Quantitative Tarfaya Basin Development, Morocco*

Transcription

1 Quantitative Tarfaya Basin Development, Morocco* Axel Wenke 1, Rainer Zühlke 1, Haddou Jabour 2, Oliver Kluth 3, and Torge Schümann 3 Search and Discovery Article #10420 (2012)** Posted July 16, 2012 *Adapted from oral presentation at AAPG Annual Convention and Exhibition, Long Beach, California, April 22-25, 2012 **AAPG 2012 Serial rights given by author. For all other rights contact author directly. 1 GeoResources at,, Germany (wenke@georesources.de) 2 ONHYM, Rabat, Morocco 3 RWE Dea, Hamburg, Germany Abstract The Southern Morocco on- and offshore continental margin includes a Permian to Neogene basin fill of up to 10,000 m thick. Three composite dip-oriented transects (TR1-3) have been investigated by high-resolution quantitative sequence stratigraphy and inverse flexural basin modeling. The subsidence/uplift history of the Tarfaya Basin shows nine trends (ST1-9), which show lateral variations in rates and timing but appear throughout the basin. The basin history includes the Late Permian to Triassic rift, sag and early drift stages (ST1), covering 61 m.y. ( Ma). The average subsidence rate was 68 m/m.y. and the average sediment flux 15 m 2 /m.y. Thermo-tectonic subsidence was the main component of total subsidence during the rift to early drift basin stages. A uniform basin-wide subsidence trend does not exist in ST1. ST2-4 of Toarcian to Tithonian age are bounded by the Post-Rift Unconformity (PRU) and the Mature Drift Unconformity (MDU). They extended from the onset of sea-floor spreading to final carbonate platform development. ST2 ( Ma) and ST4 ( Ma) show a decreasing trend in subsidence, while ST3 ( Ma) shows an increasing subsidence trend. Subsidence rates vary between zero to 50 m/m.y. with a maximum of >75 m/m.y. in ST3. Sediment flux varies between three and six m 2 /m.y. during the Jurassic with a maximum of 15 m 2 /m.y. in TR3 during ST3 and eight to twelve m 2 /m.y. in TR1 and TR2 during ST4. Mature drift basin architecture, sediment infill and distribution differ considerably during the Early Cretaceous mature drift stages ST5 to early ST7. TR1 and TR2 were affected by salt mobilization, while TR3 remained unaffected for its location south of the Tarfaya salt province. Subsidence rates varied between -15 m/m.y (uplift) and 60 m/m.y. In TR3, the highest subsidence rates occurred in ST5 ( MA). In TR2, peak subsidence developed in ST6 ( Ma) and early ST7 (123-65) on TR1. Peak sediment flux with more than eight m 2 /m.y. occurred in ST6 (TR3) and early ST7 (TR1). Sediment flux in TR2 stayed largely constant. The current model implies that subsidence trends where triggered by i) changes in intra-plate

2 balance forces induced by changes in sea-floor spreading rates; ii) shifts in the sea-floor spreading axes; iii) the stepwise migration of crustal separation and seafloor spreading from the Central Atlantic to the north; and iv) relative plate motions and convergence rates between Africa and Eurasia. Reference Wenke, A., R. Zuhlke, H. Jabour, and O. Kluth, 2011, High-resolution sequence stratigraphy in basin reconnaissance; example from the Tarfaya Basin, Morocco: First Break, v. 29/11, p

3 Quantitative Tarfaya Basin Development, Morocco Axel Wenke 1, Rainer Zühlke 1, Haddou Jabour 2, Oliver Kluth 3 & Torge Schümann 3 1 GeoResources at,germany; 2 ONHYM, Rabat, Morocco & 3 RWE Dea, Hamburg, Germany AAPG 2012 Annual Convention & Exhibition 22 th 25 th of April 2012, Long Beach, CA

4 Objectives Database and workflow Stratigraphic framework (2 nd order sequence stratigraphy) Time/depth conversion Flexural basin modeling Subsidence rates Sediment flux Summary & Conclusion Wenke et al. Quantitative Tarfaya Basin Development, Morocco

5 Database and key transects Seq Strat Wenke et al. Quantitative Tarfaya Basin Development, Morocco

6 Database and key transects - Subsidence Wenke et al. Quantitative Tarfaya Basin Development, Morocco

7 Workflow 1D litho- and biostratigraphic framework Basinwide 2D interpretation of stratigraphic well tops 2 nd order sequence stratigraphic model Velocity modeling and time/depth conversion Flexural basin modeling Subsidence model Wenke et al. Quantitative Tarfaya Basin Development, Morocco

8 2 nd order sequence stratigraphy Stratigraphic Framework Wenke et al. Quantitative Tarfaya Basin Development, Morocco

9 2 nd order seq strat framework TR 2 NW SE TWT [s] Onshore/ Offshore Transition Zone Lanzarote TWT [s] MO-7 Ce Al Apt MO-5 MDU Bat Aa/Baj Ti Toa Kimm Ox Call apu PRU PC- 1 (projected) Tu Co CHBK-1 st1 IRU st3 st2 EA-1 st4 Pre- Mesozoic 4 10 km 5 6 Laayoune Depression Chebeika Graben Wenke et al. (2011) 7 Wenke et al. High-resolution sequence stratigraphy and subsidence analysis of the Tarfaya Basin, Morocco

10 2 nd order seq strat framework TR 2 NW SE TWT [s] Lanzarote TWT [s] Volcanic rocks of the Canary Islands Salt Plio/Q Up Mio Lo Mio Up Ol Low Ol Eoc Pal Salt Cap Juby Discovery CJ-1 MO-2 Salt Al Apt MDU Ce Tu PC- 1 (projected) Sebkha Tah 1-2 Co Sa apu PRU Aa/Baj Toa st4 st3 st2 st1 Onshore/ Offshore Transition Zone Ti Kimm Ox Call Bat IRU Laayoune Depression 10 km 8 Wenke et al. High-resolution sequence stratigraphy and subsidence analysis of the Tarfaya Basin, Morocco

11 2 nd order seq strat framework TR 3 W E TWT [s] TWT [s] 15-A-1 (projected) Onshore/ Offshore Transition Zone Ce Apt Tu Al Co-Ma apu Lo Mio Up Mio Pal Barr -? Plio/Q Low Ol Up Ol Eoc Barr Ha Va MDU Kimm Call Aa/Baj st4 Ti Ox Bat Toa st3 st2 st1 PRU IRU 10 km 6 Laayoune Depression 7 8 Wenke et al. High-resolution sequence stratigraphy and subsidence analysis of the Tarfaya Basin, Morocco

12 Sequence Stratigraphy Well Sequence Stratigraphy Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco

13 Log Patterns 5 th 4 th 3 rd Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco Wenke et al. (2011)

14 Well Sequence Stratigraphy TR1 NW SE Wenke et al. (2011) Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco

15 Seismic Sequence Stratigraphy Seismic Sequence Stratigraphy Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco

16 Seismic Sequence Analysis OpendTect SSIS Sequence analysis Semiautomatic chronostratigraphic order of seismic reflectors Systems tract analysis Scaling and filtering of seismic transects Chronostratigraphy of seismic reflectors Determination of system tracts HST TST LST Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco

17 Seismic Sequence Analysis Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco

18 Seismic Sequence Analysis Wenke et al. (2011) Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco

19 Seismic Sequence Analysis Wenke & Zühlke High-resolution sequence stratigraphy and basin modeling of the Tarfaya Basin, Morocco Wenke et al. (2011)

20 Time/depth conversion Time/Depth Conversion Wenke et al. High-resolution sequence stratigraphy and subsidence analysis of the Tarfaya Basin, Morocco

21 3D velocity cube Wenke et al. Quantitative Tarfaya Basin Development, Morocco

22 Flexural modeling input data Wenke et al. Quantitative Tarfaya Basin Development, Morocco

23 Quantitative basin modeling Flexural Basin Modeling Wenke et al. Quantitative Tarfaya Basin Development, Morocco

24 Reverse modeling Input data Stratigraphy Paleobathymetry Eustatic sea-level Crustal flexural paramteres (Te, taper limit, mantle density) Results Basin architecture in time Subsidence evolution Sediment flux Wenke et al. Quantitative Tarfaya Basin Development, Morocco

25 Reverse modeling TR1 CCC CCC & OCC BTR CCC & OCC BTR OAE 2 OAE 1b-d OAE 1a BTR CCC & OCC OAE 1b-d OAE 1a OAE 2 OAE 1b-d OAE 1a OAE 2 PETM OAE 1b-d OAE 1a OAE 2 PETM CCC & OCC BTR CCC & OCC BTR BTR CCC & OCC Wenke et al. Quantitative Tarfaya Basin Development, Morocco

26 Reverse modeling TR2 Jurassic Turnover OAE-1b-d Oxfordian Carbonate Crisis OCC OAE-1a Berriasian Terrestrial Runoff OCC BTR OAE-3 OAE-3 OAE-3 OAE-2 OAE-2 OAE-1b-d OAE-1b-d OAE-1b-d OAE-1a OAE-1a OAE-1a PETM OCC OCC BTR OCC OAE-2 PETM BTR BTR Wenke et al. Quantitative Tarfaya Basin Development, Morocco

27 Reverse modeling TR3 CCC CCC OCC OCC CCC BTR OCC CCC BTR OAE 3 OAE 2 OAE 1 b-d OAE 1a OAE 3 OAE 2 OAE 1 b-d OAE 1a OAE 3 OAE 1 b-d OAE 1a OAE 2 OCC CCC BTR OCC CCC PETM OCC CCC PETM BTR Wenke et al. Quantitative Tarfaya Basin Development, Morocco

28 Subsidence rates and sediment flux TR 1 TR 2 TR 3 Ma Wenke et al. Quantitative Tarfaya Basin Development, Morocco Ma

29 Summary & Conclusion Accomodation space primarily controlled by subsidence and sediment input Basinward migration of depocenters during Meso- to Cenozoic Ma, ST1-4 (Kazhanian Tithonian): shelf Ma, ST 5-7 (Berriasian Early Maastrichtian): shelf, slope and basin Ma, ST 8&9 (Late Maastrichtian Neogene): slope and basin Shelf margin subsidence peaks vary moderate during basin development Shelf margin subsidence show cyclicity with a decrease of amplitude through time Regional effects overprint the spreading signal in ST6 (salt movement) and ST9 (Atlasian uplift) Subsidence history of the northern LB is independent from central and northern TB development Peaks in sediment flux took place during ST2 (Rift), ST3/ST4 (carbonate production), ST5/ST6 (Tan Tan and Boujdour Deltas) and ST9 (Atlasian uplift and erosion) Wenke et al. Quantitative Tarfaya Basin Development, Morocco

30 Wenke et al. Quantitative Tarfaya Basin Development, Morocco