Geochemistry of Archean meta-igneous rocks, Lake Despair area, Wabigoon Subprovince, northwestern Ontario

1980 ◽  
Vol 17 (8) ◽  
pp. 1046-1063 ◽  
Author(s):  
Fred J. Longstaffe ◽  
Robert H. McNutt ◽  
Henry P. Schwarcz
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Metamorphic Grade ◽  
Igneous Rocks ◽  
Rock Types ◽  
Northwestern Ontario ◽  
Metavolcanic Rocks ◽  
Plutonic Complex ◽  
Tectonic Settings ◽  
Amphibole Fractionation

The Lake Despair area, northwestern Ontario, is underlain by a series of igneous and meta-igneous rocks including mafic and felsic metavolcanic rocks, gneisses (Footprint gneiss), and plutonic granitoids (Jackfish Lake Plutonic Complex; Northwest Bay Complex). The metavolcanic sequence consists of a bimodal suite of interlayered metabasalts of tholeiitic character and metadacites with metamorphic grade ranging from greenschist to amphibolite facies. Trace element studies of the metabasalt, while indicating an oceanic provenance, do not uniquely distinguish between possible oceanic tectonic settings. The metadacites, the Footprint gneiss, and the Northwest Bay Complex are chemically similar to the high Al tonalitic rocks common in other Archean terrains. The Footprint gneiss, which forms part of the gneissic core of the Rainy Lake batholith, was derived from an igneous parent, and was quasi-isochemically metamorphosed.The youngest major intrusion, the Na-alkalic Jackfish Plutonic Complex, is composed of hornblende diorite and monzodiorite with minor leucodiorite, quartz monzodiorite, granodiorite, and Na-syenite. The diorite and monzodiorite crystallized from an intermediate magma formed by partial melting of a garnet and (or) amphibole-rich basaltic parent. Remaining residual liquids, enriched in alkalis and silica by amphibole fractionation, crystallized to form the more leucocratic rock types. Perthitic microcline megacrysts, characteristic of the quartz monzodiorite and granodiorite, formed near the end of magmatic processes. The Na-syenite was emplaced as a separate pulse of magma or possibly was produced by the interaction of alkalis and the upper portions of the solidified rim of the magma chamber.

Lunar differentiation processes as characterized by trace element abundances

1977 ◽  
Vol 285 (1327) ◽  
pp. 199-205 ◽  
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Melting Process ◽  
Reasonable Assumption ◽  
Lunar Crust ◽  
Crustal Layer ◽  
Element Abundances ◽  
Rock Types ◽  
Incompatible Elements ◽  
Partial Melting Process

The pattern of incompatible elements (K, Rb, Ba, r.e.e., H f etc.) is the same for most samples from the lunar highlands. It is suspected that this pattern of incompatible elements is typical for the whole lunar crust. This seems to be a reasonable assumption as one can show from heat flow data that a large part of the Moon’s total U (and consequently other incompatible elements) has to be concentrated in a thin crustal layer, which certainly contributes to the sampled highland rock types. It is supposed that a partial melting process of the major part of the Moon has extracted the trace elements from the interior into the crust. The patterns of incompatible elements of mare basalts are those expected if a second partial melting process were applied to the trace-element-depleted interior. Some consequences of this model are discussed. A relatively constant Sr and Eu distribution through the whole Moon is inferred, implying a positive Eu-anomaly in the lunar interior.

Crustal recycling during subduction at the Eocene Cordilleran margin of North America: a petrogenetic study from the southwestern Yukon

2003 ◽  
Vol 40 (12) ◽  
pp. 1805-1821 ◽  
Author(s):  
George A Morris ◽  
Robert A Creaser
Keyword(s):  
Partial Melting ◽  
Continental Margin ◽  
Pyroclastic Flows ◽  
Canadian Cordillera ◽  
Early Eocene ◽  
Crustal Recycling ◽  
Rock Types ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Cordilleran Margin

The early Eocene (57.3–55.4 Ma) Bennett Lake and Mount Skukum Volcanic Complexes lie on the Coast Plutonic Complex and Intermontane Belt boundary of the Canadian Cordillera at the British Columbia – Yukon border, some 200 km east of the current and Eocene continental margin. Both complexes contain rock types from basaltic andesite to rhyolite in a series of lava and pyroclastic flows. The location relative to the continental margin, the rock types, and the presence of an enhanced LILE/HFSE (large-ion lithophile / high field strength element) signatures in all samples imply that contemporaneous subduction was the controlling factor in the formation of these complexes. The majority of samples, however, return unusually low compatible element concentrations for given rock types. We interpret this data to show that partial melting of the crust was the major source of erupted magmas. One formation of andesites at Mount Skukum and one late dyke at Bennett Lake do show higher concentrations of compatible trace elements, suggesting the presence of primitive magmas in the crust at the time of eruption, which contaminated and were erupted with the crustal melts. Sr–Nd isotopic data at both complexes are consistently primitive regardless of rock type and compatible element content, requiring a primitive crustal source for these magmas. We propose that the complexes were formed as a result of early Eocene subduction of the Kula Plate beneath the Canadian Cordillera. Intrusion of hot primitive melts caused partial melting of young crust to produce the majority of lavas observed. Contamination of these melts by primitive magmas is observed at both Mount Skukum and Bennett Lake.

Rb–Sr ages of silicic igneous rocks and deformation, Burlington Peninsula, Newfoundland

1978 ◽  
Vol 15 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Ian R. Pringle
Keyword(s):  
Trace Element ◽  
Igneous Rocks ◽  
Late Palaeozoic ◽  
Metavolcanic Rocks ◽  
Present Study Area ◽  
Lower Ordovician ◽  
Mineral Isochron ◽  
History Of ◽  
Element Migration

The Burlington Peninsula, east of the Baie Verte Lineament, is underlain by the Eastern Division of the Fleur de Lys Supergroup, a sequence of metasediments and metavolcanic rocks that is intruded by plutonic masses of granitic to granodioritic composition. This sequence has been designated as Cambrian or older and the deformation and metamorphism in the area interpreted as pre-Ordovician. Recently, however, it has been shown that at least part of the succession is post Lower Ordovician and a mid or late Palaeozoic age has been proposed for the major deformation affecting the area.Rb–Sr ages obtained in the present study area are: (a) whole-rock isochrons—Dunamagon Granite, 413 ± 10 Ma; Cape Brulé Porphyry, 393 ± 25 Ma; Cape St. John Group Ignimbrites, 343 ± 15 Ma and 429 ± 50 Ma; Mic Mac Group Ignimbrite, 375 ± 15 Ma; (b) Biotite ages—Dunamagon Granite, 334, 356 and 358 Ma; (c) Mineral isochron—Burlington Granodiorite, 422 ± 40 Ma. Because of extensive trace element migration in at least some of these units, the interpretation of the ages is complex and does not allow a unique history of the area to be determined. However, the ages do support the proposed mid or late Palaeozoic age for the major deformation and indicate that pre-Ordovician orogeny did not prevail on the scale previously envisaged.

scholarly journals U-Pb dating, Lu-Hf isotope systematics and chemistry of zircon from the Morro do Polvilho meta-trachydacite: constraints on sources of magmatism and on the depositional age of the São Roque Group

2018 ◽  
Vol 18 (2) ◽  
pp. 45-56 ◽  
Author(s):  
Renato Henrique-Pinto ◽  
Valdecir De Assis Janasi ◽  
Ginaldo Ademar da Cruz Campanha
Keyword(s):  
High Temperature ◽  
Trace Element ◽  
Metamorphic Grade ◽  
Geochronological Data ◽  
Trace Element Chemistry ◽  
Reducing Conditions ◽  
Metavolcanic Rocks ◽  
Depositional Age ◽  
Isotope Systematics

We present new in situ geochronological data of controversial silicic metavolcanic rocks from the lower terrigenous-metavolcanic sequence of the São Roque Group, Ribeira Belt, confirming that they are older than the rocks of higher-metamorphic grade sequences of the Serra do Itaberaba Group. The age of the Polvilho meta-trachydacite was established at 1760 ± 17 Ma, furthermore the results suggest that the bi-modal volcanism of the Boturuna Formation has parent melts from an old (Archean to Paleoproterozoic) continental crust that was melted in a within-plate environment. Trace-element chemistry of zircon, suggests similarities with high-temperature melts (T Zrsat = 900–915ºC) similar to A-type granites (high negative EuN/EuN* and moderate positive CeN/CeN*) from continental sources under reducing conditions.

scholarly journals The role of sulphur on the melting of Ca-poor sediment and on trace element transfer in subduction zones: an experimental investigation

2021 ◽  
Author(s):  
Anne-Aziliz Pelleter ◽  
Gaëlle Prouteau ◽  
Bruno Scaillet
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Subduction Zones ◽  
Sediment Flux ◽  
Arc Magmas ◽  
Trace Element Contents ◽  
The Stability ◽  
Element Transfer ◽  
High Sediment

Abstract We performed phase equilibrium experiments on a natural Ca-poor pelite at 3 GPa, 750-1000 °C, under moderately oxidizing conditions, simulating the partial melting of such lithologies in subduction zones. Experiments investigated the effect of sulphur addition on phase equilibria and compositions, with S contents of up to ∼ 2.2 wt. %. Run products were characterized for their major and trace element contents, in order to shed light on the role of sulphur on the trace element patterns of melts produced by partial melting of oceanic Ca-poor sediments. Results show that sulphur addition leads to the replacement of phengite by biotite along with the progressive consumption of garnet, which is replaced by an orthopyroxene-kyanite assemblage at the highest sulphur content investigated. All Fe-Mg silicate phases produced with sulphur, including melt, have higher MgO/(MgO+FeO) ratios (relative to S-free/poor conditions), owing to Fe being primarily locked up by sulphide in the investigated redox range. Secular infiltration of the mantle wedge by such MgO and K2O-rich melts may have contributed to the Mg and K-rich character of the modern continental crust. Addition of sulphur does not affect significantly the stability of the main accessory phases controlling the behaviour of trace elements (monazite, rutile and zircon), although our results suggest that monazite solubility is sensitive to S content at the conditions investigated. The low temperature (∼ 800 °C) S-bearing and Ca-poor sediment sourced slab melts show Th and La abundances, Th/La systematics and HFSE signatures in agreement with the characteristics of sediment-rich arc magmas. Because high S contents diminish phengite and garnet stabilities, S-rich and Ca-poor sediment sourced slab melts have higher contents of Rb, B, Li (to a lesser extent), and HREE. The highest ratios of La/Yb are observed in sulphur-poor runs (with a high proportion of garnet, which retains HREE) and beyond the monazite out curve (which retains LREE). Sulphides appear to be relatively Pb-poor and impart high Pb/Ce ratio to coexisting melts, even at high S content. Overall, our results show that Phanerozoic arc magmas from high sediment flux margins owe their geochemical signature to the subduction of terrigenous, sometimes S-rich, sediments. In contrast, subduction of such lithologies during Archean appears unlikely or unrecorded.

scholarly journals Geochemical signatures of mineralizing events in the Juomasuo Au–Co deposit, Kuusamo belt, northeastern Finland

2021 ◽  
Author(s):  
Mikael Vasilopoulos ◽  
Ferenc Molnár ◽  
Hugh O’Brien ◽  
Yann Lahaye ◽  
Marie Lefèbvre ◽  
...  
Keyword(s):  
Trace Element ◽  
Sulfur Isotope ◽  
Mineral Chemistry ◽  
Chemical Compositions ◽  
Metasedimentary Rocks ◽  
Metavolcanic Rocks ◽  
Icp Ms ◽  
Stage 1 ◽  
Host Rocks ◽  
Relationship Of

AbstractThe Juomasuo Au–Co deposit, currently classified as an orogenic gold deposit with atypical metal association, is located in the Paleoproterozoic Kuusamo belt in northeastern Finland. The volcano-sedimentary sequence that hosts the deposit was intensely altered, deformed, and metamorphosed to greenschist facies during the 1.93–1.76 Ga Svecofennian orogeny. In this study, we investigate the temporal relationship between Co and Au deposition and the relationship of metal enrichment with protolith composition and alteration mineralogy by utilizing lithogeochemical data and petrographic observations. We also investigate the nature of fluids involved in deposit formation based on sulfide trace element and sulfur isotope LA-ICP-MS data together with tourmaline mineral chemistry and boron isotopes. Classification of original protoliths was made on the basis of geochemically immobile elements; recognized lithologies are metasedimentary rocks, mafic, intermediate-composition, and felsic metavolcanic rocks, and an ultramafic sill. The composition of the host rocks does not control the type or intensity of mineralization. Sulfur isotope values (δ34S − 2.6 to + 7.1‰) and trace element data obtained for pyrite, chalcopyrite, and pyrrhotite indicate that the two geochemically distinct Au–Co and Co ore types formed from fluids of different compositions and origins. A reduced, metamorphic fluid was responsible for deposition of the pyrrhotite-dominant, Co-rich ore, whereas a relatively oxidized fluid deposited the pyrite-dominant Au–Co ore. The main alteration and mineralization stages at Juomasuo are as follows: (1) widespread albitization that predates both types of mineralization; (2) stage 1, Co-rich mineralization associated with chlorite (± biotite ± amphibole) alteration; (3) stage 2, Au–Co mineralization related to sericitization. Crystal-chemical compositions for tourmaline suggest the involvement of evaporite-related fluids in formation of the deposit; boron isotope data also allow for this conclusion. Results of our research indicate that the metal association in the Juomasuo Au–Co deposit was formed by spatially coincident and multiple hydrothermal processes.

scholarly journals Major and trace element analyses of igneous rocks by polarizing energy dispersive X-ray fluorescence spectrometry (EDXRF)

2014 ◽  
Vol 43 (2) ◽  
pp. 47-53 ◽  
Author(s):  
Toshio MIYAZAKI ◽  
Shin-ichi YAMASAKI ◽  
Noriyoshi TSUCHIYA ◽  
Satoshi OKUMURA ◽  
Ryoichi YAMADA ◽  
...  
Keyword(s):  
Trace Element ◽  
Igneous Rocks ◽  
Energy Dispersive ◽  
Fluorescence Spectrometry ◽  
X Ray

The role of synmetamorphic igneous rocks in the metamorphism and partial melting of metasediments, Northwest Adirondacks

1985 ◽  
Vol 90 (4) ◽  
pp. 401-409 ◽  
Author(s):  
Roger E. Powers ◽  
Steven R. Bohlen
Keyword(s):  
Partial Melting ◽  
Igneous Rocks

Geochemistry and geochronology of OIB-type, Early Jurassic magmatism in the Zhangguangcai range, NE China, as a result of continental back-arc extension

2018 ◽  
Vol 158 (1) ◽  
pp. 143-157 ◽  
Author(s):  
Guangying Feng ◽  
Yildirim Dilek ◽  
Xiaolu Niu ◽  
Fei Liu ◽  
Jingsui Yang
Keyword(s):  
East Asia ◽  
Trace Element ◽  
Partial Melting ◽  
Early Jurassic ◽  
Ne China ◽  
Mafic Rocks ◽  
Asthenospheric Mantle ◽  
Trace Element Contents ◽  
Pacific Slab ◽  
Back Arc

AbstractThe Zhangguangcai Range in the Xing’an Mongolian Orogenic Belt, NE China, contains Early Jurassic (c. 188 Ma) Dabaizigou (DBZG) porphyritic dolerite. Compared with other island-arc mafic rocks, the DBZG dolerite is characterized by high trace-element contents, relatively weak Nb and Ta enrichments, and no Zr, Hf or Ti depletions, similar to OIB-type rocks. Analysed rocks have (87Sr/86Sr)i ratios of 0.7033–0.7044, relatively uniform positive ɛNd(t) values of 2.3–3.2 and positive ɛHf(t) values of 8.5–17.1. Trace-element and isotopic modelling indicates that the DBZG mafic rocks were generated by partial melting of asthenospheric mantle under garnet- to spinel-facies conditions. The occurrence of OIB-like mafic intrusion suggests significant upwelling of the asthenosphere in response to lithospheric attenuation caused by continental rifting. These processes occurred in an incipient continental back-arc environment in the upper plate of a palaeo-Pacific slab subducting W–NW beneath East Asia.

scholarly journals A plate model for the simulation of trace element fractionation during partial melting and magma transport in the Earth's upper mantle

1997 ◽  
Vol 102 (B11) ◽  
pp. 24771-24784 ◽  
Author(s):  
Jacques Vernières ◽  
Marguerite Godard ◽  
Jean-Louis Bodinier
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Upper Mantle ◽  
Plate Model ◽  
Magma Transport ◽  
Element Fractionation ◽  
Trace Element Fractionation
Sign in / Sign up

Export Citation Format

Share Document