TY - JOUR

T1 - Rare earth element geochemical characteristics of the late Permian Badamlu karst bauxite deposit, NW Iran

AU - Abedini, Ali

AU - Khosravi, Maryam

AU - Dill, Harald G.

N1 - Funding Information: This work was financially fully supported by the Bureau of Deputy of Research and Complementary Education of Urmia University . We would like to state our appreciation to the authorities of this bureau. We extend our gratitude also to Damien Delvaux, editor-in-chief of the Journal of African Earth Sciences for his editorial handling and two anonymous reviewers for reviewing and making critical comments on this manuscript. The authors thank Noel White of the University of Tasmania, Australia for English editing of the final version of the manuscript.

PY - 2020/12

Y1 - 2020/12

N2 - The Badamlu karst bauxite deposit, located 55 km southeast of Miandoab city in northwestern Iran occurs in karstic depressions of carbonates of the late Permian Nessen Formation. The studied bauxitic ores have a dominant pelitomorphic texture, and locally developed ooidic, pisoidic, and clastic textures in a pelitomorphic matrix. Mineralogically, the bauxite ores are composed mostly of diaspore, hematite, and kaolinite, as well as lesser amounts of rutile, chlorite, goethite, and illite. In addition, REE minerals, such as churchite and cerianite were detected. Cerianite occurs in the core of ooids, and churchite is surrounded by a kaolinite-rich matrix. Churchite and cerianite formed in acidic and oxidizing conditions in the uppermost part of the weathered profile, respectively. Total rare earth elements La-Lu contents in the bauxite ores range widely from 29.1 to 2138.2 ppm (average = 746.5 ppm, std = 722.3 ppm), with Ce being the dominant REE (1.3–1825.0 ppm, average = 606.7 ppm, std = 645.1 ppm). The ΣREE contents, (LREE/HREE)ch ratio, and Ce anomaly in the bauxite ores increase upward through the profile, in which LREE and HREE are La–Eu and Gd–Lu, respectively. The Ce anomaly in the bauxite ores has a bimodal distribution with higher Ce anomalies in the upper 7.5–m-thick succession (2.7–20.8, average 10.5), compared to the lower and middle 4.5–m-thick succession (0.1–0.3, average 0.1). The downward decrease in the Ce anomaly may be due to the lack of cerianite and a decrease in the oxidation state. The REE distribution patterns normalized to chondrite exhibit a variable depletion/enrichment of LREE and HREE, with a negative Eu anomaly (0.3–0.7).

AB - The Badamlu karst bauxite deposit, located 55 km southeast of Miandoab city in northwestern Iran occurs in karstic depressions of carbonates of the late Permian Nessen Formation. The studied bauxitic ores have a dominant pelitomorphic texture, and locally developed ooidic, pisoidic, and clastic textures in a pelitomorphic matrix. Mineralogically, the bauxite ores are composed mostly of diaspore, hematite, and kaolinite, as well as lesser amounts of rutile, chlorite, goethite, and illite. In addition, REE minerals, such as churchite and cerianite were detected. Cerianite occurs in the core of ooids, and churchite is surrounded by a kaolinite-rich matrix. Churchite and cerianite formed in acidic and oxidizing conditions in the uppermost part of the weathered profile, respectively. Total rare earth elements La-Lu contents in the bauxite ores range widely from 29.1 to 2138.2 ppm (average = 746.5 ppm, std = 722.3 ppm), with Ce being the dominant REE (1.3–1825.0 ppm, average = 606.7 ppm, std = 645.1 ppm). The ΣREE contents, (LREE/HREE)ch ratio, and Ce anomaly in the bauxite ores increase upward through the profile, in which LREE and HREE are La–Eu and Gd–Lu, respectively. The Ce anomaly in the bauxite ores has a bimodal distribution with higher Ce anomalies in the upper 7.5–m-thick succession (2.7–20.8, average 10.5), compared to the lower and middle 4.5–m-thick succession (0.1–0.3, average 0.1). The downward decrease in the Ce anomaly may be due to the lack of cerianite and a decrease in the oxidation state. The REE distribution patterns normalized to chondrite exhibit a variable depletion/enrichment of LREE and HREE, with a negative Eu anomaly (0.3–0.7).

KW - Badamlu bauxite deposit

KW - Cerianite

KW - Churchite

KW - Geochemistry

KW - Northwestern Iran

KW - Rare earth elements

UR - http://www.scopus.com/inward/record.url?scp=85089469178&partnerID=8YFLogxK

U2 - 10.1016/j.jafrearsci.2020.103974

DO - 10.1016/j.jafrearsci.2020.103974

M3 - Article

AN - SCOPUS:85089469178

VL - 172

JO - Journal of African Earth Sciences

JF - Journal of African Earth Sciences

SN - 1464-343X

M1 - 103974

ER -