During the Early Cretaceous a regionally extensive cover of dominantly siliciclastic sediments was deposited across the North African continental margin. Historically, these siliciclastic sediments have been considered to be a relatively homogeneous lithofacies known as the ‘Nubian sandstone’. This lithofacies is generally described as coarse grained, cross-bedded sandstone and is ascribed to a braided fluvial depositional environment. However, there have been few detailed sedimentological studies carried out on these sediments. Furthermore, the stratigraphic relationships between regional Early Cretaceous continental strata in different North African countries has only briefly been described and has only locally been related to equivalent marine deposits. In order to address these problems, this study focuses upon two main approaches. Firstly, outcrop analysis of the Messak Fm (SW Libya) and the Sidi Aïch Fm (C Tunisia) details and contrasts the lithofacies variability of Early Cretaceous siliciclastic sediments in North Africa. Secondly, a unified stratigraphic framework is erected for the Early Cretaceous of Algeria, Tunisia, Libya and Egypt and the palaeogeographic evolution is reconstructed. Detailed sedimentological investigation of the Messak Fm has identified greater variation in lithofacies and depositional processes than was previously recognised. By lithostratigraphic correlation with outcrops in northwest Libya, we show a fluvial system transported sediment northward into a wide fluvio-paralic basin covering western Libya. Several episodes of marine influence culminating in a distinct and regionally correlatable transgressive episode are identified. This is the first time that marine influence has been identified in the Murzuq Basin and increases the maximum known extent of marine transgression in the Early Cretaceous of Libya by 600km. The sedimentology of the Messak Fm is contrasted with the sandstone dominated Sidi Aïch Fm which, although showing similar lithofacies, was deposited in a marginal-shallow marine environment.Building upon previous reviews and new insights from the Messak Fm and Sidi Aïch Fm, a synthesis and reinterpretation of the spatial and temporal heterogeneity of sediments and depositional environments in this region throughout the Early Cretaceous is presented. During the Berriasian-Barremian, the North African platform coastline was dominated by a dry subtropical climate with moderate vegetation. The interior of the platform experienced a Savannah-like semi-arid climate with limited vegetation and palaeosol development but was crossed by extensive fluvial networks draining the equatorial tropics. During the Late Barremian-Early Aptian, simultaneous aridification and marine transgression led to a decreased detrital flux to the marginal basins and widespread deposition of marine carbonates and mudstones. During the Late Aptian-Albian the platform returned to a humid tropical climate. Widespread coarse grained fluvial sediments mark the base of this sequence and palaeosols occur locally. The results of this work have implications for the development and controls of large-scale fluvio-paralic systems and illustrate the fact that, in a limited accommodation epicontinental setting, relative sea-level may be the key control on sedimentation and depositional processes for many hundreds of kilometres inland of the lowstand coastline.

At the Castle Creek study area, levee deposits are well-exposed over an area of ~2.6 km wide and ~90 m thick. This provides an opportunity to describe their lateral and vertical lithological changes, and accordingly details about their reservoir geometry and stratal continuity. Here, levee deposits are divided vertically into packages, each consisting of a sand-rich lower part overlain sharply by a mud-rich upper part. Each lower part displays a consistent thickening then thinning trend laterally away from its genetically related channel. The characteristics of these packages suggest that they were controlled by recurring changes in the structure of channellized flows, which in turn was controlled by grain size and grain sorting. This ultimately was controlled by short-term changes in relative sea level. Moreover, some mud- and sand-rich strata are rich in residual carbon suggesting that mid-fan levees can serve as source rocks for hydrocarbon generation, and also reservoirs.

This paper describes the Mississippian. Exshaw, Banff and Rundle units, a remnant of ? Pennsylvania strata and cherty sandstones of the Permian Ishbel Group; paleontological details include information on the megafossils, foraminifers and algae. The Exshaw Formation includes a sanidine bearing tuffaceous sandstone. The Banff was subdivided into four rock units - Basal Shale, Cherty Unit, Crinoidal Unit and Upper Unit. The Rundle Group was divided into the Pekisko, Shunda, Turner Valley and Mount Head Formations. The term Jasper Lake Formation is applied to a sequence of crinoidal biosparites and dolomites at the South Berland River section which are bank-marginal lateral equivalents of eastern Shunda micrites. The Mississippian rocks of the three stratigraphic sections upon which this study is based are assigned to eight main petrographic facies and six petrographic subfacies. Facies A - calcisiltite: argillaceous crinoidal biomicrite and associated calcareous shales Facies B - an interbedded sequence offacies A and B Facies C - calcarenite: argillaceous crinoidal biomicrite Facies D - calcarenites: crinoidal biosparite Subfacies Da - calcarenite: ‘mature’ crinoidal intrasparite Subfacies Db - calcarenite: intraclast bearing crinoidal biosparite Facies E - oolitic and/or grapestone bearing calcarenites Subfacies Ea - fossiliferous intraclast bearing oosparite Subfacies Eb - intrasparites and sparry intramierites; four lithotypes are recognized (1) oolitic micritic crinoidal intrasparite (2) grapestone bearing intrasparite (3) oolite bearing partially merged intrasparite (4) grapestone and oolite bearing, sparry intramicrite Facies F - pure limestone micrites Subfacies Fa - crinoidal micrite Subfacies Fb - micrites, pelsparites, pelmicrites and dismicrites Facies G - unfossiliferous micrograined dolomite, commonly with microbedding Facies H - dolomite breccias The progression through the facies and subfacies from A to H reflects a change in depositional environment from that of normal marine deep quiet waters to lagoonal and evaporitic conditions; modern sedimentation of the Bahama Banks is used as a partial model. The facies distribution pattern for the Rundle carbonates of the area shows a tendency toward lagoonal facies in the east (Mturtm Creek section), bank-marginal facies in the west (South Berland River section) and intermediate facies at the Eagles Nest Pass section. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

D.Phil. / The tectonic history of the Kheis Terrane and its relationship with the Namaqua-Natal Metamorphic Province (NNMP) along the western margin of the Kaapvaal Craton were the focus of this study. Major issues addressed in this study are the origin and timing of formation of the Kheis Terrane and the recognition and definition of terrane boundaries in the area. Results of detailed measured sections across the Kheis Terrane, heavy mineral provenance studies, 40Ar/39Ar analyses of metamorphic muscovite, U-Pb SHRIMP dating of detrital zircon grains from 12 samples from the Kheis- and Kakamas Terranes and one igneous body from the Kakamas Terrane are presented. A new stratigraphic unit, the Keis Supergroup, comprising the Olifantshoek-, Groblershoop- and Wilgenhoutsdrif Groups, is defined. The base of the Keis Supergroup is taken at the basal conglomerate of the Neylan Formation. The Mapedi- and Lucknow Formations, previously considered part of the Olifantshoek Group, are now incorporated into the underlying Transvaal Supergroup. The Dabep Fault was found not to represent a terrane boundary. Rather, the Blackridge Thrust represents the boundary between the rocks of the Kheis Terrane and the Kaapvaal Craton. Provenance studies indicate that the rocks of the Keis Supergroup were deposited along a passive continental margin on the western side of the Kaapvaal-Zimbabwe Craton with the detritus derived from a cratonic interior. Detrital zircon grains from the rocks of the Keis Supergroup of the Kheis Terrane all gave similar detrital zircon age populations of ~1800Ma to ~2300Ma and ~2500Ma to ~2700Ma. The Kaapvaal Craton most probably never acted as a major source area for the rocks of the Keis Supergroup because of the lack of Paleo- to Mesoarchean zircon populations in the Keis Supergroup. Most of the detrital zircon grains incorporated into the Keis Supergroup were derived from the Magondi- and Limpopo Belts and the Zimbabwe Craton to the northeast of the Keis basin. The rock of the Kakamas Terrane was derived from a totally different source area with ages of ~1100Ma to ~1500Ma and ~1700Ma to ~1900Ma which were derived from the Richtersveld- and Bushmanland Terranes as well as the ~1166Ma old granitic gneisses ofthe Kakamas Terrane. Therefore the rocks of the Kheis- and Kakamas Terranes were separated from each other during their deposition. Detrital zircon populations from the Sprigg Formation indicate that it this unit was deposited after the amalgamation of the Kheis- and Kakamas Terranes and therefore does not belong to the Areachap Group. Results provide clear evidence for a tectonic model characterised by the presence of at least two Wilson cycles that affeected the western margin of the Kaapvaal Craton in the interval between the extrusion of the Hartley lavas at 1.93Ga and the collision with the Richtersveld tectonic domain at ~1.13Ga. According to the revised plate tectonic model for the western margin of the Kaapvaal- Zimbabwe Craton, the Neylan Formation represents the initiation of the first Wilson Cycle, with rifting at ~1927Ma ago, on the western margin of the Kaapvaal-Zimbabwe Craton. The metasedimentary rocks of the Olifantshoek Group were deposited in a braided river environment which gradually changed into a shallow marine environment towards the top of the Olifantshoek Group in the Top Dog Formation. The metasedimentary rocks of the Groblershoop Group were deposited in a shallow, passive or trailing continental margin on the western side of the Kaapvaal-Zimbabwe Craton. The rocks of the Wilgenhoutsdrif Group overlie the Groblershoop Group unconformably. This unconformity is related to crustal warping as a volcanic arc, represented by the metavolcanics of the Areachap Group, approached the Kaapvaal-Zimbabwe Craton from the west. The rocks of the Keis Supergroup were deformed into the Kheis Terrane during the collision of the Kaapvaal-Zimbabwe Craton, Areachap Arc and the Kgalagadi Terrane to form the Kaapvaal-Zimbabwe-Kgalagadi Craton. This event took place sometime between 1290Ma, the age of deformed granites in the Kheis Terrane and 1172Ma, the initiation of rifting represented by the Koras Group. This is supported by 40Ar/39Ar analyses of metamorphic muscovite from the Kheis Terrane that did not provide any evidence for a ~1.8Ga old Kheis orogeny (an age commonly suggested in the past for this orogeny). This collisional event resulted in the deformation of the rocks of the Keis Supergroup into the Kheis Terrane sometime between 1290Ma and 1172Ma.The second Wilson cycle was initiated during rifting along the Koras-Sinclair-Ghanzi rift on the Kaapvaal-Zimbabwe-Kgalagadi Craton at ~1172Ma. It was followed soon after by the initiation of subduction underneath the Richtersveld cratonic fragment at ~1166Ma after which the rocks of the Korannaland Group were deposited. The closure of the oceanic basin between the Kaapvaal-Zimbabwe-Kgalagadi Craton and the Richtersveld cratonic fragment occurred about 50Ma later (~1113Ma, the age of neomorphic muscovite in the metasedimentary rocks of the Kakamas Terrane) and resulted in the large open folds characterising the Kheis terrane and NNMP. Detrital zircon populations in the Sprigg Formation show that this formation does not belong to the Areachap Group and that it was deposited after the closure of the oceanic basin between the Kaapvaal-Zimbabwe-Kgalagadi Craton and the Richtersveld cratonic fragment at ~1113Ma. The Areachap Group can be extended towards the north and into Botswana along the Kalahari line where it forms the boundary between the Kaapvaal-Zimbabwe Craton to its east and the Kgalagadi Terrane to its west. The Areachap Terrane is thus related to the collision of the Kaapvaal-Zimbabwe Craton and Kgalagadi Terrane and was deformed a second time during the oblique collision of the Richtersveld cratonic fragment with the combined Kaapvaal-Zimbabwe-Kgalagadi Craton. The extension of the Areachap Group to the north along the Kalahari line opens up new exploration prospects for Coppertontype massive sulphide deposits underneath the Kalahari sand.

O registro sedimentar do final do Neoproterozóico tem sido alvo de intensas pesquisas desde a retomada dos modelos de glaciação extrema e rápidas mudanças climáticas, com destaque para a hipótese Snowball Earth. Esses modelos baseiam-se na identificação, em todos os continentes, de sucessões neoproterozóicas que compreendem diamictitos sobrepostos por carbonatos, interpretados, respectivamente, como depósitos glaciais e pós-glaciais. A fim de explicar o caráter global da distribuição dos diamictitos e sua aparente transição rápida para carbonatos, alguns autores propuseram hipóteses de que o planeta teria sofrido mudanças climáticas extremas, e de que estas teriam ocorrido na forma de três eventos glaciais durante o Criogeniano e o Ediacarano (Sturtian, Marinoan e Gaskiers). Outros autores consideram que a correlação global destes depósitos pode ser explicada pelo modelo Zipper-rift, que considera a existência de geleiras de altitude, condicionadas pelo soerguimento das ombreiras de sistemas de rifts, supostamente abertos durante a fragmentação do supercontinente Rodínia. Apesar de intensos esforços para correlacionar estas sucessões, ainda persistem dúvidas a esse respeito. Isto se deve, em parte, à ênfase dada ao estudo das sucessões carbonáticas sobrejacentes, em detrimento das pesquisas nos próprios diamictitos. Dentro desse contexto, o presente estudo tem como alvo a sucessão sedimentar inferior do Grupo Una, interpretada como representativa do evento Sturtian, localizada na porção norte do Cráton do São Francisco, Bahia, Brasil. Foram realizadas análises de fácies, de associações de fácies e de proveniência sedimentar com o objetivo de testar os modelos de dinâmica glacial propostos para o período e avaliar localmente o caráter da transição entre diamictitos e carbonatos. O Grupo Una apresenta área de afloramento de aproximadamente 16.000 km2 e compreende depósitos sedimentares isentos de metamorfismo, que se encontram distribuídos em três sinclinais (Salitre, Irecê e Una-Utinga). Na base, compreende arenitos, diamictitos e pelitos com clastos esparsos da Formação Bebedouro, interpretada em termos das associações de fácies (1) Transicional marinha influenciada por banquisas e/ou icebergs e (2) Marinha de plataforma continental. A passagem para a unidade de topo ocorre de forma brusca, em contato plano com dolomitos maciços a laminados com pseudomorfos de aragonita, sobrepostos por ritmitos de calcarenitos e calcilutitos com laminação planoparalela, laminação cruzada cavalgante, estromatólitos e slumps, dividos nas associações de fácies de (3) Plataforma carbonática rasa influenciada por ondas e (4) Rampa carbonática influenciada por escorregamentos. Dados de contagem de litotipos em clastos e seções delgadas indicam variação lateral de proveniência, com fontes particulares para cada uma das áreas investigadas. Essa variação é interpretada como resultado de aporte de geleiras de vale ou do tipo outlet na margem glacio-marinha, indicando a presença de altos topográficos. A datação U-Pb SHRIMP de seixos revelou predomínio de fontes próximas, com contribuição local de fontes mais distantes, sugerindo alguma deposição a partir de icebergs provenientes da margem oposta da bacia, talvez a mais de 150 km à leste, sobre os Blocos Jequié ou Itabuna-Salvador- Curaçá. Datações de cristais de zircão detrítico da matriz dos diamictitos confirmam os dados obtidos a partir de seixos, e permitem a identificação de uma fonte jovem, de fora do cráton, com cerca de 850 Ma. Esse dado limita a idade máxima da unidade. Ainda que a proveniência da Formação Bebedouro indique a existência de altos topográficos adjacentes à bacia, a ausência de controles tectônicos na sedimentação, evidenciada pela grande persistência lateral de sistemas deposicionais com pouca variação de espessura, não corrobora o modelo de desenvolvimento das geleiras neoproterozóicas em margens de sistemas de rifts. / The sedimentary record of Neoproterozoic age has become a major subject of research since the rebirth of the models of extreme glaciation and rapid climatic changes for the period, including the Snowball Earth hypothesis. These models are founded on the identification, in all continents, of Neoproterozoic diamictites directly overlain by carbonates, which are interpreted respectively as glacial and post-glacial deposits. In order to explain the global distribution of diamictites and their apparently rapid transition to carbonates, some authors have proposed hypothesis of extreme climatic change related to three glacial episodes during the Cryogenian and the Ediacaran (Sturtian, Marinoan e Gaskiers). On the other hand, some authors consider that the global correlation of these deposits is the consequence of altitude-nucleated glaciers formed on the shoulders of rift systems during the breakup of the Rodinia Supercontinent, in what is called the Zipper-rift model. Despite the efforts to establish a chronological correlation among the several successions, many questions still persist, in part due to the great emphasis on the study of the carbonate successions and the scarce work on the diamictites. The present work aims at studding the lower section of the Una Group, interpreted as related to the Sturtian glacial event and located in the northern region of the São Francisco Craton, Bahia, Brazil. Facies, facies associations and clastic provenance analysis were performed in order to test the current models on the Neoproterozoic glacial dynamics and to locally evaluate the passage from diamictites to carbonates. The Una Group crops out in a area of approximately 16,000 km2 and is composed of sedimentary deposits without metamorphism, preserved in three synclinal folds (Salitre, Irece e Una-Utinga). At its base, the unit comprises sandstones, diamictites and mudstones with dropstones grouped into the Bebedouro Formation. This formation comprises two facies associations: (1) Marine transitional deposits influenced by ice-shelves and/or icebergs and (2) Continental platform marine deposits. The passage to the upper unit is marked by a sharp planar surface above which lay two facies associations: (3) Wave influenced shallow carbonatic platform deposits, comprising massive to laminated dolomites, locally with aragonite pseudomorph crystals, overlain by (4) Carbonatic ramp influenced by slumps, composed of calcareous grainstones and mudstones with plane-parallel lamination, climbing ripples, slump structures and locally stromatolites. Pebble lithology and thin section compositional data indicate great spatial variation of provenance, with specific sources for each of the investigated areas. This variation is interpreted as the consequence of valley or outlet glaciers feeding the glaciomarine margin, thus indicating the presence of topographically elevated areas near the basin. U-Pb SHRIMP dating of selected pebbles reveals the dominance of nearby sources, with the local contribution of far-traveled clasts, suggesting mixing with sediments deposited from icebergs which came from the opposite basin margin, as far as 150 km to the east. U-Pb SHRIMP dating of detrital zircon grains from the matrix of the diamictites confirmed this model and lead to the identification of a source from outside the craton with approximately 850 Ma. This data constraints the maximum depositional age of the Bebedouro Formation. Despite provenance from the Bebedouro Formation indicates the presence of topographically elevated areas near the basin, the absence of tectonic controls on the sedimentation, evidenced by the great lateral continuity of the depositional systems and their small thickness variation, does not confirm the model of development of neoproterozoic glaciers over the shoulders of rift systems.

O presente trabalho consiste na investigação dos processos formativos envolvidos na construção do sambaqui costeiro Jabuticabeira II - SC, considerando que os sambaquis são estruturas intencionalmente erigidas por uma população em processo de sedentarização, adensamento demográfico e de complexificação da organização social. Este estudo é realizado a partir de análises estratigráficas detalhadas das seções já abertas e documentadas de várias áreas do sítio, que consideram sua morfologia, constituição, recorrência e incremento dos estratos, associação entre as camadas, bem como as datações obtidas para o entendimento da cronologia de sua formação. Nesta dissertação pretende-se descrever detalhadamente os processos formativos envolvidos na construção desse sítio. Objetiva-se também definir possíveis padrões que estruturam a composição e organização estratigráfica e propor modelos explicativos para os processos envolvidos nessa construção / The present dissertation consists of the investigation in formative processes involved in the construction of the coastal shellmound, Jabuticabeira II, SC. This takes into consideration the fact that the shellmounds are structures purposely built by a population in process of sedentary development, demographic densification and complexity in the social organization. This study is done as from detailed stratigraphy analyses of the already open sections and documented from various areas of the site, which consider its morphology, constitution, recurrence and strata increment, the association between the layers, as well as the dating processes obtained for the understanding of its chronology formation. In this dissertation it is intended the description in detail of the formative processes involved in the construction of the site. It is also aimed at defining possible standards which form the composition and the stratigraphy organization and proposes explanatory models for the involved processes in this construction

This Dissertation combines the investigation of the sedimentological impacts of the Deepwater Horizon (DwH) blowout event in the deep-sea benthos, with the refinement and advancement of methods and approaches for high-resolution investigations of events preserved in sedimentary records. An approach that combined, rapid collection of cores, a continued annual time series collection of cores, and high-resolution sampling and analyses, in particular short-lived Radioisotopes (SLRad), enabled the temporal resolution required to detect the sedimentary response to the short-duration DwH event, and evaluate post-event sedimentation patterns at a comparable time scale (months). The collection of 179 sediment cores from 80 sites between the fall of 2010 and 2016 included four sites that were utilized as an annual time-series collection to define the sedimentary response to the DwH blowout event and how the sedimentary system evolved/recovered post-event. High-resolution (2mm) sub-sampling was utilized to maximize the temporal resolution of analyses and age control using SLRad. The rapid collection of cores to define the immediate benthic impact(s), as well as the use of time-sensitive indicators of the event that may degrade over time, as well as indicators for very short time scale (months) sedimentation, such as 234Thxs. 234Thxs inventories and mass accumulation rates (MAR’s) were one of the most diagnostic characteristics of the sedimentary response. The DwH blowout event led to a Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) event that caused a depositional pulse to the seafloor. This was defined by increased sedimentation rates and the shutdown of bioturbation as indicated by 234Thxs inventories and MAR’s. The annual collection of sediment cores as a time-series allowed for continued high-resolution analyses and use of 234Thxs to determine post-event sedimentation rates and baselines on monthly time scales for direct comparison to the depositional pulse. Within ~one year sedimentation rates decreased and within three years site specific return of bioturbation occurred and sedimentation rates on monthly scale (234Thxs) stabilized. Also, within ~three years the sedimentary signature of the depositional pulse became undetectable with respect to sediment texture and composition possibly due to dilution of this indicator by mixing/bioturbation and/or compaction of the event layer. Without the use of high-resolution sampling and geochronological tools such as 234Thxs the depositional pulse would not have been detected in the sedimentary system. The continued use of these high-resolution methods allowed for further defining the magnitude of the sedimentary response to the DwH event as well as provide baseline sedimentation patterns at a monthly time scale. The annual time series defines the post-event evolution of the sedimentary system as well as the assessment of the post-depositional alterations that influence the integration and preservation of such sedimentation events in the sedimentary record. This includes the potential for re-mobilization of event sediments, potential re-exposure of ecosystems to contaminated sediments and redistribution of event sediments. Alternatively, burial and alteration of the sedimentary signature over time influences the preservation potential of sedimentation events such as DwH, with decreasing ability to detect events due to bioturbation, degradation of signature and compaction. The refinement of methodology and approaches, in particular short-lived radioisotope (SLRad) geochronology, allowed for the high-resolution determination of the sedimentary impacts of the DwH blowout event. In turn, the opportunity to investigate the DwH event in real time provided the opportunity to advance high-resolution methodologies in an applied fashion. Continued refinement of high-resolution approaches and methods, in particular geochronologies, will allow for the detection of short-duration and subtle sedimentary events in real time as well as in the sedimentary record. Through the application of such approaches and methods to real events, these methods can be further refined and assessed for their utility and limitations.

Two sections, Všeradice and Kosov, represent continuous sedimentary succession situated in the Prague Basin. No detailed research on stratigraphical level equal the N. kozlowskii graptolite zone focusing on chitinozoans, has not yet been conducted in the Prague Basin and is also very scarce globally. Limestone beds, examined for chitinozoans, were not very productive. Chitinozoan reaction on extinction is visible, if we compile data from both sections. The pre-extinct chitinozoan fauna is characterized by the Conochitinidae family. Samples from the post-extinct interval contained no chitinozoas. The interval of fauna recovery is characterized mainly by the Eisenackitina genera. In this interval, global zone for the uppermost Ludfordian, represented by E. barrandei, can be confirmed. In agreement with all the published literature, we have not found E. philipi, index taxa of the former global zone in the Prague Basin. E. lagenomorpha appears stratigraphically only slightly below E. barrandei and therefore it cannot substitute E. philipi, as it is used in Baltika region. chitinozoa, Prague Basin, Kozlowskii, Lau, extinction, Ludfordian, stratigraphy

This thesis addresses the systematics and taxonomics of the ammonite assemblages of the Lower and Middle Turonian of the Bohemian Cretaceous Basin (BCB). It describes nineteen species of fifteen genera. Amongst others it concerns: Watinoceras coloradoense (Henderson), Spathites (Jeanrogericeras) reveliereanum (Courtiller), Paramammites sp. cf. P. polymorphus (Perervinquière), and Lecointricecras carinatum (Kennedy et al.) from the BCB, which have been described for the very first time. Another important taxon that is described is Prionocyclus albinus (Fritsch), which has not been encountered in the BCB since the year 1872 when it was established as a holotype by A. Fritsch. This specimen is now deposited in the National Museum in Prague. Most of these significant taxa belong to the collection of Dr. J. Soukup. He collected the specimens in various locations near Žďánice u Kouřimi mainly in the first half of the 20th century. The locations no longer exist. Stratigraphically important zonal ammonites, primarily W. coloradoense and Fagesia catinus (Mantell), are a direct evidence of the presence of two ammonite zones in the lower Lower Turonian in this part of the BCB (the zones Watinoceras coloradoense/devonense and Fagesia catinus). They also illustrate a larger stratigraphical extent of...

Acquiring GPR data at multiple frequencies is useful because higher-frequency profiles have better spatial resolution, although they suffer from reduced depth penetration. Lower-frequencies can generally resolve to greater depths, but at the cost of spatial resolution. For concise presentation of GPR data, it would be useful to combine the best features of each profile into a composite radargram. This study explores effective ways to present GPR data acquired at multiple frequencies. An example is shown from a survey of hurricane overwash deposits from Santa Rosa Island, Florida. The methodology used to create a composite radargram is dependent on which of two goals the composite radargram is designed to achieve. These goals are broadening the spectral bandwidth of GPR data to increase the effectiveness of deconvolution and enhancing the resolution and depth of GPR data by plotting high-frequency data at early two-way travel times, low-frequency data at late two-way travel times, and using filters to smoothly transition from high-frequency to lower-frequency data. The steps towards creating a composite radargram include: 1) applying standard processing to nominal frequency data sets, 2) creating spatially coincident data sets, 3) equalizing the amplitude spectra among each nominal frequency data set, and 4) summing nominal frequency data sets together. Spectral bandwidth broadening is achieved by applying optical spectral whitening and summing nominal frequency data sets using a single ramped. Deconvolving this composite radargram did not show the same success observed by Booth et al. (2009). Enhancing the resolution and depth of GPR data can be achieved by applying amplitude envelope equalization (AEE) and summation using double ramped filters. AEE calculates the coefficients required to make equivalent average amplitude envelopes for GPR data that has been gained with automatic gain control . Double ramped filters suppress low-frequency energy for two-way travel times when a higher-frequency data set has adequate signal strength and higher frequency energy for two-way travel times when higher- frequency energy exhibits significant attenuation. A composite radargram built with AEE and double ramped filters achieves the goal enhancing resolution and depth of GPR data. Shallow reflections are interpreted as dune and hurricane overwash stratigraphy.