CORRELATION BETWEEN PHOSPHATE CONTENT AND THE FORAMINIFERAL PLANKTON/BENTHOS RATIO IN CHALKS (LATE CRETACEOUS, NORTHERN ISRAEL): PALEOENVIRONMENTAL SIGNIFICANCE?     

A. FLEXER  A. STARINSKY 《Sedimentology》1970,14(3-4):245-258

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Clinoptilolite, paragenesis and stratigraphy     

YAACOV NATHAN  AKIVA FLEXER 《Sedimentology》1977,24(6):845-855

Clinoptilolite, a zeolite of the heulandite group, occurs commonly in sediments as an authigenic mineral. In the Middle Eocene of southern Israel, it constitutes from a few per cent up to 80 per cent of the insoluble residue of the chalks and limestones. It is associated with opal C-T, montmorillonite and palygorskite. These chalks and limestones overlie the Danian-Palaeocene Taqiya marls which also contain a well-established clay mineral sequence consisting of opal C-T, montmorillonite, palygorskite, sepiolite, and clinoptilolite. This paragenesis of minerals is shown to be typical of the Upper Cretaceous to Eocene times. It is world-wide, occurs in deep-sea sediments as well as in shallow water sediments, and results from the abundance of silica which probably reflects a warmer climate during this time period. The concentration of magnesium in the sea-water and its ratio to the other cations seem to determine which authigenic silicate will be formed.  相似文献