TY  - JOUR
AU  - Thébault Julien, Schöne Bernd R.
PY  - 2009//
TI  - Investigation of Li/Ca variations in aragonitic shells of the ocean quahog Arctica islandica, northeast Iceland
T2  - 1525-2027
JO  - Geochemistry, Geophysics, Geosystems
SP  - Q12008-
VL  - 10
IS  - 12
KW  - bivalve
KW  - lithium
KW  - calcification
KW  - shell growth rate
KW  - weathering
KW  - Iceland
KW  - 0424 Biosignatures and proxies
KW  - 0438 Diel
KW  - seasonal
KW  - and annual cycles
KW  - 0454 Isotopic composition and chemistry
KW  -
N2  - Interannual and intra-annual variations in lithium-to-calcium ratio were investigated with high temporal resolution in the aragonitic outer shell layer of juvenile Arctica islandica (Mollusca; Bivalvia) collected alive in 2006 off northeast Iceland. Li/Cashell ranged between 7.00 and 11.12 mol mol1 and presented well-marked seasonal cycles with minimum values recorded at the annual growth lines; a general pattern was a progressive increase in Li/Cashell from March to May, followed by a plateau in June and a decrease down to minimum values in JulyAugust. Li/Cashell was correlated with 18Oshell-derived temperature, but the strength of this relationship was weak (r2 < 0.25 and p < 0.05). It covaried significantly with microgrowth increment width and with the discharge from one of the closest rivers. Seasonal variations of Li/Cashell in A. islandica may most likely be explained (1) by calcification rate and/or (2) by significant river inputs of Li-rich silicate particles flowing to the sea as soon as snow melts. In the first case, Li/Cashell may be a useful proxy for addressing seasonal variations of growth rate in bivalves that lack discernable microgrowth patterns. Abrupt decreases of Li/Cashell may, in turn, help identify growth retardations due to harsh environmental conditions. Alternatively, if Li/Cashell variations are linked to particulate Li inputs by rivers, this could be a new proxy for the intensity of mechanical weathering of Icelandic basalts, with interesting perspectives for the reconstruction of frequency and intensity of past jökulhlaups (subglacial outburst floods). Further works, including experimental studies, are needed to test these hypotheses.
SN  - 1525-2027
UR  - http://dx.doi.org/10.1029/2009GC002789
N1  - exported from refbase (http://publi.ipev.fr/polar_references/show.php?record=37), last updated on Tue, 09 Jul 2024 05:36:33 +0200
ID  - ThebaultJulien2009
ER  -