Contact-metamorphic effect on parameters for kerogen maturation

Ujié, Yoshihiro

doi:10.1016/0146-6380(86)90119-1

Cited by 9 publications

(3 citation statements)

References 11 publications

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“…Late Miocene tuffaceous siltstones of the Nuruyu Formation (Muraoka & Hase 1990) were thermally metamorphosed by a 17.5‐m‐wide Pliocene andesite dyke in a quarry located at 40°31′30″ N, 140°33′30″ E (Ujiié 1984, 1986). The light brown color of the Nuruyu Formation changes to dark brown within 1 m of the dyke (Aizawa et al.…”

Section: Samplingmentioning

confidence: 99%

Relationship between statistical thermal alteration index and vitrinite reflectance for sedimentary rocks in northern Japan with reference to effects for unconformity, faulting, and contact metamorphism

Ujiié¹

2009

Island Arc

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Two organic maturity indices, the statistical thermal alteration index (stTAI) and vitrinite reflectance (R O ), are used to gain insight into the geological histories of sequences of Tertiary and Upper Cretaceous sediments in northern Japan that contain an unconformity and which are affected by faulting and contact metamorphism. The stTAI is based on the brightness, or gray level, of fossil pollen of Pinus, Podocarpus, Abies, and Picea species. Pollen brightness is measured using a transmitted-light microscope equipped with a computer-driven digital image processor. The stTAI represents the mean value of the modes for the complete array of indigenous pollen in rock samples. The stTAI indicates the level of organic maturation for Neogene sedimentary rocks of Japan, from incipient diagenesis to early catagenesis (R O Յ1.0%). With the progressive diagenesis and catagenesis of sedimentary rocks, stTAI values generally show a progressive decrease, whereas R O values increase. The effects of an unconformity and faulting are more clearly recorded in stTAI trends than in R O trends. During early stages of organic maturation (R O Յ0.7%), stTAI shows a rapid decrease, while R O shows a rapid increase during the mature and post-mature stages (R O Ն0.8%). The occurrence of a range in R O values for a given level of organic maturity makes it difficult to determine the influence of the unconformity on the increasing R O trend. R O values show a progressive increase toward an igneous dyke, but this trend is not apparent in stTAI values. Measurements of Tertiary and Upper Cretaceous rocks in Japan reveal that stTAI is more sensitive to heating duration than R O , although R O is more sensitive to heating temperature.

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Section: Samplingmentioning

confidence: 99%

Relationship between statistical thermal alteration index and vitrinite reflectance for sedimentary rocks in northern Japan with reference to effects for unconformity, faulting, and contact metamorphism

Ujiié¹

2009

Island Arc

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“…O calor advindo de tais intrusões propicia a maturação da matéria orgânica presente nas rochas-fontes, diminui a densidade do óleo e aumenta a velocidade de migração de hidrocarbonetos para rochas-reservatório (Ujié, 1986;Chen et al, 1999;Thomaz Filho et al, 2008;Wang et al, 2012). Em contrapartida, o mesmo calor pode diminuir a quantidade de óleo armazenado, gerando mais gás, e minimizar a permeabilidade e a porosidade de rochas-reservatório em decorrência da recristalização de alguns minerais, podendo até destruir completamente a matéria orgânica do reservatório original (Thomaz Filho et al, 2008;Eiras e Wanderley Filho, 2003).…”

Section: Introductionunclassified

Modelamento termal de uma auréola metamórfica em torno de uma intrusão básica hipabissal paleógena na Bacia Potiguar, Nordeste do Brasil

Valcácio

Souza

Moreira

et al. 2017

Geol. USP. Sér. Cient.

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ResumoA Bacia Potiguar possui um volume considerável de rochas básicas alcalinas. Os efeitos térmicos associados a essas rochas em bacias sedimentares podem ocasionar um tipo peculiar de metamorfismo de contato, o pirometamorfismo, capaz de fundir parcialmente as rochas encaixantes e gerar novas rochas. Este trabalho reporta o efeito térmico dessas intrusões cenozoicas, conhecidas como Magmatismo Macau, em rochas cretáceas da Bacia Potiguar, com auxílio de dados de campo, petrografia e petrofísica. Para isso, foi simulado o arrefecimento térmico por meio de modelos matemáticos no entorno do plug São João, localizado a nordeste de Pedro Avelino (estado do Rio Grande do Norte, Nordeste do Brasil), correlacionando-o a mudanças mineralógicas identificadas nas rochas encaixantes. As modificações físicas e texturais mais expressivas na evolução de altas para baixas temperaturas são a fusão parcial e recristalização das rochas encaixantes, compactação e fraturamento hidráulico. O modelamento térmico indica que a auréola metamórfica pode atingir até 150 m do contato. Além disso, as associações minerais relacionadas ao metamorfismo de contato (cordierita, tridimita e espurrita, além de vidro) permitem estimar condições de temperaturas mínimas da ordem de 1.000 °C e pressões de 0,5 kbar. O modelamento térmico sugere que as mudanças mineralógicas e texturais foram efetivas com temperaturas a partir de 400 °C. O tempo de resfriamento estimado para o plug São João é de aproximadamente 10 mil anos. Tais dados são relevantes para entender o efeito do magmatismo na remobilização de hidrocarbonetos e sua influência nos sistemas petrolíferos da Bacia Potiguar.Palavras-chave: Pirometamorfismo; Petrofísica; Bacia Potiguar; Nordeste do Brasil. AbstractThe Potiguar Basin encompasses a considerable volume of alkaline basic rocks. The thermal effects associated with the emplacement of igneous rocks on sedimentary sequences can cause a peculiar type of contact metamorphism, the pyrometamorphism, which produces partial melting of host rocks and generate new rocks. This paper discusses the thermal effects caused by Cenozoic intrusions, known as Macau Magmatism, over Cretaceous rocks of the Potiguar Basin by means of field, petrographic and petrophysical data. Using mathematical models, the thermal cooling was simulated in the proximity of the São João plug, northeastern of Pedro Avelino village (state of Rio Grande do Norte, NE, Brazil). The results were correlated with mineralogical changes in the surrounding rocks. The most significant physical and textural changes from high to low temperatures are partial melting and recrystallization, compression and hydraulic fracturing. The thermal modeling indicates that the metamorphic aureole can reach up to 150 m from the contact. In addition, mineral assemblages related to contact metamorphism (cordierite, tridymite, spurrite, besides glass) allow to estimate minimum temperature conditions of the order of 1,000 °C and pressure of 0.5 kbar. Thermal modeling suggests that mineralogical and textur...

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“…Vitrinite reflectance also has been successfully applied to areas of geothermal activity to assess the maximum thermal maturation of organic particles in the sediments (Barker et al, 1986;Barker, 1991). Bostick and Pawlewicz (1984) and Ujiié (1986) have demonstrated the sensitivity of vitrinite to thermal changes near igneous intrusions and have shown how this approach can document the sphere of thermal alteration around these intrusive bodies.…”

Section: Introductionmentioning

confidence: 99%

Thermal Evolution of Sediments from Leg 139, Middle Valley, Juan de Fuca Ridge: An Organic Petrological Study

Mao¹,

Eglinton²,

Whelan³

et al. 1994

Proceedings of the Ocean Drilling Program, 139 Scientific Results

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This study is a petrographic examination of the thermal evolution of organic material in sediments from Ocean Drilling Program Leg 139, Middle Valley, Juan de Fuca Ridge. Thermal Alteration Indices (TAI), vitrinite reflectance (%VR 0) and spore fluorescence color (SFC) are used to provide thermal maturation data from four distinct hydrologic environments in this sedimented rift system. Extremely sharp increases in thermal maturity at Sites 856 and 858 characterize past and present hydrothermally active systems, respectively. Site 857 also shows accelerated maturation but may differ from Site 856 and 858 in that lateral fluid flow may be involved. Site 855A is presently immature and gives a good indication of the regional background thermal maturity. A paleotemperature correlation between TAI and other maturity and thermal indicators has been attempted in conjunction with laboratory experiments.

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Contact-metamorphic effect on parameters for kerogen maturation

Cited by 9 publications

References 11 publications

Relationship between statistical thermal alteration index and vitrinite reflectance for sedimentary rocks in northern Japan with reference to effects for unconformity, faulting, and contact metamorphism

Relationship between statistical thermal alteration index and vitrinite reflectance for sedimentary rocks in northern Japan with reference to effects for unconformity, faulting, and contact metamorphism

Modelamento termal de uma auréola metamórfica em torno de uma intrusão básica hipabissal paleógena na Bacia Potiguar, Nordeste do Brasil

Thermal Evolution of Sediments from Leg 139, Middle Valley, Juan de Fuca Ridge: An Organic Petrological Study

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