Variations on a Theme — Latitiduninal Impacts on Sequence Stratigraphy

Abstract

Sequence stratigraphy is a powerful tool for analyzing and interpreting the rock record. Decades of outcrop, subsurface, flume and modern analog studies have elucidated how significant surfaces form, and the genetic relationships of strata between them. The capacity of this tool to predict the nature of strata beyond the extent of available data is a key component of stratigraphic analysis, especially in frontier exploration. For a variety of reasons, studies from which conventional sequence stratigraphy was developed are largely based on low to mid latitude examples, introducing both a bias and limitation to the methodology for high latitude systems. Many low-mid latitude sedimentary processes are either diminished or absent in high latitude settings; conversely, important processes that impact deposition at high latitudes are either diminished or non-existent at low latitudes. This variability will manifest as disparities in timing, lithology, stacking patterns, and prominence of significant surfaces when comparing high and low latitude basins. In conventional sequence stratigraphy, the forcing factors of tectonics and climate are considered to be globally distributed and synchronous via their influence on eustasy. During glacio-eustatic periods, climatic changes drive accommodation loss via the creation of continental ice sheets and corresponding removal of water from the ocean basins. High latitude systems are adjacent to the primary source of change (ice sheets). Therefore, their response will reflect the primary control (ice sheet growth and decay) as well as the derivative controls, eustasy, glacial-isostasy and hydro isostasy. Low latitude systems, being further from the ice sheets, respond dominantly to the derivative control, eustasy. Mid-latitude systems may appear to be more akin to high or low latitude systems dependent on their paleogeographic location. Application of conventional seismic/sequence stratigraphy in high latitude icehouse systems requires understanding the variance that proximity to ice sheets imparts on the rock record. Changes in timing, forcing, and magnitude of accommodation differ, and resultant systems tract characteristics will not suitably correlate with an age equivalent low latitude system. Exploration in high latitude settings also requires the understanding that the early TST, rather than the LST, contains most of the conventional reservoir targets.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016