Cambro-Ordovician Sequence In The Petra Area, Jordan

The RamGroup in Jordan forms part of a massive and voluminous quartz-rich blanketthat covered North Africa and Arabia, the former northern margin of Gondwana duringthe Early Paleozoic. The lack ofvegetation on the vast peneplained and tectonically stablemargin resulted in the development of extensive alluvial systems markedly different inscale from modern systems. In the Petra area, the RamGroup is conformed by the Salib,Abu Kusheiba and Umm Ishrin formations.
Its onset and development are admirablydisplayed allowing a unique oportunity to perform detailed sedimentological studies.
In thepaleogeographic context of the Early Paleozoic, the detailed analysis of fivelithofacies and interpretation of their three major associations in terms of architecturalelements, the study of themineralogical development throughout the sequence and the ich-nofacies content from new ichnofossil discoveries are all gathered in order to reconstructa depositional and architectural model for the RamGroup.
The base of the sequenceburies a remarkable 100-metre high paleorelief of the Precambrian basement inheritedfrom volcanic activity.
Upward, the sedimentary package describes a110-metre-thickfining/thinning (salib Formation) and coarsening/thickening (Abu Kusheiba Formation)cycle until drastic development of a >500-metre-thick, massive, medium-grained cross-bedded quartzarenite (Umm IshrinFormation).
The environments of depositions evolved from shallow marine shelf to delta-front anddelta braidplain until definite onset of a continent-wide alluvial plain dominated by shal-low,perennial, sand-bed braided rivers on the distal margins of Gondwana. Short-livedtransgressions and tidal currents reworked parts of abandoned braidplains.
The Umm Ishrin Formation is an excellent analoguefor subsurface braided hydrocar-bon reservoirs. Reservoir characterization from outcrop studies results in a vertical stackof laterally extensive sheet-like units with remarkable high net-to-gross...