The Main Karoo Basin of South Africa is renowned for its exceptional palaeontological record and while its vertebrate fossils have been extensively researched, Karoo floras have received considerably less attention. Poor yields of palynomorphs from the Beaufort and “Stormberg” groups have complicated the task of erecting a comprehensive palynozonation scheme for the Karoo Supergroup. For this study, 65 palynologically productive samples from the Dwyka, Ecca, Beaufort and “Stormberg” groups allowed for systematic descriptions of all palynomorphs, as well as the ranges of the different taxa through the entire Karoo stratigraphic succession. Taxa with restricted ranges are useful for biostratigraphic correlation and these palynomorphs were used to delineate microfloral zones for the Karoo basin. The Dwyka Group contains high numbers of acritarchs and is generally low in species diversity. Useful biostratigraphic taxa for the Ecca Group include Cannanoropollis, Hamiapollenites, Platysaccus and Striatopodocarpites. Aratrisporites is a marker for the Latest Permian / Early Triassic Beaufort Group, while Cyathidites, Dictyophyllidites, Equisetosporites and Uvaesporites are indicators of the Late Triassic / Early Jurassic “Stormberg” Group. Palynostratigraphic zones correlate largely with the Karoo vertebrate biozones and severe and sudden extinction events are recognised among Karoo palynomorphs in the upper Tapinocephalus and Dicynodon assemblage zones. The first comprehensive palynological biozonation scheme for the Main Karoo Basin is proposed and the study provides a broad overview of Gondwanan Carboniferous - Jurassic floras. This study demonstrates that palynology is useful in correlating age equivalent lithostratigraphic units in the proximal and distal sectors of the Karoo Basin. Microfloras from previous South African studies are integrated within the proposed palynostratigraphic scheme, and palynological signatures of the various Karoo formations are shown to be consistent. Despite the constraints of floral provincialism, South African microfloras can be correlated to selected Gondwanan biozonations from Australia, Africa, Antarctica, New Zealand and South America. Future studies should focus on sampling more intensively over smaller stratigraphic intervals, which will assist in the correlation of time equivalent lithostratigraphic units in the different sectors of the basin, thus aiding in refinement of basin development models. Key words: palynology, Karoo, vertebrate biozones, stratigraphy, Gondwana

Orientadores: Ticiano José Saraiva dos Santos, Eberhard Wernick / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-19T20:14:18Z (GMT). No. of bitstreams: 1 Zincone_Stefano_M.pdf: 16857590 bytes, checksum: 4b0636005af48882fc3aafbbe07b1745 (MD5) Previous issue date: 2011 / Resumo: A evolução magmática na porção norte da Província Borborema (NPB) está relacionada a amalgamação de Gondwana Ocidental e reflete parte do fechamento do paleo-oceano Farusiano, a subdução de litosfera oceânica, acresção de blocos continentais (Granja e Ceará Central-Rio Grande do Norte), colisão continental (cratons Amazonas, São Luiz- W. Africa e São Francisco-Congo) e magmatismo pós-orogênico. Esta evolução é sumarizada em cinco fases magmáticas que se interrelacionam com a trama estrutural-tectônica. A Fase Magmática Santa Quitéria (FMSQ) (658-606 Ma) é pré- a sin- empurrão e reúne três unidades magmáticas, todas fatiadas, deformadas e deslocadas por falhas inversas do Cinturão de Cavalgamento Ceará Central: (i) magmatismo félsico de monzogranito megaporfirítico, metaluminoso, magnesiano, cálcio-alcalino alto-K e shoshonítico, e que possui enclaves diorítico de afinidade shoshonítica e ultrapotássica; ii) magmatismo intermediário de clinopiroxênio hornblenda monzodioritos a monzogranitos melanocráticos, equigranulares, geneticamente relacionados a unidade félsica; iii) magmatismo máfico constituído por enclaves gabróicos esparsamente encontrados ao longo do Batólito Santa Quitéria (BSQ) e pelo complexo máfico de Malhada Grande, caracterizado por olivina gabro, afetado por metamorfismo sub-solidus de fácies granulito, cuja origem se relaciona a trinca da laje oceânica subduzida e consequente ascensão da astenosfera. A Fase Magmática Tamboril (FMT) é tardi- empurrão a sin- transcorrência e compreende duas unidades, sendo uma epizonal de granitos equigranulares rosa, ferroso, cálcio-alcalina de alto-K e shoshonítico e outra de migmatitos de injeção, cujas morfologias são controladas pela estrutura e composição das rochas invadidas, número de injeções e distância entre o pluton magmático e as rochas encaixantes. A FMT transgride o limite do BSQ e afeta o embasamento proterozóico e arqueano. A evolução magmática procede com as Fases Magmáticas Quixeramobim (FMQ), Seridó (FMS) e Bimodal Final (FMBF). A FMQ é controlada pela implantação (ca. 580 Ma) e reativação (ca. 530 Ma) das zonas de cisalhamento transcorrente. A FMS (ca. 520 Ma) corresponde ao magmatismo residual pegmatítico e a processos metassomáticos de alterações hidrotermais e pneumatolíticas, que culminaram na transformação de gabros em rochas calciossilicáticas, mineralizações e desvolatização da crosta continental espessada. Por fim, a FMBF (ca. 470 Ma) representa o magmatismo pluto-vulcânico, bimodal de alta temperatura, que está relacionada à implantação de calderas vulcânicas, complexos anelares e diques hipoabissais, originados em regime extensional sob litosfera continental cratônica e temporalmente associada à deposição dos primeiros estratos da Bacia do Parnaíba. Os dados isotópicos de Nd indicam que a gênese da FMSQ e FMT ocorreu pela mistura de um componente mantélico juvenil com rochas crustais em processo de interação manto-crosta. A FMQ e FMBF mostram maior sobreposição isotópica com as rochas do embasamento circundante, sugerindo processos de fusão intracrustal com menores incursões mantélicas. Os dados Nd de rochas do Arqueano ao Ordoviciano do NPB refletem a variação sistemática das características isotópicas em segmentos crustais sucessivamente mais jovens, que resulta na diferenciação progressiva e irreversível do fracionamento mantélico e crustal, assim como o aumento da diversidade e complexidade do componente crustal através do tempo / Abstract: The magmatic evolution observed in the northern Borborema Province (NBP) is related to West Gondwana amalgamation and reflects part of the closure of the paleocean Pharusian, subduction of oceanic lithosphere, accretion of cratonic blocks (Granja and Ceará Central-Rio Grande do Norte), continental collision (Amazonia, São Luiz-W. Africa, São Francisco-Congo), and post-orogenic magmatism. This evolution is summarized in five magmatic stages, which are interrelated with the development of the structural-tectonic fabric. Santa Quitéria Magmatic Stage (SQMS) (658-606 Ma) is pre- to syn- thrust and comprises three magmatic units, all sliced, displaced and deformed by reverse faults of Ceará Central Thrust Belt: (i) felsic unit represented by high-K calc-alkaline and shoshonite megaporphyritic monzogranites of metaluminous and magnesian affinity, associated to dioritic enclaves of shoshonite and ultrapotassic series; (ii) intermediate unit of equigranular, melanocratic monzodiorites to monzogranite with clinopiroxene and hornblende, which is genetically correlated with the felsic unit; the main textural feature corresponds to gabbro-diorite micro enclaves of shoshonite series; (iii) mafic unit consists of gabbroic enclaves sparsely found along the Santa Quitéria Batholith (SQB) and the mafic complex of Malhada Grande, which is composed of olivine gabbro affected by sub solidus metamorphism at granulite facies. The origin of this complex is interpreted as related to slab tearing and rise of the asthenosphere. Tamboril Magmatic Stage (TMS) is late thrust to syn transcurrence and comprises two units: an epizonal equigranular pink granitic unit of high-K calc-alkaline and shoshonite series of ferroan affinity and an injection migmatite unit whose morphologies are controlled by structure and composition of host rock, the distance of intrusive suite and the number of successive injections. The TMS transgress the limits of SQB and affects the Archean and Proterozoic basement. The magmatic evolution proceeds with Quixeramobim Magmatic Stage (QMS), Seridó Magmatic Stage (SMS) and Final Bimodal Magmatic Stage (FBMS). QMS is controlled by the onset (ca. 580 Ma) and reactivation (ca. 530 Ma) of transcurrent shear zones. SMS (ca. 520 Ma) corresponds to residual pegmatite magmatism and metassomatic process associated to hydrothermal and pneumatolytic alteration, which culminated in the transformation of gabbro to calc-silicate rocks and mineralization in a devolatized thickened continental crust. FBMS (ca. 470 Ma) represents the plutono-volcanic, bimodal, high temperature magmatism related to caldera volcanoes, ring complex and subvolcanic dyke swarms on extensional environment on the cratonic lithosphere, which is temporally associated with deposition of the first sediments of the Parnaíba Basin. Nd isotopic data indicate that the genesis of SQMS and TMS corresponds to a mixture of a juvenile mantle component and older crustal rocks during a process of mantle crust interaction. SMS and FBMS show isotopic overlapping with surround basement rocks, suggesting intracrustal melting with less mantle incursions. Nd data for Archean to Ordovician rocks of NBP reflect the evolution of continental crust and show a systematic change of isotopic characteristics at successively younger crustal segments, which must reflect the irreversible progressive mantle fractionation and the increasing diversity and complexity of the crustal component trough time / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências