Description of manganese deposits from the Papago mine, Saipan, Mariana Islands

Saipan, situated about 15° N. and 146° E., is one of the larger and more southerly of the Mariana Islands. The 15 small islands of this chain are strung along an eastwardly convex ridge for more than 400 miles north to south, midway between Honshu and New Guinea and about 1,200 miles east of the Philippines. Paralleling this ridge 60 to 100 miles further east is a deep submarine trench, beyond which lies the Pacific Basin proper. To the west is the Philippine Sea, generally deeper than 2,000 fathoms. The trench coincides with a zone of negative gravity anomalies, earthquake foci occur at increasing depths westward from it, and silica- and alumina-rich volcanic rocks characterize the emergent island chain itself. The contrast between these features and those of the Pacific Basin proper to the east is held to favor the conclusion that the Mariana island arc and trench define the structural and petrographic front of Asia.

(Table S1) Stable isotope record and growth rates of cultured Mytilus edulis

To study the effects of temperature, salinity, and life processes (growth rates, size, metabolic effects, and physiological/genetic effects) on newly precipitated bivalve carbonate, we quantified shell isotopic chemistry of adult and juvenile animals of the intertidal bivalve Mytilus edulis (Blue mussel) collected alive from western Greenland and the central Gulf of Maine and cultured them under controlled conditions. Data for juvenile and adult M. edulis bivalves cultured in this study, and previously by Wanamaker et al. (2006, doi:10.1029/2005GC001189), yielded statistically identical paleotemperature relationships. On the basis of these experiments we have developed a species-specific paleotemperature equation for the bivalve M. edulis [T °C = 16.28 (±0.10) - 4.57 (±0.15) {d18Oc VPBD - d18Ow VSMOW} + 0.06 (±0.06) {d18Oc VPBD - d18Ow VSMOW}**2; r**2 = 0.99; N = 323; p < 0.0001]. Compared to the Kim and O'Neil (1997) inorganic calcite equation, M. edulis deposits its shell in isotope equilibrium (d18Ocalcite) with ambient water. Carbon isotopes (d13Ccalcite) from sampled shells were substantially more negative than predicted values, indicating an uptake of metabolic carbon into shell carbonate, and d13Ccalcite disequilibrium increased with increasing salinity. Sampled shells of M. edulis showed no significant trends in d18Ocalcite based on size, cultured growth rates, or geographic collection location, suggesting that vital effects do not affect d18Ocalcite in M. edulis. The broad modern and paleogeographic distribution of this bivalve, its abundance during the Holocene, and the lack of an intraspecies physiologic isotope effect demonstrated here make it an ideal nearshore paleoceanographic proxy throughout much of the North Atlantic Ocean.