Arc-Related Carbonate Platform Systems

Steven L. Dorobek
Texas A&M University, College Station, TX

Carbonate platforms are commonly associated with volcanic-arc systems along convergent margins, although in ancient, highly deformed examples, it may be difficult to place them in their proper tectonic and geomorphologic setting. Continental-margin arc systems have distinctly different histories than intra-oceanic arc systems, especially regarding potential locations and time of initial development of shallow-marine carbonate platforms. Continental margin arcs may be near base-level throughout their history, so areally extensive carbonate platforms may form at any time. In contrast, carbonate platforms only form within intra-oceanic arc systems when accretionary prisms or submarine volcanism have constructed sufficient topography so that the seafloor is within photic depths. Most shallow-marine carbonate platform successions within volcanic-arc systems are thin, rarely exceeding a few hundred meters thickness. The areal dimensions of arc-related carbonate platforms are also generally limited because of the active deformation and volcanic activity in these settings. Carbonate platforms may form on the crest of shallowly submerged accretionary prisms, on fault-controlled highs within underfilled forearc basins, along the flanks of volcanically constructed edifices, or on fault-bounded structural highs within or surrounding the volcanic arc. Rapid rates of deformation and differential subsidence or uplift across many volcanic-arc systems may lead to rapid drowning, areally restricted platform dimensions, steep-sided platform profiles, and complex internal stratal patterns. Sediment-filled forearc or backarc basins, however, may provide broad substrates for the development of wide carbonate platforms (ramp profiles are common), especially in tropical settings and during high-frequency sea-level rises.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005