Early diagenetic cycling, incineration, and burial of sedimentary organic carbon in the central Gulf of Papua (Papua New Guinea)

Robert C. Aller*, Neal E. Blair, Gregg J. Brunskill

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

The clinoform complex of the Gulf of Papua represents a major deltaic system in Oceania. Two seasons largely control seafloor dynamics and sedimentary C cycling: the relatively quiescent NW monsoon, and the SE trades, characterized by remobilization and reoxidation of topset deposits. Surface sediments (∼20 cm.) are reactive with ΣCO2 production fluxes ∼35-42 mmol M-2 d-1 at mangrove channel and topset sites during the monsoon, and ∼10-20 mmol m-2 d-1 on the foreset-bottomset (>40 m). Fluxes decrease by a factor of ∼0.3 on the topset during the transition period and trades. The 13,14C isotopic compositions of pore water ΣCO2 reveal diagenetic fractionation, with dominant utilization of young (Δ 14C = 1.4-31.1‰), terrestrial C substrates inshore (channels, topset δ13C = -29 to -25‰) and a progressive increase of young marine C sources seaward (outer topset, foreset; bottomset δ13C = -22.2 to -19.5). Remineralization patterns of terrestrial and marine Corg demonstrate cross-shelf exchange. Multiple tracers show that a suboxic, mobile mud layer, ∼10-60 cm thick (usually ∼10-30 cm), characterizes : the central gulf topset and Umuda Valley off the Fly River and unconformably overlies methanic deposits releasing old ΣCO214C = -159 to -229‰). Residual terrestrial Corg delivered to the bioturbated foreset continues to be remineralized slowly, generating ΣCO2 having net Δ14C = -270 within sediments deposited 100-200 years ago. The reactivity of Corg below ∼0.5 m in the foreset is ∼10-20 times lower than expected based on accumulation rates, reflecting loss of >50% of sedimentary Corg on the topset, which functions as a suboxic incinerator.

Original languageEnglish (US)
Article numberF01S09
JournalJournal of Geophysical Research: Earth Surface
Volume113
Issue number1
DOIs
StatePublished - Mar 24 2008

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

Fingerprint Dive into the research topics of 'Early diagenetic cycling, incineration, and burial of sedimentary organic carbon in the central Gulf of Papua (Papua New Guinea)'. Together they form a unique fingerprint.

Cite this