Diopsidites from a Neoproterozoic–Cambrian suture in southern India

2010 ◽  
Vol 147 (5) ◽  
pp. 777-788 ◽  
Author(s):  
M. SANTOSH ◽  
V. J. RAJESH ◽  
T. TSUNOGAE ◽  
S. ARAI
Keyword(s):  
Rare Earth ◽  
Subduction Zone ◽  
Rare Earth Element ◽  
Earth Element ◽  
Suture Zone ◽  
Dharwar Craton ◽  
Southern India ◽  
The North ◽  
Calcic Amphibole ◽  
Gondwana Supercontinent

AbstractWe report the occurrence and characteristics of diopsidite dykes and veins from the Palghat-Cauvery Suture Zone (PCSZ) marking the boundary between the Archaean Dharwar craton to the north and the Proterozoic Madurai Block to the south, which is considered as a trace of the Cambrian Gondwana suture zone in southern India. The diopsidites are composed predominantly of coarse crystals of diopside [Mg no. (100 Mg/(Mg+Fetot)) up to 89] surrounded by retrograde calcic amphibole, plagioclase and phlogopite with accessory titanite and calcite. The major, trace and rare earth element characteristics of the diopside crystals suggest their formation in a subduction zone setting. We correlate the petrogenesis of the diopsidites with the tectonics associated with the subduction and closure of the Neoproterozoic Mozambique Ocean prior to the final collisional assembly of the Gondwana supercontinent in Cambrian.

scholarly journals Supplementary material to "Particulate Rare Earth Element behavior in the North Atlantic (GEOVIDE cruise)"

2020 ◽  
Author(s):  
Marion Lagarde ◽  
Nolwenn Lemaitre ◽  
Hélène Planquette ◽  
Mélanie Grenier ◽  
Moustafa Belhadj ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
North Atlantic ◽  
Earth Element ◽  
The North ◽  
Supplementary Material ◽  
The North Atlantic

Eu anomaly- reliability of the proxy in inferring source composition of clastic Sedimentary rocks: A case study from western Dharwar craton, Karnataka, India

2020 ◽  
Author(s):  
Anirban Mitra ◽  
Sukanta Dey
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Sedimentary Rocks ◽  
Dharwar Craton ◽  
Source Rocks ◽  
Granitic Rocks ◽  
Negative Anomaly ◽  
Eu Anomaly ◽  
Ree Pattern

<p>Use of trace and rare earth element concentration of terrigenous sedimentary rocks to deduce the composition of their source rocks in the hinterland is a very common and efficient practice. The results of geochemical analysis of the metaquartzarenites located at the basal part of Bababudan and Sigegudda belt, late Archean greenstone sequences of western Dharwar craton show that the sediments were most possibly supplied from Paleo to Mesoarchean granitoids of western Dharwar Craton. Rare earth element patterns of these basal quartzites display fractionated REE pattern in variable degree (La<sub>N</sub>/Yb<sub>N</sub> =1.47-10.63) with moderate to highly fractionated LREE (La<sub>N</sub>/Sm<sub>N</sub>=2.67-8.93) and nearly flat to slighly elevated HREE (Gd<sub>N</sub>/ Yb<sub>N</sub>=0.62-1.29) and a significant Eu negative anomaly (avg. Eu/Eu*=0.67). In general, presence of negative Eu anomaly in clastic rocks reflect the widespread occurrence of granitic rocks in the source area, which possess negative Eu anomaly. On the other hand, mechanical enrichment of zircon (having negative Eu anomaly, high HREE concentration and low La<sub>N</sub>/Yb<sub>N</sub>), if present, will hamper the whole REE pattern of the sediments and necessarily, do not actually mimic the source composition. Here, in our study, the Th/Sc vs Zr/Sc diagram show mineral Zircon has been concentrated by mechanical concentration in the sedimentary rocks. Few quartzite samples which have high Zr content typically exhibit low La<sub>N</sub>/Yb<sub>N</sub> values, reflecting pivotal role of mineral zircon in controlling the REE pattern of the sediments. Hence, in this case, we should be cautious in interpreting of the Eu negative anomaly of the basal quartzites for meticulously identifying their source rock composition. More geochemical and other analytical approaches are required in this regard.</p>

Molecular modelling of rare earth element complexation in subduction zone fluids

2009 ◽  
Vol 73 (13) ◽  
pp. 3934-3947 ◽  
Author(s):  
Jelle van Sijl ◽  
Neil L. Allan ◽  
Gareth R. Davies ◽  
Wim van Westrenen
Keyword(s):  
Rare Earth ◽  
Subduction Zone ◽  
Rare Earth Element ◽  
Molecular Modelling ◽  
Earth Element

From subduction initiation to hot subduction: Life of a Neoarchean subduction zone from the Dengfeng Greenstone Belt, North China Craton

2021 ◽  
Author(s):  
Hao Deng ◽  
Ning Jia ◽  
Timothy Kusky ◽  
Ali Polat ◽  
Guanglei Peng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Subduction Zone ◽  
Rare Earth Element ◽  
Mantle Source ◽  
North China Craton ◽  
Greenstone Belt ◽  
Earth Element ◽  
North China ◽  
Subduction Initiation ◽  
Magmatic Association

We report a spatially and temporally linked arc magmatic association of 2.55−2.50 Ga mid-ocean ridge basalt (MORB)-affinity gabbros, arc-affinity basalts, high-Mg basalts/basaltic andesites (HMBA), Nb-enriched basalts (NEB), and a tonalite-trondhjemite-granodiorite (TTG)-like granodiorite from the Dengfeng greenstone belt (DFGB), North China Craton. These are identical to arc magmatic rock suites from hot subduction in the present plate mosaic, and resemble suites formed during subduction initiation. Laser ablation−inductively coupled plasma−mass spectrometry zircon U-Pb dating indicates that gabbros and granodiorites intruded at ca. 2.55 Ga and the HMBAs formed at ca. 2.50 Ga, indicating a long duration of subduction zone magmatic activity of at least 50 m.y. in the DFGB. The gabbros are characterized by flat light-rare earth element (LREE) patterns without negative Nb and Zr anomalies, showing a MORB-like geochemical affinity. Combined with previously reported normal-MORB-type basalts, we suggest that they may represent magmatic products during intraoceanic subduction initiation where their mantle source was slightly metasomatized by subduction-derived fluids during the initiation stage. The arc-affinity basalts are characterized by slightly enriched LREE patterns with negative Nb and Zr anomalies. The HMBAs have higher contents of MgO, Ni, and Cr and display more fractionated rare earth element (REE) patterns and large negative Nb and Zr anomalies than the arc-affinity basalts. The NEBs are characterized by high absolute contents of Nb (9.9−14 ppm) and high ratios of Nb/Laprimitive mantle (pm) (0.40−0.46) and Nb/Thpm (0.44−0.54), and moderately fractionated REE and minor negative Nb anomalies with no Zr anomalies. One granodiorite sample is characterized by a highly fractionated REE pattern and negative Nb and Zr anomalies. Geochemical modeling suggests that the association of the normal arc-affinity basalt (NAB)-HMBA-NEB can be interpreted to be generated by hybridization of mantle wedge peridotites by slab-derived TTG-like melts. Positive values of whole-rock εNd (t) and zircon εHf (t) of the 2.55−2.50 Ga magmatic associations are consistent with a long-term depleted mantle source for the mafic assemblage. The 2.55−2.50 Ga magmatic association from MORB-affinity gabbros and basalts to arc-affinity NAB-HMBA-NEB may record a continuous Neoarchean geodynamic process from intraoceanic subduction initiation to mature arc magmatism. The NAB-HMBA-NEB association with regional sanukitoids and high-Al TTGs indicates that hot subduction may have played an important role in the production of arc-related magmatism during the Archean.

Rare earth element enrichment in Palaeoproterozoic Fengzhen carbonatite from the North China block

2016 ◽  
Vol 58 (15) ◽  
pp. 1940-1950 ◽  
Author(s):  
Meng Feng ◽  
Cheng Xu ◽  
Jindrich Kynicky ◽  
Liang Zeng ◽  
Wenlei Song
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
North China ◽  
North China Block ◽  
The North ◽  
Element Enrichment
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