Knowledge Resource Center for Ecological Environment in Arid Area
| DOI | 10.1016/j.chemgeo.2019.07.023 |
| Chlorine isotope fractionation recorded in atacamite during supergene copper oxidation | |
| Reich, Martin1,2,3; Barnes, Jaime D.4; Breecker, Daniel O.4; Barra, Fernando1,2,3; Milojevic, Catalina1,2,3; Drew, Dana L.4,5 | |
| 通讯作者 | Reich, Martin |
| 来源期刊 | CHEMICAL GEOLOGY
 |
| ISSN | 0009-2541 |
| EISSN | 1872-6836 |
| 出版年 | 2019 |
| 卷号 | 525页码:168-176 |
| 英文摘要 | In the Atacama Desert of northern Chile, large amounts of the copper hydroxy-chloride mineral atacamite (Cu2Cl (OH)(3)) are formed in the supergene oxidation zone of Cu deposits. Since atacamite requires saline water to form and is commonly preserved under hyperarid conditions, it has been proposed as a climate-sensitive mineral marker that can also provide relevant geochemical information regarding halogen (in particular chlorine) fluid sources during supergene Cu oxidation. However, chlorine stable isotope data for atacamite in Cu deposits are scarce and no experimental data for chlorine isotope fractionation between atacamite and water are currently available that could provide constraints on the possible mechanisms of fractionation. In this study we report delta Cl-37 values of atacamite along a thick (similar to 100 m) and well-developed supergene enrichment profile at the Barreal Seco iron oxide-copper-gold (IOCG) deposit in the Atacama Desert. The delta Cl-37 values of atacamite along this profile range from +2.1% to -0.6% (mean = + 0.4% +/- 0.7%; median = + 0.3%), and show a distinct trend with depth, characterized by higher delta Cl-37 values towards the top of the profile, with lower values at the bottom. In addition, the chlorine isotope compositions of experimentally synthetized atacamite crystals and coexisting CuCl2 solutions were determined at room temperature (23 degrees C). The per mil fractionation factor (Delta Cl-37(atacamite-Cl)) was determined at +0.75%, showing that the heavy isotope (Cl-37) is preferentially incorporated into atacamite. We used numerical models to test two possible scenarios that might explain the observed delta Cl-37 profile at Barreal Seco. A first scenario involves lowering of the water table with concomitant precipitation of atacamite, which removes Cl from solution following a Rayleigh fractionation process. This model qualitatively fits our observations but does not explain the full magnitude of the observed delta Cl-37 shift along the supergene profile. In contrast, a model that simulates Cl- diffusion following the upward injection of a deep brine that overlies fresh groundwater reproduces well the observed delta Cl-37 data, suggesting that seismic pumping of basinal brines, followed by Cl diffusion, is a feasible mechanism to explain the formation of atacamite at Barreal Seco. These data are a first step towards interpreting delta Cl-37 profiles of atacamite in Cu deposits in the Atacama Desert and exploring the potential use of stable chlorine isotopes to monitor Cu weathering and enrichment in supergene environments. |
| 英文关键词 | Chlorine isotopes Atacamite Copper deposits Supergene enrichment Atacama Desert Barreal Seco IOCG |
| 类型 | Article |
| 语种 | 英语 |
| 国家 | Chile ; USA |
| 开放获取类型 | Bronze |
| 收录类别 | SCI-E |
| WOS记录号 | WOS:000501715700012 |
| WOS关键词 | NORTHERN CHILE ; CU DEPOSITS ; DESERT ; ENRICHMENT ; EXPLORATION ; MINERALIZATION ; IODINE ; GEOCHEMISTRY ; INVOLVEMENT ; EVOLUTION |
| WOS类目 | Geochemistry & Geophysics |
| WOS研究方向 | Geochemistry & Geophysics |
| EI主题词 | 2019-10-20 |
| 资源类型 | 期刊论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/310315 |
| 作者单位 | 1.Univ Chile, FCFM, Dept Geol, Plaza Ercilla 803, Santiago, Chile; 2.Univ Chile, FCFM, Andean Geothermal Ctr Excellence CEGA, Plaza Ercilla 803, Santiago, Chile; 3.Univ Chile, FCFM, Millennium Nucleus Met Tracing Subduct, Santiago, Chile; 4.Univ Texas Austin, Dept Geol Sci, Austin, TX 78712 USA; 5.Lawrence Livermore Natl Lab, Nucl & Chem Sci Div, Livermore, CA 94550 USA |
| 推荐引用方式 GB/T 7714 | Reich, Martin,Barnes, Jaime D.,Breecker, Daniel O.,et al. Chlorine isotope fractionation recorded in atacamite during supergene copper oxidation[J],2019,525:168-176. |
| APA | Reich, Martin,Barnes, Jaime D.,Breecker, Daniel O.,Barra, Fernando,Milojevic, Catalina,&Drew, Dana L..(2019).Chlorine isotope fractionation recorded in atacamite during supergene copper oxidation.CHEMICAL GEOLOGY,525,168-176. |
| MLA | Reich, Martin,et al."Chlorine isotope fractionation recorded in atacamite during supergene copper oxidation".CHEMICAL GEOLOGY 525(2019):168-176. |
| 条目包含的文件 | 条目无相关文件。 | |||||
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