TY  - JOUR
AU  - Demény, Attila
AU  - Czuppon, György
AU  - Kern, Zoltán
AU  - Leél-Őssy, Szabolcs
AU  - Németh, Alexandra
AU  - Szabó, Máté Zoltán
AU  - Tóth, Mária
AU  - Wu, C-C
AU  - Shen, C-C
AU  - Molnár, Mihály
AU  - Németh, Tibor
AU  - Németh, Péter
AU  - Óvári, Mihály
TI  - Recrystallization-induced oxygen isotope changes in inclusion-hosted water of speleothems - Paleoclimatological implications
JF  - QUATERNARY INTERNATIONAL
J2  - QUATERN INT
VL  - 415
PY  - 2016
SP  - 25
EP  - 32
PG  - 8
SN  - 1040-6182
DO  - 10.1016/j.quaint.2015.11.137
UR  - https://m2.mtmt.hu/api/publication/3042991
ID  - 3042991
AB  - The issue of diagenetic alteration of carbonate deposits in caves (speleothems) has gained increasing importance in recent years, as this process has serious consequences for speleothem-based paleoclimate studies. In this study stable hydrogen and oxygen isotope data of water trapped in fluid inclusions were collected for recently forming stalagmites and flowstones in order to determine how dripwater compositions are reflected and preserved in the inclusion water compositions. Hydrogen isotope compositions were found to reflect dripwater values, whereas the oxygen isotope data were increasingly shifted from the local dripwater compositions with the time elapsed after deposition. The δ18O data are correlated with X-Ray diffraction full width at half maximum values (related to crystal domain size and lattice strain), suggesting that the oxygen isotope shift is related to recrystallization of calcite. Transmission electron microscope analyses detected the presence of nanocrystalline (<50 nm) calcite, whose crystallization to coarser-grained calcite crystals (>200 nm) may have induced re-equilibration between the carbonate and the trapped inclusion water. The Ostwald ripening process provides an explanation for unexpectedly low oxygen isotope compositions in the inclusion water. The detected diagenetic alteration and its isotopic effects should be taken into consideration during sampling strategies and data evaluation as speleothems containing nanocrystalline calcite during their deposition are prone to late-stage oxygen isotope water-carbonate re-equilibration, which may shift the oxygen isotope composition of the inclusion water to more depleted values while the hydrogen isotope composition remains intact. © 2016.
LA  - English
DB  - MTMT
ER  -