Percorrer por autor "Spina, Amalia"
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- Assessing thermal maturity through a multi-proxy approach: a case study from the Permian Faraghan Formation (Zagros Basin, Southwest Iran)Publication . Spina, Amalia; Cirilli, Simonetta; Sorci, Andrea; Schito, Andrea; Clayton, Geoff; Corrado, Sveva; Fernandes, Paulo; Galasso, Francesca; Montesi, Giovanni; Pereira, Zelia; Rashidi, Mehrab; Rettori, RobertoThis study focuses on the thermal maturity of Permian deposits from the Zagros Basin, Southwest Iran, employing both optical methods (Thermal Alteration Index, Palynomorph Darkness Index, Vitrinite Reflectance, UV Fluorescence) and geochemical analyses of organic matter (Rock Eval Pyrolysis and MicroRaman spectroscopy) applied to the Faraghan Formation along two investigated Darreh Yas and Kuh e Faraghan surface sections. Furthermore, an integrated palynofacies and lithofacies analysis was carried out in order to integrate the few studies on the depositional environment. The Faraghan Formation, which is widely distributed in the Zagros area, generally consists of shale intercalated with sandstones and pebble conglomerates in the lower part, followed by a succession of sandstone, siltstone and shaly intercalations and with carbonate levels at the top. The integrated palynofacies and lithofacies data confirm a coastal depositional setting evolving upwards to a shallow marine carbonate environment upwards. Rock Eval Pyrolysis and Vitrinite Reflectance analysis showed that the organic matter from samples of the Darreh Yas and Kuh e Faraghan sections fall in the mature to postmature range with respect to the oil to gas generation window, restricting the thermal maturity range proposed by previous authors. Similar results were obtained with MicroRaman spectroscopy and optical analysis such as Thermal Alteration Index and UV Fluorescence. Palynomorph Darkness Index values were compared with Rock Eval Pyrolysis and vitrinite reflectance values and discussed for the first time in the late stage of oil generation.
- First record of Permo-Triassic palynomorphs of the N'Condedzi sub-basin, Moatize-Minjova Coal Basin, Karoo Supergroup, MozambiquePublication . Galasso, Francesca; Pereira, Zelia; Manuel Carvalho Fernandes, Paulo; Spina, Amalia; Marques, JoaoPermian-Triassic ages have been identified for the first time in the Karoo Supergroup of the N'Condedzi sub-basin, Moatize-Minjova Coal Basin, Mozambique. This transition was identified in a coal exploration borehole that penetrated the Matinde and Cadzi formations. The top of the Matinde Formation is dated latest Permian (Lopingian), and the Cadzi Formation is attributed to Triassic based on palynostratigraphy. The Lopingian age is established by the identification of three palyno-assemblages: Assemblage L1 based on the first occurrence (FO) of Guttulapollenites pollen, Assemblage L2 is marked by the FO of Thymospora pseudothiessenii, and Assemblage L3 is defined by the FO of Osmundacidites senectus. Triassic palynomorphs were identified for the first time in Mozambique (Karoo basins). The data allowed the identification of three assemblages: Assemblage T1 defined by the FO of Densoisporites nejburgii of Induan age, Assemblage T2 is marked by the FO of Platysaccus queenslandi and assigned to the Olenekian age, and Assemblage T3 is defined by the FO of Samaropollenites speciosus and Enzonalasporites vigens, indicating a Carnian age. No Middle Triassic rocks were identified, and the early Triassic sediments are overlain by sedimentary rocks of Carnian age, a hiatus that may correspond to an important tectonic event with uplift and erosion. This tectonic event is also suggested by the occurrence of common reworked Permian palynomorphs in the Carnian sedimentary rocks. These new data constrain the age of the Karoo Supergroup formations of Mozambique and contribute to improve the palaeoecological, palaeoclimatic evolution, and the palaeogeographic position of the Karoo Mozambique basins within the Gondwana supercontinent. (C) 2019 Elsevier Masson SAS. All rights reserved.
- Thermal history and basin evolution of the Moatize - Minjova Coal Basin (N'Condedzi sub-basin, Mozambique) constrained by organic maturation levelsPublication . Galasso, Francesca; Manuel Carvalho Fernandes, Paulo; Montesi, Giovanni; Marques, Joao; Spina, Amalia; Pereira, ZeliaKerogen concentrates obtained from Lopingian (Late Permian) to Upper Triassic mudrock lithologies of seven coal exploration boreholes, drilled in the Moatize - Minjova Coal Basin (N'Condedzi sub-basin, Mozambique), were studied by means of vitrinite reflectance (VR), spore fluorescence and spore colour, in order to constrain the thermal history and basin evolution by organic maturation levels. VR increases with depth, indicating organic maturation related to sediment burial for most of the boreholes. Modelled VR data indicate a regional palaeogeothermal gradient between 35 and 40 degrees C/km. Lower Jurassic doleritic intrusions observed in three boreholes had only local thermal effects without affecting the regional palaeogeothermal gradient. Two boreholes located near the basin margin show high palaeogeothermal gradients suggesting thermal processes other than heating due to burial were involved. These processes may have involved hot diagenetic fluids circulating through fault zones and/or permeable lithologies, locally elevating geothermal gradients. Circulation of these fluids was induced by lithostatic pressure due to rapid rates of sedimentation. These high sedimentation rates lead to the accumulation of a thick succession (over 2000 m) of Lopingian (Late Permian) to Upper Triassic siliciclastic sediments. All the organic maturation indices measured and the age of the successions indicate that organic maturation occurred during or after Late Triassic times. However, the presence of reworked Permian palynomorphs into Upper Triassic sediments and the absence of Middle Triassic sediments indicate an exhumation and erosion of Permian strata in Middle Triassic times. The organic maturation levels of the reworked palynomorph population are considerably higher than the indigenous Upper Triassic population, indicating that they attained higher burial temperatures prior to being reworked.