| dc.description | Analyses of foraminifera and ostracoda are made from Kimmeridgian-Barremian outcrops in the Lusitanian Basin of Portugal, and wells in the Grand Banks of Newfoundland. In the Praia Azul section, a slightly brackish to marine assemblage of ostracoda including Cytherella, Cytherelloidea and Schuleridea characterize outer lagoon or bay paleoenvironments; associated foraminifera include Everticyclammina, Mesoendothyra, Freixialina and Haplophragmoides. The mesohaline to polyhaline ostracoda Pararanotacythere, Galliaecytheridea and Schuleridea characterize brackish lagoons with local oyster patch reefs; associated foraminifera include Choffatella and Rectocyclammina. Landward of the patch reefs, freshwater influence is indicated by the ostracoda Fabanella, Darwinula and Cypridea; Choffatella is the associated foraminifera. The foraminifera Eoguttulina is ubiquitous to these environments. Classification of the foraminifera on test morphology permits recognition of sub-environments, based on habitat. In the Cabo Espichel section, Choffatella and smaller agglutinated foraminifera are associated with rapid basin subsidance in the early Tithonian, whereas Anchispirocyclina is associated with lower rates of basin subsidence and shallow carbonate sedimentation during the latest Jurassic and early Berriasian. Ostracoda indicate fluctuating marine-brackish salinity. Rapid ostracod speciation in the early Berriasian, combined with opportunistic associations of Anchispiricyclina and Discorbis, may be linked to environmental instability during the Berriasian regression. At Ericeira, smaller agglutinated foraminifera are associated with Berriasian-Hauterivian marginal to non-marine sedimentation. Ammobaculites assemblages indicate river estuary paleoenvironments, whereas Ammobaculites-Trochammina and trochamminid assemblages indicate marsh paleoenvironments. Two biozonations are proposed for the Lusitanian Basin. | en_US |
