scholarly journals EVOLUTION AND ORIGIN OF THE MARONIA PLUTON, THRACE, GREECE

2004 ◽  
Vol 36 (1) ◽  
pp. 568 ◽  
Author(s):  
L. Papadopoulou ◽  
G. Christofides ◽  
Α. Koroneos ◽  
M. Bröcker ◽  
T. Soldatos ◽  
...  
Keyword(s):  
Partial Melting ◽  
Fractional Crystallization ◽  
Lithospheric Mantle ◽  
Crystallization Process ◽  
Acid Group ◽  
Magma Source ◽  
Subcontinental Lithospheric Mantle ◽  
Basic Group ◽  
Intermediate Group ◽  
Fractional Crystallization Process

The Maronia pluton is the youngest of the Tertiary plutons that occurred in Thrace. Three rock groups have been distinguished: a basic, an intermediate and an acid one. Based on geochemical and isotopie characteristics, the basic group probably represents a magma that isotopically equilibrated with the intermediate group at a certain point of its evolution. The evolution of the intermediate group can be described by an assimilation-fractional crystallization process (AFC). The acid group represents crustai melts that are not genetically related to the basic and intermediate groups. The emplacement of the pluton is related to post-collisional extension resulting from the subduction of the African under the European plate. The magma source of the basic and intermediate group is considered to be a LI LE- and LREE-enriched subcontinental lithospheric mantle. The acid group has probably derived by the partial melting of crustai rocks and in particular, gneiss.

Etude geochimique des elements en traces dans les series de roches volcaniques du rift d'Asal; identification et analyse des processus d'accretion

1980 ◽  
Vol S7-XXII (6) ◽  
pp. 851-861 ◽  
Author(s):  
J. L. Joron ◽  
M. Treuil ◽  
H. Jaffrezic ◽  
B. Villemant
Keyword(s):  
Partial Melting ◽  
Fractional Crystallization ◽  
Closed System ◽  
Mantle Source ◽  
Crystallization Process ◽  
Tectonic Activity ◽  
Dynamic Evolution ◽  
Mantle Material ◽  
Spreading Rates ◽  
Fractional Crystallization Process

Abstract Study of samples of the main volcanic units of the Afar rift, from margins to late axial series, have yielded the following conclusions: 1) the magmatic liquids are strongly differentiated by a fractional crystallization process in shallow chambers, the evolution of which is limited by injection of new primary liquids as shown in the latest axial series; 2) primary liquids are generated by melting of a homogeneous mantle source, a process whereby successive partial melting in a closed system is stopped by percolation of the generated liquid. The degrees of partial melting are closely related to spreading rates; 3) the magmatic processes involve a discontinuous dynamic evolution of spreading displayed by a pulsatory magmato-tectonic activity which is controlled by the speed of decompression of mantle material.

Salt-forming regions of seawater type solution in the evaporation and fractional crystallization process

2014 ◽  
Vol 362 ◽  
pp. 281-287 ◽  
Author(s):  
Huan Zhou ◽  
Yanjuan Bao ◽  
Xiaoqin Bai ◽  
Ruoxin Ma ◽  
Lisha Huangfu ◽  
...  
Keyword(s):  
Fractional Crystallization ◽  
Crystallization Process ◽  
Type Solution ◽  
Fractional Crystallization Process

scholarly journals The petrogenesis of tholeiitic diabases in eastern Parnaíba Basin: evidence for geochemical heterogeneities in the subcontinental lithospheric mantle in NE Brazil

2017 ◽  
Vol 47 (1) ◽  
pp. 109-126 ◽  
Author(s):  
Adriano Guilherme da Silva ◽  
Cícera Neysi de Almeida ◽  
Sérgio de Castro Valente ◽  
Leonardo Fonseca Borghi de Almeida
Keyword(s):  
Trace Element ◽  
Fractional Crystallization ◽  
Lithospheric Mantle ◽  
Sedimentary Basin ◽  
Sedimentary Rocks ◽  
Geochemical Modelling ◽  
Subcontinental Lithospheric Mantle ◽  
Tectonic Events ◽  
Tholeiitic Magmatism ◽  
Parnaíba Basin

ABSTRACT: The sedimentary rocks within the Paleozoic Parnaiba basin in NE Brazil were intruded by voluminous tholeiitic diabase sills and covered by coeval basaltic flows. This paper presents lithogeochemical data of borehole samples obtained from wells located in the eastern portion of the Parnaiba basin. The diabases are subalkaline tholeiitc rocks comprising three high-TiO2 and three low-TiO2 suites that are unrelated by differentiation processes. Fractional crystallization of olivine and augite was the predominantly evolutionary processes within individual high- and low-TiO2 suites as depicted by trace element geochemical modelling, exception being made for one low-TiO2 suite that evolved by AFC. Parental compositions for both low- and high-TiO2 suites are related with variably enriched, spinel harzburgitic sources likely to represent the heterogeneous subcontinental lithospheric mantle underneath the sedimentary basin. The geochemical provinciality of the Parnaiba tholeiitic magmatism seems unrelated with the Transbrasiliano Lineament but may be due to lithospheric mantle amalgamation and remobilization occurred during previous tectonic events.

scholarly journals Petrological and geochemical study of the Sylhet trap basalts, Shillong plateau, N.E. India: Implications for petrogenesis

2020 ◽  
Vol 2 (1) ◽  
pp. 01-18
Author(s):  
M. Faruque Hussain ◽  
Md Shofiqul Islam ◽  
Mithun Deb
Keyword(s):  
Partial Melting ◽  
Lithospheric Mantle ◽  
Crustal Contamination ◽  
Northeast India ◽  
Subcontinental Lithospheric Mantle ◽  
Shillong Plateau ◽  
Geochemical Study ◽  
Significant Enrichment

Sylhet Traps exposed along the southern margin of Shillong plateau, Northeast India are subalkaline tholeiitic basalts. The basalts are generally massive but occasionally contain large amygdules of zeolites and chalcedony. Microscopically, some basalts show porphyritic texture with olivine phenocrysts. Phenocryst assemblage of plagioclase ± clinopyroxene ± olivine implies crystallization at shallow level. SEM-EDX analysis shows occurrences of spinel with Ni and Cr within the basalts therefore indicating partial melting of the subcontinental lithospheric mantle as the possible source materials for the basalts. The multi-element plot for the basalts shows two distinct trends: one with significant enrichment of LILE and depletion of HFSE and plot similar to OIB (Type 1) while the other trends are chara cterized by slight enrichment of LILE and negative anomalies at Nb, P and Ti (Type 2). Chondrite-normalized REE patterns for Type 1 basalt shows very high enrichment of LREE and a strong right dip HREE pattern and also plots similar to typical OIB while Type 2 show a slight enrichment of LREE over HREE with small Eu anomaly. The geochemical signatures suggest crustal contamination by plume-derived magma produced by low degree of partial melting for Type 1 basalt. Type 2 basalt was produced by partial melting of subcontinental lithospheric mantle, which may be triggered by plume upwelling.

scholarly journals Caracterização Petrográfica e Geoquímica da Parte Leste do Granito Europa, Distrito Mineiro de Pitinga, AM

2007 ◽  
Vol 34 (1) ◽  
pp. 77 ◽  
Author(s):  
MAURÍCIO PRADO ◽  
JOSÉ TADEU MAXIMINO MIRRAS FERRON ◽  
EVANDRO FERNANDES DE LIMA ◽  
ARTUR CEZAR BASTOS NETO ◽  
VITOR PAULO PEREIRA ◽  
...  
Keyword(s):  
Fractional Crystallization ◽  
Genetic Relationship ◽  
Crystallization Process ◽  
Volcanic Rocks ◽  
Alkali Feldspar ◽  
Mineral Deposits ◽  
Geochemical Data ◽  
Principal Mechanism ◽  
Amazonian Region ◽  
Fractional Crystallization Process

The important mineral deposits of the Pitinga Mine, in the Amazonian region are related to A-type granites intruded in the Iricoumé Group. The Europa granite is one of these A-type rocks, intruded in the Iricoumé Group, which is represented by subaerial vulcanoclastic rocks (crystal-rich ignimbrites, thin massive tuffs and siltic tufaceous arenites) and minor hipabissal rhyolites. The volcanic rocks were probably generated in a caldera environment. The Europa granite is an alkali-feldspar peralkaline granite (hipersolvus) without genetic relationship with to the volcanic rocks of the Iricoumé Group, but it could have been generated during the resurgence stages. The petrographic and geochemical data attest that fractional crystallization process was the principal mechanism during the crystallization, which led to the generation of two different granitic facies. The Nb soil anomalies overprinted on the more differentiated facies are related to the astrophillite weathering.

Geochemistry of late Caledonian minettes from Northern Britain: implications for the Caledonian sub-continental lithospheric mantle

1996 ◽  
Vol 60 (398) ◽  
pp. 221-236 ◽  
Author(s):  
Jason C. Canning ◽  
P. J. Henney ◽  
M. A. Morrison ◽  
J. W. Gaskarth
Keyword(s):  
Trace Elements ◽  
Partial Melting ◽  
Fractional Crystallization ◽  
Lithospheric Mantle ◽  
Sr Isotope ◽  
Crustal Assimilation ◽  
Continental Lithospheric Mantle ◽  
Compositional Changes ◽  
Tectonic Dislocations

AbstractThe geochemistry of late Caledonian minettes from across the orogenic belt is compared in order to constrain the composition of the Caledonian sub-continental lithospheric mantle (SCLM). All the minettes are similar petrographically and chemically and several samples have characteristics typical of near primary mantle melts. Samples from the Northern Highlands and the Caledonian foreland show enrichment in many trace elements (notably LILE and LREE) relative to those from the Grampians, the Southern Uplands and northern England, coupled with distinct Nd and Sr isotope characteristics. Processes such as fractional crystallization, crustal assimilation, and partial melting played a negligible role in creating the differences between the two groups which reflect long-term, time-integrated differences in the compositions of their SCLM sources. The Great Glen Fault appears to represent the boundary between these two lithospheric mantle domains. Other currently exposed Caledonian tectonic dislocations cannot be correlated directly with compositional changes within the SCLM. The chemical provinciality displayed by the minettes shows some resemblance to that within other late Caledonian igneous suites, including the newer granites, suggesting that the minettes may represent the lithospheric mantle contributions to these rocks.

Composite Ordovician lamprophyre (spessartite) intrusions around the Midlands Microcraton in central Britain

1993 ◽  
Vol 130 (5) ◽  
pp. 657-663 ◽  
Author(s):  
R. S. Thorpe ◽  
J. W. Gaskarth ◽  
P. J. Henney
Keyword(s):  
Partial Melting ◽  
Fractional Crystallization ◽  
Mantle Source ◽  
Lithospheric Mantle ◽  
Sedimentary Rocks ◽  
Small Degree ◽  
Chemical Characteristics ◽  
Lower Ordovician ◽  
Lower Palaeozoic

AbstractLamprophyre sills and dykes of Ordovician age were emplaced within Cambrian–Lower Ordovician sedimentary rocks around the northern margins of the Midlands Microcraton. The intrusions show internal mineralogical and chemical variations indicating emplacement as multiple intrusions of co-magmatic pulses. The chemical characteristics of the lamprophyre magmas indicate formation by small-degree volatile-rich partial melting of lithospheric mantle enriched and modified by Lower Palaeozoic subduction (Th/Ta 5.3–11.6, La/Ta 29–82.3), together with a contribution from within-plate mantle source (Zr/Yc. 6) and/or mineralogically heterogeneous lithosphere, followed by varying degrees of fractional crystallization during uprise.

Late Triassic porphyries in the Zhongdian arc, eastern Tibet: origin and implications for Cu mineralization

2019 ◽  
Vol 157 (2) ◽  
pp. 275-288
Author(s):  
Pengsheng Dong ◽  
Guochen Dong ◽  
Zhuanrong Sun ◽  
Huawei Li ◽  
Jiahui Tang ◽  
...  
Keyword(s):  
Partial Melting ◽  
Water Content ◽  
Fractional Crystallization ◽  
Lower Crust ◽  
Late Triassic ◽  
Magma Source ◽  
High Water Content ◽  
Asthenospheric Mantle ◽  
Low Degree ◽  
Eastern Tibet

AbstractWhole-rock and Sr–Nd–Pb isotopic composition data, zircon Hf isotopic data and zircon U–Pb ages were obtained for the Late Triassic porphyries in the Zhongdian arc, eastern Tibet. These porphyries are intermediate and metaluminous and are enriched in large ion lithophile elements and depleted in high field strength elements. Moreover, they have weak negative Eu anomalies, high Sr and Ba contents, and high Sr/Y ratios. Different mineral geothermobarometers suggest that the porphyries in the Zhongdian arc crystallized at c. 640–829 °C and pressures of 2.1–2.8 kbar at depths shallower than 8 km. The porphyries have a calculated water content of 4.47–4.94 wt % and a relatively high magmatic oxygen fugacity. These porphyries were emplaced mainly at 230–203 Ma with a peak at 218–215 Ma. The Sr–Nd–Pb–Hf isotope data suggest that the porphyries in the Zhongdian arc were derived from a mixed melt of 50–65 % asthenospheric mantle and 35–50 % eclogite from the western Yangtze lower crust that experienced low-degree partial melting of 2–10 %. Subsequent fractional crystallization resulted in the decreasing trends of the major- and trace-element contents. The high Sr/Y and La/Yb values are the result of the low degree of partial melting of the western Yangtze lower crust rather than fractional crystallization, because no linear relationship was noted between Sr/Y or La/Yb and SiO2. The mixed melts from the lower crust and asthenospheric mantle provided a fertile magma source, and subsequent fractional crystallization under the favourable magmatic conditions of high water content and high oxidation state resulted in the formation of the porphyry Cu–Au deposits.

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