scholarly journals The Role of Siliceous High-Magnesium Basalts during the Formation of a Neoproterozoic Mafic-Ultramafic Intrusion in the Tarim Craton (China)

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 662
Author(s):  
Xia ◽  
Xia ◽  
Ru
Keyword(s):  
Lithospheric Mantle ◽  
Basaltic Magma ◽  
Subcontinental Lithospheric Mantle ◽  
Crystallization Sequence ◽  
Zircon Age ◽  
Exposed Area ◽  
Tarim Craton ◽  
Ultramafic Intrusion ◽  
T Values

The Xingdi No.2 intrusion in the Kuluktag Block of northeastern Tarim Craton, which intrudes into the Palaeoproterozoic basement with an exposed area of ca. 12 km2, is an orthopyroxene-rich mafic-ultramafic intrusion in a continental rift setting. It consists of gabbros, pyroxenites, and peridotites, and exhibits a crystallization sequence of the principal rock-forming minerals from olivine, orthopyroxene, clinopyroxene, to plagioclase. The gabbros show a concordant SHRIMP U-Pb zircon age of 752 ± 5.4 Ma. In addition, the olivine grains have forsterite content values of 78–85 mole% and mostly contain low NiO, MnO, CaO, and Cr2O3. The rocks are relatively enriched in large ion lithophile elements and LREE, and depleted in HSFE, have non-radiogenic Pb, low εNd (t) values (−2.8 to −23), initial 87Sr/86Sr ratios (0.7059–0.7130). It could be concluded that the rocks represent an analogue of siliceous high magnesium basaltic magma originated by the partial melting of a hydrous and enriched subcontinental lithospheric mantle and contaminated by the continental crust.

Fractionation trends in the Bay of Islands ophiolite of Newfoundland: polycyclic cumulate sequences in ophiolites and their classification

1977 ◽  
Vol 14 (5) ◽  
pp. 1156-1165 ◽  
Author(s):  
W. R. Church ◽  
L. Riccio
Keyword(s):  
Basaltic Magma ◽  
General Rule ◽  
Olivine Gabbro ◽  
Lower Velocity ◽  
Crystallization Sequence ◽  
Basaltic Rocks ◽  
Lower Temperature ◽  
High Velocity Layer ◽  
Velocity Layer ◽  
Temperature Crystallization

The fractionation range of the cumulate sequence of the allochthonous Bay of Islands ophiolite of the Western Platform of Newfoundland, measured in terms of the FeO(tolal)/MgO ratios of the liquids from which they were derived, encompasses entirely the range of known values exhibited by the overlying dikes and pillow lavas. Cryptic variations within the cumulate sequences are irregular, often inverse, and the crystallization sequences found in the cumulates suggest that they were formed from at least three different basaltic magma types, one of which is unusual in having given rise to co-existing highly aluminous clinopyroxenes and spinels. These features suggest that crystallization of the Bay of Islands plutonic rocks took place in an 'open system' magma chamber that was tapped repeatedly during fractionation to form dike rocks and lavas. Most of the cumulate rocks of the Bay of Islands ophiolite formed according to the crystallization sequence ol–cpx–(opx) or the sequence ol–plag–cpx–(opx). In contrast, the cumulate rocks of the Betts Cove ophiolite, located within the Fleur de Lys orthotectonic zone of the Newfoundland Appalachians, crystallized according to the sequences ol–opx–cpx and ol–cpx–plag. This difference in the nature of the cumulate sequences within the Bay of Islands and Betts Cove ophiolites is also reflected in the Ti characteristics of the basaltic rocks of the ophiolites, and in the morphology of the gabbroic units. Comparison with Mesozoic ophiolites suggests, as a general rule, that within ophiolite cumulate successions there is a tendency for ol–opx sequences to be followed by ol–cpx sequences, and for ol–cpx sequences to be followed by ol–plag sequences. Such a relationship may be related to processes involving remelting of lower-temperature crystallization products in a system open to either continuous or periodic additions of high temperature basaltic liquid. In terms of oceanic structures the Bay of Islands ophiolite corresponds to sonobouy model 2 of Christensen and Salisbury: the basal high velocity layer corresponding to the olivine-gabbro cumulate rocks, and the lower velocity 'gabbroic' layer to the upper part of the olivine-free cumulate sequence and overlying massive uralitized roof gabbro and dike rocks.

scholarly journals Examine the Role of Family Environment to the Development of Psychological Resilience among Urban and Rural Adolescents

2017 ◽  
Vol 5 (1) ◽  
Author(s):  
Ashwini P. Patil
Keyword(s):  
Family Environment ◽  
Sampling Method ◽  
Rural Adolescents ◽  
Psychological Resilience ◽  
Rural Living ◽  
Urban Adolescent ◽  
Significant Difference ◽  
The Mean ◽  
T Values

The present study examined the role of family environment to the development of psychological resilience among urban and rural adolescents. The sample consisted of 120 adolescents were selected for the study which includes 60 urban and 60 rural from Kolhapur districts. Random sampling method was used for the data collection. Resilience was measured by Adolescent Resilience Questionnaire (Deirdre Gartland, 2006) and family environment was measured by Family Environment Scale (Bhatia and Chadha, 1993). The Method of central tendency was used for data analysis and computes the Mean, SD and calculated ‘r’ and ‘t’ values. The results indicated that the there is a positive correlation between resilience and family environment among urban and rural adolescents. Whereas the mean score of rural adolescents is more than urban adolescent with respect to resilience and family environment, it’s showed that the level of resilience and family environment among rural living adolescents is higher than that of urban living adolescents. The findings also indicated that there is no significant difference found between resilience and family environment among urban and rural living adolescents.

scholarly journals Highly siderophile elements mobility in the subcontinental lithospheric mantle beneath southern Patagonia

Lithos ◽  
2018 ◽  
Vol 314-315 ◽  
pp. 579-596 ◽  
Author(s):  
Santiago Tassara ◽  
José M. González-Jiménez ◽  
Martin Reich ◽  
Edward Saunders ◽  
Ambre Luguet ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Subcontinental Lithospheric Mantle ◽  
Highly Siderophile Elements ◽  
Southern Patagonia ◽  
Siderophile Elements

scholarly journals Role of syn-eruptive plagioclase disequilibrium crystallization in basaltic magma ascent dynamics

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
G. La Spina ◽  
M. Burton ◽  
M. de’ Michieli Vitturi ◽  
F. Arzilli
Keyword(s):  
Basaltic Magma ◽  
Magma Ascent

Quaternary sodic and potassic intraplate volcanism in northeast China controlled by the underlying heterogeneous lithospheric structures

Geology ◽  
2021 ◽  
Author(s):  
Xingli Fan ◽  
Qi-Fu Chen ◽  
Yinshuang Ai ◽  
Ling Chen ◽  
Mingming Jiang ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Northeast China ◽  
Velocity Structure ◽  
Seismic Velocity ◽  
Subcontinental Lithospheric Mantle ◽  
Seismic Velocities ◽  
S Wave ◽  
Crust And Upper Mantle ◽  
Potassic Volcanism

The origin and mantle dynamics of the Quaternary intraplate sodic and potassic volcanism in northeast China have long been intensely debated. We present a high-resolution, three-dimensional (3-D) crust and upper-mantle S-wave velocity (Vs) model of northeast China by combining ambient noise and earthquake two-plane wave tomography based on unprecedented regional dense seismic arrays. Our seismic images highlight a strong correlation between the basalt geochemistry and upper-mantle seismic velocity structure: Sodic volcanoes are all characterized by prominent low seismic velocities in the uppermost mantle, while potassic volcanoes still possess a normal but thin upper-mantle “lid” depicted by high seismic velocities. Combined with previous petrological and geochemical research findings, we propose that the rarely erupted Quaternary potassic volcanism in northeast China results from the interaction between asthenospheric low-degree melts and the overlying subcontinental lithospheric mantle. In contrast, the more widespread Quaternary sodic volcanism in this region is predominantly sourced from the upwelling asthenosphere without significant overprinting from the subcontinental lithospheric mantle.

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