Paleoenvironment and paleolithofacies constrains on the Mesozoic paleogeographic maps
|Category||Paleontology and Stratigraphy|
|Location||International Geological Congress,oslo 2008|
|Holding Date||07 October 2008|
The paper presents the detailed paleoenvironment and paleolithofacies maps during the Triassic, Jurassic and Cretaceous time intervals. The relationship of the continental configuration, lithofacies, tectonics and climate is clearly depicted on this series of reconstructions. The distribution of lithofacies shows climatic change associated with continental disassembly and assembly. The breakup of continents and origin of oceans generated basins related to rifting and passive margin development. The assembly of continents contributed to the formation of foreland basins. The subduction zones are related to the back-arc basins. The biological extinction events were perhaps related to the plate reorganization and mantle plume activity. Carbonate platforms with reefs existed throughout the entire Mesozoic in the Tethys area. Continental clastic prevailed in the interior of continents as well as in rift areas during Triassic time. Shallow marine environments with carbonates and clastic deposits prevailed during Late Jurassic and Cretaceous times.
During Triassic time Pangea begins to stretch, initiating the rifting and future breakup of the supercontinent. The continued northward drift of the Cimmerian continent corresponded with the closing and progressive consumption of Paleotethys oceanic crust and the opening of the Neotethys Ocean. The most significant Late Triassic convergent event was the Indosinian orogeny, the collision of Indochina and Indonesia with South China and consolidation of Chinese blocks. The time around the Triassic-Jurassic boundary marked the very important extinction event. Plate tectonic activity caused paleogeographic and paleoclimatic change, which triggered mass extinction. During the Early Jurassic the Paleotethys Ocean was finally closed and the Cimmerian continent collided with Asia causing the Cimmerian orogeny. The start of rifting in the Central Atlantic, Gulf of Mexico and Ligurian Tethys also happened during the Early Jurassic and was followed by Middle Jurassic sea-floor spreading. Late Jurassic spreading rifted the Lhasa block from Gondwana. By 160 Ma the inboard terranes of western North America had begun to collide with North America. During the collision and obduction of Stikinia onto the North American craton, terrane material was also obducted onto the Brooks Range Province of Alaska and the Franciscan formation was accreted onto southwestern North America. Cretaceous was the time of the further spreading of Central Atlantic, as well as origin of South Atlantic and Indian Ocean. These events were leading to the maximum dispersion of continents during Phanerozoic times.