Paleolimnological reconstruction of a marginal area of Jurassic Capianga Lake, Jatobá Basin, northeast Brazil

• Published in: Journal of paleolimnology Vol. 63; no. 2; pp. 113 - 128
• Main Authors: Guzmán-González, Juliana, Sial, Alcides N., Piovesan, Enelise Katia, Oliveira, Edison Vicente, Fambrini, Gelson Luís
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.02.2020; Springer Nature B.V
• Subjects: Alicenula; Area; Bedding; Carbonates; Climate Change; Earth and Environmental Science; Earth Sciences; Flooding; Freshwater; Freshwater & Marine Ecology; Geology; Gondwana; Hydrology; Inland water environment; Isotopes; Jurassic; Lake basins; Lakes; Lithofacies; Littoral environments; Littoral zone; Mesozoic; Original Paper; Paleontology; Physical Geography; Ripple marks; Sedimentary rocks; Sedimentology; Stable isotopes; Structural basins; Variation; Brazil; Gondwana; Aliança formation; Ostracodes; Biogenic carbonate; Stable isotopes; Jatobá Basin; Paleolimnology
• ISSN: 0921-2728; 1573-0417
• DOI: 10.1007/s10933-019-00105-0

The Aliança Formation, within the Brazilian Recôncavo–Tucano–Jatobá Rift System, is a succession of Late Jurassic sedimentary rocks that record the maximum flooding surface of shallow Capianga Lake in the Afro-Brazilian Depression, Gondwana. Several aulacogens and drift-marginal Mesozoic basins of eastern Brazil and western Africa recorded the great extensional event that occurred during the early stage of Gondwana break-up. Lithologic, petrographic, micropaleontological and geochemical analyses of lacustrine carbonates collected near the city of Ibimirim, Pernambuco State, were carried out to establish the paleolimnological evolution of a marginal area of Capianga Lake, in the Jatobá Basin. The ostracode fauna, obtained from grainstone and calcareous quartzarenite, is constituted by Theriosynoecum pricei , Theriosynoecum uninodosa , Theriosynoecum quadrinodosum , Reconcavona ? jatobaensis and Alicenula ? spp. Carbon and oxygen stable isotopes in bulk rock, Theriosynoecum pricei and Alicenula ? spp. were measured. Theriosynoecum pricei displays the most negative δ 13 C values, between − 2.1 and − 1.3‰. The δ 13 C values obtained from Alicenula ? spp. and bulk rock were also negative. The δ 18 O values for Theriosynoecum pricei range from − 10.1 to + 4.1‰. Alicenula ? spp. show δ 18 O values between − 4.6 and + 5.8‰. The bioclastic character of the carbonates and the presence of cross-bedding and ripple marks suggest deposition in a low-energy, low-gradient, ramp-type littoral zone of a shallow, balanced-fill lake. The ostracode association, characteristic of permanent, alkaline, freshwater bodies, corresponds to the Theriosynoecum pricei ostracode biozone, which is of Tithonian age. The lithofacies, along with covariation of δ 13 C and δ 18 O, and large δ 18 O fluctuations, suggest that this marginal area of Capianga Lake was characterized by stable hydrological conditions in a closed basin. The δ 13 C values display a slightly narrower range, suggesting oligotrophic to slightly mesotrophic conditions, and holomixis in this marginal area of Capianga Lake.