scholarly journals Geochemical Implications of Rare Earth Elements in Terra Rossa in Tropical Karst Area: A Case Study in Northern Vietnam

2020 ◽  
Vol 10 (3) ◽  
pp. 858 ◽  
Author(s):  
Zhang Liankai ◽  
Ji Hongbing ◽  
Wang Shijie ◽  
Luo Gang ◽  
Liu Xiuming ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Chemical Weathering ◽  
Karst Area ◽  
Oxidation Condition ◽  
Terra Rossa ◽  
Northern Vietnam ◽  
Material Sources ◽  
Karst Areas ◽  
Tropical Karst

Research on weathered crusts on carbonate rock is essential for paleoenvironmental studies in karst areas. Terra rossa, widely distributed in tropical karst areas, has not been studied in terms of its material sources and geochemistry. Two typical terra rossa profiles on dolomite (SC profile located at Sang Cai, Hoa Binh province) and limestone (TG profile located at Tong Gia, Lao Cai province) in Northern Vietnam were selected to examine the geochemical characteristics and the evolutionary processes of rare earth elements (REEs). Chondrite and bedrock normalized patterns indicated that these two profiles are in situ weathering crusts, meaning they are the residual material remaining after chemical weathering of the lower carbonate rocks. The average value of total REE in the SC profile is 381.19 ppm, which is 30 times higher than the bedrock. In the TG profile, the value is 386.26 ppm, 13 times higher than the bedrock. Compared with the profiles in nearby subtropical areas in Southeast China, the REE enrichment coefficients of terra rossa in Northern Vietnam are much higher. The REE depletion was also different between the SC and TG profiles. The light and heavy REE fractionations in the SC profile are higher than in the TG profile. Paleoclimate inversion analysis shows that the SC profile experienced a stable oxidation condition, whereas the TG profile was subjected to several reducing environments since a weathering crust formed.

scholarly journals Identifying Correlation of Coal Seams in the Tien Hai Area, Northern Vietnam by Using Multivariate Statistic Methods

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
The Hung KHUONG ◽  
Phuong NGUYEN ◽  
Thi Cuc NGUYEN ◽  
Nhu Sang PHAM ◽  
Danh Tuyen NGUYEN
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Coal Seam ◽  
Rare Earth Elements ◽  
Major And Trace Elements ◽  
Coal Seams ◽  
Multivariate Statistic ◽  
Northern Vietnam ◽  
Coal Deposits ◽  
Indicator Elements

In northern Vietnam, the Tien Hai area is considered a high potential area of coal deposits. Twohundred fifty-six geochemical coal samples of 13 cores in the Tien Hai area investigate coal seams andcoal deposits to identify the correlation of coal seams. According to the statistical method and clusteranalysis of geochemical samples, the results indicate that the Mg, V, As, Ca, Zn, Cr, Co, K, Na, Sr, Fe,Ge, Re, U, Mo, Th, and Ga elements are good indicator elements of the major and trace elements in coal.Most of them comply with the normal or lognormal distribution rules. Besides, the Yb, Sc, Ho, Er, Tm,Lu, Y, Tb, Pr, Dy, and Sm elements are also good indicator elements for rare earth elements in the region.Therefore, the selected elements are used to identify the correlation of the coal seams in the Tien Hai area.Based on the similarity degree between studied objects, the results of grouping boreholes in coal seamsshow that the correlation of coal seam TV2-11 is suitable and acceptable, the coal seams TV3-6a, TV3-6b, and TV3-6c can be grouped into the coal seam TV3-6. These results present that the models can helpstudy geochemical coal samples and identify the correlation of the coal seams in the Tien Hai area.Additionally, the statistical analysis shows a remarkable degree to determine the correlation of the coalseams. Geochemical coal data can help to evaluate the indicator elements of the major, trace elements,and rare earth elements in coal seams and coal rashing of adjoining and pillar rocks in the Tien Hai area,northern Vietnam.

scholarly journals Chemical weathering intensity and rare earth elements release from a chlorite schist profile in a humid tropical area, Bengbis, Southern Cameroon

2021 ◽  
Vol 16 (2) ◽  
pp. 123-145
Author(s):  
Vincent Laurent Onana ◽  
Estelle Ndome Effoudou ◽  
Sylvia Desirée Noa Tang ◽  
Véronique Kamgang Kabeyene ◽  
Georges Emmanuel Ekodeck
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Chemical Weathering ◽  
Weathering Profile ◽  
Ree Distribution ◽  
Weathering Intensity ◽  
Southern Cameroon ◽  
La Modification ◽  
Co Precipitation ◽  
Hydrolysis Of

RésuméUn profil d’altération développé sur chloritoschistes de la zone de Bengbis (Sud Cameroun) a été choisi pour quantifier l’intensité de l’altération et comprendre le comportement des terres rares. Les valeurs de l’indice d’altération mafique combinées aux diagrammes ternaires du système Al – Fe – Mg – Ca – Na – K montrent que l’hydrolyse des feldspaths est proportionnelle à celle des minéraux mafiques (pertes en Mg), bien que l’hydrolyse des plagioclases (Ca, Na) soit plus intense que celle des minéraux ferromagnésiens. Les matériaux d’altération étudiés sont localisés dans le domaine de la kaolinitisation, à l’exception des matériaux nodulaires qui sont légèrement latritiss. La modification du comportement du Mg dans le milieu d’altération s’exprime par les faibles valeurs du rapport Ca/Mg. Le potassium et Be sont lessivés dans le sol en association avec Mg. L’ordre de mobilité des éléments dans l’environnement d’altération étudié est : Ca ≈ Na > Fe2+ ≈ Sr > Mg ≈ Co > Mn > Li > Ba > Rb > P > Cd > Ni > Si > Be > K > Sn. Les enrichissements en K, Cs et Be dans les saprolites sont liés à la présence d’illite. L’accumulation en Cs dans le sol est due à la présence de kaolinite. Le système le plus stable dans le milieu d’altération étudié est : Hf – Nb – W – U. Les saprolites, les matériaux nodulaires et les matériaux argileux meubles superficiels sont appauvris en terres rares par rapport à la roche mère. Les terres rares présentent trois types de comportement le long du profil d’altération, comme l’indiquent les valeurs du rapport (La/Yb)N ((La/Yb)N < 1, (La/Yb)N ~ 1 et (La/Yb)N > 1). Les terres rares légères et les terres rares moyennes s’accumulent dans les matériaux d’altération pour des valeurs de pH comprises entre 5,5 et 5,6 et pour celles de Eh variant entre +60 et +70mV. L’ordre de mobilité de ces éléments dans ces matériaux est le suivant : terres rares moyennes > terres rares lourdes terres rares légères. Ce fait est contre-intuitif, car les terres lourdes sont plus mobiles dans les environnemenst supergènes que les terres rares légères. L’adsorption ou la co-précipitation de ces terres rares sur les oxydes de fer peut principalement contrôler la concentration de ces éléments dans le profil d’altération. Les faibles anomalies en Ce dans les matériaux d’altération de la zone de Bengbis, dues au changement de Ce3+ en Ce4+, sont probablement dues à la présence de faibles quantités de rhabdophane. Les matériaux d’altération étudiés présentent un fractionnement en Gd (Gd/Gd* ~0.70 – 0.84) dues à une intense lixiviation. Ce fait a rarement été signalé dans un environnement d’altération latéritique. Il semble qu’une partie de la distribution et de la remobilisation du gadolinium soit contrôlée par des minéraux mafiques dans les matériaux d’altération étudiés. La distribution et la mobilisation des terres rares sont donc contrôlées par (1) l’adsorption ou la coprécipitation dans les minéraux mafiques et Fe, (2) et légèrement par les minéraux contenant des terres rares tels que le rhabdophane, rencontrés dans les matériaux d’altération étudiés. Abstract An in situ weathering profile overlying chlorite schists in southern Cameroon was chosen to quantify chemical weathering intensity and to study the behaviour of rare earth elements (REE). Mafic index alteration values combined with the ternary diagrams of the Al – Fe – Mg – Ca – Na – K system show that the hydrolysis of feldspars is proportional to that of mafic minerals (losses in Mg), although the hydrolysis of the plagioclases (Ca, Na) is more intense than that of ferromagnesian minerals. The studied materials are localised in the domain of kaolinitisation, except for nodular materials which are slightly lateritised. The change in the behaviour of Mg in the weathering environment is expressed by the low values in Ca/Mg ratio. Potassium and Be are leached in the soil in association with Mg. The order of mobility of the elements in the weathering environment is: Ca ≈  Na > Fe2+ ≈ Sr > Mg ≈ Co > Mn > Li > Ba > Rb > P > Cd > Ni > Si > Be > K > Sn. The enrichments in K, Cs and Be in saprolites are linked to the presence of illite. Cesium accumulation in the soil is due to the presence of kaolinite. The most stable system is: Hf – Nb – W – U. Saprolites, nodular and loose clayey materials are depleted in REE relative to the parent rock. REE exhibit three types of behaviour along the Bengbis profile like indicated by (La/Yb)N ratio values ((La/Yb)N < 1, (La/Yb)N ~ 1 and (La/Yb)N > 1). Light REE and Middle REE accumulate in the weathering materials for pH values ranging between 5.5 and 5.6 and for those of Eh varying between +60 and +70mV. The order of mobility of REE in these horizons is: Middle REE > Heavy REE ≈ Light REE. This fact is counter-intuitive, because Heavy REE are more mobile in supergene environment than Light REE. Adsorption or co-precipitation of LREE onto Fe oxides mainly may control the concentration of these elements in the profile. Weak Ce anomalies in the weathering materials of Bengbis area, due to the change in Ce3+ to Ce4+, are probably due to the presence of low amounts in rhabdophane. The studied weathering materials show a fractionation in Gd (Gd/Gd* ~0.70 – 0.84) due to intense chemical leaching. This fact has been rarely reported in lateritic weathering environment. It appears that, a part of Gd distribution and remobilization is controlled by mafic minerals in the studied weathered materials. REE distribution and mobilization are thus controlled by (1) adsorption or co-precipitation in mafic and Fe minerals, (2) and slightly by REE-bearing minerals such as rhabdophane found in the studied weathering profile.  

Rare earth elements: a potential proxy for identifying the lacustrine sediment source and soil erosion intensity in karst areas

2014 ◽  
Vol 14 (10) ◽  
pp. 1693-1702 ◽  
Author(s):  
Xing-Yue Wen ◽  
Cheng-Min Huang ◽  
Ya Tang ◽  
Suo-Lang Gong-Bo ◽  
Xin-Xin Hu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Soil Erosion ◽  
Rare Earth Elements ◽  
Lacustrine Sediment ◽  
Sediment Source ◽  
Karst Areas ◽  
Erosion Intensity

scholarly journals Saprolitization’s Characteristics of Rare Earth Elements in Volcanic Regolith on Drill Core #65 in Western Sulawesi, Indonesia

2019 ◽  
Vol 7 (4) ◽  
Author(s):  
Shaban Godang ◽  
Arifudin Idrus ◽  
Fadlin, Bambang Priadi ◽  
Nurcahyo Indro Basuki
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Chemical Weathering ◽  
Gradual Increase ◽  
Drill Core ◽  
High Concentration ◽  
Adsorption Ability ◽  
Ti Oxides ◽  
Weathering Degree ◽  
The Relationship

The enrichment of Rare Earth Elements (REEs) in regolith depends on greatly number of chemical weathering degree, the ability of the ion-adsorption on clay, precipitation of REEs, minimum uptake by plants, and minor REE leaching out by lessivage. The degree of chemical weathering depends on the decaying of four base weathering elements (Mg, Ca, Na, K) in minerals and is relatively less dependent on the slow leaching of silica. Therefore, a study of regolith profile from weathering’s Adang Volcanics (western Sulawesi, Indonesia) is performed to understand the relationship between degree of chemical weathering, nature migration of REE and the characteristics of saprolitization REEs. The result of drill core samples shows the increasing of degree of chemical weathering (Degree of Saprolitization; DOS) is equal to gradual increasing of alumina by saprolitization, and has also gradual increase in Fe-Ti-oxides by ferruginization; furthermore, there is also a gradual enrichment of REEs occurred in the saprolite zone on Adang Volcanics regolith. The enrichment of REEs in the saprolite zones (E and B horizons) is 2.73 times (TREY = 2,579 ppm, in avg) compared to the parent mafic trachytic rocks (944 ppm) reveal the high adsorption ability on lateritic-ferruginous clay. The thickness of high concentration REEs (2,435 ppm, in avg) is starting from A to E, and B-horizon which is about 5 m. The ratio of LREE and HREE is 87.42% and 12.58%, respectively in parent rock which indicates the genesis of rare-earth is more influenced by replacement of Ca2+, Na+ and K+ in minerals of diopside, apatite and leucite/pseudoleucite rather than the substitution by zircon (Zr4+).

Rare earth elements geochemistry of groundwater from Shanmuganadhi, Tamilnadu, India: Chemical weathering implications using geochemical mass-balance calculations

Geochemistry ◽  
2020 ◽  
Vol 80 (4) ◽  
pp. 125668
Author(s):  
F. Vinnarasi ◽  
K. Srinivasamoorthy ◽  
K. Saravanan ◽  
S. Gopinath ◽  
R. Prakash ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Mass Balance ◽  
Chemical Weathering ◽  
Geochemical Mass Balance

scholarly journals Petrographic and geochemical characteristics of the Nui Chua pegmatoid mafic-ultramafic series, Northern Vietnam: Significance in petrogenesis and Fe-Ti-V metallogenesis

2020 ◽  
Vol 43 (1) ◽  
pp. 80-94
Author(s):  
Pham Thi Dung ◽  
Tran Tuan Anh ◽  
Tran Quoc Hung ◽  
Tran Trong Hoa ◽  
R. A. Shelepaev ◽  
...  
Keyword(s):  
Rare Earth ◽  
Chemical Composition ◽  
Rare Earth Elements ◽  
Fractional Crystallization ◽  
Geochemical Characteristics ◽  
Ultramafic Rocks ◽  
Magma Source ◽  
Distribution Characteristics ◽  
Magmatic Origin ◽  
Northern Vietnam

The pegmatoid intrusions of the Nui Chua complex are one of the important mafic-ultramafic intrusive series associated with Fe-Ti-V ores in northern Vietnam. These intrusions consist of plagiowebsterite, clinopyroxenite, melanogabbronorite, mesogabbro, gabbronorite, and leucogabbronorite. The Fe-Ti oxide ores being massive or disseminated appear layered or veined in pegmatoid rocks. The geochemical characteristics of pegmatoid rocks are rich in Fe, Ti, V and poor Mg; their HREE are higher than LREE, with [La/Yb]N of 0.49 to 0.91 (average: 0.67), showing negative anomalies at Nb, Ta, Th, U, Sr, Zr and positive anomalies at Cs, Ti, and K. The chemical composition and distribution characteristics of trace and rare earth elements of mafic and ultramafic rocks show that they share the same magma source. Having the same geochemical tendency of intrusive formations, Fe-Ti oxide ores are magmatic origin associated with intrusive pegmatoid rocks. The pegmatoid rocks of the Nui Chua complex and Fe-Ti oxide ores are formed as a product of the fractional crystallization of Fe-Ti-rich residual melts after crystallization of the layered rocks.

scholarly journals Provenance and Tectonic Setting of Lower Cretaceous Huanhe Formation Sandstones, Northwest Ordos Basin, North-Central China

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1376
Author(s):  
Xiaoneng Luo ◽  
Ziying Li ◽  
Yuqi Cai ◽  
Chao Yi ◽  
Zilong Zhang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Lower Cretaceous ◽  
Chemical Weathering ◽  
Tectonic Setting ◽  
Ordos Basin ◽  
Distribution Patterns ◽  
Passive Margin ◽  
Central China ◽  
Average Value

In adjustment to fulfill the requirements of the investigation regarding the lower Cretaceous sandstone uranium deposit in the Naogaodai area within the northwest of Ordos Basin, twenty-seven sandstone samples obtained from the Lower Cretaceous Huanhe Formation were analyzed for major, trace and rare earth elements (REE). The source of clastic and tectonic background was additionally analyzed. The results show that Huanhe sandstone is feldspar rich sandstone, and also the mineral composition is principally quartz, albite and plagioclase; the ratio of light to heavy rare earth elements (LREE/HREE) is 9.25–10.83, with an average value of 10.00; (La/Yb)CN is 10.20–12.53, with an average value of 11.24, demonstrating that LREE is enriched and fractionated compared with HREE. REE distribution patterns are similar, which additionally reveals that Huanhe sandstone has a homogenous source; the Index of Compositional Variability (ICV) value is 1.17–1.73, with an average value of 1.35, both greater than 1, showing an immature property, which may be first-order cycle deposition. The average value of the Chemical Index of Alteration (CIA) is 50.29, suggesting that the source rock has encountered weak chemical weathering; sandstones are near-source first-cycle provenance, which is not significantly influenced by sedimentary sorting and recycling. The geochemical qualities further indicate that Huanhe sandstone was deposited in a passive margin and experienced moderate weathering.

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