Browsing by Author "Jorge, Raul C. G. S."
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- Detrital zircon U-Pb geochronology of the moatize and n'condédzi coalfields, zambezi karoo basin of Mozambique: implications for provenance, sediment dispersal and basin evolutionPublication . Fernandes, Paulo; Jorge, Raul C. G. S.; Albardeiro, Luís; Chew, David; Drakou, Foteini; Pereira, Zélia; Marques, JoãoDetrital zircon U-Pb geochronology of the Moatize and N'Condedzi coalfields in the Zambezi Karoo Basin of Mozambique provides key insights into the regional provenance, sediment dispersal pathways and basin evolution. Borehole cores from the two coalfields reveal a stratigraphy spanning the early Roadian (middle Permian) to the Carnian (Upper Triassic). The Permian sandstones of the Moatize Coalfield (MC) yield three detrital zircon populations, with ages ranging from 1150 to 950 Ma, 900-780 Ma and 650-490 Ma. In contrast, the Permian sandstones of the N'Condedzi Coalfield (NC) have only one population, which ranges from 1150 to 950 Ma. During the Permian, the provenance area for the NC was the Tete-Chipata Terrane and Malawi Complex (1150-950 Ma) to the north-northeast. In the MC, the detrital zircon populations of the early lake delta depositional setting (Roadian to Wordian) indicate a main provenance in the Zambezi Belt (900-780 Ma) located to the south of the MC, with minor sourcing from the Nampula Block (1150-950 Ma and 650-490 Ma) to the east. The transition from a lake delta to an alluvial depositional setting is attributed to a major tectonic event in the MC, which involved the formation of a braided channel belt. Sandstones from this braided channel belt yield three detrital zircons populations (650-490 Ma, 900-780 Ma and 1150-950 Ma), indicating provenance from both the Zambezi Belt and the Nampula Block. The overlying sandstones in the MC show only a minor population from the Zambezi Belt (900-780 Ma), implying a shift in provenance to the Nampula Block that was likely induced by tectonics. The absence of detrital zircon populations of 900-780 Ma and 650-490 in the Permian sandstones of NC implies that the two coalfields were not connected during the mid to late Permian. It is likely that an intra-rift horst (the Mesoproterozoic Gabbro-Anorthosite Tete Suite) separated the two coalfields. The Lower Triassic sandstones of the NC yield a main detrital zircon population indicating provenance from the TeteChipata Terrane and Malawi Complex (1150-950 Ma). A minor population at 650-490 Ma is linked to increased aridity at the Permian - Triassic boundary, which caused expansion of the watershed across the Tete-Chipata Terrane and the Malawi Complex. The Upper Triassic sandstones in the NC yield a 1150-950 Ma detrital zircon population, indicating provenance from the Tete-Chipata Terrane and Malawi Complex and a return to the source-to-sink conditions seen in the mid to late Permian.
- Late Permian palaeoenvironmental evolution of the Matinde Formation in the Muaradzi Sub-basin, Moatize-Minjova Basin, MozambiquePublication . Lopes, Gilda; Pereira, Zelia; Fernandes, Paulo; Mendes, Marcia; Marques, Joao; Jorge, Raul C. G. S.A multidisciplinary study involving lithofacies analysis, palynofacies, and palynology is presented for the Muaradzi Sub-basin. This sub-basin is part of the Moatize-Minjova Basin (MMB), an important Karoo aged coalfield in Mozambique. A total of 99 core samples from 3 coal exploration boreholes (DW11, DW21, and DW141) were analysed and all the successions were assigned a Lopingian age based on palynology. According to the data, in the Muar ' adzi Sub-basin, a vast lowland fluvial setting existed with floodplains and wetlands, in an area controlled by tectonic movements associated with a continental rifting phase. Typical vegetation of the Glossopteris Province is recorded in the palynological assemblages of this sub-basin, which allowed for the characterization of a flora dominated by glossopterids (Protohaploxypinus and Striatopodocarpites) and gymnosperm pollen (Alisporites). Other palynomorphs revealed the presence of gingkoales, ferns (Filicopsida), sphenopsids, and lycopsids in the area, indicating a typical lowland setting. Humid and warm climates, associated with higher CO2 atmospheric levels, promoted the growth of widespread vegetation that led to the development of the thick coal beds in anoxic to dysoxic depositional environments.
- Reply to "Comment on "Stratigraphy of the Northern Pulo do Lobo Domain, SW Iberia Variscides: A palynological contribution" by Zelia Pereira et al. (2018) - Geobios 51, 491-506"Publication . Pereira, Zelia; Manuel Carvalho Fernandes, Paulo; Matos, Joao X.; Jorge, Raul C. G. S.; Oliveira, Jose T.We acknowledge M. Francisco Pereira, D. Martínez Poyatos, I. Pérez-Cáceres, Cristina Gama and António Azor for the interest shown in our work, and appreciate the chance to clarify a few questions raised by Pereira et al.’s (2018) research. The main aim of Pereira et al. (2018) study was to better constrain the ages of the lithostratigraphic units that make the Northern Pulo do Lobo Domain, SW Iberia Variscides.
- The transition from Pangea amalgamation to fragmentation: Constraints from detrital zircon geochronology on West Iberia paleogeography and sediment sourcesPublication . Dinis, Pedro A.; Fernandes, Paulo; Jorge, Raul C. G. S.; Rodrigues, Bruno; Chew, David M.; Tassinari, Colombo G.Detrital zircon U-Pb geochronology data from late Carboniferous to Triassic clastic sedimentary rocks in SW Iberia were used to investigate the regional paleogeography during the transition from Pangea amalgamation to breakup. The major U-Pb zircon age peaks are middle Devonian to Carboniferous (similar to 390-300 Ma), Cambrian Ordovician (similar to 530-440 Ma), Cryogenian-Ediacaran (similar to 750-540 Ma), Stenian-Tonian (similar to 1.2-0.9 Ga) and Paleoproterozoic (similar to 2.3-1.8 Ga). Rapid exhumation of Variscan crystalline rocks at the contact between the South Portuguese zone and Ossa Morena Zone, explains the abundance of late Paleozoic ages in the upper Carboniferous-lower Permian continental successions. The U-Pb zircon data constrain the maximum depositional age of the Santa Susana Basin to c. 304 Ma and the Viar Basin to c. 297 Ma. The Triassic sequences, despite being c. 100 Ma younger than the Variscan tectonothermal events, contain low proportions of late Paleozoic zircon. The major peaks in all zircon spectra closely resemble those found in the adjacent basement rocks, indicating small source areas, mainly located near the rift shoulders. Longer travelled fluvial systems are postulated for the eastern portions of the Algarve Basin, which was closer to the westward advancing Tethys Ocean than the rift basins of West Iberia. Sequences that contain significant proportions of similar to 1.2-0.9 Ga zircon are probably recycled from post-collisional Carboniferous-Permian continental deposits that were more extensive than those found today. (C) 2017 Elsevier B.V. All rights reserved.