GEOCHEMISTRY AND PETROGRAPHY OF SPELEOTHEMS FROM TURKEY AND IRAN: PALAEOCLIMATE AND DIAGENESIS

Wickens, Leretta (2013) GEOCHEMISTRY AND PETROGRAPHY OF SPELEOTHEMS FROM TURKEY AND IRAN: PALAEOCLIMATE AND DIAGENESIS. Doctoral thesis, University of East Anglia.

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Abstract

Abstract
Speleothems contain key archives of palaeoclimatic information, which can be interpreted
through multiple geochemical and petrographic proxies, and precisely dated by Uranium
Series dating. As U/Th dating is only viable for samples up to approximately 700 kyr of age,
U/Pb dating must be used to date older samples. In this study, U/Pb methods were used to
date an aragonite layer in a speleothem from Iran, following the use of autoradiography to
select samples with appropriately high uranium.
Aragonite is metastable at earth surface conditions, and is therefore prone to
recrystallisation as calcite if it comes into contact with a fluid that is undersaturated with
respect to aragonite. This process affected two speleothems from Dim Cave, SW Turkey,
and one speleothem from Torang Cave, Iran. The older Dim Cave stalagmite, which
precipitated during MIS 5e, was not identified as a recrystallised stalagmite at first, as the
mineralogy of the growth axis appeared to show a change in primary mineral rather than
recrystallisation. Despite the fact that recrystallisation had occurred, it was possible to
create an age model, as the system had not opened to a great degree. The persistence of
an aragonite layer in this speleothem, as well as several other geochemical proxies,
indicates that an arid phase occurred during early MIS 5e in SW Turkey. The second
recrystallised speleothem from Dim Cave provides useful insights into the geochemical and
petrographic character of recrystallised speleothems. The recrystallised speleothem from
Torang Cave produced a record of climatic instability in southern Iran during MIS period 9-
7, although the age model was not precise enough to draw precise conclusions.
A small aragonitic Holocene growth from Dim Cave grew during a time which corresponds
to an early Holocene pluvial period that affected the entire eastern Mediterranean Basin,
coinciding with the deposition of Sapropel 1.

*[N.B.: Additional data was attached to this thesis at the time of its submission. Please refer to the author for further details.]

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Mia Reeves
Date Deposited: 05 Mar 2014 12:52
Last Modified: 05 Mar 2014 12:52
URI: https://ueaeprints.uea.ac.uk/id/eprint/47931
DOI:

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