In situ mineral chemistry of chlorite in Donghua area, Dehua‐Youxi‐Yongtai ore district, Fujian Province , south‐east China : Elemental characteristics and their implications for exploration

2021 ◽  
Author(s):  
Si‐Da Niu ◽  
Jian Guo ◽  
Guang‐Fu Xing ◽  
Zhao‐Qiang Huang ◽  
Hua‐Ying Wu ◽  
...  
Keyword(s):  
Mineral Chemistry ◽  
East China ◽  
Fujian Province ◽  
Ore District

Mineral chemistry, P-T pseudosection and in-situ U-Th-Pbtotal monazite geochronology of Banded Iron Formation from Bundelkhand craton North-Central India, and its geodynamic significance

2021 ◽  
Author(s):  
Mohd Baqar Raza ◽  
Pritam Nasipuri ◽  
Hifzurrahman
Keyword(s):  
Central India ◽  
Mineral Chemistry ◽  
Iron Formation ◽  
Age Group ◽  
Banded Iron Formation ◽  
Tectonic Zone ◽  
Third Age ◽  
The Third ◽  
Hydrothermal Activities

<p>The Banded Iron Formation (BIF) in Bundelkhand craton (BuC) occurred as supracrustals associated with TTG’s, amphibolites, calcsilicate rocks, and quartzite within the east-west trending Bundelkhand tectonic zone (BTZ). The BIFs near Mauranipur do not show any prominent iron-rich and silica-rich layer band and are composed of garnet, amphibole, quartz, and magnetite. The volumetrically dominant monoclinic-amphiboles are grunerite in composition. X<sub>Mg</sub> of grunerite varies between 0.39-0.37. The garnets are Mn-rich, the X<sub>Spss</sub> of garnet ranges from 0.26-0.20, X<sub>Pyp</sub> and X<sub>Grs </sub>vary between 0.10-0.06 and 0.07-0.05, respectively. P-T pseudosection analysis indicates that by destabilizing iron-silicate hydroxide phases through a series of dehydration and decarbonation reactions, amphibole and garnet stabilized in BIF at temperature 400-450°C and pressure 0.1-0.2 GPa.</p><p>Massive type BIFs have monazite grains that vary from 10 to 50 µm in size, yield three distinct U-Th-Pb<sub>total</sub> age clusters. 10-20 µm sized monazite grains yield the oldest age, 3098±95 Ma. 2478±37 Ma average age is obtained from the second group, which is relatively larger and volumetrically predominant. The third age group of Monaiztes gives an age of 2088±110 Ma. ~3100 Ma monazite suggests the older supracrustal rocks of Bundelkhand craton, similar to those obtained from Singhbhum and the Dharwar craton. The 2478±37 Ma age is constrained as the timing of metamorphism and stabilization of BuC. The third age group, 2088±110 Ma probably associated with renewed hydrothermal activities, leading to rifting and emplacement of mafic dykes in BuC.</p>

scholarly journals Effectiveness of stocking Sparus macrocephalus fry in situ in the East China Sea

2019 ◽  
Vol 4 (2) ◽  
pp. 74-79
Author(s):  
Qingsong Hu ◽  
Ning Bao ◽  
Hafiz Abdur Rahman ◽  
Yazhou Jiang ◽  
Shouyu Zhang ◽  
...  
Keyword(s):  
East China Sea ◽  
East China ◽  
The East China Sea ◽  
China Sea ◽  
Sparus Macrocephalus

Silicate and Oxide Mineral Chemistry and Textures of the Norilsk-Talnakh Ni-Cu-Platinum Group Element Ore-Bearing Intrusions

2020 ◽  
Vol 115 (6) ◽  
pp. 1227-1243 ◽  
Author(s):  
Louise Schoneveld ◽  
Stephen J. Barnes ◽  
Morgan Williams ◽  
Margaux Le Vaillant ◽  
David Paterson
Keyword(s):  
Mineral Chemistry ◽  
Relative Reduction ◽  
Phase Assemblage ◽  
Significant Drop ◽  
Liquid Component ◽  
Crystallization Sequence ◽  
History Of ◽  
Ultramafic Cumulate ◽  
Insight Into

Abstract A large proportion of the disseminated sulfide ores of the Norilsk-Talnakh camp are hosted within olivine-rich, ultramafic cumulate layers called picro-gabbrodolerite units. In this study we quantitatively analyze the chemistry and textures of the silicate and oxide minerals within olivine-bearing cumulates of the Kharaelakh, Norilsk 1, and Talnakh intrusions to determine how these intrusions compare to each other and to establish the liquidus phase assemblage and crystallization sequence and how the liquid component evolved during solidification. Crystal size distributions indicate that much of the olivine and clinopyroxene oikocrysts grew together in situ as the first of the cumulus phases at contrasting growth rates. These large clinopyroxene oikocrysts record a significant drop in Cr in the system by a significant decrease in Cr content of the outer rims compared to the cores. The chadacrysts of olivine and spinel within the clinopyroxene record the chemistry of the first stages of crystallization, while the minerals in the framework of the cumulate show a relative reduction in Cr and enrichment in incompatible elements such as Ti, Zn, Y, and the rare earth elements, indicative of the enrichment through reactions with the trapped liquid during postcumulate growth. Due to the entrapment of the olivine and spinel in rapidly growing clinopyroxene, these minerals record a history of the changing chemistry during cumulate and postcumulate growth, giving us an insight into the changing conditions during the solidification of intrusions.

scholarly journals Cross-shelf water exchange in the East China Sea as estimated by satellite altimetry and in situ hydrographic measurement

2016 ◽  
Vol 121 (9) ◽  
pp. 7192-7211 ◽  
Author(s):  
Ruibin Ding ◽  
Daji Huang ◽  
Jiliang Xuan ◽  
Bernhard Mayer ◽  
Feng Zhou ◽  
...  
Keyword(s):  
East China Sea ◽  
Satellite Altimetry ◽  
Water Exchange ◽  
East China ◽  
Shelf Water ◽  
The East China Sea ◽  
China Sea

Glass-bearing felsic nodules from the crystallizing sidewalls of the 1944 Vesuvius magma chamber

2000 ◽  
Vol 64 (3) ◽  
pp. 481-496 ◽  
Author(s):  
P. Fulignati ◽  
P. Marianelli ◽  
A. Sbrana
Keyword(s):  
Magma Chamber ◽  
Melt Inclusions ◽  
Mineral Chemistry ◽  
Glassy Matrix ◽  
Crystal Mush ◽  
Stratigraphic Sequence ◽  
Shallow Magma Chamber ◽  
Mineral Assemblages ◽  
Pressure Crystallization

AbstractIn the 1944 Vesuvius eruption, the shallow magma chamber was disrupted during the highly energetic explosive phases. Abundant cognate xenoliths such as subvolcanic fergusites and cumulates, hornfels, skarns and rare marbles occur in tephra deposits.Mineral chemistry, melt inclusions in minerals and glassy matrix compositions show that fergusites (highly crystalline rocks made of leucite, clinopyroxene, plagioclase, olivine, apatite, oxides and glass) do not correspond to melt compositions but result from combined sidewall accumulation of crystals, formed from K-tephriphonolitic magma resident in the chamber, and in situ crystallization of the intercumulus melt. Very low H2O contents in the intercumulus glass are revealed by FTIR and apatite composition. Whole rock compositions are essentially determined by the bulk mineral assemblages.Glass–bearing fergusites constitute the outer shell of the magma chamber consisting of a highly viscous crystal mush with a melt content in the range 20–50 wt.%. The leucite/(clinopyroxene+olivine) modal ratio, varies with the extraction order of magmas from the chamber, decreasing upwards in the stratigraphic sequence. This reflects a vertical mineralogical zonation of the crystal mush. These data contribute to the interpretation of the subvolcanic low–pressure crystallization processes at the magma chamber sidewalls affecting alkaline potassic magmas.

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