Contemporary Red Sea as an Analog for Ancient Carbonates in Rift Settings

Purkis, Sam J.; Harris, Paul (Mitch); Ellis, James

In terms of its large size, the Red Sea is a unique contemporary analog for carbonate deposition in a marine rift setting. The Red Sea covers a full 20° of latitude, which is sufficiently long to display pronounced climate differences, and the clear tropical waters support vigorous coral reef growth and associated production of carbonate sediment. Six focus areas within the Red Sea, each covering 1,600 sq. km, were selected to illustrate and analyze the variability of reefal and other carbonates in a rift setting. Five of the focus areas are located on a north-south transect along the sea's western margin - (1) Gubal Straits (Egypt), (2) Shalatayn (Egypt), (3) Trinkitat (Sudan), (4) Dahlak (Eritrea), and (5) Halib (Eritrea); and one is from the eastern margin - (6) Farasan Banks (Saudi Arabia). Using Landsat imagery, water depth and two marine facies classes "reefal frameworks" and "sediments" were mapped. These two classes were lumped to define "carbonate bodies", in turn analyzed for trends in orientation, as guided by local fault networks, and size-frequency distribution. Fault lineaments, which were digitized from the literature, are shown to direct the orientation of carbonate bodies with areas exceeding 5 sq. km. Smaller bodies do not preferentially align with fault trends. Relationships between water depth and the occurrence of reefal frameworks and sediments were explored for the six focus areas. No deterministic relationship was found. Used as an analog, the assembled data from the contemporary Red Sea may provide insight into the orientation and scale of accumulation of carbonates in subsurface marine rift settings.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013