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Deepwater Carbonate Signals. The Central High Atlas Type Examples. C. G. St. C. Kendall. Department of Geological Sciences, University of South Carolina. High Atlas. Study Area. Outline of Presentation. Introduction to deepwater sediments of High Atlas Geological setting of High Atlas
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Deepwater Carbonate Signals The Central High Atlas Type Examples C. G. St. C. Kendall Department of Geological Sciences, University of South Carolina
High Atlas Study Area
Outline of Presentation • Introduction to deepwater sediments of High Atlas • Geological setting of High Atlas • Oed Ziz Jurassic carbonates & marls • Generation & sequestration of deepwater sediments of High Atlas • Jebel bou Dehar Jurassic carbonates & marls • Amellago Jurassic carbonates & marls • Significance of High Atlas as deepwater play model • Conclusions
Hiya Jurassic High Atlas & Middle Atlas Basins Expanded & then Compressed As North America Moved West in Response to Spreading of Atlantic & Movement East of the Moroccan Meseta
Sections with Deepwater Jurassic Carbonate Sediment Sequestered in Basin Pliensbachian Jebel bou Dehar Aalenian adjacent to village of Amellago Sinemurian – Oed Ziz Tunnel de Legionaire to Rich
Rt Lateral Motion of Jurassic Shelf Atlas Fold Mts Jurassic Carbonate Sediment Sequestered in Basin & on Shelves Formed in Response to Spreading of Atlantic Rt Lateral Motion of Jurassic Shelf
High Atlas – Structure & Locals Rt Lateral Motion of Jurassic Shelf Atlas Fold Mts MIDELT RICH Oed Ziz Bou Dahar Amellago RASHIDIA Rt Lateral Motion of Jurassic Shelf Jurassic Carbonate Sediment Sequestered in Basin and on Shelves!
Jurassic High Atlas Basin • Site of “turbidite” and other “non-cohesive density flow” carbonate sediments and “mass-transport deposits (MTD)” downslope from carbonate margins • Ages range from: • Sinemurian - Oed Ziz from Tunnel de Legionaire to Rich • Pliensbachian – In col formed by Jebel bou Dehar • Aalenian – In col formed by Djebels Tikajoine, Bou Iflilou, Tamoussat, Mijdider & Tagountsa • Demonstrably functions of local & global controls
High Atlas Oed Ziz Sections • Site of “turbidite” and other “non-cohesive density flow” carbonate sediments and “mass-transport deposits (MTD)” downslope from carbonate margins • Age of basin fill ranges from Sinemurian through Bajocian • Oed Ziz traverse from Tunnel de Legionaire to Rich and on to Midelt
Oued Ziz Traverse Basin Syn Depositional Folds Old Salt Structures? Shelf to Basin Shelf
Oed Ziz – High AtlasBasin looking South Mountain Ridge Overthrust Northward – Triassic Salt Cores?
Shelf/Basin Transition Basin Shelf to Basin Shelf
Shelf Sediment Contribution • Shelf carbonate sediments of High Atlas range from sand to mud to shale prone • Sediments differences due to water depth, and wave energy to carbonate shelves & input of clastics from updip continental areas • Finer carbonate mud sediments comprise at least 70% of total succession & is "mud-rich" • Closer to margin more "sand-rich" with a high net-to-gross ratio of carbonate sand & mud accumulations thicker than mud-dominated successions in the basin
Oed Ziz – Jurassic Shelf Cycles of limestone & marls
Oed Ziz – Jurassic Shelf Cycles of limestone & marls
Oed Ziz – Jurassic Shelf Shallow grain carbonates common
Fine Grain Size Contribution • Deepwater carbonate sediments of High Atlas range from sand to mud prone • Differences due to sediments eroded from adjacent carbonate shelves & Liassic and older basin margin • Finer carbonate mud sediments comprise at least 70% of total succession & is "mud-rich" • Closer to margin more "sand-rich" with a high net-to-gross ratio of carbonate sand & mud accumulations thicker than mud-dominated successions basin-ward
Oed Ziz - Tunnel De Legionnaire/Rich • Sinemurian turbidite and other non-cohesive density flow carbonate sediments and mass-transport deposits (MTD) accumulate downslope from the carbonate margins of the High Atlas Basin as functions of local and global controls • Downslope carbonate elements include • channels sands • levee sands • distal overbank supra fan mud sheets • slumped downslope small-scale soft-sediment deformation features • Tectonic history suggests that local uplift in the basin was penecontemporaneous with deposition
Oed Ziz - Looking SouthShelf Basin Transition Shelf Shelf Margin Turbidites
Oed Ziz - Tunnel De Legionnaire/Rich Downslope carbonate elements • channels sands & muds • levee sands & muds • distal overbank supra fan mud sheets • slumped downslope blocks • small-scale soft-sediment deformation features Tectonic history suggests that local uplift in the basin occurred with deposition
Tunnel de Legionaire Channels & Levees
Tunnel de Legionaire Channels & Levees
Tunnel de Legionaire Channel
Oed Ziz - Tunnel De Legionnaire/Rich Downslope carbonate elements • channels sands & muds • levee sands & muds • distal overbank supra fan mud sheets • slumped downslope blocks • small-scale soft-sediment deformation features Tectonic history suggests that local uplift in the basin occurred with deposition
Tunnel de Legionaire Levees
Tunnel de Legionaire Levee Graded Bed
Tunnel de Legionaire Levee Graded Bed
TunnelDeLegionaire LeveeGradedBed
Tunnel de Legionaire Downslope Channels & Lobes
Tunnel de Legionaire Downslope Channel Fill
Oed Ziz - Tunnel De Legionnaire/Rich Downslope carbonate elements • channels sands & muds • levee sands & muds • distal overbank supra fan mud sheets • slumped downslope blocks • small-scale soft-sediment deformation features Tectonic history suggests that local uplift in the basin occurred with deposition
TunnelDeLegionaire Hiya BoumaCycles
Tunnel de Legionaire Bouma Cycles
TunnelDeLegionaire Hiya BoumaCycles
Tunnel de Legionaire Flute MarksOn Bed Plane
Oed Ziz - Tunnel De Legionnaire/Rich Downslope carbonate elements • channels sands & muds • levee sands & muds • distal overbank supra fan mud sheets • slumped downslope blocks • small-scale soft-sediment deformation features Tectonic history suggests that local uplift in the basin occurred with deposition
Tunnel de Legionaire Downslope Block
Oed Ziz - Tunnel De Legionnaire/Rich Downslope carbonate elements • channels sands & muds • levee sands & muds • distal overbank supra fan mud sheets • slumped downslope blocks • small-scale soft-sediment deformation features Tectonic history suggests that local uplift in the basin occurred with deposition
Tunnel de Legionaire Disturbed Soft Sediment