Build-and-Fill Sequences in Carbonate Systems: An Emerging Picture

Franseen, Evan K.¹, Robert H. Goldstein¹, Marcello Minzoni¹ (1) University of Kansas, Lawrence, KS

Internal architecture of build and fill is emerging from both icehouse and greenhouse systems exhibiting thin sequences (10's of meters thick) that maintain similar thickness throughout wide geographic areas, despite having a complex internal architecture of building and filling relief. Build-and-fill sequences develop in settings in which carbonate productivity is less than optimal, leading to underfilled accommodation and incipient drowning during rises, and subsequent fill of low areas, typically during highstand or falling sea level. Fine-grained siliciclastics and adverse paleoceanographic conditions may inhibit carbonate productivity and lead to build-and-fill sequence development.

In icehouse systems the build-and-fill zone develops in medial positions on broad shelves/ramps, and in inner platform/lagoon positions on high-standing rimmed platforms. Icehouse build-and-fill sequences result from the interaction of high-amplitude, high-frequency sea-level fluctuations with paleotopography and sediment dispersal processes. In greenhouse systems, the build-and-fill zone appears to develop only in inner platform/lagoon positions on high-standing rimmed platforms, where sea-level fluctuations and relatively shallow water interacts with paleotopography in areas of suppressed carbonate productivity.

Examples from the Miocene, Pennsylvanian, Permian, Early Triassic, and Cretaceous illustrate build-and-fill sequences from various settings and systems. These examples indicate that given accommodation in the build-and-fill zone, topographic highs may be favored areas to build relief by boundstone and grainstone. The fill phase may be favored by limited accommodation. Localized deposition of delta-like siliciclastics may modify relief in paleo-low areas, given a paleotopographic focus. Where shallow-water conditions intersect complex topography, currents may be focused, depositing grainy carbonate and siliciclastic facies in lows. If energies are too high along topographic highs, boundstone/wackestone/packstone facies may accumulate (fill) in the topographic lows where current energies are weaker.