Pb concentrations, Pb isotopic composition, and amount of metalliferous components in pelagic sediments from the Pacific Ocean

• Main Authors: Peucker-Ehrenbrink, Bernhard, Hofmann, Albrecht W, Hart, Stanley R
• Format: Dataset
• Language: English
• Published: PANGAEA 1994
• Subjects: 16-161A; 16-162; 19-183; 34-319; 35-323; 5-37; 5-39; 85-574C; 8-74; 8-75; 91-596; 92-597; 9-77B; Antarctic Ocean/PLAIN; Components indeterminata; Deep Sea Drilling Project; Distance; relative; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Elevation of event; Event label; Glomar Challenger; Latitude of event; Lead; Lead-206/Lead-204 ratio; Lead-207/Lead-204 ratio; Lead-208/Lead-204 ratio; Leg16; Leg19; Leg34; Leg35; Leg5; Leg8; Leg85; Leg9; Leg91; Leg92; Longitude of event; Mass spectrometer Finnigan MAT 251; North Pacific/CONT RISE; North Pacific/HILL; North Pacific/PLAIN; North Pacific/TROUGH; Sample code/label; South Pacific; South Pacific/BASIN; South Pacific/CONT RISE; Antarctic; Antarctic Ocean; Pacific; Antarc*
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.712126; https://doi.org/10.1594/PANGAEA.712126

The amount of lead annually transferred from oceanic crust to metalliferous sediments was estimated in order to test the hypothesis that a non-magmatic flux of lead causes the Pb surplus in the continental crust. A Pb surplus has been inferred from global crust-mantle lead mass balances derived from lead concentration correlations with other trace elements and from lead isotope systematics in oceanic basalts. DSDP/ODP data on the amount of metalliferous sediments in the Pacific Ocean and along a South Atlantic traverse are used to calculate the mean worldwide thickness of 3 (+/-1) m for purely metalliferous sediment componens. Lead isotope ratios of 39 metalliferous sediments from the Pacific define mixing lines between continent-derived (seawater) and mantle-derived (basaltic) lead, with the most metal-rich sediments usually having the most mantle-like Pb isotope composition. We used this isotope correlation and the Pb content of the 39 metalliferous sediments to derive an estimate of 130 (+/-70) µg/g for the concentration of mantle-derived lead in the purely metalliferous end-member. Mass balance calculations show that at least 12 (+/-8)% of the lead, annually transferred from upper mantle to oceanic crust at the ocean ridges, is leached out by hydrothermal processes and re-deposited in marine sediments. If all of the metalliferous lead is ultimately transferred to the continental crust during subduction, the annual flux of this lead from mantle to continental crust is 2.6 (+/-2.0) * 10**6 kg. Assuming this transfer rate to be proportional to the rate of oceanic plate production, one can fit the lead transfer to models of plate production rate variations through time. Integrating over 4 Ga, hydrothermal lead transfer to the continental crust accounts for a significant portion of the Pb surplus in the continental crust. It therefore appears to be one of the main reasons for the anomalous behavior of lead in the global crust-mantle system.