Isotopic study of basaltic dikes in the Nain Plutonic Suite: evidence for enriched mantle sources

1993 ◽  
Vol 30 (6) ◽  
pp. 1141-1146 ◽  
Author(s):  
R. W. Carlson ◽  
R. A. Wiebe ◽  
R. I. Kalamarides
Keyword(s):  
Mantle Source ◽  
Incompatible Element ◽  
Isotopic Study ◽  
Major Element Composition ◽  
Enriched Mantle ◽  
Mantle Sources ◽  
Mineral Isochron ◽  
Lithospheric Mantle Source ◽  
Nain Plutonic Suite ◽  
Alkalic Basalts

Basaltic dikes cutting the Nain Plutonic Suite (NPS) of Labrador include two chemically distinct groups. One is a high-Fe tholeiitic to transitional alkalic composition similar to some of the magmas involved in the formation of the NPS. The other, distinguished by high phosphorus and incompatible element contents, is similar in major element composition to intraplate oceanic alkalic basalts. A Rb–Sr mineral isochron for one high-P2O5 sample defines an age of 1276 ± 23 Ma indicating that it is similar in age to, or only slightly younger than, the circa 1305 Ma anorthosites.Compositional and isotopic characteristics of the high- and low-P2O5 dikes show that the gross features of their initial isotopic characteristics (i.e., low 87Sr/86Sr, negative εNd, nonradiogenic Pb) probably derive from a distinct lithospheric mantle source with similar characteristics. To have developed these isotopic characteristics by the time of dike emplacement, their mantle source must have formed and separated from oceanic-type upper mantle well prior to Nain anorthosite genesis, possibly between 2.0 and 2.6 Ga.

scholarly journals Ore and Geochemical Specialization and Substance Sources of the Ural and Timan Carbonatite Complexes (Russia): Insights from Trace Element, Rb–Sr, and Sm–Nd Isotope Data

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 711
Author(s):  
Irina Nedosekova ◽  
Nikolay Vladykin ◽  
Oksana Udoratina ◽  
Boris Belyatsky
Keyword(s):  
Trace Element ◽  
Mantle Source ◽  
Crustal Evolution ◽  
Trace Element Data ◽  
The Urals ◽  
Nd Isotope ◽  
Enriched Mantle ◽  
Depleted Mantle ◽  
Mantle Sources ◽  
Geochemical Specialization

The Ilmeno–Vishnevogorsk (IVC), Buldym, and Chetlassky carbonatite complexes are localized in the folded regions of the Urals and Timan. These complexes differ in geochemical signatures and ore specialization: Nb-deposits of pyrochlore carbonatites are associated with the IVC, while Nb–REE-deposits with the Buldym complex and REE-deposits of bastnäsite carbonatites with the Chetlassky complex. A comparative study of these carbonatite complexes has been conducted in order to establish the reasons for their ore specialization and their sources. The IVC is characterized by low 87Sr/86Sri (0.70336–0.70399) and εNd (+2 to +6), suggesting a single moderately depleted mantle source for rocks and pyrochlore mineralization. The Buldym complex has a higher 87Sr/86Sri (0.70440–0.70513) with negative εNd (−0.2 to −3), which corresponds to enriched mantle source EMI-type. The REE carbonatites of the Chetlassky сomplex show low 87Sr/86Sri (0.70336–0.70369) and a high εNd (+5–+6), which is close to the DM mantle source with ~5% marine sedimentary component. Based on Sr–Nd isotope signatures, major, and trace element data, we assume that the different ore specialization of Urals and Timan carbonatites may be caused not only by crustal evolution of alkaline-carbonatite magmas, but also by the heterogeneity of their mantle sources associated with different degrees of enrichment in recycled components.

scholarly journals Geochemical and isotopical variations within the Campanian Comagmatic Province: implications on magma source composition

2021 ◽  
Vol 47 (4) ◽  
Author(s):  
Monica Piochi ◽  
Lucia Pappalardo ◽  
Gianfilippo De Astis
Keyword(s):  
Mantle Source ◽  
Lithospheric Mantle ◽  
Campi Flegrei ◽  
Magma Source ◽  
Isotopic Ratios ◽  
Italian Peninsula ◽  
Mantle Sources ◽  
Compositional Variations ◽  
Volcanic Islands ◽  
Lithospheric Mantle Source

A spatial variation in chemical and isotopical composition is observed between the volcanoes belonging to the Campanian Comagmatic Province. At a given MgO content, magmas from volcanic islands (Procida and Ischia) are enriched in Ti, Na, depleted in La, Ba, Rb, Sr, Th, K contents, and shows lower LREE/HFSE (e.g., La/Nb = = 1-2), lower Sr-Pb isotopic ratios and higher Nd isotopic ratios with respect to magmas from volcanoes locat- ed inland (Campi Flegrei and Somma-Vesuvius). The observed compositional variations are explained involving two different mantle sources in the genesis of the magmas erupted in this region: a deeper asthenospheric man- tle source, from which the Tyrrhenian magmas also derived and a lithospheric mantle source enriched by slab- derived fluids. The contribution of the enriched-lithospheric mantle became more pronounced moving from the Tyrrhenian abyssal plain through the Italian Peninsula where it dominates, likely in response to the thickening of the lithosphere observed under the Peninsula

A geochemical and Sr-Nd-O isotopic study of the Proterozoic Eriksfjord Basalts, Gardar Province, South Greenland: Reconstruction of an OIB signature in crustally contaminated rift-related basalts

2003 ◽  
Vol 67 (5) ◽  
pp. 831-853 ◽  
Author(s):  
R. Halama ◽  
T. Wenzel ◽  
B. G. J. Upton ◽  
W. Siebel ◽  
G. Markl
Keyword(s):  
Trace Element ◽  
Granulite Facies ◽  
Alkaline Basalt ◽  
Isotopic Study ◽  
Nd Isotope ◽  
Crustal Component ◽  
Isotope Data ◽  
Enriched Mantle ◽  
Mantle Sources ◽  
Lower Crustal

AbstractBasalts from the volcano-sedimentary Eriksfjord Formation (Gardar Province, South Greenland) were erupted at around 1.2 Ga into rift-related graben structures. The basalts have compositions transitional between tholeiite and alkaline basalt with MgO contents <7 wt.% and they display LREE-enrichment relative to a chondritic source. Most of the trace element and REE characteristics are similar to those of basalts derived from OIB-like mantle sources. Initial 87Sr/86Sr ratios of clinopyroxene separates range from 0.70278 to 0.70383 and initial ϵNd values vary from –3.2 to +2.1. The most unradiogenic samples overlap with the field defined by carbonatites of similar age and can be explained by mixing of isotopically depleted and enriched mantle components. Using AFC modelling equations, the Sr-Nd isotope data of the more radiogenic basalts can successfully be modelled by addition of <5% lower crustal granulite-facies gneisses as contaminants. δ18Ov-smow values of separated clinopyroxene range from +5.2 to +6.0% and fall within the range of typical mantle-derived rocks. However, up to 10% mixing with an average lower crustal component are permitted by the data.

New insights for the mantle source components of the most primitive recent basaltic rocks from central and western Anatolia: Evidences for the involvement of pyroxenite and the peridotite source domains

2020 ◽  
Author(s):  
Biltan Kurkcuoglu ◽  
Tekin Yurur
Keyword(s):  
Mantle Source ◽  
Incompatible Element ◽  
Central Anatolia ◽  
Spinel Peridotite ◽  
Western Anatolia ◽  
The West ◽  
Cinder Cones ◽  
Basaltic Rocks ◽  
Mantle Sources ◽  
Source Component

&lt;div&gt; &lt;p&gt;Basaltic activities&amp;#160; developed&amp;#160; extensively in central and western Anatolia since middle &amp;#8211;Miocene to quaternary time, the most primitive lavas are&amp;#160; situated at&amp;#160; the eastern end of&amp;#160; central Anatolia, (southern Sivas) and the most recent ones&amp;#160; are situtated in central (basaltic cinder cones at south of Hasanda&amp;#287;) and also in western Anatolia (Kula region),&amp;#160; Among those&amp;#160; primitive recent&amp;#160; lavas, mantle sources that are responsible for the generation of basaltic rocks is&amp;#160; still a matter of a debate. &amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt; &lt;p&gt;Previous studies suggested&amp;#160; that&amp;#160; spinel peridotite source&amp;#160;&amp;#160; is the dominant source&amp;#160; component&amp;#160; for many of the basaltic rocks which are situated in several different locations in central Anatolia, including, Erciyes and Hasanda&amp;#287; stratovolcanoes,&amp;#160; Erkilet, Develida&amp;#287;, Karap&amp;#305;nar vents and Salanda fissure eruptions while Sivas fissure basalts in the east, &amp;#160;Gediz and Kula&amp;#160; basalts in the west, were&amp;#160; derived&amp;#160; mostly&amp;#160; from&amp;#160; the&amp;#160; garnet peridotite sources, but , the &amp;#160;specific&amp;#160; incompatible element ratios&amp;#160; and the melting model based on Rare Earth Elements obviously&amp;#160; indicate that&amp;#160; these basaltic rocks could not be solely generated&amp;#160; from&amp;#160; the garnet- spinel transition zone, &amp;#160;&amp;#160;instead another mantle source component need to be involved&amp;#160; in the generation of the basaltic rocks.&lt;/p&gt; &lt;p&gt;Tb/Yb(N) and Zn/Fe&amp;#160; ratios provide significant values&amp;#160; &amp;#160;in order to constraint for the magmas&amp;#160; generated from the asthenosphere.&amp;#160; Tb/Yb(N) ratio seperates&amp;#160; garnet &amp;#8211; spinel transition [1]&amp;#160; and Zn/Fe&amp;#160; ratio&amp;#160; displays separation between the peridotite-derived (Zn/Fe &lt;12, [2,3]) and pyroxenite-derived (13-20 [2,3]) melts. &amp;#160;Zn/Fe, as well as&amp;#160; the&amp;#160; Tb/Yb(N) ratios and the melting model display&amp;#160; that single spinel&amp;#160; source&amp;#160;&amp;#160; component&amp;#160; is not solely&amp;#160;&amp;#160; responsible for&amp;#160; the generation of&amp;#160; the basaltic rocks,&amp;#160;&amp;#160; pyroxenite&amp;#160; source domain&amp;#160; should&amp;#160;&amp;#160;&amp;#160; also&amp;#160; be involved in&amp;#160; &amp;#160;during&amp;#160; the genesis of these rocks as well, besides, the &amp;#160;contributions from &amp;#160;the both of the&amp;#160; mantle source domains also explain the&amp;#160; depleted&amp;#160; magma nature that is observed&amp;#160; in some of recent basaltic rocks ( e.g, Salanda &amp;#160;and &amp;#160;Hasanda&amp;#287;&amp;#160; volcanic&amp;#160; systems) which is diffrent &amp;#160;from the dominated alkaline character, &amp;#160;generally observed&amp;#160; as&amp;#160; the &amp;#160;&amp;#160;final products&amp;#160; of central Anatolian &amp;#160;magmatism &amp;#160;&amp;#160;&lt;/p&gt; &lt;p&gt;&lt;em&gt;1.Wang et al., 2002, J.Geophys.Res.vol:107,ECV 5 1-21&lt;/em&gt;&lt;/p&gt; &lt;p&gt;&lt;em&gt;2 .Le Roux, et al.,2011,EPSL, vol:307, 395-408&lt;/em&gt;&lt;/p&gt; &lt;/div&gt;&lt;p&gt;&lt;em&gt;3. Ducea, et al.,2013, GEOLOGY, Vol:41, 413-417&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;This study&amp;#160;&amp;#160; is financially supported by Hacettepe University, BAB project no: FHD-2018-17283&lt;/em&gt;&lt;/p&gt;

Minettes from Schirmacher Oasis, East Antarctica — indicators of an enriched mantle source

1998 ◽  
Vol 10 (4) ◽  
pp. 476-486 ◽  
Author(s):  
Marion Hoch ◽  
Heinz J. Tobschall
Keyword(s):  
Trace Element ◽  
Mantle Source ◽  
Incompatible Element ◽  
East Antarctica ◽  
Magma Ascent ◽  
Element Abundances ◽  
Enriched Mantle ◽  
Schirmacher Oasis ◽  
Compatible Elements ◽  
Ree Patterns

Minette dykes intersect the Precambrian crystalline basement of Schirmacher Oasis, East Antarctica. The rocks have intermediate to basic compositions, showing shoshonitic to ultrapotassic character. The samples show enhanced concentrations of compatible elements and high mg# combined with extreme enrichments in LILE (especially Ba) and LREE. Mantle-normalized trace element patterns are characterized by coupled relative depletions of Nb and Ti and strong fractionations between LILE and HFSE. The minettes display fractionated chondrite-normalized REE patterns with high and varying LREE concentrations in contrast to relative low and nearly constant HREE contents. High magma-ascent and cooling rates of lamprophyric magmas argue against a fundamental change of the primary geochemical signatures in minette magmas by interactions with the continental crust during ascent. The major and trace element abundances of the studied minettes point to varying degrees of partial melting of a mantle source, which was enriched in LILE and LREE during or before the melting event. Incompatible element signatures argue for the involvement of subducted pelagic sediments.

Association of dolerite and lamprophyre dykes, Jetty Peninsula (Prince Charles Mountains, East Antarctica)

1993 ◽  
Vol 5 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Eugene V. Mikhalsky ◽  
John W. Sheraton
Keyword(s):  
Mantle Source ◽  
Incompatible Element ◽  
Source Region ◽  
Element Abundances ◽  
High Grade Metamorphism ◽  
Group 3 ◽  
Group 2 ◽  
Island Basalt ◽  
Lithospheric Mantle Source ◽  
Group 1

A compositionally varied swarm of mafic dykes in the Jetty Peninsula area was emplaced about 320 Ma ago (K-Ar age). There are three major groups: Group 1 dykes range from transitional-alkaline dolerites to camptonites, Group 2 are trachydolerites, and Group 3 are diorite to quartz diorite porphyries. Group 1 dykes have very similar ratios of most incompatible elements and were derived from the same (or a very similar) enriched lithospheric mantle source region (∈Nd −0.18 to −3.05) with high Nb and Ta (i.e., OIB, ocean island basalt, characteristics). However, the presence of several distinct subgroups with different incompatible element abundances implies significantly different degrees of melting. Group 2 trachy dolerites are much more fractionated (mg 22–36), but were apparently derived from a similar, although somewhat more enriched (∈Nd −2.26 to −4.63) source. Group 3 diorites are compositionally quite distinct and may have been derived by intracrustal melting. Enrichment of the mantle source(s) of Groups 1 and 2 dykes apparently occurred about the same time as high-grade metamorphism in the area, and may have been coeval with crust formation in nearby parts of Gondwana.

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.

Geochemical and isotopic (Nd–Sr–Hf–Pb) evidence for a lithospheric mantle source in the formation of the alkaline Monteregian Province (Quebec)

2013 ◽  
Vol 50 (6) ◽  
pp. 650-666 ◽  
Author(s):  
Emilie Roulleau ◽  
Ross Stevenson
Keyword(s):  
Mantle Source ◽  
Lithospheric Mantle ◽  
North Atlantic Ocean ◽  
Crustal Contamination ◽  
Ocean Island Basalts ◽  
The North ◽  
Enriched Mantle ◽  
Lithospheric Extension ◽  
Depleted Mantle ◽  
Lithospheric Mantle Source

We present new major element and isotopic (Nd–Sr–Hf–Pb) data and modelling from alkaline rocks of the Monteregian Igneous Province of southern Quebec (Canada) that constrain the mantle source and the magmatic origin of these rocks. The whole-rock chemical composition of the intrusions is consistent with fractional crystallization of an assemblage of olivine ± clinopyroxene (± plagioclase) derived from ocean island basalts (OIB)-like magmas, and variations in the Sr and Nd isotope compositions suggest as much as 20% crustal contamination. The bulk of the Nd–Sr–Hf and Pb isotopic data form a tight cluster between a depleted mantle end-member (HIMU, high-U/Pb mantle) and an enriched mantle (EMI) end-member and are thought to reflect a sub-continental lithospheric mantle that was metasomatized by a convecting asthenospheric plume. Variations in these isotopic compositions along the west–east axis of the Monteregian Province (from the Oka carbonatite to the Mount Shefford intrusion) may reflect various degrees of mixing between HIMU and EMI enriched mantle reservoirs. Anomalously low 207Pb/204Pb and 208Pb/204Pb isotopic ratios from some of the intrusions likely indicate incorporation of an Archean component within the lithospheric mantle. We propose a model in which Monteregian magmatism formed from melting of a predominantly Proterozoic metasomatized lithospheric mantle in response to lithospheric extension during the opening of the North Atlantic Ocean at ca. 124 Ma.

Geochemistry of Ferrar Dolerite sills and dykes at Terra Cotta Mountain, south Victoria Land, Antarctica

1995 ◽  
Vol 7 (1) ◽  
pp. 73-85 ◽  
Author(s):  
A.D. Morrison ◽  
A. Reay
Keyword(s):  
Trace Element ◽  
Mantle Source ◽  
Source Region ◽  
Crustal Component ◽  
Enriched Mantle ◽  
Victoria Land ◽  
Trace Element Signature ◽  
Geochemical Variation ◽  
Element Enrichment ◽  
Taylor Glacier

At Terra Cotta Mountain, in the Taylor Glacier region of south Victoria Land, a 237 m thick Ferrar Dolerite sill is intruded along the unconformity between basement granitoids and overlying Beacon Supergroup sedimentary rocks. Numerous Ferrar Dolerite dykes intrude the Beacon Supergroup and represent later phases of intrusion. Major and trace element data indicate variation both within and between the separate intrusions. Crystal fractionation accounts for much of the geochemical variation between the intrusive events. However, poor correlations between many trace elements require the additional involvement of open system processes. Chromium is decoupled from highly incompatible elements consistent with behaviour predicted for a periodically replenished, tapped and fractionating magma chamber. Large ion lithophile element-enrichment and depletion in Nb, Sr, P and Ti suggests the addition of a crustal component or an enriched mantle source. The trace element characteristics of the Dolerites from Terra Cotta Mountain are similar to those of other Ferrar Group rocks from the central Transantarctic Mountains and north Victoria Land, as well as with the Tasmanian Dolerites. This supports current ideas that the trace element signature of the Ferrar Group is inherited from a uniformly enriched mantle source region.

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