Тип бассейна: Платформ
Подтип бассейна: Пассивных окраин (перикратонно-океанический)
Класс бассейна: Периокеанический
Возраст бассейна: Зрелый - Мезозойский
Тип полезных ископаемых:
Геологический возраст начало:
Геологический возраст конец:
Площадь: 76239.87 км²
Ceara Basin
The Ceara Basin is bounded to the east by the Fortaleza High, to the west by the Tutoia High, to the south by basement rocks, and to the north by the RFZ (Figure 1) (Costa et al., 1990). Because of the distinct tectonic character along and across the margin, the Ceara Basin has been divided into four subbasins, from east to west: Mundau, Icaraı, Acarau, and Piauı–Camocim (Figure 1). The Piauı–Camocim is separated from the Acarau subbasin by the Ceara High (Figure 1B). The Acarau and Icaraı subbasins have, as a common limit, the Sobral–Pedro II lineament. In addition, the Icara ́ı is separated from the Mundau subbasin by an important fault in flection (Morais Neto et al., 2003) (Figure 1B).
Figure 1. (A) Map of the northeast Brazilian margin depicting the location of sedimentary basins on the Brazilian equatorial margin (Fozdo Amazonas, Para-Maranhão, Barreirinhas, Ceara, and Potiguar basins), as well as the larger fracture zones in the area. (B) The Ceara Basin is compartmentalized into four subbasins: Piauı–Camocim, Acarau, Icaraı, and Mundau. The study area is located in the Mundausubbasin. The topographic model was provided by the Brazilian Geological Service. The structural data were compiled from Zalan (1985), Silva et al. (1998), and Morais Neto et al. (2003). The basin boundaries were provided by Brazilian National Petroleum Agency and the subbasins boundaries were adapted from Morais Neto et al. (2003). FZ = fault zone.
The tectono-sedimentary evolution of the Mundau subbasin consists of three major megasequences (Beltrami et al., 1994): synrift, transitional, and drift. The synrift phase is characterized by the development of northwest-southeast normal faults forming asymmetric half grabens, and continental sedimentation marked by fluvial–deltaic sandstones and shales of the Mundau Formation, particularly toward proximal parts of the margin (Beltrami et al., 1994) (Figure 2).
Figure 2. Correlation panel among interpreted seismic units (SU), stratigraphic information from the Ceara Basin (Conde et al., 2007), gamma-ray and sonic logs at the Pecem well. MD = measured depth.
The transitional sequence (upper Aptian to lower Albian) is marked by the first marine incursions recorded in subordinate evaporites were also deposited at this stage. These rocks comprise the Paracuru Formation (Costa et al., 1990; Beltrami et al., 1994; Conde et al., 2007) (Figure 2).
The drift or marine megasequence (Albian to Holocene), developed in association with continental drift, records a phase of thermal subsidence on the whole of the BEM. The Ubarana Formation comprises two members (Figure 2). The first one, the Uruburetama Member, corresponds to a marine transgression spanning from the Albian to the Campanian, and predominantly consists of shales. The second member, Itapage Member, correlates with a regressive marine phase developed from Campanian to Eocene, and comprises turbiditic shales and sandstones (Costa et al., 1990; Beltrami et al., 1994; Conde et al., 2007).
The Guamare Formation consists of shelf carbonates, whereas the Tibau Formation comprises proximal sandstones. The clastic continental strata of the Barreiras Formation (Miocene - Holocene) comprises the youngest unit in the basin (Conde et al., 2007) (Figure 2).
Magmatism in the Ceara Basin occurred between the middle Eocene and early Oligocene. It was associated with a mafic event represented by intrusive bodies of basalt and diabase, some of which were sampled in several exploration wells (Conde et al., 2007). Data from K-Ar and Rb-Sr (Mizusaki et al., 2002) indicate that volcanic rocks range in age from the Eocene (44 Ma) on the Ceara High, to the Oligocene (32 Ma) on the Fortaleza High. Locally, near the Xareu field (Figure 2), a diabase provided a K-Ar age at circa 83 Ma, and may be related to the Cuo magmatic event also recorded in the Potiguar Basin and dated as Santonian–Turonian (Conde et al., 2007).
The Mundau subbasin is an oil- and gas-producing basin with four fields in its shallow waters (Xareu, Atum, Espada, and Curimã) (Figure 3). Exploration started in the 1970s and has continued until the present day. In 2012, Petrobras recorded the first deep-water discovery in the Pecem well. According to the Brazilian National Petroleum Agency (ANP), in situ volumes are estimated at
4.9 billion bbl of oil. The region is particularly attractive because it has already established infrastructure for hydrocarbon transport and downstream activities.
Figure 3. Four producing fields (Xareu, Atum, Curimã, and Espada) in the Mundau subbasin. The location of the wells and seismic data (two-dimensional [2-D] and three-dimensional [3-D]) are shown on the bathymetric map. The bathymetric data were provided by the Brazilian Geological Service.
Data source: Tectono-sedimentary evolution and petroleum systems of the Mundau´ subbasin: A new deep-water exploration frontier in equatorial Brazil. Narelle Maia de Almeida, Tiago M. Alves, Francisco Nepomuceno Filho, GeorgeSatander S´a Freire, Ana ClaraBraga de Souza. AAPG Bulletin, v. 104, no. 4 (April 2020), pp. 795–824
Следующий Бассейн: Upper Magdalena Valley