less well-developed porphyry Cu–Au <a title="Learn more about Mineralization from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/mineralization" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/mineralization">mineralization</a> are ~</span><span> </span><span>366</span><span> </span><span>Ma. <a title="Learn more about Trace Element Geochemistry from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/trace-element-geochemistry" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/trace-element-geochemistry">Trace element geochemistry</a> of zircons in the Late Devonian intrusions associated with the porphyry Cu–Au systems contain distinct Th/U and Yb/Gd ratios, as well as Hf and Y concentrations that reflect mixing of magma of distinct compositions. These characteristics are missing in the unmineralized Carboniferous intrusions. High Sr/Y and evidence for magma mixing in syn- to late-mineral intrusions distinguish the Late Devonian rocks associated with giant Cu–Au deposits from younger magmatic suites in the district.</span></p>
application/pdf
10.1016/j.gr.2010.11.012
en
Elsevier
U-Pb (zircon) and geochemical constraints on the age, origin, and evolution of Paleozoic arc magmas in the Oyu Tolgoi porphyry Cu-Au district, southern Mongolia
article