| Literature DB >> 29507221 |
Li Zhang1, Hongsheng Yuan2, Yue Meng3, Ho-Kwang Mao1,4.
Abstract
A deep lower-mantle (DLM) water reservoir depends on availability of hydrous minerals which can store and transport water into the DLM without dehydration. Recent discoveries found hydrous phases AlOOH (Z = 2) with a CaCl2-type structure and FeOOH (Z = 4) with a cubic pyrite-type structure stable under the high-pressure-temperature (P-T) conditions of the DLM. Our experiments at 107-136 GPa and 2,400 K have further demonstrated that (Fe,Al)OOH is stabilized in a hexagonal lattice. By combining powder X-ray-diffraction techniques with multigrain indexation, we are able to determine this hexagonal hydrous phase with a = 10.5803(6) Å and c = 2.5897(3) Å at 110 GPa. Hexagonal (Fe,Al)OOH can transform to the cubic pyrite structure at low T with the same density. The hexagonal phase can be formed when δ-AlOOH incorporates FeOOH produced by reaction between water and Fe, which may store a substantial quantity of water in the DLM.Entities:
Keywords: X-ray diffraction; deep-water cycle; hydrous mineral; lower mantle
Year: 2018 PMID： 29507221 PMCID： PMC5866593 DOI： 10.1073/pnas.1720510115
Source DB: PubMed Journal: Proc Natl Acad Sci U S A ISSN： 0027-8424 Impact factor: 11.205