Publication Date:
2021-06-22
Description:
Geochemical behaviour of rare earth elements (REE), Zr, andHfwas investigated in CO2-richwaters circulating in
Pantelleria Island also including ‘Specchio di Venere’ Lakewithin a calderic depression. A wide range of total dissolved
REE concentrationswas found (2.77–12.07 nmol L−1),with the highest contents in the lake. Themain REE
complexes in the CO2-rich waters are [REE(CO3)2]− and [REECO3]+, showing changeable proportions as a function
of pH. The REE normalized to post-Archean Australian Shale (PAAS) showed similar features with heavy REE
(HREE) enrichments in CO2-rich waters collected from springs and wells, whereas a different REE pattern was
found in the ‘Specchio di Venere’ Lake water with middle REE (MREE) enrichments. The PAAS normalized concentration
ratios (LREE/HREE)N and (MREE/HREE)N in waters are b1, except for the lake water in which
(MREE/HREE)N N 1. Positive Eu anomalies were found in the investigated waters owing to water–rock interactions
with less evolved host rocks. Ce anomalies as a function of Eh values were recognized, with the highest
Ce anomaly occurring in the lake water with respect to the CO2-rich waters. The Y/Ho and Zr/Hf molar ratios
are higher in the investigated waters (except for lake water) than that in the local rocks, with values ranging
from 35.4 to 77.9 and from 76.3 to 299, respectively. The precipitation of authigenic phases was considered to
be responsible for the increase in the Y/Ho and Zr/Hf ratios owing to enhanced Hf and Ho removal with respect
to Zr and Y.
The REE patterns in the lake water show a similar shape (MREE-enriched and a positive Ce anomaly) as those
found in the settling dust and in the desert varnish coating of the rocks in arid environments,which mainly contain
Fe- and Mn-oxyhydroxides and clay minerals. Similarly, Y/Ho and Zr/Hf ratios in the ‘Specchio di Venere’
Lake (35.4 and 76.3, respectively) show a desert varnish signature. These data, coupled with the presence of
iron oxyhydroxides and phyllosilicates in the shallowest water layer of the ‘Specchio di Venere’ Lake, verify the
aeolian input from the Sahara Desert
Description:
Published
Description:
1-11
Description:
6A. Geochimica per l'ambiente e geologia medica
Description:
JCR Journal
Keywords:
Rare earth elements
;
Zirconium
;
Hafnium
;
CO2-rich waters
;
Lake
;
Aeolian input
;
05.09
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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