− | The factors that control primary productivity are light intensity, nutrient inputs (nitrate and phosphate), and climate.<ref name=Begonetal_1996>Begon, M., Harper, J. L., and Townsend, C. R., 1996, Ecology. Individuals, Populations and communities: Blackwell Scientific Publications, 1088 p.</ref> Today maximum productivity in the oceans is recorded on the inner shelf of the continental platforms and in ocean upwellings because of high nutrient concentration and relatively clear water.<ref name=Barnesandhughes_1982>Barnes, R. S. K., and Hughes, R. N., 1982, An introduction to marine ecology: Blackwell Scientific Publications.</ref> The paleogeographic configurations of the late Paleozoic-Mesozoic time interval is dominated by E-W oceans, particularly in North Africa, Arabia, and the Middle East, where they extended mainly from the equator to the tropics; indeed, for most of this interval the Tethyan Seaway was present at very low latitudes north of Africa and Arabia, indenting the Pangea supercontinent. Paleocurrent models for a general Pangea configuration (e.g., Kutzbach et al., 1990; Kiessling et al., 1999; Winguth et al., 2002, 2005) envisage a westward-flowing equatorial surface current which, upon reaching the continental shelves of the western Tethys Seaway, deflected southeastward and northeastward; in the meanwhile, a deep water circulation brought cold waters from high latitudes to the equator. Ocean upwellings of these cold and nutrient-rich bottom waters were created by monsoonal wind circulation<ref name=Crowleyetal_1989>Crowley T. J., Hyde, W. T., and Short, D. A., 1989, Seasonal cycle variation on the supercontinent of Pangaea: Geology, v. 17, p. 457–460.</ref> <ref name=Parish_1993>Parrish, J. T., 1993, Climate of the supercontinent Pangaea: Journal of Geology, v. 101, p. 215–233.</ref> <ref name=Peyserandpoulsen_2008>Peyser, C. E., and Poulsen, C. J. 2008, Controls on Permo-Carboniferous precipitation over tropical Pangaea: A GCM sensitivity study: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 268, p. 181–192.</ref> along the Gondwanan margin and in the lee of continental blocks scattered in the Paleo- and Neo-Tethys, as well as at the equatorial divergence zone. | + | The factors that control primary productivity are light intensity, nutrient inputs (nitrate and phosphate), and climate.<ref name=Begonetal_1996>Begon, M., Harper, J. L., and Townsend, C. R., 1996, Ecology. Individuals, Populations and communities: Blackwell Scientific Publications, 1088 p.</ref> Today maximum productivity in the oceans is recorded on the inner shelf of the continental platforms and in ocean upwellings because of high nutrient concentration and relatively clear water.<ref name=Barnesandhughes_1982>Barnes, R. S. K., and Hughes, R. N., 1982, An introduction to marine ecology: Blackwell Scientific Publications.</ref> The paleogeographic configurations of the late Paleozoic-Mesozoic time interval is dominated by E-W oceans, particularly in North Africa, Arabia, and the Middle East, where they extended mainly from the equator to the tropics; indeed, for most of this interval the Tethyan Seaway was present at very low latitudes north of Africa and Arabia, indenting the Pangea supercontinent. Paleocurrent models for a general Pangea configuration<ref name=Kutzbachetal_1990>Kutzbach, J. E., Guetter, P. J., and Washington, W. M., 1990, Simulated circulation of an idealized ocean for Pangaean time: Paleoceanography, v. 5, p. 299–317.</ref> <ref name=Kiesslingetal_1999>Kiessling, W., Flügel, E., and Golonka, J., 1999, Paleoreef maps: Evaluation of a comprehensive database on Phanerozoic reefs: AAPG Bulletin, v. 83, p. 1552–1587.</ref> <ref name=Winguthetal_2002>Winguth, A. M. E., Heinze, C. Kutzbach, J. E., Maier-Reimer, E., Mikolajewicz, U., Rowley, D., Rees, A., and Ziegler, A. M., 2002, Simulated warm polar currents during the middle Permian: Paleoceanography, v. 17, no. 4, p. 1057, doi:10.1029/2001PA000646.</ref> envisage a westward-flowing equatorial surface current which, upon reaching the continental shelves of the western Tethys Seaway, deflected southeastward and northeastward; in the meanwhile, a deep water circulation brought cold waters from high latitudes to the equator. Ocean upwellings of these cold and nutrient-rich bottom waters were created by monsoonal wind circulation<ref name=Crowleyetal_1989>Crowley T. J., Hyde, W. T., and Short, D. A., 1989, Seasonal cycle variation on the supercontinent of Pangaea: Geology, v. 17, p. 457–460.</ref> <ref name=Parish_1993>Parrish, J. T., 1993, Climate of the supercontinent Pangaea: Journal of Geology, v. 101, p. 215–233.</ref> <ref name=Peyserandpoulsen_2008>Peyser, C. E., and Poulsen, C. J. 2008, Controls on Permo-Carboniferous precipitation over tropical Pangaea: A GCM sensitivity study: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 268, p. 181–192.</ref> along the Gondwanan margin and in the lee of continental blocks scattered in the Paleo- and Neo-Tethys, as well as at the equatorial divergence zone. |