Recent studies argue that subduction-modified, Cu-fertilized lithosphere controls the formation of porphyry Cu deposits in orogenic belts. However, it is unclear if and how this fertilization process operates at cratonic edges, where numerous large non-arc Au-rich deposits form. Here we report data from lower crustal amphibolite and garnet amphibolite xenoliths hosted by Cenozoic stocks that ar...

There are two basic Fe-rich lithologies at Weld Range: (l) banded iron-formation containing minnesotaite, siderite, quarlz,magnetite, greenalite, stilpnomelane, pyrite, and chamosite with trace amounts of pyrrhotite, arsenopyrite, chalcopyrite, apatite, and rockbridgeite; Q) Fe-shale. which occurs as laminated 2-30cm-thick bands within banded iron-formation, containing chamosite, stilpnomelane,...

U-Pb analyses of zircon from ten samples of augen gneisses, eight mafic and intermediate metaigneous rocks and six metasediments from some tectonic domains along the Calabria-Peloritani Terrane (Southern Italy) contribute to knowledge of peri-Gondwanan evolution from Late-Proterozoic to Paleozoic times. All samples were equilibrated under amphibolite to granulite facies metamorphism during the ...

Archaean komatiites of the greenstone belt in Manica area, western Mozambique contains accessory amount of disseminated chromite grains. The komatiite rocks comprise peridotitic and basaltic komtiite. These komatiites are affected by regional metamorphism as all of the studied area. It is observed that only chromian spinel is preserved as the primary mineral and that all the other primary miner...

Activities of titanite (Ttn, CaTiSiO5) and ⁄or rutile (Rt, TiO2) phase components were calculated for 45 well-characterized natural titaniteor rutile-undersaturated epidote–amphibolites by using the equilibria: (i) 3 anorthite + 2 zoisite ⁄ clinozoisite + rutile + quartz = 3 anorthite + titanite + water (referred to as TZARS) and (ii) anorthite + 2 titanite = grossular + 2 rutile + quartz (refe...

There has been controversy over the number and timing of orogenies in the Precambrian Moine block in the Scottish Caledonides since the earliest radiometric dating in the 1960s. This work challenges a recent hypothesis, that this sector of the Laurentian margin was subjected to continuous crustal extension between .900 and 470 Ma. U–Pb dating (thermal ionization mass spectrometry) of titanite f...

A Silurian regional tectonometamorphic event has been widely recorded by different geochronological methods in the Sierras Pampeanas, NW Argentina and Precordillera. It took place between ca. 445 420 Ma after Hirnantian (late Ordovician) glaciogenic sedimentation. Three domains are recognized. 1) The eastern Pampeanas Puna mainly record focused westward ductile thrusting heating. 2) In westernm...

Magmatic augites reacted with high temperature aqueous solutions to form secondary calcic pyroxenes during the subsolidus cooling of the Skaergaard intrusion. Secondary, hydrothermal clinopyroxenes replace wall rock igneous augites at the margins of veins filled with calcic amphibole. These veins are up to several millimeters wide and tens of meters in length. Hydrothermal clinopyroxenes are a ...

New calcite Sr/Sr data for 47 limestones from the metamorphosed and deformed Neoproterozoic–Cambrian Dalradian Supergroup of Scotland and Ireland are used to identify secular trends in seawater Sr/Sr through the Dalradian succession and to constrain its depositional age. Dalradian limestones commonly have Sr .1000 ppm, indicating primary aragonite and marine diagenesis. Low Mn, Mn/Sr ,0.6, O an...

Sm-Nd ages of pegmatite dikes that crosscut gold-bearing structures in the southern Yilgarn Craton, Western Australia, provide minimum age constraints of 2640 6 11 Ma, 2628 6 10 Ma, and 2620 6 36 Ma for gold mineralization at the Westonia and Nevoria (Yellowdine Terrane) and Scotia (Norseman Terrane) gold deposits, respectively. Similarly, a post–gold mineralization dike at Westonia has a U-Pb ...