Sedimentary structure preservation as an indicator of channel mobility

Abstract

A clear understanding of basin architecture is critical to successful reservoir engineering and hydrocarbon exploration. Climate is a key control on fluvial processes like channel mobility that disperse sediment, and therefore exerts a strong influence on channel stacking patterns in sedimentary basins. This field study aims to quantify channel mobility throughout a stratigraphic sequence spanning the Paleocene–Eocene Thermal Maximum (PETM) in the Piceance Basin of western Colorado. The PETM was a period of rapid climate warming in which rising temperatures drastically enhanced the hydrologic cycle, and altered rainfall patterns significantly perturbed fluvial dynamics in the Piceance Basin. While it has been proposed that Piceance rivers responded to the PETM by increasing their gradients to accommodate altered water and sediment flux, our recent results indicate that in fact, Piceance rivers did not steepen. Instead, our observations suggest that rivers became more mobile, which reworked the floodplain surface so that sand was preferentially retained in the alluvial strata, and mud was exported downstream. To quantify channel mobility in the Piceance Basin and test this hypothesis, I will conduct a field campaign to collect drone images of outcrops across the basin. Compiling these images into 3D models, I will measure sedimentary structures that indicate scour and erosion, and estimate the relative amount of channel reworking from deposits bracketing the PETM. By connecting changes in hydrology channel mobility and alluvial enrichment in sand, this study will bolster research in other depositional basins. Incorporating sedimentological effects of climatic factors into basin analysis will lead to more efficient exploration and exploitation of fluvial sand reservoirs.

AAPG Datapages/Search and Discovery Article #90351 © 2019 AAPG Foundation 2019 Grants-in-Aid Projects