Sedimentalogical and stratigraphic analyses of the Lagoa Feia Formation, rift phase of Campos Basin, offshore Brazil

Abstract

AB STRA CT Th e Cam pos Basin is located offshore the State of Rio de Janeiro alo ng the So utheast Brazilian Continental Margi n. It comprises an approx ima te area of 100,00 km 2 up to 3,400 m Isob ath .Th e Lagoa Feia Form at ion comprises mainly the rift phase sediments of the basin. Intense tecto nic activi ty generated normal faulting with a preferential nor theastern direction and great vert ical displacement. Large basalt flo ws. with ages var ying between 120 Ma and 130 Ma, represent the onset of the rift system forming the basement upon which Lagoa Feia form ation sedime nts were depos ited. The lack of marine fossils indicates non-marin e deposition al environments for this formatio n. The forma tion can be subdivided into four deposi tio n seq uences: Basal Clastic Seq uence. Talc-Srevensltic Sequence. Coquinas Seq uence. and Clastic-Evaporitic Seq uence. Sed iments of the three basa l sequences are indicative of typical lacustrine envi ronments. T he prese nce of talc and stevensite clay-minerals. and the diagenetic assemblage of the Coquinas Sequence sugges t that this lake had alkaline brackis h to saline waters. Alluvial fans and their associated facies deve loped o n the weste rn border and adjace nt to o ther highs o f the basin. Sand flat and mud flat facies compose the marginal portions of the lake. while in deepe r waters hydrocarbon generating shales were deposited. T he Coquinas Sequence rep resents an expressive amount o f pelecipo d calcirudi tes, and calcarenites deposits. which no w are important hydrocar bon reservo irs. An impo rtant and regionally widespread ero sional unconformity separates the Coq uinas Sequence of the overlyin g Clastic-Evaporitic Sequence, which is characteri zed by shallo w water sedimentation defined throu gh stro matolitic and nodu lar limestones associated with extensive deposition of alluvial fans. Th e top o f the Lagoa Feia Formation is marked by a thick evapo ritic layer deposited under hot ar id to sem i-a rid cli mate and relative ly stable tectoni c conditions. con nected with the ocea n at the south. RESUM O ANA LISE SE DIMENTOLOO ICA E EST RAT IGRAF ICA DA FORMA<;AO LAGOA FEIA ESTAGtO Ri FfE DA BACIA DE CAMPOS LlTORAL DO BRAS IL. A Bacia de Cam pos esta situada ao longo do lite ral do Es tado do Rio de Janeiro, Brasil. ocupando urna area de ap roximadamente 100.000 km 2 ate a cola batimetrica de 3.400 m. A Formacao Lagoa Feia engloba os sedimentos depositados dura nte 0 estdglo rift e .A intensa atividadc tcctdni ca desta fase provocou falha mentos de direc;ao preferencial NE e de grandes rejeitos verticals. Bxpre ssivos derrames de roc has basdlticas, com idades entre 120 e 130 Ma , marcam os estag los iniciais da fase rlfte, formand o 0 substrato sobre 0 qual se depositaram os sedimentos da Formacao Lag oa Feia. A ausencia de f6ssei s rnarinhos indica urn ambien te de deposicao nao-marinh o para a forma cao. Esta formacao foi subdivid ida em quatro seq u!nc ias deposiclon ais: Seq uencia Clastics Basal. Seq uencia Ta lco-Es tevensltica, Sequencia d...

Influence of Diagenesis On the Quality of Lower Cretaceous Pre-salt Lacustrine Carbonate Reservoirs from Northern Campos Basin, Offshore Brazil

“…The Barremian to Aptian rift stage was characterized by increased lithospheric extension and asthenospheric uplift (McKenzie 1978;White and McKenzie 1988), associated with extensive intracratonic tholeiitic volcanism (Turner et al 1994;Mohriak et al 2008;Torsvik et al 2009). Elongated deep lakes formed parallel to basement lineaments, and were filled with both volcanic and sedimentary rocks (Dias et al 1988;Mizusaki et al 1988). The presence of transfer zones played an important role in the partitioning of the rifted margin in subbasins (Meisling et al 2001;Muniz 2014).…”

“…The Lagoa Feia Group, originally defined by Schaller (1973) as the Lagoa Feia Formation, unconformably overlies pre-rift flood basalts from the Cabiúnas Formation, comprising the nonmarine to transitional sequences from the Campos Basin. Subsequently, the Lagoa Feia Formation has been subdivided into four distinct depositional sequences bounded by unconformities, including: the Basal Clastic Sequence, the Talc-Stevensitic Sequence, the Coquinas Sequence, and the Clastic-Evaporitic Sequence (Dias et al 1988). The last two sequences are separated by the pre-Alagoas unconformity.…”

“…Sag phase deposits from the Macabu Formation were referred to by Dias et al (1988) as carbonate facies consisting of nodular diagenetic limestones and laminated limestones, ''probably algal in origin (stromatolites).'' Later, Dias (2005) interpreted laminites and microbial stromatolites as supratidal and upper-intertidal facies, overlain by lower-intertidal clay-rich facies and subtidal mudstones deposited in an epicontinental context with extensive pre-evaporitic clastics located in shallow proximal regions.…”

Early Cretaceous ostracod biostratigraphy of eastern Brazil and western Africa: An overview

“…14). Their study utilised the stratigraphic partitioning proposed by Dias et al (1988), who subdivided the Lagoa Fig. 12.…”

Morfotectônica de províncias distensionais ativas: implicações para o modelo de preenchimento de bacias tipo rift

“…Lacustrine deposits within other extensional basins in the South Atlantic are often interpreted as marginal deposits influenced by alluvial, carbonate and chemical deposition, intercalated with thin shale units commonly containing mudcracks (e.g. Dias et al, 1988;Milani et a/., 2007;Mohriak et al,2008). lnterestingly enough, the Recôncavo-Tucano-Jatobá rift, which shows deep-lacustrine facies, is the only part of the system that resembles modern linear systems, such as the East Afrícan Rift System and the Baikal Rift, beìng characterized by one continuous area of deposition of more than 42,000 km2, formed by great displacement concentrated on a major master fault in each segment ( figure 4A and 48).…”