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A major light rare-earth element (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan

Economic Geology

By:
, , , , , ,
DOI: 10.2113/econgeo.107.2.197

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Abstract

The rapid rise in world demand for the rare-earth elements (REEs) has expanded the search for new REE resources. We document two types of light rare-earth element (LREE)-enriched rocks in the Khanneshin carbonatite complex of southern Afghanistan: type 1 concordant seams of khanneshite-(Ce), synchysite-(Ce), and parisite-(Ce) within banded barite-strontianite alvikite, and type 2 igneous dikes of coarse-grained carbonatite, enriched in fluorine or phosphorus, containing idiomorphic crystals of khanneshite-(Ce) or carbocernaite. Type 1 mineralized barite-strontianite alvikite averages 22.25 wt % BaO, 4.27 wt % SrO, and 3.25 wt % ∑ LREE2O3 (sum of La, Ce, Pr, and Nd oxides). Type 2 igneous dikes average 14.51 wt % BaO, 5.96 wt % SrO, and 3.77 wt % ∑ LREE2O3. A magmatic origin is clearly indicated for the type 2 LREE-enriched dikes, and type 1 LREE mineralization probably formed in the presence of LREE-rich hydrothermal fluid. Both types of LREE mineralization may be penecontemporaneous, having formed in a carbonate-rich magma in the marginal zone of the central vent, highly charged with volatile constituents (i.e., CO2, F, P2O5), and strongly enriched in Ba, Sr, and the LREE. Based on several assumptions, and employing simple geometry for the zone of LREE enrichment, we estimate that at least 1.29 Mt (million metric tonnes) of LREE2O3 is present in this part of the Khanneshin carbonatite complex.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
A major light rare-earth element (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan
Series title:
Economic Geology
DOI:
10.2113/econgeo.107.2.197
Volume
107
Issue:
2
Year Published:
2012
Language:
English
Publisher:
Society of Economic Geologists
Publisher location:
Littleton, CO
Contributing office(s):
Eastern Geology and Paleoclimate Science Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Economic Geology
First page:
197
Last page:
208
Country:
Afghanistan