Metastable Si-Fe phases in hydrothermal sediments of Atlantis II Deep, Red Sea

N. Taitel-Goldman, A. Singer

Research output: Contribution to journalArticlepeer-review


Amorphous silicate sediments comprise most of the upper part of the sedimentary column of the Atlantis II Deep, whereas more crystalline phases are found in the lower part. The objective of this study was to focus on the newly-formed, metastable, hydrothermal phases, that eventually transform into clays or Fe oxides. Short-range ordered Si-Fe phases (Si/Fe = 0.2-0.6) rounded to elliptical in shape, and amorphous Si-Fe platy phases (Si/Fe = 0.09-pure Si) comprise some of the amorphous sediments in Atlantis II Deep. The rounded particles have distinct electron-dense (thicker, relatively ordered) margins and a less crystalline inner core. They have rhombohedral symmetry with unit-cell parameters of a = 0.504 nm and c = 1.08 nm. They presumably transform into crystalline clay minerals in statu nascendi (at the formative stage) in the sediments. Synthesis in NaCl brines designed to simulate crystallization of the rounded particles, was performed successfully. Similar rounded phases (Si/Fe = 0.26) were synthesized under saline, neutral, hydrothermal conditions (40 C, pH 7, 2 M NaCl) with initial Si/Fe = 1.5. We suggest that the metastable rounded particles precipitate from the hot brine created by the encounter between Red Sea Deep Water and the hydrothermal brine underneath. Within a few thousands years they disintegrate and transform into clay minerals, probably nontronite.

Original languageEnglish
Pages (from-to)235-248
Number of pages14
JournalClay Minerals
Issue number2
StatePublished - Jul 2002


  • Amorphous
  • Atlantis II deep
  • Hydrothermal
  • Rounded particles
  • Short range ordered
  • Si-Fe phase


Dive into the research topics of 'Metastable Si-Fe phases in hydrothermal sediments of Atlantis II Deep, Red Sea'. Together they form a unique fingerprint.

Cite this