Publication Date:
2017-06-07
Description:
Live-collected samples of four common reefbuilding
coral genera (Acropora, Pocillopora, Goniastrea,
Porites) from subtidal and intertidal settings of Heron Reef,
Great Barrier Reef, show extensive early marine diagenesis
where parts of the coralla less than 3 years old contain
abundant macro- and microborings and aragonite, high-Mg
calcite, low-Mg calcite, and brucite cements. Many types of
cement are associated directly with microendoliths and
endobionts that inhabit parts of the corallum recently abandoned
by coral polyps. The occurrence of cements that generally
do not precipitate in normal shallow seawater (e.g.,
brucite, low-Mg calcite) highlights the importance of
microenvironments in coral diagenesis. Cements precipitated
in microenvironments may not reXect ambient seawater
chemistry. Hence, geochemical sampling of these
cements will contaminate trace-element and stable-isotope
inventories used for palaeoclimate and dating analysis.
Thus, great care must be taken in vetting samples for both
bulk and microanalysis of geochemistry. Visual inspection
using scanning electron microscopy may be required for
vetting in many cases.
Type:
Article
,
PeerReviewed
Format:
text
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