Basaltic rocks in the Rensselaer Plateau and Chatham slices of the Taconic allochthon: Chemistry and tectonic setting

1987 ◽  
Vol 99 (4) ◽  
pp. 511 ◽  
Author(s):  
N. M. RATCLIFFE
Keyword(s):  
Tectonic Setting ◽  
Basaltic Rocks

Geochemistry and origin of Mesoproterozoic metavolcanic rocks from Fisher Massif, Prince Charles Mountains, East Antarctica

1996 ◽  
Vol 8 (1) ◽  
pp. 85-104 ◽  
Author(s):  
E. V. Mikhalsky ◽  
J. W. Sheraton ◽  
A. A. Laiba ◽  
B. V. Beliatsky
Keyword(s):  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Granulite Facies ◽  
Island Arc ◽  
Crustal Component ◽  
Basaltic Rocks ◽  
Metavolcanic Rocks ◽  
High K ◽  
Low K

Fisher Massif consists of Mesoproterozoic (c. 1300 Ma) lower amphibolite-facies metavolcanic rocks and associated metasediments, intruded by a variety of subvolcanic and plutonic bodies (gabbro to granite). It differs in both composition and metamorphic grade from the rest of the northern Prince Charles Mountains, which were metamorphosed to granulite facies about 1000 m.y. ago. The metavolcanic rocks consist mainly of basalt, but basaltic andesite, andesite, and more felsic rocks (dacite, rhyodacite, and rhyolite) are also common. Most of the basaltic rocks have compositions similar to low-K island arc tholeiites, but some are relatively Nb-rich and more akin to P-MORB. Intermediate to felsic medium to high-K volcanic rocks, which appear to postdate the basaltic succession, have calc-alkaline affinities and probably include a significant crustal component. On the present data, an active continental margin with associated island arc was the most likely tectonic setting for generation of the Fisher Massif volcanic rocks.

Tectonic setting of late Archean bimodal volcanism in the Michipicoten (Wawa) greenstone belt, Ontario

1987 ◽  
Vol 24 (6) ◽  
pp. 1120-1134 ◽  
Author(s):  
Paul J. Sylvester ◽  
Kodjo Attoh ◽  
Klaus J. Schulz
Keyword(s):  
Greenstone Belt ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Depositional Environments ◽  
Oceanic Island ◽  
Island Arc ◽  
Basaltic Rocks ◽  
Bimodal Volcanism ◽  
Continental Arc ◽  
Convergent Plate Margin

The tectono-stratigraphic relationships, depositional environments, rock associations, and major- and trace-element compositions of the late Archean (2744–2696 Ma) bimodal basalt–rhyolite volcanic rocks of the Michipicoten (Wawa) greenstone belt, Ontario, are compatible with an origin along a convergent plate margin that varied laterally from an immature island arc built on oceanic crust to a more mature arc underlain by continental crust. This environment is similar to that of the Cenozoic Taupo–Kermadec–Tonga volcanic zone. Michipicoten basaltic rocks, most of which are proximal deposits compositionally similar ([La/Yb]n = 0.63–1.18) to modern oceanic island-arc tholeiites, are interpreted as having formed along the largely submerged island arc. Voluminous Michipicoten rhyolitic pyroclastic rocks ([La/Yb]n = 4.3–18.7, Ybn = 5.7–15.9) probably erupted subaerially from the continental arc, with distal facies deposited subaqueously on the adjacent oceanic island arc and proximal facies deposited in subaerial and shallow subaqueous environments on, or along the flanks of, the continental arc. The compositional similarity between the lower (2744 Ma) and upper (2696 Ma) volcanic sequences of the belt suggests that this island- and continental-arc configuration existed for at least 45 Ma. The Michipicoten belt may be a remnant of a larger, laterally heterogeneous volcanic terrane that also included the Abitibi greenstone belt.

Peridotites and basaltic rocks within an ophiolitic mélange from the SW igneous province of Puerto Rico: relation to the evolution of the Caribbean Plate

2016 ◽  
Vol 154 (1) ◽  
pp. 96-118
Author(s):  
NADJA OMARA CINTRON FRANQUI ◽  
SUNG HI CHOI ◽  
DER-CHUEN LEE
Keyword(s):  
Puerto Rico ◽  
Tectonic Setting ◽  
Geochemical Data ◽  
Transform Fault ◽  
Caribbean Plate ◽  
Basaltic Rocks ◽  
The North ◽  
Ophiolitic Mélange ◽  
Igneous Province ◽  
The Caribbean

AbstractThe geology of Puerto Rico is divided into three regions: the north, central and SW igneous provinces. Characterized by its Jurassic ophiolitic mélange basement, lithology of the SW Igneous Province (SIP) is not related to either of the other two provinces. The ophiolitic mélange is exposed in three peridotite belts: Monte del Estado, Rio Guanajibo and Sierra Bermeja. We present geochemical data to identify the tectonic setting of the SIP peridotite formation and its relation to the evolution of the Caribbean Plate. Comparisons of spinel Cr no. (13–21), Mg no. (63.3–69.6) and TiO2suggest an abyssal peridotite origin; however, only Sierra Bermeja presents high TiO2characteristics of a mid-ocean-ridge-basalt- (MORB-) like melt reaction. Temperatures determined with two-pyroxene geothermometers indicated a cold thermal regime ofc. 800–1050°C, with characteristics of large-offset transform fault abyssal peridotites. The geochemistry and Sr–Nd–Hf–Pb isotopic compositions of basalts within the mélange were also analysed. Las Palmas amphibolites exhibited normal-MORB-like rare earth element (REE) and trace-element patterns, whereas metabasalts and Lower Cajul basalts exhibited island-arc tholeiitic-like patterns. Highly radiogenic Sr isotopes (0.70339–0.70562) of the basalts suggest seawater alteration; however, Pb–Pb and Nd–Hf isotope correlations represent the primary compositions of a Pacific/Atlantic MORB source for the amphibolites, metabasalts and Lower Cajul basalts. We propose that the SIP ophiolitic mélange was formed along a large-offset transform fault, which initiated subduction and preserved both proto-Pacific and proto-Caribbean lithospheric mantle. Younger Upper Cajul basalts exhibited enriched-MORB-like geochemical and isotopic signatures, which can be attributed to a tectonized Caribbean ocean plateau.

scholarly journals Lithogeochemical and Hyperspectral Halos to Ag-Zn-Au Mineralization at Nimbus in the Eastern Goldfields Superterrane, Western Australia

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 254
Author(s):  
Steven P. Hollis ◽  
Sabri Foury ◽  
Stefano Caruso ◽  
Sean Johnson ◽  
Vitor Barrote ◽  
...  
Keyword(s):  
Western Australia ◽  
Tectonic Setting ◽  
Hanging Wall ◽  
Massive Sulfide ◽  
White Mica ◽  
Sulfide Mineralization ◽  
Basaltic Rocks ◽  
Rapid Acquisition ◽  
Ca Depletion ◽  
Significant Mass

With new advances in rapid-acquisition geochemical and hyperspectral techniques, exploration companies are now able to detect subtle halos surrounding orebodies at minimal expense. The Nimbus Ag-Zn-(Au) deposit is unique in the Archean Yilgarn Craton of Western Australia. Due to its mineralogy, alteration assemblages, geochemical affinity, and tectonic setting, it is interpreted to represent a shallow water (~650 mbsl) and low-temperature (<250 °C) volcanogenic massive sulfide (VMS) deposit with epithermal characteristics (i.e., a hybrid bimodal felsic deposit). We present a detailed paragenetic account of the Nimbus deposit, and establish lithogeochemical and hyperspectral halos to mineralization to aid exploration. Mineralization at Nimbus is characterized by early units of barren massive pyrite that replace glassy dacitic lavas, and underlying zones of polymetallic sulfides that replace autoclastic monomict dacite breccias. The latter are dominated by pyrite-sphalerite-galena, a diverse suite of Ag-Sb ± Pb ± As ± (Cu)-bearing sulfosalts, minor pyrrhotite, arsenopyrite, and rare chalcopyrite. The main sulfosalt suite is characterized by pyrargyrite, and Ag-rich varieties of boulangerite, tetrahedrite, and bournonite. Zones of sulfide mineralization in quartz-sericite(±carbonate)-altered dacite are marked by significant mass gains in Fe, S, Zn, Pb, Sb, Ag, As, Cd, Ni, Cu, Ba, Co, Cr, Tl, Bi, and Au. Basaltic rocks show reduced mass gains in most elements, with zones of intense quartz-chlorite-carbonate±fuchsite alteration restricted to thick sequences of hyaloclastite, and near contacts with dacitic rocks. Broad zones of intense silica-sericite alteration surround mineralization in dacite, and are marked by high Alteration Index and Chlorite-Carbonate-Pyrite Index (CCPI) values, strong Na-Ca depletion, and an absence of feldspar (albite) in thermal infrared (TIR) data. White mica compositions are predominantly muscovitic in weakly altered sections of the dacitic footwall sequence. More paragonitic compositions are associated with zones of increased sericitization and high-grade polymetallic sulfide mineralization. Chlorite in dacitic rocks often occurs adjacent to zones of sulfide mineralization and is restricted to narrow intervals. Carbonate abundance is sporadic in dacite, but is most abundant outside the main zones of Na-Ca depletion. Basaltic rocks are characterized by strongly paragonitic white mica compositions, and abundant chlorite and carbonate. Shifts from Ca carbonates and Fe-rich chlorites to more Mg-rich compositions of both minerals occur in more intensely hydrothermally altered basaltic hyaloclastite, and near contacts with dacitic rocks. Hanging-wall polymict conglomerates are characterized by minor amounts of muscovitic to phengitic white mica (2205–2220 nm), and an absence of chlorite and carbonate alteration.

Lahroud, a Paleo-Tethys Remnant in Northwestern Iran: Implications for Geochemistry, Radioisotope Geochronology, and Tectonic Setting

2021 ◽  
Author(s):  
S. Hassanpour
Keyword(s):  
Oceanic Crust ◽  
Crystallization Process ◽  
Tectonic Setting ◽  
Late Triassic ◽  
Calc Alkaline ◽  
Pb Isotope ◽  
Basaltic Rocks ◽  
Mantle Sources ◽  
Northwestern Iran ◽  
Isotope Studies

Abstract —The Lahroud Ophiolite in northwestern Iran contains extensive zones of Paleozoic ophiolite as remnants of the Paleo-Tethys oceanic crust. The principal rock units are gabbro overlain by pillow basalt, which is intruded by granites and interbedded with pelagic sedimentary units including radiolarian cherts. Geochemistry and radioisotope studies, supported by Nd, Sm, Sr, and Pb isotope data, indicate that the Lahroud Ophiolite originates from a within-plate basaltic mantle source. The isotope studies show that the basalts are derived from Indian-type oceanic mantle sources. The radiogenic data indicate the involvement of subduction-related terrigenous materials in the source magma. All the rocks are geochemically cogenetic and were generated by fractionation of a melt with a composition of average E-MORB with a calc-alkaline signature. Two 40Ar/39Ar ages, 343 ± 3 Ma for muscovite minerals and 187.7 ± 7.7 Ma for glasses, suggest that metamorphic and basaltic rocks formed during the Late Paleozoic to Early Jurassic, respectively. Microfossil studies show the presence of Paleozoic biostratigraphy. The crystallization process and rifting into the oceanic crust in the Lahroud Ophiolite probably began in the Carboniferous, with volcanic activity continuing during the Late Triassic.

scholarly journals TECTONIC SETTING AND DEFORMATION OF THE KALLIDROMO MT, CENTRAL GREECE

2017 ◽  
Vol 43 (1) ◽  
pp. 320
Author(s):  
G. Migiros ◽  
Vas. Antoniou ◽  
I. Papanikolaou ◽  
Var. Antoniou
Keyword(s):  
Lower Cretaceous ◽  
Tectonic Setting ◽  
Shear Zones ◽  
Deformation Pattern ◽  
Complex Deformation ◽  
Entire Study ◽  
Alpine Orogeny ◽  
Basaltic Rocks ◽  
Tectonic Study ◽  
Tectonic Mélange

Kallidromo Mt. consists of alpine formations which in places are unconformably covered by Neogene and Quaternary sediments. The ophiolites are overthrusted on the massive Mesozoic platform carbonate sequence, which forms the basement unit. The base of the tectonic nappe is characterized by a tectonic melange that consists of sandstones, clay stones, limestones, cherts and basaltic rocks that are mainly observed in pillow forms. Two distinct compressional deformation phases (D1, D2) are traced. Deformation D1 whereas the fold axes, the predominant schistocity planes and shear zones clearly follow a N295o (±10o )-115o (±10o ) trend that relates to the Upper Jurrasic-Lower Cretaceous ophiolitic emplacement of the Eo-alpine orogeny and is the predominant feature over the entire study area. Deformation D2 relates to the Cretaceous-Eocene alpine orogeny, follows a N020o (±15o )-N200o (±15o ) trend and has a much weaker and secondary imprint in the study area. The tectonic study of the alpine and post-alpine formations shows a complex deformation pattern with a variety of quantitative and qualitative characteristics. These variations can be correlated with different phases and stages of deformation (compressional to extensional) from the timing of the tectonic emplacement of the ophiolites inUpperJurrasic-Lower Cretaceous up to the present-day field.

scholarly journals Geochemistry, geothermobarometry and tectonic setting of basaltic rocks of the north of Serow (NW-Urmia)

2021 ◽  
Vol 12 (1) ◽  
pp. 21-40
Author(s):  
Shahab Yousefvand ◽  
Ahmad Ahmadi Khalaji ◽  
Narges Beiranvandpour ◽  
Ali Moradpour ◽  
Rasoul Esmaeili ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Basaltic Rocks ◽  
The North

Two different basalt provinces (MORB vs. WPB) in the evaporitic Permian Haselgebirge Formation (Eastern Alps, Austria) and possible tectonic implications

2021 ◽  
Author(s):  
Christoph Leitner
Keyword(s):  
Trace Elements ◽  
Tectonic Setting ◽  
Eastern Alps ◽  
Earth Planet ◽  
Basaltic Rocks ◽  
Tectonic Implications ◽  
East West ◽  
Plate Type ◽  
Xrf Analyses

&lt;p&gt;The evaporitic Haselgebirge Formation hosts in many places small occurrences of basaltic rocks. The geochemistry of these basalts can potentially provide information about the tectonic setting of the Haselgebirge Formation and the evolution of the Meliata ocean, respectively. We present here 70 new XRF analyses of these basaltic rocks from various localities (Pfennigwiese, Annaberg, Wienern, Hallstatt, Moosegg, Lammertal) and compare the results with previous data from local studies (GRUBER et al., 1991; KIRCHNER 1979; KIRCHNER 1980a; KIRCHNER 1980b; KRALIK et al, 1984; LEITNER et al., 2017; SCHORN et al., 2013; ZIEGLER, 2014; ZIRKL, 1957). Based on the concentrations of immobile trace elements (Zr, Nb, Y, Ti), a predominance of MORB-like compositions is observed for the Lower Austrian occurrences and for the locality Wienern (Grundlsee). On contrast, basalts from the localities Lammertal, Moosegg and Hallstatt have predominantly within-plate-type compositions.&lt;/p&gt;&lt;p&gt;We discuss this striking regional (east-west) difference of basalt types in terms of existing palinspastic models for the Haselgebirge formation (LEITNER et al., 2017; STAMPFLI &amp; BOREL, 2002; McCANN et al., 2006).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;GRUBER, P., FAUPL, P., KOLLER, F. (1991) Mitt. &amp;#214;sterr. Miner. Ges., 84, 77-100.&lt;/p&gt;&lt;p&gt;KIRCHNER, E. (1979) Tschermaks Min. Petr. Mitt. 26, 149-162.&lt;/p&gt;&lt;p&gt;KIRCHNER, E. (1980a) Mitt. &amp;#214;sterr. Miner. Ges.71/72, 385-396.&lt;/p&gt;&lt;p&gt;KIRCHNER, E. (1980b) Verh. Geol. Bundesanstalt 1980, 249-279.&lt;/p&gt;&lt;p&gt;KRALIK, M., KOLLER, F., POBER, E. (1984) Mitt. &amp;#214;sterr. Miner. Ges., 77, 37-55.&lt;/p&gt;&lt;p&gt;LEITNER, C., WIESMAIER, S., K&amp;#214;STER, M.H., GILG, H.A, FINGER, F, NEUBAUER, F. (2017) GSA Bulletin 129, 1537-1553.&lt;/p&gt;&lt;p&gt;McCANN, T., PASCAL, C., TIMMERMAN, M.J., KRZYWIEC, P., L&amp;#211;PEZ-G&amp;#211;MEZ, J., WETZEL, L., KRAWCZYK, C.M., RIEKE, H., LAMARCH, J. (2006) Mem. Geol. Soc. London, 32, 355-388.&lt;/p&gt;&lt;p&gt;SCHORN A, NEUBAUER F, GENSER J, BERNROIDER M (2013) Tectonophysics 583, 28-48.&lt;/p&gt;&lt;p&gt;STAMPFLI G.M., BOREL G.D. (2002) Earth Planet. Sci. Lett. 196, 17-33.&lt;/p&gt;&lt;p&gt;ZIEGLER, T. (2014) Unpubl. MSc thesis University of Salzburg, p. 174.&lt;/p&gt;&lt;p&gt;ZIRKL, E.J. (1957) Jb. Geol. Bundesanstalt 100, 10-137-177.&lt;/p&gt;

The age, chemistry, and tectonic setting of the Middle Proterozoic Moyie sills, Purcell Supergroup, southeastern British Columbia

1989 ◽  
Vol 26 (11) ◽  
pp. 2305-2317 ◽  
Author(s):  
Trygve Höy
Keyword(s):  
British Columbia ◽  
Tectonic Setting ◽  
Coarse Grained ◽  
High Iron ◽  
Basaltic Rocks ◽  
Typical Sequence ◽  
Minimum Age ◽  
Intracratonic Basin ◽  
Chemical Trends ◽  
Middle Proterozoic

Moyie sills comprise an extensive suite of basaltic rocks that have intruded Middle Proterozoic Purcell Supergroup rocks in southeastern British Columbia. The sills are spatially restricted to the Aldridge and Fort Steele formations in the lower part of the Purcell succession and are distinct from a suite of mafic sills higher in the succession. They may constitute up to 30% of a typical sequence but generally decrease in volume upsection as the abundance of thick-bedded A–E turbidites decreases. A number of the sills have textures and contact relationships that suggest they intruded unconsolidated or partly consolidated wet sediments.A U–Pb zircon Middle Proterozoic date of 1445 Ma from a coarse-grained sill is interpreted as being the minimum age of emplacement. Because the sills are penecontemporaneous with Aldridge sedimentation, this date defines the minimum age of deposition of lower and basal middle Aldridge rocks.Two distinct compositions of Moyie sills are recognized. Most are subalkaline, high-iron tholeiitic basalts, whereas others are alkaline basalts. The two different chemical trends are typical of volcanism in an incipient rift environment or in the early stages of continental rifting. This supports a model for deposition of Belt–Purcell rocks in a large, subsiding intracratonic basin formed by Middle Proterozoic rifting.

Sign in / Sign up

Export Citation Format

Share Document