geochronology for Strickland River flood plains, Papua New Guinea

The Strickland River is the primary sediment source for the Fly River system, a large tropical river that ranks in the global top 20 for both water and sediment discharge. Over the past decade the Strickland sediment discharge has been gauged at many locations. Comprehensive studies are now underway to study the delivery, transport, and storage of sediment throughout this system. A key question regards the timing and rates of sediment accumulation on the flood plains. Here we present the first geochronological results from an intensive flood plain coring campaign conducted in 2003, outline our procedure for dating PNG sediment with Pb geochronology, and summarize some early results from 36 cores. Flood plain accumulation rates appear to be highest upstream near the gravel–sand transition, low in the middle portion of the river, and higher again in the lower reaches of the Strickland near to its confluence with the Fly River. Overall patterns of sedimentation seem to be both spatially consistent, for series of cores collected along single flood plain transects, and temporally uniform in the sense that the nature of accumulation (constant or episodic) has not generally changed over the century of record.