Cenozoic tectonics of the Pacific Northwest (PNW) and the associated mantle structures are remarkable, the latter revealed by EarthScope seismic data. In this thesis we model teleseismic body waves constrained by ambient-noise surface waves and teleseismic receiver function analysis in order to recover better-controlled higher resolution images of the PNW continuously from the surface of the crust to the base of the upper mantle. We focus on and have clearly imaged two major upper mantle structures: (1) the high-velocity Farallon slab (the "Siletzia curtain") extending vertically beneath the Challis-Kamloops-Absaroka volcanic flareup (~53-47 Ma) of western Idaho and central Washington; and (2) a high-velocity anomaly beneath the Wallowa Mountains of northeast Oregon associated with the main Columbia River flood basalts source region. The proximity of these two structures along with the tectono-magmatic history of the PNW leads us to reexamine the origin of the Columbia River Basalts ~ 16 Ma. This thesis includes co-authored material submitted for publication.

The focus of this research is to characterize the risk of carbon sequestration under downhole conditions with regards to wellbore cement integrity. The primary research objective was to understand the geochemical interactions of simulated sequestration brines and wellbore cement. There are four key focuses of this study with regards to cement interaction: 1) Simulated brines saturated with Supercritical CO2 and CO2-O2; 2) Adjacent formation host rock under sequestration conditions; 3) Geochemical modeling using CHIM-XPT based on the experimental studies of points 1) and 2) above; 4) Geomechanical strength tests of CO2 exposed cements. First, the interaction of cement with supercritical CO2, CO2-saturated brines, and CO2-O2 mixtures at 50 °C, 85 °C, and 28.9 MPa was evaluated. Cement exposed to a lower salinity brine (1 M) had a larger alteration depth (1.25 mm) compared to cement exposed to a higher salinity brine (2.2 M) (0.836 mm). CO2-O2 exposed cements displayed alteration depths of 1.6 mm at 85 °C and 0.7 mm at 50 °C for 1 M. The cement exposed to the 2.17 M solution had an alteration extending 1.685 mm. The second focus studied the influence of adjacent formations and observed mineral trapping in the Grande Ronde Basalt-cement. Studies of Mt. Simon Sandstone-cement interaction provided evidence for high CO2 storage capacity. The third focus is geochemical modeling using CHIM-XPT. Pure CO2 saturated brines yielded a pH of 3.0 at 1 M and 3.85 at 2.17 M. The CO2-O2 gas run calculated a pH of 3.96 at 1 M and 3.85 at 2.17 M. The Pasco solution after exposure had a pH of 6.97 and an estimated dissolved 161 g of CO2 (g). The pH of the Illinois Basin brine and Mt. Simon sandstone [and cement paste] was 5.8 with an estimated 139 g of CO2 consumed. Lastly, geomechanical tests on CO2 exposed cements indicated that addition of oxygen or changes in temperature play a key role in compressive and tensile strength, decreasing strength by 20-35%. This research highlighted the importance of representing the in-situ wellbore environment when conducting laboratory experiments. This dissertation includes previously published and unpublished co-authored material.

A Sucessão Magmática do Arquipélago de Abrolhos é composta por quatro unidades, quais sejam: Olivina-Plagioclásio Basalto (b1), Piroxênio-Plagioclásio-Olivina Basalto (b2), Piroxênio-Plagioclásio Basalto (b3) e Cumulado (b4). As unidades não são correlacionáveis litoestratigraficamente e estão empilhadas da base para o topo em unidade b1, b2, b3 e b4. As unidades da sucessão magmática são diferentes quanto à textura, estrutura e mineralogia. A análise litogeoquímica de vinte e três amostras de rochas basálticas das unidades da sucessão magmática discriminou uma série transicional de afinidade alcalina para as rochas estudadas. As razões Nb/Y > 1 das rochas estudadas corroboraram a afinidade alcalina da série. As rochas foram classificadas como basaltos e traqui-basaltos (unidades b1 e b2), basaltos, traqui-basaltos, basanitos e tefritos (unidades b3 e b4). A análise de diagramas de variação para elementos maiores e traços e das razões de elementos traços da amostra representativa do líquido parental e do líquido mais evoluído indicaram cristalização fracionada sem mudança de assembléia francionante como possível processo evolutivo da série transicional estudada. A incongruência entre a assembléia fracionante e a assembléia de fenocristais (identificada na petrografia), além de feições indicativas de desequilíbrio cristal-líquido mostraram que a cristalização fracionada foi o único processo evolutivo na geração dos basaltos do Arquipélago de Abrolhos. Modelos evolutivos mais complexos devem ser considerados, como, por exemplo, um modelo de reabastecimento de câmaras crustais com subseqüentes pulsos de magmas basálticos. As razões La/Yb (N) >1 e La/Nb (N) <1 indicaram que as unidades mapeadas no Arquipélago de Abrolhos estão associadas a uma mesma fonte mantélica fértil (tipo pluma). / The Magmatic Succession of Abrolhoss Archipelago is composed by four units: Olivine-Plagioclase Basalt (b1), Pyroxene-Plagioclase-Olivine Basalt (b2), Pyroxene-Plagioclase Basalt (b3) and Cumulado (b4). The units are not stratigraphically correlated. They are stacked from the basis to the top in units: b1, b2, b3 and b4. The units of the magmatic succession are different in terms of texture, structure and mineralogy. The litogeochemical analyses of twenty three samples of basaltic rocks discriminated a transitional series of alkaline affinity to the studied rocks. The values of Nb/Y ratios higher than unity of the studied rocks corroborate the alkaline affinity of the series. The rocks were classified as basalts, tracky-basalts, basanites and tephrites (units b3 and b4), basalts and tracky-basalts (units b1 and b2). The interpretation of variation diagrams to major and trace elements together with the trace elements ratios of the representative sample of the parental and the more evaluated liquids indicated fractional crystallization without changing of fractionated assemblage as the evolutionary process of the studied transitional series. The incongruity between the fractionated assemblage and porphyries assemblage (recognized by the petrography) in addition to the indicative features of crystal-liquid disequilibrium discard fractional crystallization as the evolutionary process in the generation of the basaltic rocks of Abrolhoss Archipelago. More complex evaluative models should be considered as, for example, a refueling model of crustal chambers with subsequent pulses of basaltic magmas. The La/Yb (N) ratio >1 and La/Nb (N) ratio <1 indicated that the mapped units of Abrolhoss Archipelago are associated to a fertile mantellic source (plume-like type).

Made available in DSpace on 2014-06-11T19:25:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-29Bitstream added on 2014-06-13T18:47:24Z : No. of bitstreams: 1 lourencojunior_ba_me_botib.pdf: 660573 bytes, checksum: 4ae96ad0c23c03d89b2191f4a14d90bd (MD5) / A nutrição mineral constitui um dos aspectos mais críticos na produção de mudas. Os nutrientes quando fornecidos aos vegetais em dosagens adequadas e equilibradas entre si, possibilitam incrementos de produtividade. Apesar da utilização atual de pó de basalto como fonte alternativa de nutrição, ainda são poucos os estudos com base científica, que avaliem e comparem seus efeitos no desenvolvimento vegetal. O presente estudo objetivou avaliar a translocação orgânica, produtividade e a anatomia foliar da laranjeira Pêra‟ Citrus sinensis (L.) Osbeck enxertadas em limoeiro „Cravo‟ Citrus limonia e cultivadas com variação da fertilização e pó de basalto. O delineamento experimental foi inteiramente ao acaso, com seis repetições, em esquema fatorial 6 x 5, ou seja, 6 tratamentos constituídos por diferentes níveis de basalto em adição à fertilização, e cinco épocas de colheitas, realizadas aos 60, 90, 120, 150 e 180 após a enxertia, onde foi mensurado nº de folhas, diâmetro do caule, altura, massa de matéria seca de folha, caule, raiz e total, além do cálculo dos índices fisiológicos razão de área foliar (RAF), área foliar específica (AFE), taxa de crescimento relativo (TCR), taxa de assimilação líquida (TAL) e razão de massa foliar (RMF). Aos 180 dias após a enxertia e 170 dias de plantio em campo, foram realizadas análises de teores foliares de minerais. Foram mensuradas as trocas gasosas com o auxílio de um sistema aberto portátil de fotossíntese (LI-6400, LI-COR, Lincoln, NE, USA) nas plantas aos 170 dias após o plantio e avaliação anatômica do limbo e nervura foliar principal. De maneira geral, as plantas cultivadas com 36 kg de pó de basalto m-³ de substrato e 2∕3 da fertilização apresentaram desenvolvimento semelhante... / The mineral nutrition is one of the most critical in the production of seedlings. Nutrients to plants when supplied in adequate dosages and balance one another, allow increased productivity. Despite the current use of basalt powder as an alternative source of nutrition, there are few scientific studies that evaluate and compare their effects on plant development. This study aimed to evaluate the translocation organic productivity and leaf anatomy of the Sweet Orange „Pêra‟ Citrus sinensis (L.) Osbeck grafted on Rangpur Lime Citrus limonia cultivated with basalt powder. The experimental design was completely randomized design with six replications in a factorial 5 x 6, or 6 treatments consisting of different levels of basalt in addition to fertilization, and five harvests, performed at 60, 90, 120, 150 e 180 after grafting, when leaf number, stem diameter, height, and leaf, stem, root and total dry matter for growth analysis were measured. At 180 days after grafting and 170 days of planting, were analyzed mineral content in leaves. Gas exchange was evaluated through a closed portable photosynthesis system (LI-6400, LI-COR, Lincoln, NE, USA) on plants 170 days after planting and anatomical assessment of the limbus and the main leaf vein. In general, the plants cultivated with36 kg of basalt powder m-³ and 2∕3 of the fertilization showed development similar or higher in those grown without basalt powder. Anatomical changes can result in greater resistance in the field

Tradicionalmente, os estudos que tinham a exploração pecuária como foco, se limitavam a análise de seus indicadores produtivos e econômicos, ou seja, dava-se um enfoque parcial, setorial ou disciplinar. Igualmente, de um ponto de vista estático e baixo equilíbrio. Por sua vez, a exploração pecuária é um sistema aberto, submetido à influência de um entorno que denominamos ambiente, e que, gerido pelo pecuarista, persegue determinadas finalidades. Por conseqüência, a exploração pecuária é sensível a um amplo leque de fatores de natureza biofísica, sociológica, econômica e de políticas. Neste sentido, as explorações pecuárias como sistemas sociais, são dinâmicas, reativas ou evolutivas, o que significa que as características mais importantes aparecem ao longo do tempo. Por isso, o estudo dos sistemas pecuários requer a consideração explícita da dita variável, tempo. O presente estudo pretende dar resposta a seguinte questão: que mudanças aconteceram nas explorações pecuárias da região de Basalto como reação aos condicionantes do entorno socioeconômico, em constante mudança, mas também, dependentes de fatores e características internas a própria exploração? A região de Basalto, a mais extensa do Uruguai, correspondente a 21% do território nacional, é caracterizada fundamentalmente por estar associada a sistemas extensivos de produção pecuária de baixa produtividade e investimento, onde pastoreiam conjuntamente, bovinos e ovinos. A abordagem metodológica utilizada neste estudo baseou-se na comparação do processamento de informações correspondentes aos anos 1994 e 2008, utilizando como ferramenta, entrevistas dirigidas as mesmas explorações pecuárias da região de Basalto com áreas superiores a 200 hectares. O reconhecimento das mudanças ocorridas nos sistemas pecuários da região de Basalto, no marco das transformações recentes do setor agropecuário do Uruguai, é fundamental para explorar evoluções distintas da pecuária extensiva daquela região, apesar da incerteza a respeito das políticas agrárias dos condicionantes socioeconômicos. Os resultados encontrados sugerem a existência de fatores que ameaçam a continuidade das explorações pecuárias em longo prazo e, conseqüentemente, a sustentabilidade dos ecossistemas pastoris. Estes fatores são de natureza diversa: ambientais econômicos e sociais. / Traditionally, the livestock production studies limited the analysis to productive and economic results, which is to say from a partial approach, or from only one discipline. Also, they were done from a static point of view and supposing a situation at equilibrium. However, the livestock farm is an open system, exposed the influence of its environment, and managed by livestock farmers who have certain purposes. Consequently, the cattle operation is sensible to an ample variety of factors of biophysical, sociological, economic, and ecological nature and also to policies. In this sense, the cattle operations like social systems are dynamic, reactive or adaptive, which means that the most important characteristics appear on the long time. For this reason, the study of the cattle systems requires the explicit consideration this variable, time. The present study tries to give answer to the following question: What changes arose in the cattle operations of the Basalt reacting to the conditions of the socio-economic environment in constant change, but also depending on the own operation internal factors and characteristics? The Region of the Basalt, the most extensive of Uruguay, 21% of the national territory, has been characterized essentially as having extensive systems of cattle production of low productivity and investment; where bovine and ovine graze simultaneously. The methodological approach in this study is based on the comparison of information corresponding to years 1994 and 2008, from the same sample of farms - of the Region of the Basalt with surfaces majors to the 200 hectares -. The data of the changes occurred in the cattle systems of the Basalt Region within the framework of the recent transformations of the farming sector of Uruguay, is fundamental to explore extensive cattle ranch different evolutions, in presence of the uncertainty with respect to the agrarian policies and to the socio-economic conditions. The results suggest the existence of factors that threaten the continuity of the cattle operations in the long term, and therefore, the sustainability of the pastoral ecosystems. These factors are of diverse nature: environmental, economic and social.

abstract: ABSTRACT The Sentinel-Arlington Volcanic Field (SAVF) is the Sentinel Plains lava field and associated volcanic edifices of late Cenozoic alkali olivine basaltic lava flows and minor tephra deposits near the Gila Bend and Painted Rock Mountains, 65 km-100km southwest of Phoenix, Arizona. The SAVF covers ~600 km2 and consists of 21+ volcanic centers, primarily low shield volcanoes ranging from 4-6 km in diameter and 30-200 m in height. The SAVF represents plains-style volcanism, an emplacement style and effusion rate intermediate between flood volcanism and large shield-building volcanism. Because of these characteristics, SAVF is a good analogue to small-volume effusive volcanic centers on Mars, such as those seen the southern flank of Pavonis Mons and in the Tempe Terra region of Mars. The eruptive history of the volcanic field is established through detailed geologic map supplemented by geochemical, paleomagnetic, and geochronological analysis. Paleomagnetic analyses were completed on 473 oriented core samples from 58 sites. Mean inclination and declination directions were calculated from 8-12 samples at each site. Fifty sites revealed well-grouped natural remanent magnetization vectors after applying alternating field demagnetization. Thirty-nine sites had reversed polarity, eleven had normal polarity. Fifteen unique paleosecular variation inclination and declination directions were identified, six were represented by more than one site with resultant vectors that correlated within a 95% confidence interval. Four reversed sites were radiometrically dated to the Matuyama Chron with ages ranging from 1.08 ± 0.15 Ma to 2.37 ± 0.02 Ma; and one normal polarity site was dated to the Olduvai normal excursion at 1.91 ± 0.59 Ma. Paleomagnetic correlations within a 95% confidence interval were used to extrapolate radiogenic dates. Results reveal 3-5 eruptive stages over ~1.5 Ma in the early Pleistocene and that the SAVF dammed and possibly diverted the lower Gila River multiple times. Preliminary modeling of the median clast size of the terrace deposits suggests a maximum discharge of ~11300 cms (~400,000 cfs) was necessary to transport observed sediment load, which is larger than the historically recorded discharge of the modern Gila River. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2015

Orientador: Carmen Sílvia Fernandes Boaro / Banca: Dirceu Maximino Fernandes / Banca: Susette Aparecida de Barros Cardoso / Resumo: A nutrição mineral constitui um dos aspectos mais críticos na produção de mudas. Os nutrientes quando fornecidos aos vegetais em dosagens adequadas e equilibradas entre si, possibilitam incrementos de produtividade. Apesar da utilização atual de pó de basalto como fonte alternativa de nutrição, ainda são poucos os estudos com base científica, que avaliem e comparem seus efeitos no desenvolvimento vegetal. O presente estudo objetivou avaliar a translocação orgânica, produtividade e a anatomia foliar da laranjeira Pêra‟ Citrus sinensis (L.) Osbeck enxertadas em limoeiro „Cravo‟ Citrus limonia e cultivadas com variação da fertilização e pó de basalto. O delineamento experimental foi inteiramente ao acaso, com seis repetições, em esquema fatorial 6 x 5, ou seja, 6 tratamentos constituídos por diferentes níveis de basalto em adição à fertilização, e cinco épocas de colheitas, realizadas aos 60, 90, 120, 150 e 180 após a enxertia, onde foi mensurado nº de folhas, diâmetro do caule, altura, massa de matéria seca de folha, caule, raiz e total, além do cálculo dos índices fisiológicos razão de área foliar (RAF), área foliar específica (AFE), taxa de crescimento relativo (TCR), taxa de assimilação líquida (TAL) e razão de massa foliar (RMF). Aos 180 dias após a enxertia e 170 dias de plantio em campo, foram realizadas análises de teores foliares de minerais. Foram mensuradas as trocas gasosas com o auxílio de um sistema aberto portátil de fotossíntese (LI-6400, LI-COR, Lincoln, NE, USA) nas plantas aos 170 dias após o plantio e avaliação anatômica do limbo e nervura foliar principal. De maneira geral, as plantas cultivadas com 36 kg de pó de basalto m-³ de substrato e 2∕3 da fertilização apresentaram desenvolvimento semelhante... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The mineral nutrition is one of the most critical in the production of seedlings. Nutrients to plants when supplied in adequate dosages and balance one another, allow increased productivity. Despite the current use of basalt powder as an alternative source of nutrition, there are few scientific studies that evaluate and compare their effects on plant development. This study aimed to evaluate the translocation organic productivity and leaf anatomy of the Sweet Orange „Pêra‟ Citrus sinensis (L.) Osbeck grafted on Rangpur Lime Citrus limonia cultivated with basalt powder. The experimental design was completely randomized design with six replications in a factorial 5 x 6, or 6 treatments consisting of different levels of basalt in addition to fertilization, and five harvests, performed at 60, 90, 120, 150 e 180 after grafting, when leaf number, stem diameter, height, and leaf, stem, root and total dry matter for growth analysis were measured. At 180 days after grafting and 170 days of planting, were analyzed mineral content in leaves. Gas exchange was evaluated through a closed portable photosynthesis system (LI-6400, LI-COR, Lincoln, NE, USA) on plants 170 days after planting and anatomical assessment of the limbus and the main leaf vein. In general, the plants cultivated with36 kg of basalt powder m-³ and 2∕3 of the fertilization showed development similar or higher in those grown without basalt powder. Anatomical changes can result in greater resistance in the field / Mestre

A Sucessão Magmática do Arquipélago de Abrolhos é composta por quatro unidades, quais sejam: Olivina-Plagioclásio Basalto (b1), Piroxênio-Plagioclásio-Olivina Basalto (b2), Piroxênio-Plagioclásio Basalto (b3) e Cumulado (b4). As unidades não são correlacionáveis litoestratigraficamente e estão empilhadas da base para o topo em unidade b1, b2, b3 e b4. As unidades da sucessão magmática são diferentes quanto à textura, estrutura e mineralogia. A análise litogeoquímica de vinte e três amostras de rochas basálticas das unidades da sucessão magmática discriminou uma série transicional de afinidade alcalina para as rochas estudadas. As razões Nb/Y > 1 das rochas estudadas corroboraram a afinidade alcalina da série. As rochas foram classificadas como basaltos e traqui-basaltos (unidades b1 e b2), basaltos, traqui-basaltos, basanitos e tefritos (unidades b3 e b4). A análise de diagramas de variação para elementos maiores e traços e das razões de elementos traços da amostra representativa do líquido parental e do líquido mais evoluído indicaram cristalização fracionada sem mudança de assembléia francionante como possível processo evolutivo da série transicional estudada. A incongruência entre a assembléia fracionante e a assembléia de fenocristais (identificada na petrografia), além de feições indicativas de desequilíbrio cristal-líquido mostraram que a cristalização fracionada foi o único processo evolutivo na geração dos basaltos do Arquipélago de Abrolhos. Modelos evolutivos mais complexos devem ser considerados, como, por exemplo, um modelo de reabastecimento de câmaras crustais com subseqüentes pulsos de magmas basálticos. As razões La/Yb (N) >1 e La/Nb (N) <1 indicaram que as unidades mapeadas no Arquipélago de Abrolhos estão associadas a uma mesma fonte mantélica fértil (tipo pluma). / The Magmatic Succession of Abrolhoss Archipelago is composed by four units: Olivine-Plagioclase Basalt (b1), Pyroxene-Plagioclase-Olivine Basalt (b2), Pyroxene-Plagioclase Basalt (b3) and Cumulado (b4). The units are not stratigraphically correlated. They are stacked from the basis to the top in units: b1, b2, b3 and b4. The units of the magmatic succession are different in terms of texture, structure and mineralogy. The litogeochemical analyses of twenty three samples of basaltic rocks discriminated a transitional series of alkaline affinity to the studied rocks. The values of Nb/Y ratios higher than unity of the studied rocks corroborate the alkaline affinity of the series. The rocks were classified as basalts, tracky-basalts, basanites and tephrites (units b3 and b4), basalts and tracky-basalts (units b1 and b2). The interpretation of variation diagrams to major and trace elements together with the trace elements ratios of the representative sample of the parental and the more evaluated liquids indicated fractional crystallization without changing of fractionated assemblage as the evolutionary process of the studied transitional series. The incongruity between the fractionated assemblage and porphyries assemblage (recognized by the petrography) in addition to the indicative features of crystal-liquid disequilibrium discard fractional crystallization as the evolutionary process in the generation of the basaltic rocks of Abrolhoss Archipelago. More complex evaluative models should be considered as, for example, a refueling model of crustal chambers with subsequent pulses of basaltic magmas. The La/Yb (N) ratio >1 and La/Nb (N) ratio <1 indicated that the mapped units of Abrolhoss Archipelago are associated to a fertile mantellic source (plume-like type).

This study aims to produce a type of concrete with both good thermal and mechanical properties by using environmentally friendly and low cost materials. In addition, the resistance of this concrete to fire conditions was investigated. The experimental work comprises two parts. In the first part, recycled glass was used as a partial replacement for natural sand (at proportions 20%, 40% and 60%) together with basalt fibre having different volume fractions (0.1%, 0.3%, and 0.5%). The results obtained from the experimental work showed that the optimum content is 20% glass and at 28 days, there was a 4.23% and 15% enhancement in the compressive strength and the splitting tensile strength respectively. Above 20% glass there was a slight reduction (6.6% and 22%) in the compressive strength and the splitting tensile strength when 60% glass was used. The results also showed that when glass sand and basalt fibre content increase, there is a decrease in the thermal conductivity range from 4.35% to 50% at temperature levels between 60oC to 600oC. The structural behaviour of this type of concrete was investigated in the second part of this study by carrying out small-scale slab tests at ambient and elevated temperatures. The results show that there is an increase in the load carrying capacity above the theoretical yield line load, due to membrane action, for all percentages of glass and volume fractions of basalt fibre ranging from 1.35 to 1.68 for the slab tested at ambient temperature and from 3.13 to 3.26 for the slabs tested at elevated temperature. Also the slabs with higher glass sand and basalt fibre content had a higher load enhancement and failed at a higher displacement compared to the control mix.A comparison between the simplified method and the finite element software package ABAQUS showed that the ABAQUS model gives reasonable predictions for the load-vertical displacement and the temperature-displacement relationships at both ambient and elevated temperature conditions, while the simplified method gives conservative predictions for the maximum allowable vertical displacement for the slab at elevated temperature. A parametric study showed that a 10 mm cover depth is the optimum depth as well as the reinforcement temperature predicted reduced with increasing load ratio (applied load/yield line load).

New geochemical data consisting of major and 15 trace element analyses are presented for 41 rocks from three andesitic and associated basaltic rock occurrences in the North Eastern Cape Province. These include the Pronksberg, Belmore and Roodehoek localities. Field evidence suggests that the three andesites were emplaced during the early stages of Karoo volcanicity. Geochemical variations within the Pronksberg and Roodehoek andesite are small, manifesting the undifferentiated nature of the magmas. Variations within the Belmore andesite are interpreted as representing fractionation of orthopyroxene, accompanied by only minor plagioclase fractionation. Differences in trace element concentrations and inter-element ratios between the andesites and associated basalts of the Pronksberg and Belmore volcanic suites precludes the possibility of the two rock types being genetically related. Geochemical differences constrain the possibility of the three andesites being cogenetic. Magmatic processes resulting in their formation are, however, thought to be similar. The differences in chemistry between the Pronksberg Basalt (High K Type) and Pronksberg Basalt (Drumbo Type) are interpreted as representing the combined influence of weathering, the presence of amygdales and the within-flow variations of alkali elements on the Pronksberg Basalt (High K Type). Similarities in petrography and chemistry justifies a correlation of the Pronksberg Basalt (Drumbo Type) with the Drumbo Basalt Member in the Barkly East area. Data for the Drumbo Basalt (This study) in the Barkly East area confirms and complements previously presented data. Normative chemistry and strontium isotope data indicate a process involving crustal assimilation or melting of crustal rocks as being the most likely explanation for the genesis of the Karoo andesites / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in