Brucite-driven CO 2 uptake in serpentinized dunites (Ligurian Ophiolites, Montecastelli, Tuscany)
| Autor: | Boschi C.[1], Dini A.[1], Baneschi I.[1], Bedini F.[1, Perchiazzi N.[2], Cavallo A.[3] |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
carbonation
Lacustrine succession Paleoclimate Carbonate minerals Geochemistry Mineralogy Weathering 010501 environmental sciences engineering.material 010502 geochemistry & geophysics 01 natural sciences brucite chemistry.chemical_compound serpentinite Geochemistry and Petrology Ultramafic rock Paragenesis Hydromagnesite 0105 earth and related environmental sciences Magnetite Stable isotopes hydromegnesite Brucite Geology Paleoclimate Stable isotopes Lacustrine succession Tephrochronology layered double hydroxides chemistry Tuscany engineering Carbonate Tephrochronology |
| Zdroj: | Lithos (Oslo. Print) 288-289 (2017): 264–281. doi:10.1016/j.lithos.2017.07.005 info:cnr-pdr/source/autori:Boschi C.[1], Dini A.[1], Baneschi I.[1], Bedini F.[1,2], Perchiazzi N.[2], Cavallo A.[3]/titolo:Brucite-driven CO2 uptake in serpentinized dunites (Ligurian Ophiolites, Montecastelli, Tuscany)/doi:10.1016%2Fj.lithos.2017.07.005/rivista:Lithos (Oslo. Print)/anno:2017/pagina_da:264/pagina_a:281/intervallo_pagine:264–281/volume:288-289 |
| DOI: | 10.1016/j.lithos.2017.07.005 |
| Popis: | Understanding the mechanism of serpentinite weathering at low temperature – that involves carbonate formation – has become increasingly important because it represents an analog study for a cost-efficient carbon disposal strategy (i.e. carbon mineralization technology or mineral Carbon dioxide Capture and Storage, CCS). At Montecastelli (Tuscany, Italy), on-going spontaneous mineral CO 2 sequestration is enhanced by brucite-rich serpentinized dunites. The dunites are embedded in brucite-free serpentinized harzburgites that belong to the ophiolitic Ligurian Units (Northern Apennine thrust-fold belt). Two main serpentinization events produced two distinct mineral assemblages in the reactive dunite bodies. The first assemblage consists of low-T pseudomorphic, mesh-textured serpentine, Fe-rich brucite (up to 20 mol.% Fe(OH) 2 ) and minor magnetite. This was overprinted by a non-pseudomorphic, relatively high-T assemblage consisting of serpentine, Fe-poor brucite (ca. 4 mol% Fe(OH) 2 ) and abundant magnetite. The harzburgite host rock developed a brucite-free paragenesis made of serpentine and magnetite. Present-day interaction of serpentinized dunites with slightly acidic and oxidizing meteoric water, enhances brucite dissolution and leads to precipitation of both Mg-Fe layered double hydroxides (coalingite-pyroaurite, LDHs) and hydrous Mg carbonates (hydromagnesite and nesquehonite). In contrast, the brucite-free serpentinized harzburgites are not affected by the carbonation process. In the serpentinized dunites, different carbonate minerals form depending on brucite composition (Fe-rich vs Fe-poor). Reactions in serpentinized dunites containing Fe-rich brucite produce a carbonate assemblage dominated by LDHs and minor amount of hydromagnesite. Serpentinites with a Fe-poor brucite assemblage contain large amounts of hydromagnesite and minor LDHs. Efficiency of CO 2 mineral sequestration is different in the two cases owing to the distinct carbon content of LDHs (ca. 1.5 wt.%) and hydromagnesite (ca. 10 wt.%). Here, for the first time, we link the mineral composition of serpentinized ultramafic rocks to carbonate formation, concluding that Fe-poor brucite maximizes the mineral CCS efficiency. |
| Databáze: | OpenAIRE |
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