Patterns of sedimentation in the contemporary Red Sea as an analog for ancient carbonates in rift settings

摘要

Patterns of sedimentation in the Red Sea offer a contemporary analog for carbonate deposition in marine rift settings. Covering 20u of latitude, the sea 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 exactly 1,600 sq. km, illustrate the variability of spatial patterns in reefal and other carbonates in this rift setting. Five of the focus areas are located on a north-south transect along the western margin of the sea: (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. Lumping these two classes define "carbonate bodies" that were analyzed for trends in orientation, relation to local fault networks, and size-frequency distribution. Fault lineaments digitized from the literature are closely related to the orientation of carbonate bodies with areas exceeding 5 sq. km. Smaller bodies do not preferentially align with fault trends.Water depth and the occurrence of reefal frameworks and sediments for the six focus areas are not systematically related. Used as an analog, these data from the contemporary Red Sea may provide insight into the orientation and scale of accumulation of carbonates in subsurface marine rift settings