Middle Jurassic ultramafic lamprophyre dyke within the Ferrar magmatic province, Pensacola Mountains, Antarctica

2000 ◽  
Vol 64 (1) ◽  
pp. 95-111 ◽  
Author(s):  
P. T. Leat ◽  
T. R. Riley ◽  
B. C. Storey ◽  
S. P. Kelley ◽  
I. L. Millar
Keyword(s):  
Trace Elements ◽  
Mantle Plume ◽  
Lithospheric Mantle ◽  
Liquid Immiscibility ◽  
Radiogenic Isotopes ◽  
Ultramafic Lamprophyre ◽  
Low Degree ◽  
Layered Gabbro ◽  
Partial Fusion ◽  
Incompatible Trace Elements

AbstractAn ultramafic lamprophyre dyke is described from the otherwise tholeiitic Ferrar magmatic province of Antarctica. We report an Ar-Ar age of 183 ± 2.2 Ma for the dyke, indistinguishable from those of the Ferrar tholeiites. However, the dyke has mineralogical and major and trace element compositions, and radiogenic isotopes ratios, very different from the Ferrar tholeiites. The sample consists of olivine and rare clinopyroxene phenocrysts with perovskite and spinel microphenocrysts in a groundmass of amphibole, nepheline and biotite. Carbonatitic globules contain calcite, dolomite, Fe-rich carbonate, nepheline, biotite, orthoclase, pyrite, clinopyroxene, apatite and silicate glass, and were formed by liquid immiscibility. The rock is mildly potassic and classifies as an ouachitite. It is strongly enriched in both moderately and highly incompatible trace elements and is the first high-Ti rock to be described from the Ferrar magmatic province. The rock has similar initial 143Nd/144Nd to OIB, notably Bouvet, Crozet and Réunion, but significantly higher initial 87Sr/86Sr. The lamprophyre magma is interpreted as having been generated by low-degree partial fusion of metasomatized lithospheric mantle as a result of heat conducted from an underlying Jurassic mantle plume. The same mantle plume was probably also responsible for generating one of the world’s largest layered gabbro bodies, the Dufek-Forrestal intrusions.

scholarly journals Petrogenesis of Quaternary Shoshonitic Volcanism in NE Iran (Ardabil): Implication for Postcollisional Magmatism

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Habib Shahbazi Shiran
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Mantle Source ◽  
Lithospheric Mantle ◽  
Volcanic Rocks ◽  
Enriched Mantle ◽  
Low Degree ◽  
Continental Lithospheric Mantle ◽  
Ne Iran ◽  
Postcollisional Magmatism

Trachyandesites, trachytes, andesites, and pyrocalstic rocks, with shoshonitic signature, are the main Quaternary volcanic rocks in the Sabalan region (Ardabil). Plagiocalse, K-feldspar, biotite associated with clinopyroxene, and glass are the main constituents of these lavas. Plagioclases are andesine to labradorite while clinopyroxenes have augitic composition. The Sabalan volcanic rocks show enrichment in LREEs (relative to HREEs) and are characterized by enrichment in LILEs and depletion in HFSEs. Petrological observations, along with rare earth and trace elements geochemistry, suggest shoshonitic signature for Sabalan lavas. This signature highlights derivation from a subduction-related source. The Sabalan volcanic rocks are isotopically characterized by derivation from an enriched mantle source with a tendency to plot in the fields defined by island-arc basalts (IAB) and OIBs (in εNd versus 87Sr/86Sr diagram). The geochemical and isotopic characteristics of the Sabalan lavas suggest that their magma has been issued via low degree partial melting of a subduction-metasomatized continental lithospheric mantle. The formation of these lavas is related to slab steepening and breakoff in a postcollisional regime.

The Origin of Carbonatites from Amba Dongar within the Deccan Large Igneous Province

2019 ◽  
Vol 60 (6) ◽  
pp. 1119-1134 ◽  
Author(s):  
Jyoti Chandra ◽  
Debajyoti Paul ◽  
Andreas Stracke ◽  
François Chabaux ◽  
Mathieu Granet
Keyword(s):  
Mantle Plume ◽  
Crustal Contamination ◽  
Liquid Immiscibility ◽  
Large Igneous Province ◽  
Carbonatite Complex ◽  
Silicate Magma ◽  
Low Degree ◽  
Wide Range ◽  
Igneous Province ◽  
Amba Dongar

Abstract There are disparate views about the origin of global rift- or plume-related carbonatites. The Amba Dongar carbonatite complex, Gujarat, India, which intruded into the basalts of the Deccan Large Igneous Province (LIP), is a typical example. On the basis of new comprehensive major and trace element and Sr–Nd–Pb isotope data, we propose that low-degree primary carbonated melts from off-center of the Deccan–Réunion mantle plume migrate upwards and metasomatize part of the subcontinental lithospheric mantle (SCLM). Low-degree partial melting (∼2%) of this metasomatized SCLM source generates a parental carbonated silicate magma, which becomes contaminated with the local Archean basement during its ascent. Calcite globules in a nephelinite from Amba Dongar provide evidence that the carbonatites originated by liquid immiscibility from a parental carbonated silicate magma. Liquid immiscibility at crustal depths produces two chemically distinct, but isotopically similar magmas: the carbonatites (20% by volume) and nephelinites (80% by volume). Owing to their low heat capacity, the carbonatite melts solidified as thin carbonate veins at crustal depths. Secondary melting of these carbonate-rich veins during subsequent rifting generated the carbonatites and ferrocarbonatites now exposed at Amba Dongar. Carbonatites, if formed by liquid immiscibility from carbonated silicate magmas, can inherit a wide range of isotopic signatures that result from crustal contamination of their parental carbonated silicate magmas. In rift or plume-related settings, they can, therefore, display a much larger range of isotope signatures than their original asthenosphere or mantle plume source.

Distribution of niobium, tantalum, and other highly incompatible trace elements in the lithospheric mantle: The spinel paradox

1996 ◽  
Vol 60 (3) ◽  
pp. 545-550 ◽  
Author(s):  
J.-I. Bodinier ◽  
C. Merlet ◽  
R.M. Bedini ◽  
F. Simien ◽  
M. Remaidi ◽  
...  
Keyword(s):  
Trace Elements ◽  
Lithospheric Mantle ◽  
Incompatible Trace Elements

scholarly journals Contents, distribution, and fractionation of soil organic carbon and trace elements in soils under a green manure application

2020 ◽  
Vol 16 (No. 1) ◽  
pp. 50-58
Author(s):  
Yana Timofeeva ◽  
Lyudmila Purtova ◽  
Alexey Emelyanov ◽  
Maxim Burdukovskii ◽  
Irina Kiseleva ◽  
...  
Keyword(s):  
Trace Elements ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Green Manure ◽  
Mineral Soil ◽  
Water Soluble ◽  
Household Waste ◽  
Nickel Ions ◽  
Low Degree ◽  
Soluble Components

We quantified the soluble fractions of the soil organic carbon (SOC) concentrations and the total and water-soluble trace elements in soils contaminated by household waste and remediated via the addition of green manure over 13 years and identified the main factors controlling the vertical distribution and accumulation of the trace elements. Green manure favoured the active formation of soil organic matter. The SOC of the examined soils was characterised by the active stabilisation by mineral soil compounds, but by a low degree of humification. The soils showed increased concentrations of Cr and Ni ions. The SOC and different soil compounds enriched by Si, Ca, and Mn ions were the important determinant for the distribution of Sr, V and Cu ions, as well as for the distribution of Pb and Cr ions bound to the water-soluble components of the soils. The low degree of SOC humification may be one of the main reasons of the high concentrations of Cu and Pb ions in the composition of the water-soluble soil compounds. The nickel ions were mainly associated with compounds enriched by the Al and Fe ions. The extremely high percentage concentration of the Ni ions in the water-soluble components of the soils may be result of the absence of the Ni ions adsorption by humic substances.

scholarly journals Rhombic calcite microcrystals as a textural proxy for meteoric diagenesis

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Mohammed S. Hashim ◽  
Stephen E. Kaczmarek
Keyword(s):  
Trace Elements ◽  
Laboratory Experiments ◽  
Crystal Form ◽  
Geochemical Data ◽  
Carbonate Sediments ◽  
Geochemical Evidence ◽  
Meteoric Diagenesis ◽  
Low Degree ◽  
Rock Record ◽  
High Degree

AbstractNumerous Phanerozoic limestones are comprised of diagenetic calcite microcrystals formed during mineralogical stabilization of metastable carbonate sediments. Previous laboratory experiments show that calcite microcrystals crystallizing under conditions similar to those that characterize meteoric diagenetic settings (impurity-free, low degree of supersaturation, high fluid:solid ratio) exhibit the rhombic form/morphology, whereas calcite microcrystals crystallizing under conditions similar to those that prevail in marine and marine burial diagenetic settings (impurity-rich, high degree of supersaturation, low fluid:solid ratio) exhibit non-rhombic forms. Based on these experimental observations, it is proposed here that rhombic calcite microcrystals form exclusively in meteoric environments. This hypothesis is tested using new and previously published textural and geochemical data from the rock record. These data show that the vast majority of Phanerozoic limestones characterized by rhombic microcrystals also exhibit petrographic and/or geochemical evidence (depleted δ13C, δ18O, and trace elements) indicative of meteoric diagenesis whereas non-rhombic forms are associated with marine burial conditions. By linking calcite microcrystal textures to specific diagenetic environments, our observations bring clarity to the conditions under which the various microcrystal textures form. Furthermore, the hypothesis that rhombic calcite microcrystals form exclusively in meteoric environments implies that this crystal form may be a useful textural proxy for meteoric diagenesis.

Miocene Olivine Leucitites in the Hoh Xil Basin, Northern Tibet: Implications for Intracontinental Lithosphere Melting and Surface Uplift of the Tibetan Plateau

2020 ◽  
Vol 61 (1) ◽  
Author(s):  
Yue Qi ◽  
Qiang Wang ◽  
Ying-Tang Zhu ◽  
Lian-Chang Shi ◽  
Ya-Nan Yang
Keyword(s):  
Tibetan Plateau ◽  
Lithospheric Mantle ◽  
The Tibetan Plateau ◽  
Nd Isotope ◽  
Northern Tibet ◽  
Surface Uplift ◽  
Enriched Mantle ◽  
Magmatic Rocks ◽  
Low Degree ◽  
Pliocene Magmatism

Abstract The generation of Miocene–Pliocene post-collisional magmatic rocks in northern Tibet was coeval with surface uplift, meaning that understanding the petrogenesis of these rocks should provide clues to the mechanism of uplift of the Tibetan Plateau. However, the nature of the source(s) of Miocene–Pliocene post-collisional rocks is unresolved, especially for potassic–ultrapotassic rocks. This study focuses on 16 Ma olivine leucitites in the Hoh Xil Basin of northern Tibet, which display the lowest SiO2 (43·4–48·8 wt%) contents of all Miocene–Pliocene magmatic rocks in northern Tibet and have high MgO (4·85–8·57 wt%) contents and high K2O/Na2O (>1) ratios. Whole-rock geochemical compositions suggest that the olivine leucitites did not undergo significant fractional crystallization or crustal assimilation. All samples are enriched in large ion lithophile elements relative to high field strength elements, and they exhibit uniform whole-rock Sr–Nd isotope [(87Sr/86Sr)i = 0·7071–0·7077 and εNd(t) = −3·1 to −3·9] and olivine O isotope (5·8–6·6 ‰, mean of 6·2 ± 0·2 ‰, n = 21) compositions. We propose that the olivine leucitites were derived by low-degree partial melting of phlogopite-lherzolite in garnet-facies lithospheric mantle. Given the tectonic evolution of the Hoh Xil Basin and adjacent areas, we suggest that southward subduction of Asian (Qaidam block) lithosphere after India–Asia collision transferred potassium and other incompatible elements into the lithospheric mantle, forming the K-enriched mantle source of the Miocene–Pliocene potassic–ultrapotassic rocks. Removal of lower lithospheric mantle subsequently induced voluminous Miocene–Pliocene magmatism and generated >1 km surface uplift in the Hoh Xil Basin.

Pleistocene alkaline rocks of Martin Vaz volcano, South Atlantic: low-degree partial melts of a CO2-metasomatized mantle plume

2018 ◽  
Vol 61 (3) ◽  
pp. 296-313 ◽  
Author(s):  
Anderson C. Santos ◽  
Mauro C. Geraldes ◽  
Wolfgang Siebel ◽  
Julio Mendes ◽  
Everton Bongiolo ◽  
...  
Keyword(s):  
Mantle Plume ◽  
South Atlantic ◽  
Alkaline Rocks ◽  
Low Degree ◽  
Partial Melts ◽  
Metasomatized Mantle

scholarly journals Correction to: Phosphorus and aluminum zoning in olivine: contrasting behavior of two nominally incompatible trace elements

2019 ◽  
Vol 174 (12) ◽  
Author(s):  
Thomas Shea ◽  
Julia E. Hammer ◽  
Eric Hellebrand ◽  
Adrien J. Mourey ◽  
Fidel Costa ◽  
...  
Keyword(s):  
Trace Elements ◽  
Incompatible Trace Elements

scholarly journals The antecryst compositional influence on Cretaceous alkaline lamprophyre dykes, SE Brazil

2015 ◽  
Vol 45 (1) ◽  
pp. 79-93 ◽  
Author(s):  
Saulo Gobbo Menezes ◽  
Rogério Guitarrari Azzone ◽  
Gaston Eduardo Enrich Rojas ◽  
Excelso Ruberti ◽  
Renata Cagliarani ◽  
...  
Keyword(s):  
Trace Elements ◽  
Bulk Composition ◽  
Chrome Spinel ◽  
Magmatic System ◽  
Serra Do Mar ◽  
Se Brazil ◽  
The Matrix ◽  
Geochemical Analyses ◽  
Incompatible Trace Elements ◽  
Compositional Zonation

The question of whether the antecryst assemblage affects the bulk composition of lamprophyre dykes, and could be responsible for the compositional zonation between their centers and borders is addressed through a detailed study involving four monchiquite and camptonite dykes (basanites and tephrites) representative of the Arco de Ponta Grossa and Serra do Mar alkaline provinces. In them, antecrysts are interpreted as early-crystallized minerals that are no longer in equilibrium with their host-liquid, albeit still linked to the same magmatic system. They represent recycled crystals of earlier stages of the magmatic system at depth. The antecryst microtextures, such as zoned clinopyroxene megacrysts (augite cores and titanaugite rims) with partly corroded cores, olivine crystals with corroded rims surrounded by biotite coronas, chrome-spinel inclusions in clinopyroxene and olivine megacryst cores, and titanomagnetite crystals surrounded by biotite coronas, suggest chemical re-equilibrium with the matrix. The greatest antecryst cargo in these dykes is found in their centers. After subtracting the antecryst volume from the center analyses of each body, the calculated compositions are very similar to the border analyses. The mafic antecryst cargo of each occurrence proportionally leads to enrichment of MgO, FeO, TiO2, CaO, compatible trace elements (Cr, Ni and Co), and depletion of SiO2, K2O, Na2O, Al2O3 and incompatible trace elements (Ba, Sr and REE). The whole-rock geochemical analyses of each dyke represent the combination of accumulated crystals and melt. The compositional zonation of the studied dykes is associated with the antecryst cargo rather than different magmatic pulses.

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