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Why we can use corals for paleo-proxies Deposit annual high density/ low density bands which provides timescale (like tree rings) High density = winter Low density = summer Corals are very sensitive to changes in temperature, salinity, nutrients, These changes are reflected in the make-up of the coral’s skeleton Decreased/increased growth Changes in stable isotope ratios Nutrients trapped within coral skeleton
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Using Corals for Proxy Temperature and Salinity Why we can use
corals for paleo-proxies
Deposit annual high density/ low density bands which
providestimescale (like tree rings) High density = winter Low
density = summer Corals are very sensitive to changes in
temperature, salinity, nutrients, These changes are reflected in
the make-up of the corals skeleton Decreased/increased growth
Changes in stable isotope ratios Nutrients trapped within coral
skeleton Basic coral anatomy Zooxanthellae CaCO3 Ca2+ Coral
Calcification Coral Drilling Pneumatic hand drill Larger pneumatic
drills
Coral Drilling Larger pneumatic drills Porites astreoides Diploria
strigosa : 3 = ( 2 ) Proxy SST Ca2+ How to use isotopic ratios for
proxy SST
Obtain annual CaCO3 samples Lazer ablation Digestions of annual
CaCO3 deposits. Inductively coupled plasma mass spectrometry
(ICPMS) Mg2+/Ca2+, Ba2+/ Ca2+, Sr2+/ Ca2+ Multiple linear
regression SST = (X2+/Ca2+)m + b Proxy SSS Ca2+ How 18O reflects
SSS P E Two major oxygen isotopes: 18O and 16O
Controlled by evaporation (E) and precipitation (P) 18O 18O 16O 16O
18O 16O P E 16O 18O 16O 18O 16O 16O 18O 18O 18O 18O 18O 18O
Bleaching recorded in coral skeletons
Nutrients recorded in coral skeletons Thank you!