Illitization decrypted by B and Li isotope geochemistry of nanometer-sized illite crystals from bentonite beds, East Slovak Basin

作     者：Clauer, Norbert Williams, Lynda B. Lemarchand, Damien Florian, Pierre Honty, Miroslav 

作者机构：Univ Strasbourg CNRS Ecole & Observ Sci Terre 1 Rue Blessig F-67084 Strasbourg France Arizona State Univ Sch Earth & Space Explorat Tempe AZ 85287 USA Univ Strasbourg CNRS Lab Hydrol & Geochim Strasbourg F-67084 Strasbourg France Univ Orleans CNRS CEMHTI UPR3079 F-45071 Orleans France SCK CEN Hlth Environm & Safety Inst B-2400 Mol Belgium 

出 版 物：《CHEMICAL GEOLOGY》 (化学地质学)

年 卷 期：2018年第477卷

页      面：177-194页

核心收录：

学科分类：0709[理学-地质学] 081803[工学-地质工程] 07[理学] 08[工学] 0708[理学-地球物理学] 0818[工学-地质资源与地质工程] 

基　　金：US National Science Foundation [EAR-0948878] TGIR-RMN-THC Fr3050 CNRS 

主　　题：B and Li concentrations and isotope compositions B solid-state nuclear magnetic resonance Illite-type nanometer-sized crystals Crystal nucleation and growth Bentonite beds East Slovak Basin 

摘      要：Boron and lithium contents and isotopic compositions were determined in nucleating and growing nanometersized illite crystals ( 0.02 to 0.2 mu m) separated from mixed-layered illite-smectite particles of bentonite beds from East Slovak Basin. Substituted into tetrahedral and octahedral sites of illite, respectively, they were used to deduce fluid sources and chemical changes during nucleation and crystal growth. The positively correlated contents in most size separates suggest that the substitution of both B and Li is probably coincident and that illitization progressed via direct precipitation from pore fluids and not by solid-state substitution. As B and Li are released from their sources into the pore fluids, their trends are recorded in the isotopic compositions of the authigenic illite crystals. The overall concept is that the B and Li contents of nanometer-sized illite crystal record the abundance variations of the interacting fluids, while the isotopic ratios inform about the temperature and fluid isotopic compositions. Preliminary solid-state Nuclear Magnetic Resonance( NMR) spectroscopic determinations of B in various size fractions of three bentonite beds demonstrate an excellent potential to distinguish its crystallographic location in nucleating illite relative to the initial smectite crystals, followed by growth of illite crystals and probable dissolution of smectite. Generally, bentonite beds collected near salt-bearing sediments contain illite crystals with high B contents (475 mu g/g) and heavy delta B-11 (+ 7%). This combination suggests precipitation of the coarse illite crystals older than 10 Ma from saline brines. The younger illite populations yield lower B contents (30-100 mu g/g) and lighter delta B-11 that decreased from - 5 to - 17% while B contents increased. The initial saline fluids were apparently not enriched in Li, as the older, coarse illite fractions yield low Li contents( 20 mu g/g) and high delta Li-7 (+ 7%), reflecting in turn a