Aubry
Marie-Pierre
Aubry
Marie-Pierre
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PreprintGenesis and geometry of tilted blocks in the Theban Hills, near Luxor (Upper Egypt)( 2011-02-16) Dupuis, Christian ; Aubry, Marie-Pierre ; King, Christopher ; Knox, Robert W. O'B. ; Berggren, William A. ; Youssef, Moustafa ; Galal, Wael Fathi ; Roche, MarcThe desertic Theban hills between the edge of the alluvial plain of the Nile and the prominent cliffs at the eastern edge of the Theban Plateau consist of imbricated tilted blocks organized in parallel groups representing successive generations of gravitational collapse structures (or slumps). The older (distal) generations correspond to low, rounded hills farther from the Theban cliffs. The youngest (proximal) generation forms higher hills with young relief. Reverse faults occur at the contact between proximal and distal tilted blocks whereas the proximal tilted blocks rest along listric faults on the substratum (Tarawan Chalk and Esna Shale Formations) and against the Theban cliffs. We hypothesize that the emplacements of the tilted blocks were related to major Pleistocene pluvial episodes, each marked by active flow of the Nile River and significant recess of the Theban cliffs. Tectonic thinning and intensive erosion of the Esna Shale Formation were determinant in shaping the Theban landscape.
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ArticleSubseries/Subepochs approved as a formal rank in the international stratigraphic guide(International Union of Geological Sciences, 2020-07-01) Aubry, Marie-Pierre ; Head, Martin J. ; Piller, Werner E. ; Berggren, William A.The International Subcommission on Stratigraphic Classification, as the constituent body of the International Commission on Stratigraphy (ICS) responsible for the International Stratigraphic Guide, has voted to include the subseries/ subepoch as a formal rank in the next edition of the Guide. This acknowledges the recent ratification of formal subseries and their corresponding stages for the Holocene Series/Epoch but allows individual subcommissions within ICS the freedom to decide whether or not to adopt this rank for their particular stratigraphic/time interval.
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ArticleFormation of the Isthmus of Panama(American Association for the Advancement of Science, 2016-08-17) O’Dea, Aaron ; Lessios, Harilaos ; Coates, Anthony ; Eytan, Ron I. ; Restrepo-Moreno, Sergio A. ; Cione, Alberto L. ; Collins, Laurel S. ; de Queiroz, Alan ; Farris, David W. ; Norris, Richard D. ; Stallard, Robert ; Woodburne, Michael ; Aguilera, Orangel ; Aubry, Marie-Pierre ; Berggren, William A. ; Budd, Ann F. ; Cozzuol, Mario A. ; Coppard, Simon E. ; Duque-Caro, Hermann ; Finnegan, Seth ; Gasparini, Germán M. ; Grossman, Ethan L. ; Johnson, Kenneth G. ; Keigwin, Lloyd D. ; Knowlton, Nancy ; Leigh, Egbert G. ; Leonard-Pingel, Jill S. ; Marko, Peter B. ; Pyenson, Nicholas ; Rachello-Dolmen, Paola G. ; Soibelzon, Esteban ; Soibelzon, Leopoldo ; Todd, Jonathan A. ; Vermeij, Geerat J. ; Jackson, Jeremy B. C.The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed many millions of years earlier than the widely recognized age of approximately 3 million years ago (Ma), a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas. To bring clarity to the question of when the Isthmus of Panama formed, we provide an exhaustive review and reanalysis of geological, paleontological, and molecular records. These independent lines of evidence converge upon a cohesive narrative of gradually emerging land and constricting seaways, with formation of the Isthmus of Panama sensu stricto around 2.8 Ma. The evidence used to support an older isthmus is inconclusive, and we caution against the uncritical acceptance of an isthmus before the Pliocene.
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ArticleThe Dababiya corehole, Upper Nile Valley, Egypt : preliminary results(Austrian Geological Society, 2012) Berggren, William A. ; Alegret, Laia ; Aubry, Marie-Pierre ; Cramer, Ben S. ; Dupuis, Christian ; Goolaerts, Sijn ; Kent, Dennis V. ; King, Christopher ; Knox, Robert W. O'B. ; Obaidalla, Nageh ; Ortiz, Silvia ; Ouda, Khaled A. K. ; Abdel-Sabour, Ayman ; Salem, Rehab ; Senosy, Mahmoud M. ; Soliman, Mamdouh F. ; Soliman, AliThe Dababiya corehole was drilled in the Dababiya Quarry (Upper Nile Valley, Egypt), adjacent to the GSSP for the Paleocene/ Eocene boundary, to a total depth of 140 m and bottomed in the lower Maastrichtian Globotruncana aegyptiaca Zone of the Dakhla Shale Formation. Preliminary integrated studies on calcareous plankton (foraminifera, nannoplankton), benthic foraminifera, dinoflagellates, ammonites, geochemistry, clay mineralogy and geophysical logging indicate that: 1) The K/P boundary lies between 80.4 and 80.2 m, the Danian/Selandian boundary between ~ 41 and 43 m, the Selandian/Thanetian boundary at ~ 30 m (within the mid-part of the Tarawan Chalk) and the Paleocene/Eocene boundary at 11.75 m (base [planktonic foraminifera] Zone E1 and [calcareous nannoplankton] Zone NP9b); 2) the Dababiya Quarry Member (=Paleocene/Eocene Thermal Maximum interval) extends from 11.75 to 9.5 m, which is ~1 m less than in the adjacent GSSP outcrop.; 3) the Late Cretaceous (Maastrichtian) depositional environment was nearshore, tropical-sub tropical and nutrient rich; the latest Maastrichtian somewhat more restricted (coastal); and the early Danian cooler, low(er) salinity with increasing warmth and depth of water (i.e., more open water); 4) the Paleocene is further characterized by outer shelf (~ 200 m), warm water environments as supported by foraminifera P/B ratios > 85% (~79-28 m), whereas benthic foraminifera dominate (>70%) from ~27-12 m (Tarawan Chalk and Hanadi Member) due, perhaps, in part to increased dissolution (as observed in nearby outcrop samples over this interval); 5) during the PETM, enhanced hydrodynamic conditions are inferred to have occurred on the sea-floor with increased river discharge (in agreement with sedimentologic evidence), itself a likely cause for very high enhanced biological productivity on the epicontinental shelf of Egypt; 6) correlation of in situ measured geophysical logs of Natural Gamma Ray (GR), Single-Point Resistance (PR), Self-Potential (SP), magnetic susceptibility (MS), and Resistivity, and Short Normal (SN) and Long Normal (LN) showed correspondence to the lithologic units. The Dababiya Quarry Member, in particular, is characterized by very high Gamma Ray and Resistivity Short Normal values.
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PreprintAnatomy of a mountain : the Thebes Limestone Formation (Lower Eocene) at Gebel Gurnah, Luxor, Nile Valley, Upper Egypt( 2017-05) King, Christopher ; Dupuis, Christian ; Aubry, Marie-Pierre ; Berggren, William A. ; Knox, Robert W. O'B. ; Galal, Wael Fathi ; Baele, Jean-MarcWe present a detailed geologic study of the Thebes Formation at Gebel Gurnah in its locus typicus on the West Bank (opposite Luxor) of the Nile River in the Upper Nile Valley, Egypt. This is the first detailed measurement and lithologic description of the ~ 340 m thick (predominantly) carbonate section. The Thebes Formation is divided into thirteen major lithic units (A to M). We interpret data on the lithologic succession and variations, whole rock/clay mineralogy, and macro/micropaleontology in terms of deposition on a shallow carbonate platform episodically influenced by continental runoff, and describe six depositional sequences that we place in the global framework of Lower Eocene (Ypresian) sequence stratigraphy. We note however significant incompatibilities between the Thebes depositional sequences and the global sequences. We emend the definition of the Thebes Formation by defining its top as corresponding to level 326 m at the top of Nodular Limestone ‘L’ (NLL), and assigning the overlying beds to the Minia Limestone Formation. New biostratigraphic data and revision of previous studies establish the direct assignment of the Thebes Formation to planktonic foraminiferal Zones E4/P6b (upper part), E5/P7 and (indirectly) Zone E6/P8, and (probably, indirectly) Zone E7a/”P9”, and to calcareous nannofossil Zone NP12 and lower Zone NP13 of the Lower Eocene (Ypresian) and provide a temporal framework spanning ~ 2.8 Myr from <52.45 to ~49.6 Ma for the deposition of the Thebes Formation prior to the prominent sea level fall (~ 49.6 Ma) towards the end of the Early Eocene. Dominantly carbonate deposition, with a strongly reduced detrital influx, occurred on a very wide shelf (probably) at least ~ 100 km from the coastline. The thick sedimentary succession and the marked vertical lithologic variations are interpreted as resulting from sea level fluctuations imprinted on a long-term decrease in sea-level associated with rapid subsidence reflecting tectonic relaxation after the major Late Paleocene tectonic reorganization of the Syrian Arc.