Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, Programa de Pós-Graduação em Geologia, 2017. / Submitted by Raquel Almeida (raquel.df13@gmail.com) on 2017-06-20T20:32:49Z No. of bitstreams: 1 2017_CaioGurgeldeMedeiros.pdf: 3878046 bytes, checksum: b71e584315979e5bdda2c93c79ee65eb (MD5) / Approved for entry into archive by Raquel Viana (raquelviana@bce.unb.br) on 2017-06-20T21:41:44Z (GMT) No. of bitstreams: 1 2017_CaioGurgeldeMedeiros.pdf: 3878046 bytes, checksum: b71e584315979e5bdda2c93c79ee65eb (MD5) / Made available in DSpace on 2017-06-20T21:41:44Z (GMT). No. of bitstreams: 1 2017_CaioGurgeldeMedeiros.pdf: 3878046 bytes, checksum: b71e584315979e5bdda2c93c79ee65eb (MD5) Previous issue date: 2017-06-20 / A Formação Solimões compreende uma sucessão siliciclástica intercalada por níveis linhíticos, carbonáticos e ferruginosos, distribuindo-se espacialmente pelo noroeste do Brasil, sudeste da Colômbia e nordeste do Peru. O intervalo sedimentar estudado restringe-se ao Mioceno, sendo atribuído a uma sedimentação fluvial à fluvio-lacustre. A análise do material recuperado da sondagem 1-AS-33-AM, proveniente do Município de Atalaia do Norte, Estado do Amazonas, permitiu a identificação de 12 espécies de ostracodes e um nível de ocorrência de foraminíferos: Cyprideis aff. amazonica, Cyprideis caraionae, Cyprideis aff. graciosa, Cyprideis inversa, Cyprideis machadoi, Cyprideis multiradiata, Cyprideis pebasae, Cyprideis simplex, Cyprideis sulcosigmoidalis, Alicenula olivencae, Rhadinocytherura amazonensis e Perissocytheridea sp. A. Apesar do endemismo das espécies analisadas, foi possível a proposição de um zoneamento bioestratigráfico local em que os 404,15 metros da sondagem foram compartimentados em três biozonas e uma subzona: Biozona Cyprideis caraionae, Biozona Cyprideis multiradiata e Biozona Cyprideis sulcosigmoidalis, além da Subzona Rhadinocytherura amazonensis, inserida na Biozona Cyprideis multiradiata, de posição intermediária. O nível de ocorrência de foraminíferos assinala um evento ecológico local em que se observa o desaparecimento de seis espécies de ostracodes e uma visível alteração no sistema deposicional. Além da análise bioestratigráfica, dados geofísicos e petrográficos foram utilizados na compreensão deste episódio paleoambiental, interpretado como uma mudança ambiental provocada por uma incursão marinha no sistema fluvio-lacustre que dominou a atual região da bacia hidrográfica do rio Amazonas durante Mioceno. A correlação cronoestratigráfica foi realizada com base nas propostas de zoneamento efetuadas com base no material coletado na região fronteiriça entre Brasil, Colômbia e Peru. / The Solimões Formation comprises a siliciclastic succession with intercalated lignite, carbonate and ferruginous levels, spatially distributed throughout the northwest region of Brazil, southeast of Colombia and northeast of Peru. The studied sedimentary interval is restricted to the Miocene, being attributed to fluvial to fluvio-lacustrine sedimentation. The analysis of the material recovered from the 1-AS-33-AM core-drilling, from the Municipality of Atalaia do Norte, State of Amazonas, allowed the identification of 12 species of ostracode and one level of occurrence of foraminifera: Cyprideis aff. amazonica, Cyprideis caraionae, Cyprideis aff. graciosa, Cyprideis inversa, Cyprideis machadoi, Cyprideis multiradiata, Cyprideis pebasae, Cyprideis simplex, Cyprideis sulcosigmoidalis, Alicenula olivencae, Rhadinocytherura amazonensis and Perissocytheridea sp. A. The endemism of the analyzed species allowed the proposal of a local biostratigraphic zonation, in which the 404.15 meters of the core-drilling were compartmentalized in three biozones and one subzone: Cyprideis caraionae biozone, Cyprideis multiradiata biozone and Cyprideis sulcosigmoidalis biozone, in addition to the Rhadinocytherura amazonensis subzone, inserted in the Cyprideis multiradiata biozone, the intermediated one. The level of occurrence of foraminifera indicates a local ecological event in which the disappearance of six species of ostracods and a visible change in the depositional system are observed. In addition to the stratigraphic analysis, geophysical and petrographic data were used to recognize this palaeoenvironmental episode, interpreted as an environmental shift caused by a marine incursion into the fluvio-lacustrine system that dominated the region of the Amazon river basin during Miocene. The chronostratigraphic correlation was performed based on the zoning proposals made based on the material collected in the border region between Brazil, Colombia and Peru.

No description available.

The Bluefield Formation (Chesterian, Upper Mississippian) of the Appalachian Basin is a lithologically variable unit, composed of mudstones lithofacies with subordinate amounts of sandstone and limestone. By analyzing sedimentology and the prominence of ostracodes, an ostracode biofacies model was generated that provides a large-scale paleoenvironmental framework for the Bluefield Formation. Three ostracode assemblages were defined in an effort to identify environmental conditions during deposition of the Bluefield: Assemblage I - Polytylites Assemblage; Assemblage II - Sansabella Assemblage; and Assemblage III - Whipplella Assemblage. The assemblage distributions indicate that nearshore transitional marine environments were common and normal open marine conditions were very rare. The variable units and upward-shallowing sequences in the Bluefield reflect changes in the influx of freshwater that caused salinity fluctuations. Within the depositional environments of the Bluefield Formation, salinity was the most important controlling factor in the ostracode distribution.

Tese (doutorado)—Universidade de Brasília, Instituto de Geociências, Programa de Pós-Graduação em Geologia, 2015. / A bacia de Sergipe-Alagoas, localizada na região Nordeste do Brasil, tem sido alvo de diversos trabalhos em estratigrafia, geoquímica e paleontologia. A Formação Riachuelo, do Aptiano superior-Cenomaniano inferior, corresponde aos primeiros estágios de invasão do proto-oceano Atlântico Sul nesta bacia. A presente revisão da taxonomia de 39 espécies de ostracodes da formação levou à descrição de um novo gênero – Gabonorygma – quatro espécies novas – Praebythoceratina deltalata, Gabonorygma sergipana, Reticulocosta edrianae e Brachycythere smithsoniana. Esta revisão também permitiu a expansão das interpretações paleozoogeográficas e bioestratigráficas atuais sobre a formação, correlacionando-a aos demais ambientes tropicais atlânticos do fim do Eocretáceo. Um novo gênero, Gabonorygma, também é aqui proposto. O estudo taxonômico do Gênero Aracajuia Krömmelbein, 1967 comparado a Amphicytherura Butler & Jones, 1957 e Sondagella Dingle, 1969, bem como de sua espécie tipo, Aracajuia benderi Krömmelbein, 1967, levou a uma detalhada revisão da paleozoogeografia e estratigrafia daquele gênero. Aracajuia foi comum em ambientes marinhos subtropicais, onde teve origem, a tropicais, principalmente em Gondwana, durante o Eocretáceo, onde atingiu sua máxima diversidade no Albiano, ao longo das atuais África, América do Sul e Ásia (Oriente Médio). Novas inferências também são feitas quando comparadas a Província Brasil-África Ocidental Central, onde se insere a presente bacia, às demais regiões ao longo do proto-oceano Atlântico no Eocretáceo. Houve intercâmbio faunístico considerável entre aquela província e regiões no norte de Megatétis a partir do Eoalbiano. Também foram observados influxos limitados ao longo da cordilheira de Walvis, divisa entre os domínios Austral e central do proto-oceano Atlântico Sul. Estes movimentos se deram em ambos os sentidos, tanto de sul para norte (Albiano) quanto em direção contrária (Eocenomaniano). A presença de espécies de Brachycytherinae na Província Brasil-África Ocidental Central, logo no Aptiano, representa uma nova origem geográfica para esta subfamília, e ao mesmo tempo ajuda a explicar a presença do mesmo tanto em regiões austrais e no norte de Megatétis durante o Albiano. O arcabouço estratigráfico baseado em ostracodes do Albiano da bacia também foi reavaliado, e uma série de mudanças nomenclaturais e de zoneamento foi proposta: a Zona OSE-1, bem como as subzonas OSE-1.1, OSE-1.3 e OSE-1.4 tiveram seus nomes alterados, tanto para espécie guia quanto para codificação (respectivamente, MSA-0, MSA-0.1, MSA-0.3 e MSA-0.4); as duas últimas também foram alteradas em sua extensão e definição do contato. A Subzona OSE-1.2 teve seu estratótipo definido, limite inferior modificada (Albiano inferior para Aptiano superior) e código alterado para MSA-0.2, enquanto OSE-1.5 foi apenas renomeada MSA-0.5. Uma nova zona diferencial superior, Aracajuia antiqua (MSA-1), posicionada no Albiano mais superior, foi criada a partir da revisão taxonômica da espécie guia da Subzona OSE-1.6. / The Sergipe-Alagoas basin, located in northeastern Brazil, has been subject of several studies in stratigraphy, geochemistry and paleontology. The Riachuelo Formation, upper Aptian-lower Cenomanian, corresponds to the first stages of the southern proto-Atlantic ocean invasion in that basin. The present taxonomic review of 39 ostracods species of the formation led to the description of a new genus – Gabonorygma – and four new species – Praebythoceratina deltalata, Gabonorygma sergipana, Reticulocosta edrianae and Brachycythere smithsoniana. This review also heped to expand the current paleozoogeographic and biostratigraphic interpretations of the formation, correlating it to the other Atlantic tropical environments from the end of the Early Cretaceous. A new genus, Gabonorygma, is also herein proposed. The taxonomic study of the genus Aracajuia Krömmelbein 1967 compared to Amphicytherura Butler & Jones, 1957 and Sondagella Dingle, 1969, as well as its type species, Aracajuia benderi Krömmelbein, 1967 led to a detailed review of that genus’ paleozoogeography and stratigraphy. Aracajuia was common in subtropical, where it originated, marine environments to tropical, especially in Gondwana during the Early Cretaceous, where it reached its maximum diversity in the Albian, along the current Africa, South America and Asia (Middle East) continents. New inferences are also made when comparing the Brazil-Central West Africa Province, which includes this basin, to other regions along the proto-Atlantic Ocean in the Early Cretaceous. There was considerable faunal exchange between that province and regions in northern Megatethys, starting in the Early Albian. Limited inflows were also observed along the Walvis ridge, which separates austral from central areas of the Southern proto-Atlantic Ocean. These migrations took place in both directions, both from south to north (Albian) and in the opposite direction (Early Cenomanian). The presence of Brachycytherinae species in Brazil-Central West Africa Province, already in the Aptian, sets a new geographical origin for this subfamily, while helping to explain their presence in both southern and northern regions of Megatethys during the Albian. The stratigraphic framework based on ostracods of the Albian of the basin was also reassessed, and some nomenclatural changes and new zones were proposed: the OSE-1 Zone and the OSE-1.1, OSE-1.3 and OSE- 1.4 sub-zones had their names changed, both their guide species and codification (MSA-0, MSA-0.1, MSA-0.3 and MSA-0.4, respectively); the last two were also altered in its extent and contact definition. The OSE-1.2 Subzone had its code changed for MSA-0.2; also, a stratotype was stablished for it, and its lower limit repositioned in time (from early Albian to upper Aptian). The OSE-1.5 Subzone was solely renamed MSA-0.5. A new latest occurrence interval zone, Aracajuia antiqua (MSA-1), from the uppermost Albian interval, was created after taxonomic review of the OSE-1.6 Subzone guide species.

Στην παρούσα εργασία εξετάστηκαν τα πανιδικά σύνολα μικροαπολιθωμάτων με την χρήση 8 δειγμάτων που αποτελούνται από ιζήματα Κάτω πλειστοκαινικής ηλικίας τα οποία συλλέχτηκαν από τμήμα της θέσης 2 της λεκάνης Σουσακίου. Κατά τη μελέτη προσδιοριστήκαν σε επίπεδο είδους, 4 είδη οστρακωδών, 2 είδη τρηματοφόρων και 3 είδη θυσανόποδων, τα οποία χρησιμοποιήθηκαν ως παλαιοοικολογικοι δείκτες για την παλαιοοικολογική και παλαιοπεριβαλλοντική εξέλιξη της ευρύτερης περιοχής του Σουσακίου. / In this study we document microfossil units mostly ostracode assemblages in samples taken from an artificial section of Pleistocene marly sediments, in the tectonically active Sousaki basin in Southern Greece,to enhance palaeoenvironmental reconstructions.

Στην παρούσα εργασία εξετάστηκαν τα πανιδικά σύνολα μικροαπολιθωμάτων με την χρήση 9 δειγμάτων που πάρθηκαν από ιζήματα Πλειστοκαινικής ηλικίας, και συλλέχθηκαν σε μία τομή που βρίσκεται ΒΔ των Αγίων Θεοδώρων και ανήκει στην ευρύτερη λεκάνη Σουσακίου. Κατά τη μελέτη προσδιορίστηκαν σε επίπεδο είδους όπου αυτό ήταν εφικτό, οστρακώδη, τρηματοφόρα, γαστερόποδα και δίθυρα. Τα δεδομένα αυτά χρησιμοποιήθηκαν ως δείκτες για την παλαιοοικολογική και παλαιοπεριβαλλοντική εξέλιξη μέρους της λεκάνης Σουσακίου. Προέκυψε ότι η ιζηματογένεση πραγματοποιήθηκε σε δύο λεκάνες ιζηματογένεσης, μια ρηχής θαλάσσιας προέλευσης και μια λιμνοθαλάσσιας . Οι δύο αυτές ακολουθίας ήρθαν σε επαφή μέσω της τεκτονικής. / In this project, the microfossil fauna of 9 samples were studied. The sedimentary sequence is of Pleistocene age and the samples were selected within a stratigraphic sequence located NW of Ag. Theodoroi village. These sediments are part of the sedimentary sequence of Sousaki basin. Ostracodes, Foraminifera , Gastropods and Bivalves were udentified. These data were used to reconstruct the palaeoecological and palaeoenvironmental evolution of part of the Sousaki basin. The sediments were deposited in two basins, one marine and one lagoonal. These two basins are in contact through tectonics.

Since the seminal works of Wegener and Darwin the notion that things evolve, and the how and the why of it, has generated intense debate. The surface of the Earth, and the creatures that live on it, are not static entities. Landscapes evolve. Organisms evolve. Understanding the how and the why requires a firm understanding of a myriad of interdependent and complex variables such as (but not limited to) climate, ecology, and tectonics. Unravelling the complexities though which landscapes and ecosystems evolve requires a broad interdisciplinary approach, where multiple investigative tools are simultaneously brought to bear on a given question. The study of old lake sediments, or paleolimnology, is a marquee example of a powerful interdisciplinary methodology that has been used extensively in reconstructing the Earth's past. This work showcases two examples where the discipline of paleolimnology advances our understanding of evolution on a landscape scale and on a human scale. In the southwestern United States, a record of the processes involved during the late Miocene and early Pliocene (~ 5 Ma) evolution of a major continental river drainage - the Colorado River – is partially preserved along the southern border of Arizona and California as the enigmatic Bouse Formation. And in southern Kenya, nearly 170 meters of lake and wetland sediments that have accumulated in the Koora Plain preserve a one-million-year long record of the environmental conditions against which our species, Homo sapiens, evolved. My research allows me to conclude that the depositional environment of the Bouse Formation was lacustrine; a fully marine interpretation that has been previously proposed is untenable. I also demonstrate that over the past 1.0 Ma, Homo sapiens in southern Kenya evolved against a backdrop of increasing regional aridity.

The Térapa fossil vertebrate site, northcentral Sonora, Mexico, provides a rare opportunity to study the paleoenvironmental conditions present in northwestern Mexico during mid-Oxygen Isotope Stage (OIS) 3. Ostracode faunal assemblages and stable oxygen (δ18O) and stable carbon (δ13C) isotope values from ostracode calcite were used to reconstruct the seasonality of precipitation and vegetation cover at Térapa at 40-43 ka. The ostracode fauna was a non-analogue mix of temperate and tropical ostracode species composed of 13 species from 12 genera. The nearctic ostracodes Fabaeformiscandona caudata, Physocypria pustulosa, Cypridopsis vidua and the cosmopolitan ostracode Darwinula stevensoni dominate the assemblage. Two tropical ostracode genera, Chlamydotheca arcuata and Stenocypris sp., were present throughout the deposit and indicate that mean monthly summer temperatures were probably no more than 4°C to 6°C cooler than at present, based on available ecological information. Winter precipitation dominated the hydrologic cycle as evidenced by low ostracode δ18O values (-6‰ to -8‰ VPDB). Low ostracode δ13C values (-7‰ to -8‰ VPDB) suggest that local vegetation was dominated by C3 plants. A previous tooth enamel-based paleoenvironmental reconstruction at the same site favored a summer-dominated or evaporative hydrology and abundant C4 vegetation. The Térapa megafauna site exemplifies the need for multi-indicator paleoclimate reconstructions in desert environments where marked differences in the seasonality of precipitation and vegetation cover may occur.

Channing Lake Basin, located west and northwest of Channing, in the Texas Panhandle, is of substantial area and presumably includes lake beds of Pliocene and Pleistocene ages within the Rita Blanca Formation, a member of the Ogallala Group. The foci of this study were a micritic ooid layer and a directly overlying stromatolite layer, which crop out in a canyon approximately 10 kilometers west of Channing. Research was conducted primarily using petrographic and scanning electron microscopy. Significant conclusions include: organic matter was preserved in ooids as filaments and nanoscale spheroids, which served to capture ostracode carapaces within ~10% of micritic cortices; and stromatolites were deposited within an evolving alkaline lacustrine environment producing discernible zones. Potential significance includes improving the understanding the role of organic matter in calcium carbonate precipitation, which has plausible applications in medical, industrial, and academic realms.

African climate changed considerably throughout the Pleistocene (2.588 million (Ma) to 12 thousand years ago (ka)). The timing, rate, and magnitude of past climate change across the continent impacted the evolutionary and migratory history of many mammalian species, including hominins. Investigating paleoclimatic variability through time at local and regional scales allows for an assessment of the extent to which climate change affected hominin evolution in Africa. This dissertation presents three approaches for increasing the understanding of past climate change in Africa. One method is to critically synthesize the existing literature of African climate (n=85) and hominid demography (n=64) over a restricted time frame (150 ka to 30 ka) and specific spatial scale (regional). Results from this study are two-fold: 1) climate change in Africa during this period was variable by region, responding to different climate-forcing mechanisms, and 2) changes in population and climate were asynchronous and likely created alternating opportunities for migration into adjacent regions, including hominin migrations out of Africa (~140-80 ka). The second approach is to evaluate modern ecological relationships between species and their environment to better quantify interpretations of paleoecological records. A modern distribution study of 33 ostracode species from 104 sites in the southwest arm of Lake Malawi suggest that depth-dependent variables likely define species niches. Relationships between ostracodes, fish and the green algae Botryococcus, were used to inform the paleoecological interpretations in the third study of this dissertation. Additional results suggest that macrocharcoal is likely delivered to the lake basin via river rather than wind-borne methods. The third approach involves primary analysis of climatic indicators from the sedimentary record to chronicle paleoecological and paleoenvironmental change at the basin scale through time. Results from a 380.7 meter-long sediment core recovered from Lake Malawi indicate a change of state likely caused by local tectonism, which affected ostracode assemblages, but had little effect on lake level history through time. Furthermore, the local hydroclimate of Lake Malawi alternately covaried with global glacial/interglacial cycles and local insolation maxima over the past 1.25 Ma. The magnitude and frequency of hydroclimatic variability in the watershed will be further assessed in future research.