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  • 1
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Science Advances 2 (2016): e1600883, doi:10.1126/sciadv.1600883.
    Description: 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.
    Description: This study was supported by the Smithsonian Tropical Research Institute to A.O., J.B.C.J., N.K., and H.A.L.; the NSF (EAR 1325683) to A.O., P.G.R.-D., and E.L.G.; the National System of Investigators to A.O.; the Secretaría Nacional de Ciencia, Tecnología e Innovación (Panamá) to A.O., H.A.L., and S.E.C.; the U.S. Geological Survey to R.F.S.; and the Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina) to A.L.C., G.M.G., E.S., and L.S.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Location Call Number Limitation Availability
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  • 2
    Publication Date: 2022-05-26
    Description: Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Journal of African Earth Sciences 136 (2017): 61-108, doi:10.1016/j.jafrearsci.2017.05.008.
    Description: We 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.
    Description: National Geographic Society for financial support
    Keywords: Thebes Limestone ; Lower Eocene ; Gebel Gurnah ; Egypt ; Sequence stratigraphy
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 3
    Publication Date: 2023-08-04
    Description: Mn K-edge XANES spectra of KMnO4, MnO2 and MnCO3 standards and Discorhabdus striatus, Watznaueria britannica (four spectra from four different spots within the same coccolith), Discoaster falcatus and Helicosphaera carteri coccoliths. Those data were acquired through the project ES113 at ESRF. D. striatus and W. britannica are from Murtinheira section at Cabo Mondego, Portugal. Discoaster falcatus is from Wilson lake core, NJ, USA. Helicosphaera carteri is from MD05-2920 core section.
    Keywords: Absorption; Cabo_Mondego; calcareous nannofossil; CALYPSO2; Calypso Corer II; coccolith; Energy; ESRF; Event label; IMAGES XIII - PECTEN; manganese; Manus; Marion Dufresne (1995); MD052920; MD05-2920; MD148; Micropaleontology; OUTCROP; Outcrop sample; Portugal; Sample comment; Species; Wilson_Lake_outcrop; XANES
    Type: Dataset
    Format: text/tab-separated-values, 5600 data points
    Location Call Number Limitation Availability
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  • 4
    Publication Date: 2023-08-04
    Description: The data were generated at ESRF beamline ID22 with an incident energy at 17 keV. Discorhdabus striatus and Watznaueria britannica were analyzed with 0.1 µm x 0.1 µm pixel size and 2 s time analysis per pixel. Both coccoliths were picked from samples from Murtinheira section at Cabo Mondego, Portugal. D. striatus is from sample CM9 and W. britannica from sample CM60 both dated to the lower Bajocian (Middle Jurassic). Sample position in the section in Suchéras-Marx et al. (2012). Data treatment is made using PyMCA. For each calcareous nannofossil, the raw data (.edf in .zip) and the pondered spectrum (.csv) are given. One fit file is given (.cfg) and can be used for both sample. Those data were acquired through the project EC811 at ESRF. Similar results published in Suchéras-Marx et al. (2016).
    Keywords: Cabo_Mondego; calcareous nannofossil; Channels; Count rate, incoming; Energy; ESRF; Micropaleontology; OUTCROP; Outcrop sample; Portugal; Sample code/label; Species; X-ray fluorescence (XRF); XRF
    Type: Dataset
    Format: text/tab-separated-values, 20480 data points
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  • 5
    Publication Date: 2024-02-02
    Description: The data were generated at ESRF beamline ID21 with an incident energy at 7.5 keV. Coccolithus pelagicus, Discorhabdus striatus, Helicosphaera carteri and Watznaueria britannica were analyzed with 0.4 µm x 0.4 µm pixel size and 3 s time analysis per pixel. Calcidiscus leptoporus was analyzed with 0.2 µm x 0.2 µm pixel size and 1.5 s time analysis per pixel. Dicoaster falcatus was analyzed with 0.5 µm x 0.5 µm pixel size and 3 s time analysis per pixel. Data treatment is made using PyMCA. For each calcareous nannofossil, the raw data (.edf in .zip) and the pondered spectrum (.csv) are given. One fit file is given (.cfg). It may be applied to any sample but for further calculation, new fit file specifically adapted to the sample should be used. Those data were acquired through the project ES113 at ESRF. Coccolithus pelagicus is from North Atlantic sediment coretop GIK23066. Discorhabdus striatus is from Murtinheira section at Cabo Mondego, Portugal sample CM9. Watznaueria britannica is from Murtinheira section at Cabo Mondego, Portugal sample CM60. Sample position in the Murtinheira section at Cabo Mondego in Suchéras-Marx et al. (2012). Helicosphaera carteri and Calcidiscus leptoporus are from South Atlantic sediment coretop GeoB3721-4. Discoaster falcatus is from Wilson lake core, NJ, USA.
    Keywords: Cabo_Mondego; calcareous nannofossil; Channels; Count rate, incoming; Energy; ESRF; Event label; GeoB3721-4; Giant box corer; GIK23066-1; GKG; M2/2; M34/2; Meteor (1986); Micropaleontology; MUC; MultiCorer; Northern Cape Basin; Norwegian Sea; OUTCROP; Outcrop sample; Portugal; Sample code/label; Species; Wilson_Lake_outcrop; X-ray fluorescence (XRF); XRF
    Type: Dataset
    Format: text/tab-separated-values, 105000 data points
    Location Call Number Limitation Availability
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