The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Dayong Wang - One of the best experts on this subject based on the ideXlab platform.
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heat model analysis of wall rocks below a diabase sill in huimin sag china compared with thermal alteration of mudstone to carbargilite and Hornfels and with increase of vitrinite reflectance
Geophysical Research Letters, 2007Co-Authors: Dayong Wang, Xiancai Lu, Xuejun Zhang, Shijin Xu, Wenxuan Hu, Liangshu WangAbstract:[1] This paper presents an application of heat flow modeling in a study on the thermal alteration of the underlying sedimentary rocks caused by an isolated intrusive sill in Huimin Sag, Bohai Bay Basin, China. It is found that during the cooling of the sill, the assignment of the heat transferred into its both sides can be acquired according to the ratio of the thickness of the overlying and underlying thermally altered rocks. Heat-transfer modeling indicates that the transition temperatures for the alteration from calcareous mudstone to carbargilite and successively to Hornfels are identified as 245 ± 9°C and as 449 ± 19°C, respectively. The peak temperature calculated from vitrinite reflectance higher than 3.0% of the altered wall rocks is generally lower than expected values. Especially in the Hornfels zone, vitrinite reflectance ever decreased with increased temperature. The thermal alteration of mudstone is possibly an important factor causing such a decrease.
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Heat‐model analysis of wall rocks below a diabase sill in Huimin Sag, China compared with thermal alteration of mudstone to carbargilite and Hornfels and with increase of vitrinite reflectance
Geophysical Research Letters, 2007Co-Authors: Dayong Wang, Xiancai Lu, Xuejun Zhang, Shijin Xu, Wenxuan Hu, Liangshu WangAbstract:[1] This paper presents an application of heat flow modeling in a study on the thermal alteration of the underlying sedimentary rocks caused by an isolated intrusive sill in Huimin Sag, Bohai Bay Basin, China. It is found that during the cooling of the sill, the assignment of the heat transferred into its both sides can be acquired according to the ratio of the thickness of the overlying and underlying thermally altered rocks. Heat-transfer modeling indicates that the transition temperatures for the alteration from calcareous mudstone to carbargilite and successively to Hornfels are identified as 245 ± 9°C and as 449 ± 19°C, respectively. The peak temperature calculated from vitrinite reflectance higher than 3.0% of the altered wall rocks is generally lower than expected values. Especially in the Hornfels zone, vitrinite reflectance ever decreased with increased temperature. The thermal alteration of mudstone is possibly an important factor causing such a decrease.
Jennifer A Thomson - One of the best experts on this subject based on the ideXlab platform.
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beneath the stillwater complex petrology and geochemistry of quartz plagioclase cordierite or garnet orthopyroxene biotite spinel Hornfels mountain view area montana
American Mineralogist, 2008Co-Authors: Jennifer A ThomsonAbstract:A 50 m drill core (core no. 383-334) collected from the contact metamorphic aureole in the Mouat Ni-Cu prospect in the Mountain View area of Stillwater County, Montana, exhibits evidence of in situ fluid-absent biotite dehydration melting and local back reaction of melts derived from metasediments and metavolcanics. The drill core was investigated to characterize the mineral assemblages and their textures, to search for evidence of partial melting, and to determine mineral and whole-rock geochemistry to provide an understanding of the petrogenesis of the Hornfels close to the contact with the Stillwater Complex. The rocks investigated are predominantly quartz-plagioclase-cordierite-orthopyroxene-biotite ± spinel Hornfels, Fe-Cu-Ni sulfides, and Fe-Ti oxides. One sample contains garnet (Alm 73–77 Pyr 20–17 Sps 3 Grs 4 ) in addition to cordierite. Three samples contain cordierite-hercynite symplectites surrounded by a narrow mantle devoid of orthopyroxene, plagioclase, and biotite that are roughly ovoid to lenticular in shape. Partially melted samples show back reaction between crystallizing melt and restite such that retrograde skeletal intergrowths of biotite and quartz in the mesosome were developed. Average T-P conditions of Hornfels and melt genesis are 786 °C and 3.7 kbar. Back reactions that produced biotite occurred at somewhat lower temperatures. Whole-rock geochemistry suggests that the protolith of the Hornfelsic rocks was likely a mixture of greywacke and additional intermediate to mafic volcanogenic components.
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Beneath the Stillwater Complex : Petrology and geochemistry of quartz-plagioclase-cordierite (or garnet)-orthopyroxene-biotite ± spinel Hornfels, Mountain View area, Montana
American Mineralogist, 2008Co-Authors: Jennifer A ThomsonAbstract:A 50 m drill core (core no. 383-334) collected from the contact metamorphic aureole in the Mouat Ni-Cu prospect in the Mountain View area of Stillwater County, Montana, exhibits evidence of in situ fluid-absent biotite dehydration melting and local back reaction of melts derived from metasediments and metavolcanics. The drill core was investigated to characterize the mineral assemblages and their textures, to search for evidence of partial melting, and to determine mineral and whole-rock geochemistry to provide an understanding of the petrogenesis of the Hornfels close to the contact with the Stillwater Complex. The rocks investigated are predominantly quartz-plagioclase-cordierite-orthopyroxene-biotite ± spinel Hornfels, Fe-Cu-Ni sulfides, and Fe-Ti oxides. One sample contains garnet (Alm 73–77 Pyr 20–17 Sps 3 Grs 4 ) in addition to cordierite. Three samples contain cordierite-hercynite symplectites surrounded by a narrow mantle devoid of orthopyroxene, plagioclase, and biotite that are roughly ovoid to lenticular in shape. Partially melted samples show back reaction between crystallizing melt and restite such that retrograde skeletal intergrowths of biotite and quartz in the mesosome were developed. Average T-P conditions of Hornfels and melt genesis are 786 °C and 3.7 kbar. Back reactions that produced biotite occurred at somewhat lower temperatures. Whole-rock geochemistry suggests that the protolith of the Hornfelsic rocks was likely a mixture of greywacke and additional intermediate to mafic volcanogenic components.
Liangshu Wang - One of the best experts on this subject based on the ideXlab platform.
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heat model analysis of wall rocks below a diabase sill in huimin sag china compared with thermal alteration of mudstone to carbargilite and Hornfels and with increase of vitrinite reflectance
Geophysical Research Letters, 2007Co-Authors: Dayong Wang, Xiancai Lu, Xuejun Zhang, Shijin Xu, Wenxuan Hu, Liangshu WangAbstract:[1] This paper presents an application of heat flow modeling in a study on the thermal alteration of the underlying sedimentary rocks caused by an isolated intrusive sill in Huimin Sag, Bohai Bay Basin, China. It is found that during the cooling of the sill, the assignment of the heat transferred into its both sides can be acquired according to the ratio of the thickness of the overlying and underlying thermally altered rocks. Heat-transfer modeling indicates that the transition temperatures for the alteration from calcareous mudstone to carbargilite and successively to Hornfels are identified as 245 ± 9°C and as 449 ± 19°C, respectively. The peak temperature calculated from vitrinite reflectance higher than 3.0% of the altered wall rocks is generally lower than expected values. Especially in the Hornfels zone, vitrinite reflectance ever decreased with increased temperature. The thermal alteration of mudstone is possibly an important factor causing such a decrease.
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Heat‐model analysis of wall rocks below a diabase sill in Huimin Sag, China compared with thermal alteration of mudstone to carbargilite and Hornfels and with increase of vitrinite reflectance
Geophysical Research Letters, 2007Co-Authors: Dayong Wang, Xiancai Lu, Xuejun Zhang, Shijin Xu, Wenxuan Hu, Liangshu WangAbstract:[1] This paper presents an application of heat flow modeling in a study on the thermal alteration of the underlying sedimentary rocks caused by an isolated intrusive sill in Huimin Sag, Bohai Bay Basin, China. It is found that during the cooling of the sill, the assignment of the heat transferred into its both sides can be acquired according to the ratio of the thickness of the overlying and underlying thermally altered rocks. Heat-transfer modeling indicates that the transition temperatures for the alteration from calcareous mudstone to carbargilite and successively to Hornfels are identified as 245 ± 9°C and as 449 ± 19°C, respectively. The peak temperature calculated from vitrinite reflectance higher than 3.0% of the altered wall rocks is generally lower than expected values. Especially in the Hornfels zone, vitrinite reflectance ever decreased with increased temperature. The thermal alteration of mudstone is possibly an important factor causing such a decrease.
Naomi Marks - One of the best experts on this subject based on the ideXlab platform.
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High‐grade contact metamorphism in the Reykjanes geothermal system: Implications for fluid‐rock interactions at mid‐oceanic ridge spreading centers
Geochemistry Geophysics Geosystems, 2011Co-Authors: Naomi Marks, Peter Schiffman, Robert A ZierenbergAbstract:Granoblastic Hornfels identified in cuttings from the Reykjanes seawater-dominated hydrothermal system contains secondary pyroxene, anorthite, and hornblendic amphibole in locally equilibrated assemblages. Granoblastic assemblages containing secondary orthopyroxene, olivine, and, locally, cordierite and spinel occur within groups of cuttings that show dominantly greenschist facies hydrothermal alteration. Granoblastic plagioclase ranges continuously in composition from An54 to An96, in contrast with relict igneous plagioclase that ranges from An42 to An80. Typical hydrothermal clinopyroxene compositions range from Wo49En3Fs48 to Wo53En30Fo17; clinopyroxene from the granoblastic grains is less calcic with an average composition of Wo48En27Fs25. The Hornfels is interpreted to form during contact metamorphism in response to dike emplacement, resulting in local recrystallization of previously hydrothermally altered basalts. Temperatures of granoblastic recrystallization estimated from the 2-pyroxene geothermometer range from 927°C to 967°C. Redox estimates based on the 2-oxide oxybarometer range from log fO2 of −13.4 to −15.9. Granoblastic Hornfels comprised of clinopyroxene, orthopyroxene, and calcic plagioclase have been described in a number of ancient hydrothermal systems from the conductive boundary layer between the hydrothermal system and the underlying magma source, most notably in Integrated Ocean Drilling Program Hole 1256D, Ocean Drilling Program Hole 504B, and in the Troodos and Oman ophiolites. To our knowledge, this is the first evidence of high-grade contact metamorphism from an active geothermal system and the first description of equilibrated amphibole-absent pyroxene Hornfels facies contact metamorphism in any mid-ocean ridge (MOR) hydrothermal system. This contribution describes how these assemblages develop through metamorphic reactions and allows us to predict that higher-temperature assemblages may also be present in MOR systems.
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high grade contact metamorphism in the reykjanes geothermal system implications for fluid rock interactions at mid oceanic ridge spreading centers
Geochemistry Geophysics Geosystems, 2011Co-Authors: Peter Schiffman, Naomi Marks, Robert A ZierenbergAbstract:Granoblastic Hornfels identified in cuttings from the Reykjanes seawater-dominated hydrothermal system contains secondary pyroxene, anorthite, and hornblendic amphibole in locally equilibrated assemblages. Granoblastic assemblages containing secondary orthopyroxene, olivine, and, locally, cordierite and spinel occur within groups of cuttings that show dominantly greenschist facies hydrothermal alteration. Granoblastic plagioclase ranges continuously in composition from An54 to An96, in contrast with relict igneous plagioclase that ranges from An42 to An80. Typical hydrothermal clinopyroxene compositions range from Wo49En3Fs48 to Wo53En30Fo17; clinopyroxene from the granoblastic grains is less calcic with an average composition of Wo48En27Fs25. The Hornfels is interpreted to form during contact metamorphism in response to dike emplacement, resulting in local recrystallization of previously hydrothermally altered basalts. Temperatures of granoblastic recrystallization estimated from the 2-pyroxene geothermometer range from 927°C to 967°C. Redox estimates based on the 2-oxide oxybarometer range from log fO2 of −13.4 to −15.9. Granoblastic Hornfels comprised of clinopyroxene, orthopyroxene, and calcic plagioclase have been described in a number of ancient hydrothermal systems from the conductive boundary layer between the hydrothermal system and the underlying magma source, most notably in Integrated Ocean Drilling Program Hole 1256D, Ocean Drilling Program Hole 504B, and in the Troodos and Oman ophiolites. To our knowledge, this is the first evidence of high-grade contact metamorphism from an active geothermal system and the first description of equilibrated amphibole-absent pyroxene Hornfels facies contact metamorphism in any mid-ocean ridge (MOR) hydrothermal system. This contribution describes how these assemblages develop through metamorphic reactions and allows us to predict that higher-temperature assemblages may also be present in MOR systems.
Robert A Zierenberg - One of the best experts on this subject based on the ideXlab platform.
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High‐grade contact metamorphism in the Reykjanes geothermal system: Implications for fluid‐rock interactions at mid‐oceanic ridge spreading centers
Geochemistry Geophysics Geosystems, 2011Co-Authors: Naomi Marks, Peter Schiffman, Robert A ZierenbergAbstract:Granoblastic Hornfels identified in cuttings from the Reykjanes seawater-dominated hydrothermal system contains secondary pyroxene, anorthite, and hornblendic amphibole in locally equilibrated assemblages. Granoblastic assemblages containing secondary orthopyroxene, olivine, and, locally, cordierite and spinel occur within groups of cuttings that show dominantly greenschist facies hydrothermal alteration. Granoblastic plagioclase ranges continuously in composition from An54 to An96, in contrast with relict igneous plagioclase that ranges from An42 to An80. Typical hydrothermal clinopyroxene compositions range from Wo49En3Fs48 to Wo53En30Fo17; clinopyroxene from the granoblastic grains is less calcic with an average composition of Wo48En27Fs25. The Hornfels is interpreted to form during contact metamorphism in response to dike emplacement, resulting in local recrystallization of previously hydrothermally altered basalts. Temperatures of granoblastic recrystallization estimated from the 2-pyroxene geothermometer range from 927°C to 967°C. Redox estimates based on the 2-oxide oxybarometer range from log fO2 of −13.4 to −15.9. Granoblastic Hornfels comprised of clinopyroxene, orthopyroxene, and calcic plagioclase have been described in a number of ancient hydrothermal systems from the conductive boundary layer between the hydrothermal system and the underlying magma source, most notably in Integrated Ocean Drilling Program Hole 1256D, Ocean Drilling Program Hole 504B, and in the Troodos and Oman ophiolites. To our knowledge, this is the first evidence of high-grade contact metamorphism from an active geothermal system and the first description of equilibrated amphibole-absent pyroxene Hornfels facies contact metamorphism in any mid-ocean ridge (MOR) hydrothermal system. This contribution describes how these assemblages develop through metamorphic reactions and allows us to predict that higher-temperature assemblages may also be present in MOR systems.
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high grade contact metamorphism in the reykjanes geothermal system implications for fluid rock interactions at mid oceanic ridge spreading centers
Geochemistry Geophysics Geosystems, 2011Co-Authors: Peter Schiffman, Naomi Marks, Robert A ZierenbergAbstract:Granoblastic Hornfels identified in cuttings from the Reykjanes seawater-dominated hydrothermal system contains secondary pyroxene, anorthite, and hornblendic amphibole in locally equilibrated assemblages. Granoblastic assemblages containing secondary orthopyroxene, olivine, and, locally, cordierite and spinel occur within groups of cuttings that show dominantly greenschist facies hydrothermal alteration. Granoblastic plagioclase ranges continuously in composition from An54 to An96, in contrast with relict igneous plagioclase that ranges from An42 to An80. Typical hydrothermal clinopyroxene compositions range from Wo49En3Fs48 to Wo53En30Fo17; clinopyroxene from the granoblastic grains is less calcic with an average composition of Wo48En27Fs25. The Hornfels is interpreted to form during contact metamorphism in response to dike emplacement, resulting in local recrystallization of previously hydrothermally altered basalts. Temperatures of granoblastic recrystallization estimated from the 2-pyroxene geothermometer range from 927°C to 967°C. Redox estimates based on the 2-oxide oxybarometer range from log fO2 of −13.4 to −15.9. Granoblastic Hornfels comprised of clinopyroxene, orthopyroxene, and calcic plagioclase have been described in a number of ancient hydrothermal systems from the conductive boundary layer between the hydrothermal system and the underlying magma source, most notably in Integrated Ocean Drilling Program Hole 1256D, Ocean Drilling Program Hole 504B, and in the Troodos and Oman ophiolites. To our knowledge, this is the first evidence of high-grade contact metamorphism from an active geothermal system and the first description of equilibrated amphibole-absent pyroxene Hornfels facies contact metamorphism in any mid-ocean ridge (MOR) hydrothermal system. This contribution describes how these assemblages develop through metamorphic reactions and allows us to predict that higher-temperature assemblages may also be present in MOR systems.