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>

Origin of Late Triassic mafic–ultramafic intrusions in the Hongqiling Ni–Cu sulfide deposit, Northeast China: evidence from trace element and Sr–Nd isotope geochemistry

2018 ◽  
Vol 55 (12) ◽  
pp. 1312-1323 ◽  
Author(s):  
Xinyun Zhao ◽  
Libo Hao ◽  
Qiaoqiao Wei ◽  
Qingqing Liu ◽  
Jian Zhou ◽  
...  
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Northeast China ◽  
Eastern China ◽  
Crustal Contamination ◽  
Late Triassic ◽  
Substantial Contribution ◽  
Sulfide Deposit ◽  
Magma Evolution ◽  
Depleted Mantle

There are many Late Triassic mafic–ultramafic intrusions in the Hongqiling magmatic Ni–Cu sulfide deposit, Northeast China. Research on magma evolution leading to formation of these mafic–ultramafic intrusions is of great significance for understanding the mantle beneath Northeast China and associated Ni–Cu mineralization. A trace element study of the No. 1, 3, and 7 intrusions in the Hongqiling deposit reveals that these mafic–ultramafic intrusions are characterized by enrichment of incompatible elements, which however cannot be interpreted by subduction modification. Furthermore, model of batch partial melting of depleted mantle accompanied by upper crustal contamination can simulate the trace element patterns of these mafic–ultramafic intrusions, but partial melting of depleted mantle accompanied by lower crustal contamination model cannot work. In addition, Sr–Nd isotopic compositions of the Hongqiling No. 1, 3, and 7 intrusions also indicate that crustal contamination could have occurred mainly during the magma ascent. Consequently, a possible scenario for the magma evolution is that the primary mafic–ultramafic magma was derived from batch partial melting of a depleted mantle, and then contaminated by Cambrian–Ordovician metamorphic rocks of the Hulan Group during ascent. We conclude that the mantle source contained no significant crustal component in the Late Triassic and was also independent of substantial contribution from subducted material, and therefore the Mesozoic large-scale lithospheric delamination beneath eastern China may happen after a period of time of the Late Triassic.

Trace element evidence for mantle heterogeneity beneath the Scottish Midland Valley in the Carboniferous and Permian

1980 ◽  
Vol 297 (1431) ◽  
pp. 245-257 ◽  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Partial Melting ◽  
Mantle Source ◽  
Incompatible Element ◽  
Mantle Heterogeneity ◽  
Alkaline Rocks ◽  
Elemental Abundances ◽  
Peridotite Mantle ◽  
Incompatible Trace Elements

The alkaline rocks of Carboniferous to Permian age in the Midland Valley province range in composition from hypersthene-normative, transitional basalts to strongly undersaturated basanitic and nephelinitic varieties. They were formed by varying degrees of equilibrium partial melting of a phlogopite peridotite mantle. Ba, Ce, Nb, P, Sr and Zr were strongly partitioned into the liquid during melting; K and Rb were retained by residual phlogopite for small degrees of melting only. The composition of the mantle source is inferred to have been broadly similar to that from which oceanic alkaline basalts are currently being generated. It was, however, heterogeneous as regards distribution of the incompatible trace elements, with up to fourfold variations in elemental abundances and ratios. The mantle beneath the province may be divisible into several areas, of some hundreds of square kilometres each, which retained a characteristic incompatible element chemistry for up to 50 Ma and which imparted a distinctive chemistry to all the basic magmas generated within them.

Geochemistry, petrogenesis and structural setting of the meta-igneous Strathy Complex: a unique basement block within the Scottish Caledonides?

2004 ◽  
Vol 141 (2) ◽  
pp. 209-223 ◽  
Author(s):  
I. M. BURNS ◽  
M. B. FOWLER ◽  
R. A. STRACHAN ◽  
P. B. GREENWOOD
Keyword(s):  
Trace Elements ◽  
Mantle Source ◽  
Major And Trace Elements ◽  
Radiogenic Isotope ◽  
Margin Setting ◽  
Depleted Mantle ◽  
Juvenile Crust ◽  
Orogenic Cycle ◽  
End Members ◽  
Igneous Protoliths

The Strathy Complex of the Scottish Caledonides is a bimodal association of amphibolites and siliceous grey gneisses that structurally underlies adjacent metasediments of the Moine Supergroup. Both rock units record a common polyphase Caledonian tectonometamorphic history. New elemental and radiogenic isotope data indicate that both end-members of the Strathy suite were derived from a depleted mantle source, that they are cogenetic and that they may have been related by crystal fractionation. δ18O values and their correlations with major and trace elements suggest that the protoliths were hydrothermally altered at temperatures below 200 °C. Tectonomagmatic discrimination based on relatively immobile elements and isotope systems, plus comparison with geochemically similar bimodal supracrustal associations elsewhere, strongly support the conclusion that the igneous protoliths of the Strathy Complex formed in an oceanic destructive margin setting. If TDM model ages of c. 1000 Ma approximate protolith crystallization, the Strathy Complex may have formed as juvenile crust in the peri-Rodinian ocean broadly contemporaneous with the Grenville orogenic cycle.

Geochemistry of Cenozoic basaltic and silicic magmas in the central portion of the Loei–Phetchabun volcanic belt, Lop Buri, Thailand

1995 ◽  
Vol 32 (4) ◽  
pp. 393-409 ◽  
Author(s):  
Suporn Intasopa ◽  
Todd Dunn ◽  
Richard StJ. Lambert
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Mantle Source ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Central Portion ◽  
Alkali Basalts ◽  
Crustal Rocks ◽  
Depleted Mantle ◽  
Silicic Magmas

Cenozoic volcanic rocks outcrop in the central portion of the Loei–Phetchabun volcanic belt in central Thailand in the Lop Buri area. The volcanic rocks range in composition from basalt to high-silica rhyolite. In general, the volcanic rocks decrease in age from south to north. The oldest rocks studied are 55–57 Ma rhyolites that are isotopically and geochemically distinct from younger (13–24 Ma) rhyolites that occur farther north. Intermediate rocks (andesite and dacite) are less voluminous than rhyolite. Basalt occurs in the central and northern parts of the area and ranges in composition from olivine tholeiites to nepheline normative alkali basalts. The isotopic, major, and trace element compositions of the andesites, dacites, and younger rhyolites are consistent with an origin for these rocks by variable degrees of partial melting of metabasaltic crustal rocks, themselves derived from a depleted mantle source at approximately 530 ± 100 Ma. The apparent extent of partial melting of metabasalt increases from rhyolite to andesite. The isotopic and trace element systematics of the basalts are consistent with a refertilized depleted mantle source with characteristics of a mixture of normal mid-ocean ridge basalt source mantle and enriched mantle II type mantle.

Defining the composition of the deep mantle and the primordial He inventory of the Afar plume

2021 ◽  
Author(s):  
Finlay Stuart ◽  
Ugur Balci ◽  
Jean-Alix Barrat
Keyword(s):  
Trace Element ◽  
Red Sea ◽  
Incompatible Trace Element ◽  
Planetary Science ◽  
Basaltic Rocks ◽  
The North ◽  
Prevailing Paradigm ◽  
Deep Mantle ◽  
Mantle Component ◽  
Basalt Glasses

<p>Basaltic rocks generated by upwelling mantle plumes display a range of trace element and isotope compositions indicative of strong heterogeneity in deep material brought to Earth surface.  Helium isotopes are an unrivalled tracer of the deep mantle in plume-derived basalts.  It is frequently difficult to identify the composition of the deep mantle component as He isotopes rarely correlate with incompatible trace element and radiogenic isotope tracers. It is supposed that this is due to the high He concentration of the deep mantle compared to degassed/enriched mantle reservoirs dominating the He in mixtures, although this is far from widely accepted.  The modern Afar plume is natural laboratory for testing the prevailing paradigm.</p><p>The <sup>3</sup>He/<sup>4</sup>He of basalt glasses from 26°N to 11°N along the Red Sea spreading axis increases systematically from 7.9 to 15 R<sub>a</sub>. Strong along-rift relationships between <sup>3</sup>He/<sup>4</sup>He and incompatible trace element ratios are consistent with a binary mixture between moderately enriched shallow asthenospheric mantle in the north and plume mantle evident in basalts from the Gulf of Tadjoura, Djibouti (the Ramad enriched component of Barrat et al. 1990).  The high-<sup>3</sup>He/<sup>4</sup>He basalts have trace element-isotopic compositions that are similar, but not identical, to the high <sup>3</sup>He/<sup>4</sup>He (22 R<sub>a</sub>) high Ti (HT2) flood basalts erupted during the initial phase of the Afar plume volcanism (Rogers et al. in press). This suggests that the deep mantle component in the modern Afar plume has a HIMU-like composition. From the hyperbolic <sup>3</sup>He/<sup>4</sup>He-K/Th-Rb/La mixing relationships we determine that the upwelling deep mantle has 3-5 times higher He concentration than the asthenosphere mantle beneath the northern Red Sea.</p><p>Barrat et al. 1990.  Earth and Planetary Science Letters 101, 233-247.</p>

Archean granitoids: classification, petrology, geochemistry and origin

2019 ◽  
Vol 489 (1) ◽  
pp. 15-49 ◽  
Author(s):  
Jean-François Moyen
Keyword(s):  
Partial Melting ◽  
Mantle Source ◽  
Enriched Mantle ◽  
Mantle Sources ◽  
Tectonic System ◽  
End Members ◽  
Continuous Range ◽  
Metasomatized Mantle

AbstractThis paper describes the petrology, geochemistry and petrogenesis of Archean granitoids. Archean granites define a continuum of compositions between several end members: (i) magmas that originated by partial melting of a range of crustal sources, from amphibolites to metasediments (‘C-type’ granitoids); and (ii) magmas that formed by partial melting of an enriched mantle source, the most common agent of enrichment being felsic (TTG) melts. Differences in the degree of metasomatism results in different primitive liquids for these ‘M-type’ granitoids.Mixed sources, differentiation and interactions between different melts resulted in a continuous range of compositions, defined by variable proportions of each end member.During the Archean, evolved crustal sources (sediments or felsic crust) and metasomatized mantle sources become increasingly more important, mirroring the progressive maturation of crustal segments and the stabilization of the global tectonic system.

Trace element composition of clinopyroxene in gabbros and dolerites of the Tortuga Ophiolitic Complex, southernmost Patagonia.

2021 ◽  
Author(s):  
Fernanda Torres Garcia ◽  
Mauricio Calderón ◽  
Leonardo Fadel Cury ◽  
Thomas Theye ◽  
Joachim Opitz ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Partial Melting ◽  
Mantle Source ◽  
Trace Element Composition ◽  
Element Composition ◽  
Mid Ocean Ridge ◽  
Back Arc ◽  
Ocean Ridge ◽  
Ophiolitic Complex

<p>During the Upper Jurassic-Lower Cretaceous times the western margin of Gondwana in southern Patagonia experienced extreme lithospheric extension and generation of rift and marginal back-arc basins. The ophiolitic complexes of the Rocas Verdes basin comprises incomplete ophiolite pseudostratigraphy lacking ultramafic rocks. The Tortuga Ophiolitic Complex, the southernmost seafloor remnant of the Rocas Verdes basin, record the most advanced evolutionary stage of the back-arc basin evolution in a mid-ocean ridge-type setting. The base of the Tortuga Complex consists of massive and layered gabbros, most of which are two pyroxene and olivine gabbros, leucogabbros, and clinopyroxene troctolites intruded by dikes of basalt and diabase with chilled margins. We present new major and trace element composition of clinopyroxene from the gabbros and sheeted dikes complexes to assess the geochemical affinity of parental basaltic magmas. Clinopyroxene in gabbros is mostly augite and have Al contents of 0.06-0.14 a.p.f.u. and Mg# of 80-92. Clinopyroxene in dolerites in the sheeted dike unit (augite and diopside) have Al content of 0.11-0.12 a.p.f.u. and Mg# of 85-92. Some immobile trace elements (e.g. Zr, Ti, Y) are sensitive to the degree of partial melting and mantle source composition, and can be used as a proxy for distinguishing tectonic environments. The Ti+Cr vs. Ca diagram, coupled with moderate-high TiO<sub>2</sub> content of clinopyroxene (0.4-1.4 wt.%) suggests their generation in mid-oceanic ridge-type environment (cf. Beccaluva et al., 1989).  The high Ti/Zr ratios (of ~4-11) coupled with low Zr contents (~0.2-1.1) are expected for higher degrees of partial melting or for melting of more depleted mantle sources. Conversely, low Zr/Y ratios (0.05-0.13) plot between the range of arc basalts. Chondrite-normalized REE patterns in clinopyroxene display a strong depletion of LREE compared to HREE and have an almost flat pattern in the MREE to HREE with a positive Eu (Eu*= 0.9-1.1) anomaly, indicating that clinopyroxene crystallized from a strongly depleted mid-ocean-ridge-type basalt, formed by extensive fractional melting of the mantle source and/or fractional crystallization and accumulation of anhydrous phases. The general trend of the incompatible trace elements patterns exhibit depletion in LILEs, minor HFSEs depletion, positive anomaly of Rb and negative anomalies in Ba, Zr, Ti and Nb, consistent with their generation from a refractory mantle source barely influenced by subduction components derived from the oceanic slab. This agrees with basalt generation in a back-arc basin located far away from the convergent margin. This study was supported by the Fondecyt grant 1161818 and the Anillo Project ACT-105.</p>

Geochemistry of a Tertiary continental basalt suite, Red Sea coastal plain, Egypt: petrogenesis and characteristics of the mantle source region

2003 ◽  
Vol 140 (1) ◽  
pp. 11-24 ◽  
Author(s):  
ABDEL-KADER M. MOGHAZI
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Red Sea ◽  
Fractional Crystallization ◽  
Coastal Plain ◽  
Mantle Source ◽  
Source Region ◽  
Rift System ◽  
Mantle Source Region ◽  
Continental Basalt

Major and trace element data on Tertiary continental basalt flows from the Shalatein area, Red Sea coastal plain of Egypt, have been presented and used to obtain more information about their source region and the processes involved in their generation. The rocks are mainly alkali olivine basalt with MgO and Mg no. in the range of 9.8–5 wt % and 65–46, respectively. They display wide variations in incompatible element concentrations, particularly LREE, Zr, Nb, K, Y, Ba and Sr. There is no evidence of significant crustal contamination or a lithospheric mantle signature in these rocks. Normalized trace element patterns and diagnostic elemental ratios are very similar to those of modern ocean-island basalts (OIB) a feature which suggests that the mantle source region was the asthenosphere. Comparison with the different types of OIB indicates that the basalts may be derived from a high U/Pb (HIMU) source with slightly elevated K and Ba contents. The basalts show general trends of increasing incompatible elements (K2O, Nb, Y, Sr and Yb), and decreasing contents of compatible elements (Cr, Ni, Sc and Ca) with decreasing Mg no. Furthermore, TiO2, P2O5, LREE and Th define maxima at about Mg no.=56, suggesting late fractionation of Fe–Ti oxides and apatite. Although these variations are consistent with fractional crystallization processes, the wide variations in LREE contents and the incompatible trace element ratios Ce/Y (1.2–3.8), Zr/Nb (2.3–7.1) and Nb/Y (0.6–4) in the least fractionated samples (Mg no. > 56) suggest that fractional crystallization involving the observed phenocryst assemblage (olivine and clinopyroxene) cannot fully explain such compositional variations. Modelling of the mafic rocks (Mg no. > 56) using REE suggests varying degrees of partial melting of an enriched mantle source region in the garnet stability field. Partial melting is attributed to plume-related mantle upwelling beneath the Red Sea rift system.

Trace element constraints on mantle sources during mid-Proterozoic magmatism: evidence for a link between the Gardar (South Greenland) and Abitibi (Canadian Shield) mafic rocks

2007 ◽  
Vol 44 (4) ◽  
pp. 459-478 ◽  
Author(s):  
Ralf Halama ◽  
Jean-Louis Joron ◽  
Benoît Villemant ◽  
Gregor Markl ◽  
Michel Treuil
Keyword(s):  
Trace Element ◽  
Mantle Plume ◽  
Mantle Source ◽  
Incompatible Trace Element ◽  
Mid Ocean Ridge ◽  
Mantle Sources ◽  
Magma Sources ◽  
Ocean Ridge ◽  
Distinct Features ◽  
Island Basalt

Trace and major element compositions of mid-Proterozoic (1.20–1.16 Ga) basaltic lava flows and dikes from the Gardar Province (South Greenland) provide evidence for two geochemically distinct magma sources. Based on distinct features of incompatible trace element ratios, such as Th/Ta, Th/Tb, or Th/Hf, they differ by the composition of their mantle source and by their partial melting trends. One mantle source is compositionally transitional between mid-ocean ridge basalt (MORB)-type and ocean-island basalt (OIB)-type sources with relatively low Ta/Hf ratios (~0.2), moderate enrichment in light rare-earth elements (LREE), and slightly positive initial εNd values (+2). It can be attributed to either a lithospheric mantle source or a depleted astenospheric mantle plume component that has been enriched shortly prior to eruption. The other mantle source is characterized by high Ta/Hf ratios (~0.6), a more pronounced LREE enrichment, and initial εNd values around 0. Elevated CeN/YbN (7.0–9.8) and TbN/YbN ratios (1.6–1.8) of the rocks derived from this source indicate the presence of garnet during melting, suggesting melt generation at depths > 70 km. This mantle source has the geochemical characteristics of an OIB-type source and is interpreted as originating from a mantle plume. Samples from the slightly younger (1.14 Ga) Abitibi dike swarm (Superior Province, Canada), spatially connected to the Gardar Province, show very similar trace element characteristics and the same two distinct magma sources can be identified. The geochemical similarities between the magma sources in South Greenland and Canada support the idea of a genetic link between the two magmatic provinces. This link strengthens the idea that the system was a long-lived major intracontinental rift zone.

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