Timing of diagenetic haematite growth in red pelagic limestones from Gubbio (Italy)

Details Timing of diagenetic haematite growth in red pelagic limestones from Gubbio (Italy) Timing of diagenetic haematite growth in red pelagic limestones from Gubbio (Italy)

Apr 1982

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1982e%26psl..58..189c&link_type=abstract

Earth and Planetary Science Letters, Volume 58, Issue 2, p. 189-201.

Mathematics

Logic

59

Scientific paper

Magnetite, haematite, and to a minor extent maghaemite are recognised in the Cretaceous and Paleocene red pelagic limestones at Gubbio. The magnetite is detrital (or biological), whereas the haematite grew during diagenesis from a goethitic precursor. Thermal and AF demagnetization of samples collected from close to reversal boundaries indicate that the various magnetization components do not record the polarity reversal at exactly the same stratigraphic level. In the few tens of centimeters below a recorded geomagnetic reversal, defined by the magnetite magnetization, some of the haematite grains are magnetized in the post-reversal field. The blocking temperature spectra of this haematite fraction (with post-reversal magnetization) are found to shift toward higher temperatures as the reversal boundary is approached. The blocking temperature spectra reflect the grain size spectra of the haematite, which we interpret as arising by the continual nucleation of grains down to a certain burial depth where the conditions are no longer conducive to further haematite growth. The depth below reversal boundaries to which haematite with post-reversal magnetization can occur, is estimated to be about 60 cm (after compaction), and is equivalent to a time of about 105 years for these particular sediments. A detailed study of the magnetization components at reversal boundaries indicates that the first diagenetic growth of haematite through the single-domain critical volume occurs prior to the mechanical fixation of the detrital (or biological) magnetite. Subsequently the diagenetic haematite grains do not rotate in response to the ambient geomagnetic field polarity as easily as the magnetite, because of their occurrence as pigmentary coatings on larger non-magnetic grains.

Affiliated with

Also associated with

No associations

Rating

Timing of diagenetic haematite growth in red pelagic limestones from Gubbio (Italy) does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Timing of diagenetic haematite growth in red pelagic limestones from Gubbio (Italy), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Timing of diagenetic haematite growth in red pelagic limestones from Gubbio (Italy) will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-841283