Petrolgy of the volcanic/subvolcanic members of the volcano-sedimentary Maden Complex in Eastern Turkey

2021 ◽  
Author(s):  
Yavuz Özdemir ◽  
Çağrı Mercan ◽  
Vural Oyan ◽  
Ayşe Atakul-Özdemir ◽  
Nilgün Güleç ◽  
...  
Keyword(s):  
Mantle Source ◽  
Sedimentary Rocks ◽  
Pb Isotope ◽  
Basaltic Rocks ◽  
Asthenospheric Mantle ◽  
Mineral Phases ◽  
Eastern Turkey ◽  
Ophiolitic Rocks ◽  
Late Ypresian ◽  
Subduction Component

<p>Maden Complex exposed in Eastern Turkey, is a succession of volcano-sedimentary rocks and tectonically overlain by Bitlis Metamorphics and Cretaceous ophiolitic rocks. The succession includes shallow-water deposits and deep marine pelagic sediments intercalated with pillow lavas ranging from a few centimeters to ten meters in diameter. The planktonic foraminiferal assemblages from micritic limestones and zircon U-Pb ages from selected sedimentary rocks indicate the age of Late Ypresian - Early Lutetian. Plagioclase and  clinopyroxenes are the main mineral phases, olivine rarely found as altered phenocrysts. Clinopyroxenes are augite and diopside, and their compositions are ranging between Wo<sub>44-51</sub>, En<sub>27-43</sub>, Fe<sub>10-21</sub>. The anorthite contents of plagioclases are between 32- 67 % in unaltered grains. The crystallization temperatures and pressures obtained from clinopyroxene chemistry are ranging from 1126 to 1250<sup>o</sup>C and 3 to 8 Kbar, respectively. The majority of the volcanic/subvolcanic rocks are subalkaline-tholeiitic basalts however; a few andesitic and rhyolitic derivatives are also present. The whole – rock and  Sr-Nd-Pb isotope compositions reveal that the  basaltic rocks are originated from E-MORB like asthenospheric mantle source without a subduction component.</p>

Pyroxenes of basic rocks and rodingites from an ophiolite mélange, south-eastern Turkey

1978 ◽  
Vol 42 (324) ◽  
pp. 511-512 ◽  
Author(s):  
Robert Hall
Keyword(s):  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
South Eastern ◽  
Eastern Turkey ◽  
Igneous Origin ◽  
Basic Volcanics ◽  
Ophiolitic Rocks ◽  
Tectonic Mélange ◽  
Basic Rocks ◽  
Textural Evidence

Ophiolitic rocks occur as a tectonic mélange in the Mutki area of the Eastern Taurus Mountains of south-eastern Turkey. They form the upper part of a Tethyan ophiolite-flysch complex, which is thrust southward over sedimentary rocks of the Arabian foreland (Hall, 1976). The tectonic mélange has a matrix of serpentinite and includes blocks of basic volcanics, gabbros, picrites, and rodingites, most of which have suffered metamorphism and metasomatism. The volcanic rocks have been metamorphosed under conditions transitional between the glaucophane-lawsonite schist facies and the greenschist or greenschist-amphibolite transitional facies of Turner (1968). The picrites have escaped any significant metamorphism, while the gabbros have been partially or completely recrystallized under greenschist facies conditions. Both picrites and gabbros have also suffered calcium metasomatism resulting in the alteration of some of the gabbros to rodingites. Pyroxenes from eight separate blocks from the mélange have been analysed by microprobe (fig. 1) to determine if the pyroxene chemistry is consistent with an igneous origin (as suggested by textural evidence) or if there have been changes due to metamorphism and metasomatism.

Interpretation of Pb isotope compositions of galenas from the Midland Valley of Scotland and adjacent regions

1984 ◽  
Vol 75 (2) ◽  
pp. 85-96 ◽  
Author(s):  
John Parnell ◽  
Ian Swainbank
Keyword(s):  
Lower Devonian ◽  
Lead Isotope ◽  
Sedimentary Rocks ◽  
Isotope Ratios ◽  
Igneous Rocks ◽  
Pb Isotope ◽  
Lower Carboniferous ◽  
Granite Magma ◽  
Lower Palaeozoic ◽  
Caledonian Granite

ABSTRACTThe lead isotope compositions of 61 galenas from central and southern Scotland vary markedly between different regions. Most galenas from the southern Grampian Highlands yield isotope ratios (206Pb/204Pb 17·77 ± 0·25, 207Pb/204Pb 15·47 ± 0·05, 208Pb/204Pb 37·63 ± 0·26) less radiogenic than those from Midland Valley galenas (18·22 ± 0·12, 15·55 ± 0·05, 38·13 ± 0·14) whilst galena lead from the Southern Uplands (18·28 ± 0·12, 15·56 ± 0·03, 38·21 ± 0·18) is more radiogenic than that from the southern Midland Valley (18·12 ± 0·06, 15·52 ± 0·02, 38·06 ±0·10). The change in isotopie composition across the Highland Boundary fault reflects the presence or absence of Dalradian rocks which included a magmatic component of lead. Galenas from the Dalradian sequence in Islay, where igneous rocks are lacking, have a composition (18·14±0·04, 15·51±0·01, 37·90±0·02) more like Midland Valley galenas. In the Southern Uplands, galenas yield lead isotope ratios similar to those of feldspars from Caledonian granite (18·30 ± 0·14, 15·57 ± 0·04, 37·96 ± 0·15) analysed by Blaxland et al. (1979). The similar ratios reflect the incorporation of Lower Palaeozoic sedimentary rocks into the granite magma, rather than a granitic source for the mineralisation. The granites were then thermal-structural foci for later mineralising fluids which leached metals from the surrounding rocks. Within the Midland Valley, galenas hosted in Lower Devonian-Lower Carboniferous lavas are notably more radiogenic (18·31 ±0·12, 15·58 ± 0·06, 38·20 ± 0·16) than sediment-hosted galenas (18·14 ± 0·07, 15·52 ± 0·02, 38·08 ± 0·10). The Devonian lavas at least may have inherited lead from subducted (? Lower Palaeozoic) rock incorporated in the primary magma.

scholarly journals Lithostructural and Petrochemical Survey of Djarkadougou Gold Prospect (South West Burkina Faso / West Africa)

2017 ◽  
Vol 6 (1) ◽  
pp. 155
Author(s):  
Yao Honoré Koffi ◽  
Sagbrou Chérubin Djro ◽  
Urbain Wenmenga
Keyword(s):  
West Africa ◽  
Burkina Faso ◽  
Sedimentary Rocks ◽  
Ductile Deformation ◽  
Chemical Compositions ◽  
Calc Alkaline ◽  
Basaltic Rocks ◽  
Bimodal Volcanism ◽  
South West ◽  
Western Burkina Faso

The Djarkadougou gold prospect is located on the Birimian greenstone belt of the Houndé exploration permit held by the company Orezone Inc. The permit is at 275 km far from the capital Ouagadougou south- western Burkina Faso, West Africa. This area is based on sheared and metamorphosed greenschist facies rocks. Metamorphism locally reaches to the amphibolite facies around intrusions. There are two major lithological units whose interface is marked by a NW-SE trending shear corridor: an unit of andesite-basaltic rocks of andesitic breccias in the East and volcaniclastic and sedimentary unit composed flows, tuffs and felsic to mafic breccia, interbedded volcano-sedimentary rocks. All this together is intruded by plutonic rocks, and various felsic to mafic dykes. These rocks have undergone ductile to brittle heterogeneous deformations and hydrothermal alteration sericite ±carbonate ±quartz±sulphide within deformation corridors. The rocks of the East and West domains affected by three phases of brittle-ductile deformation (D1, D2, and D3) and the meteoric alteration is systematic in superficial facies of Djarakadougou core drilling.Geochemical analysis shows a tholeiitic to calc-alkaline volcanic serie characteristic a bimodal volcanism. The spectra of normalized REE chondrites are generally flat and constant reminding those of N-MORB basalt. The chemical compositions of andesite and basalt are deferred on several discrimination diagrams especially Th / Yb - Nb / Yb and 2 Nb - Zr / 4 - Y show that andesites and basalts of the prospect are issued in geotectonic setting of volcanism preponderant arc.

Contrasting fold styles in a volcano-sedimentary succession

1996 ◽  
Vol 33 (8) ◽  
pp. 1193-1200
Author(s):  
Pierre A. Cousineau ◽  
Robert Marquis
Keyword(s):  
Sedimentary Basin ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Structural Models ◽  
Sedimentary Basins ◽  
Basaltic Rocks ◽  
Field Evidence ◽  
Sedimentary Succession

Structural analyses of folded volcano-sedimentary basins rely heavily on the identification and use of way-up structures. These structures are more numerous and widespread in sedimentary rocks than in volcanic rocks. Structural models for such basins can therefore be biased by this fact. The Caldwell Group of the Quebec Appalachians is a folded volcano-sedimentary basin bounded bay major faults. It contains locally abundant basalt-rich bands. Near Lac-Etchemin, way-up in basalt flows is determined by pillow shelves that reflect paleohorizontal planes. The strike and dip of these shelf structures were measured and plotted on stereographic projections. Field evidence and the interpretation of stereographic projections indicate that the basalt-rich bands form open folds that plunge gently to the southwest. However, sandstone-rich bands form tight folds with undulating hinge lines (sheath-like). During initial folding, the basalt formed competent bands with limited aerial extent that were fractured by synthetic and antithetic faults rather than folded. The basalt slivers maintained a near-horizontal attitude while adjacent sedimentary rocks were folded and faulted. Further shortening tightened folds in the sediment-rich bands while producing open folds in slivers of basaltic rocks.

scholarly journals Mantle Dynamics of the Central Atlantic Magmatic Province (CAMP): Constraints from Platinum Group, Gold and Lithophile Elements in Flood Basalts of Morocco

2019 ◽  
Vol 60 (8) ◽  
pp. 1621-1652 ◽  
Author(s):  
Christian Tegner ◽  
Sandra A T Michelis ◽  
Iain McDonald ◽  
Eric L Brown ◽  
Nasrrddine Youbi ◽  
...  
Keyword(s):  
Mantle Source ◽  
Gold Mineralization ◽  
Potential Temperature ◽  
Primitive Mantle ◽  
Mantle Melting ◽  
Flood Basalts ◽  
Asthenospheric Mantle ◽  
Central Atlantic Magmatic Province ◽  
Platinum Group ◽  
Central Atlantic

Abstract Mantle melting dynamics of the Central Atlantic Magmatic Province (CAMP) is constrained from new platinum group element (PGE), gold (Au), rare earth element (REE), and high field strength element (HFSE) data and geochemical modelling of flood basalts in Morocco. The PGE are enriched similarly to flood basalts of other large igneous provinces. The magmas did not experience sulphide saturation during fractionation and were therefore fertile. The CAMP is thus prospective for PGE and gold mineralization. The Pt/Pd ratio of the Moroccan lavas indicates that they originated by partial melting of the asthenospheric mantle, not the subcontinental lithospheric mantle. Mantle melting modelling of PGE, REE and HFSE suggests the following: (1) the mantle source for all the lavas was dominated by primitive mantle and invariably included a small proportion of recycled continental crust (<8%); (2) the mantle potential temperature was moderately elevated (c. 1430°C) relative to ambient mantle; (3) intra-lava unit compositional variations are probably a combined result of variable amounts of crust in the mantle source (heterogeneous source) and fractional crystallization; (4) mantle melting initially took place at depths between c. 110 and c. 55 km and became shallower with time (c. 110 to c. 32 km depth); (5) the melting region appears to have changed from triangular to columnar with time. These results are best explained by melting of asthenospheric mantle that was mixed with continental sediments during the assembly of Pangaea, then heated and further mixed by convection while insulated under the Pangaea supercontinent, and subsequently melted in multiple continental rift systems associated with the breakup of Pangaea. Most probably the CAMP volcanism was triggered by the arrival of a mantle plume, although plume material apparently was not contributing directly (chemically) to the magmas in Morocco, nor to many other areas of CAMP.

Geochemistry of Siluro-Devonian Tobique volcanic belt in northern and central New Brunswick (Canada): tectonic implications

1989 ◽  
Vol 26 (6) ◽  
pp. 1282-1296 ◽  
Author(s):  
J. Dostal ◽  
R. A. Wilson ◽  
J. D. Keppie
Keyword(s):  
New Brunswick ◽  
Mantle Source ◽  
Upper Mantle ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Continental Rift ◽  
Basaltic Rocks ◽  
Incompatible Elements ◽  
Tectonic Implications

Siluro-Devonian volcanic rocks of the northwestern mainland Appalachians are found mainly in the Tobique belt of New Brunswick where they consist predominantly of bimodal mafic–felsic suites erupted in a continental-rift environment. The axis of the Tobique rift trends north-northeast – south-southwest, obliquely to the regional northeast–southwest trend of the Appalachians. These geometric relationships are interpreted as being the result of rifting in a sinistral shear regime produced during emplacement of the Avalon terrene. The basaltic rocks are continental tholeiites and transitional basalts derived from a heterogeneous upper-mantle source that was enriched in incompatible elements relative to the primordial mantle. The mantle source was probably affected by the subduction processes.

scholarly journals Geochemistry, petrology and tectonomagmatic significance of basaltic rocks from the ophiolite mélange at the NW External-Internal Dinarides junction (Croatia)

2010 ◽  
Vol 61 (4) ◽  
pp. 273-292 ◽  
Author(s):  
Damir Slovenec ◽  
Boško Lugović ◽  
Irena Vlahović
Keyword(s):  
Mantle Source ◽  
Spreading Ridge ◽  
Accretionary Wedge ◽  
Carbonate Sediments ◽  
Basaltic Rocks ◽  
Depleted Mantle ◽  
Unit Form ◽  
Ophiolite Mélange ◽  
Internal Dinarides ◽  
Ophiolite Melange

Geochemistry, petrology and tectonomagmatic significance of basaltic rocks from the ophiolite mélange at the NW External-Internal Dinarides junction (Croatia)At the NW inflexion of the Sava-Vardar Suture Zone ophiolite mélanges, known as the Kalnik Unit, form the surface of the slopes of several Pannonian inselbergs in the SW Zagorje-Mid-Transdanubian Zone. The Mt Samoborska Gora ophiolite mélange, thought to be a part of the Kalnik Unit, forms a separate sector obducted directly onto Dinaric Triassic carbonate sediments. Basaltic rocks, the only magmatic rocks incorporated in the mélange, include Middle-Triassic (Illyrian-Fassanian) alkali within-plate basalts and Middle Jurassic (uppermost Bathonian-Lower Callovian) tholeiitic basalts. The latter sporadically constitute composite olistoliths, and are geochemically divided into N-MORB-like (high-Ti basalts) and transitional MORB/IAT (medium-Ti basalts). These geochemically different rocks suggest crystallization at various tectonomagmatic settings, which is also indicated by the rock paragenesis and host clinopyroxene compositions. Alkali basalts reflect melts derived from an OIB-type enriched mantle source [Ti/V= 62.2-82.4; (La/Lu)cn= 6.4-12.8] with Nd-Sr isotope signatures close resembling the Bulk Earth [εNd(T=235 Ma)= + 1.6 to + 2.5]. They are recognized as preophiolite continental rift basin volcanic rocks that closely predate the opening of the Repno oceanic domain (ROD) of the Meliata-Maliac ocean system. The high-Ti and medium-Ti basalts from composite blocks derived from a similar depleted mantle source (εNd(T=165 Ma) = + 6.01 vs. + 6.35) succesively metasomatized by expulsion of fluids from a subducting slab leading to a more pronounced subduction signature in the latter [Ti/V=31.6-44.8 and (Nb/La)n=0.67-0.90 vs. Ti/V=21.5-33.9 and (Nb/La)n=0.32-0.49]. These composite blocks indicate crust formation in an extensional basin spreading over the still active subducting ridge. The majority of high-Ti basalts may represent the fragments of older crust formed at a spreading ridge and incorporated in the mélange of the accretionary wedge formed in the proto-arc-fore-arc region. The Mt Samoborska Gora ophiolite mélange represents the trailing edge of the Kalnik Unit as a discrete sector that records the shortest stage of tectonomagmatic evolution related to intraoceanic subduction in the ROD.

Pre-Variscan metagabbro from NW Sardinia, Italy: evidence of an enriched asthenospheric mantle source for continental alkali basalts

2003 ◽  
Vol 38 (2) ◽  
pp. 145-159 ◽  
Author(s):  
Marcello Franceschelli ◽  
Gabriele Cruciani ◽  
Mariano Puxeddu ◽  
Daniela Utzeri
Keyword(s):  
Mantle Source ◽  
Alkali Basalts ◽  
Asthenospheric Mantle

Mantle source characteristics of Triassic alkaline lavas within the Antalya Nappes, SW Turkey

2020 ◽  
Author(s):  
Ercan Aldanmaz ◽  
Aykut Güçtekin ◽  
Özlem Yıldız-Yüksekol
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Mantle Source ◽  
Carbonate Platform ◽  
Incompatible Trace Element ◽  
Late Triassic ◽  
Radiogenic Isotope ◽  
Basaltic Rocks ◽  
Sw Turkey ◽  
End Members

<p>The Late Triassic basaltic rocks that are dispersed as several lava sheets in a number of different tectonic slices within the Antalya nappes in SW Turkey represent the remnants of widespread oceanic magmatism with strong intra-plate geochemical signatures. The largest exposures are observed around the Antalya Bay, where pillow structured or massif lava flows are interlayered with Upper Triassic pelagic or carbonate platform sediments. Based on bulk-rock geochemical characteristics, the rocks mostly classify as alkaline basalts and display distinctive OIB-type trace element distributions characterized by significant enrichments in LILE and HFSE abundances, as well as LREE/HREE ratios, with respect to average N-MORB. Quantitative modeling of trace element data suggest that the primary melts that produced the alkaline lavas are largely the products of variable proportions of mixing between melts generated by variable, but generally low (<10) degrees of partial melting of more than one compositionally distinct mantle source. The samples, as a whole, display large variations in radiogenic isotope ratios with <sup>87</sup>Sr/<sup>86</sup>Sr = 0.703021–0.70553, <sup>143</sup>Nd/<sup>144</sup>Nd = 0.51247–0.51279, <sup>206</sup>Pb/<sup>204</sup>Pb = 18.049–20.030, <sup>207</sup>Pb/<sup>204</sup>Pb = 15.544–15.723 and <sup>208</sup>Pb/<sup>204</sup>Pb = 38.546–39.530. Such variations in isotopic ratios correlate with the change in incompatible trace element relative abundances and reflect the involvement of a number of compositionally distinct mantle end-members. These include EMI and EMII type enriched mantle components both having lower <sup>143</sup>Nd/<sup>144</sup>Nd than typical depleted MORB source with their contrasting low and high <sup>206</sup>Pb/<sup>204</sup>Pb and <sup>20</sup><sup>7</sup>Pb/<sup>204</sup>Pb ratios respectively, as well as a high time-integrated <sup>238</sup>U/<sup>204</sup>Pb component with high <sup>206</sup>Pb/<sup>204</sup>Pb at relatively low <sup>87</sup>Sr/<sup>86</sup>Sr and εNd values. The results from trace element and radiogenic isotope data are consistent with the view that the initial melt generation was likely related to partial melting of the shallow convecting upper mantle in response to Triassic rifting events, while continued mantle upwelling resulted in progressively increased melting of mantle lithosphere that contained compositionally contrasting lithological domains with strong isotopic heterogeneities.</p>

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