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. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. CPS a : â 111 â ' i 111111111111111111111111111111111 Deg. 20 Figure 3. X-Ray diffractogram of a coral Montastrea annularis from core hole 2B showing complete recrystallization of biogenic aragonite to calcite. This and all other specimens analyzed were virtually completely recrystallized and unsuitable for radiometric dating. RESULTS Core Data As can be seen in Figure 4, despite the high degree of diagenetic alteration with some loss of the skeletal record, there are two ba
. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. CPS a : â 111 â ' i 111111111111111111111111111111111 Deg. 20 Figure 3. X-Ray diffractogram of a coral Montastrea annularis from core hole 2B showing complete recrystallization of biogenic aragonite to calcite. This and all other specimens analyzed were virtually completely recrystallized and unsuitable for radiometric dating. RESULTS Core Data As can be seen in Figure 4, despite the high degree of diagenetic alteration with some loss of the skeletal record, there are two basic reef facies recognizable in these cores. A branching Pontes facies consists of Pontes branches in a microcrystalline matrix (Fig. 5). Other corals scattered throughout this facies include Montastraea annularis complex species, Montastraea cavernosa, and Manicina areolata. Molluscs, including both bivalves and gastropods, are common, often as leached casts as are well preserved echinoderm fragments. The second molluscan facies consists basically of molluscan fragments, mostly bivalves but some gastropods, in various stages of preservation, in a dense microcrystalline matrix. Echinoid fragments are also well preserved in this facies. Corals scattered throughout this facies include Manicina areolata and some Porites astreoides (Fig. 6).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Smithsonian Institution. Press; National Research Council (U. S. ). Pacific Science Board; Smithsonian Institution; National Museum of Natural History (U. S. ); United States. Bureau of Sport Fisheries and Wildlife. Washington, D. C. : [Smithsonian Press]
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