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Dayong Wang - One of the best experts on this subject based on the ideXlab platform.
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influence of different boiling points of pore water around an igneous sill on the Thermal evolution of the contact aureole
International Journal of Coal Geology, 2012Co-Authors: Dayong Wang, Yongchen SongAbstract:Abstract A low-permeability magmatic sill is capable of acting as cap rock to isolate the connection of pore fluids between overlying and underlying host rocks and consequently elevates the fluid pressure of the underlying host rocks towards the lithostatic pressure. For shallow, buried igneous sills, this will enhance the boiling point ( T boil ) of and even cause the supercritical state of the pore water in the underlying host rocks during cooling of magma. By using an isolated diabase sill in Huimin Sag, Bohai Bay Basin, China as an example, this study presents an investigation on the effect of the different T boil (300 °C vs. 350 °C) or states (volatilization vs. the supercritical state) of pore water around the sill on the Thermal evolution of the adjacent host rocks based on heat transfer models. Our results indicate: 1) Ignoring the difference in T boil between the underlying and overlying host rocks can cause the maximum deviation of ~ 20 °C in the predicted peak temperature ( T peak ) and of ~ 0.4% in the predicted vitrinite reflectance (VR r ) if the T boil below the sill is higher than that above the sill under real geological conditions; 2) Assuming the supercritical pressure for the pore water below the sill leads to the maximum deviation of more than 1.1% in VR r and of at least 50 °C in T peak , relative to the situation assuming the same T boil for all the host rocks; 3) The observation and analysis based on drill cores show that the T peak profile of the host rocks should be asymmetric to the horizontal central line of the sill. The thickness of the inner Thermal Alteration zone (hornfels zone) is somewhat larger below the sill than above the sill, whereas the outer Thermal Alteration zone (carbargilite zone) below the sill is obviously thicker than that above the sill. Only the predicted T peak profile by the model assuming the supercritical pressure for the pore water below the sill can match with such observation. This demonstrates that the assumption of the different states of pore water represents natural conditions.
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Comparable study on the effect of errors and uncertainties of heat transfer models on quantitative evaluation of Thermal Alteration in contact metamorphic aureoles: Thermophysical parameters, intrusion mechanism, pore-water volatilization and mathema
International Journal of Coal Geology, 2012Co-Authors: Dayong WangAbstract:Abstract By using a 15 m thick, well-dated basic sill as an example, this study presents an investigation on the effect of errors in thermophysical parameters of igneous intrusions and over-simplification in heat transfer equations as well as uncertainties in pore-water volatilization and intrusion mechanisms of magma on quantitative evaluation of Thermal Alteration in contact metamorphic aureoles based on heat transfer models and the EASY%Ro model. Our results indicate: 1) Using an under-estimated and temperature-independent specific heat (e.g. ~ 800 J kg − 1 °C − 1 ) of igneous intrusions instead of the temperature-dependent specific heat can cause the maximum deviation of 68 °C in peak temperature and of 1.3% in vitrinite reflectance, whereas such deviations (less than 26 °C and 0.1%) are small enough to be ignored for the model using a high, invariable specific heat (e.g. ~ 1200 J kg − 1 °C − 1 ) of igneous intrusions. The specific heat of igneous intrusions is likely a more notable error source in causing model deviations compared to the intrusion temperature and the latent crystallization heat of melted magma, if the latent crystallization heat is allowed for; 2) the effect of the uncertainty in whether pore water volatilized during cooling of intrusive magma on the model prediction can be as notable as that of the use of an under-estimated specific heat. The over-simplification in heat transfer equations (i.e. the variation of Thermal conductivity with spatial location is not used) results in an obvious underestimation of the Thermal effect of igneous intrusions on host rocks. The model deviation caused by this type of error may be far beyond that caused by the errors in thermophysical parameters of igneous intrusions or the uncertainty in pore-water volatilization; 3) the model deviations due to the errors in the thermophysical parameters and the uncertainty in pore-water volatilization can be large enough to disturb the estimation of the intrusion mechanism based on heat transfer models. By comparing the vitrinite reflectance predicted by different heat transfer models with the measured one, the results from more than one type of model can be found to match well with the observation. Only the model of the finite-time intrusion mechanism can be reasonably regarded as representing natural conditions. It is not fully reliable to validate the availability of the used heat transfer models only by observing whether the model results match with measured geothermometers due to the effect of these uncertainties, errors and over-simplification. More careful model specification and parameter estimation are required in the future use of heat transfer models of igneous intrusions.
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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: Xiancai Lu, Shijin Xu, Wenxuan Hu, Xuejun Zhang, Dayong Wang, 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.
C Maden - One of the best experts on this subject based on the ideXlab platform.
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noble gases in cm carbonaceous chondrites effect of parent body aqueous and Thermal Alteration and cosmic ray exposure ages
Geochimica et Cosmochimica Acta, 2021Co-Authors: Daniela Krietsch, H Busemann, M E I Riebe, A J King, Conel Od M Alexander, C MadenAbstract:Like most primitive carbonaceous chondrites, the CM chondrites experienced varying degrees of asteroidal aqueous Alteration, which may have overprinted pre-accretionary processing. Several aqueous Alteration scales for CM chondrites (and other carbonaceous chondrites) have been proposed based on Alteration-dependent changes in various petrological and geochemical characteristics. Given the possibility that the intensity of aqueous Alteration could be recorded in the primordial noble gas compositions, we test potential correlations between petrologic, geochemical and noble gas characteristics in a detailed study on 39 CM chondrites, including some of the most pristine CM chondrites identified to date, and 4 CM-related carbonaceous chondrites. We mainly compare our noble gas data with the Alteration schemes proposed by Alexander et al. (2013) and Howard et al. (2015). In addition to the noble gas analyses, we determined the phyllosilicate fractions of 17 of the CM chondrites using X-ray diffraction (XRD) to complement missing data points in the Howard Alteration scheme. The influence of post-hydration Thermal modification on noble gases in CM chondrites is investigated by comparison of heated and unheated samples. Cosmic-ray exposure (CRE) ages are determined for all samples in this study as well as for 26 more samples based on CM chondrite literature noble gas data. The noble gas inventory in CM chondrites represents a mixture of cosmogenic, radiogenic, and abundant primordially trapped noble gases. Additionally, about 50 % of our CM bulk samples contain detectable solar wind (SW), which implies that many but not all CM chondrites are regolith breccias or carry SW from a pre-accretion irradiation phase. Aqueous Alteration affects primordial noble gas abundances and elemental and isotopic compositions in CM chondrites. In particular, the process causes loss of an Ar-rich component, different in elemental and isotopic composition to known noble gas components. This component is lost during the early stages of aqueous Alteration until complete degassing of its carrier material (possibly upon at least partial destruction) below petrologic type of ∼1.5 on the Howard et al. (2015) scale. Likely, small amounts of Q gases were additionally released by aqueous Alteration. Strong Thermal modification at >750 °C results in a significant additional loss of noble gases, whereas peak temperatures <500 °C likely have minor effects on the noble gas inventories of CM chondrites. Some of the described trends of noble gas contents and elemental and isotopic ratios in this study are observable across multiple carbonaceous chondrite groups, in particular also the CR chondrites. Hence, these carbonaceous chondrites may have started with similar initial noble gas inventories due to accretion of material from a common reservoir. The CRE ages of most of our CM samples fall within the typical range of <10 Myr previously observed for CM chondrites. A few CM chondrites, however, show longer CRE ages, with the longest CRE age of ∼20 Myr determined for the SW-rich CM Allan Hills (ALH) 85013. The degree of aqueous and Thermal Alteration is variable among CM chondrites with similar CRE ages.
A J King - One of the best experts on this subject based on the ideXlab platform.
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noble gases in cm carbonaceous chondrites effect of parent body aqueous and Thermal Alteration and cosmic ray exposure ages
Geochimica et Cosmochimica Acta, 2021Co-Authors: Daniela Krietsch, H Busemann, M E I Riebe, A J King, Conel Od M Alexander, C MadenAbstract:Like most primitive carbonaceous chondrites, the CM chondrites experienced varying degrees of asteroidal aqueous Alteration, which may have overprinted pre-accretionary processing. Several aqueous Alteration scales for CM chondrites (and other carbonaceous chondrites) have been proposed based on Alteration-dependent changes in various petrological and geochemical characteristics. Given the possibility that the intensity of aqueous Alteration could be recorded in the primordial noble gas compositions, we test potential correlations between petrologic, geochemical and noble gas characteristics in a detailed study on 39 CM chondrites, including some of the most pristine CM chondrites identified to date, and 4 CM-related carbonaceous chondrites. We mainly compare our noble gas data with the Alteration schemes proposed by Alexander et al. (2013) and Howard et al. (2015). In addition to the noble gas analyses, we determined the phyllosilicate fractions of 17 of the CM chondrites using X-ray diffraction (XRD) to complement missing data points in the Howard Alteration scheme. The influence of post-hydration Thermal modification on noble gases in CM chondrites is investigated by comparison of heated and unheated samples. Cosmic-ray exposure (CRE) ages are determined for all samples in this study as well as for 26 more samples based on CM chondrite literature noble gas data. The noble gas inventory in CM chondrites represents a mixture of cosmogenic, radiogenic, and abundant primordially trapped noble gases. Additionally, about 50 % of our CM bulk samples contain detectable solar wind (SW), which implies that many but not all CM chondrites are regolith breccias or carry SW from a pre-accretion irradiation phase. Aqueous Alteration affects primordial noble gas abundances and elemental and isotopic compositions in CM chondrites. In particular, the process causes loss of an Ar-rich component, different in elemental and isotopic composition to known noble gas components. This component is lost during the early stages of aqueous Alteration until complete degassing of its carrier material (possibly upon at least partial destruction) below petrologic type of ∼1.5 on the Howard et al. (2015) scale. Likely, small amounts of Q gases were additionally released by aqueous Alteration. Strong Thermal modification at >750 °C results in a significant additional loss of noble gases, whereas peak temperatures <500 °C likely have minor effects on the noble gas inventories of CM chondrites. Some of the described trends of noble gas contents and elemental and isotopic ratios in this study are observable across multiple carbonaceous chondrite groups, in particular also the CR chondrites. Hence, these carbonaceous chondrites may have started with similar initial noble gas inventories due to accretion of material from a common reservoir. The CRE ages of most of our CM samples fall within the typical range of <10 Myr previously observed for CM chondrites. A few CM chondrites, however, show longer CRE ages, with the longest CRE age of ∼20 Myr determined for the SW-rich CM Allan Hills (ALH) 85013. The degree of aqueous and Thermal Alteration is variable among CM chondrites with similar CRE ages.
Jordan K Steckloff - One of the best experts on this subject based on the ideXlab platform.
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Thermal Alteration of labile elements in carbonaceous chondrites
Icarus, 2019Co-Authors: Alessondra Springmann, D S Lauretta, Bjoern Klaue, Y S Goreva, Joel D Blum, A V Andronikov, Jordan K SteckloffAbstract:Abstract Carbonaceous chondrite meteorites are some of the oldest Solar System planetary materials available for study. The CI group has bulk abundances of elements similar to those of the solar photosphere. Of particular interest in carbonaceous chondrite compositions are labile elements, which vaporize and mobilize efficiently during post-accretionary parent-body heating events. Thus, they can record low-temperature Alteration events throughout asteroid evolution. However, the precise nature of labile-element mobilization in planetary materials is unknown. Here we characterize the Thermally induced movements of the labile elements S, As, Se, Te, Cd, Sb, and Hg in carbonaceous chondrites by conducting experimental simulations of volatile-element mobilization during Thermal metamorphism. This process results in appreciable loss of some elements at temperatures as low as 500 K. This work builds on previous laboratory heating experiments on primitive meteorites and shows the sensitivity of chondrite compositions to excursions in temperature. Elements such as S and Hg have the most active response to temperature across different meteorite groups. Labile element mobilization in primitive meteorites is essential for quantifying elemental fractionation that occurred on asteroids early in Solar System history. This work is relevant to maintaining a pristine sample from asteroid (101955) Bennu from the OSIRIS-REx mission and constraining the past orbital history of Bennu. Additionally, we discuss Thermal effects on surface processes of near-Earth asteroids, including the Thermal history of “rock comets” such as (3200) Phaethon. This work is also critical for constraining the concentrations of contaminants in vaporized water extracted from asteroid regolith as part of future in situ resource utilization for sustained robotic and human space exploration.
Daniela Krietsch - One of the best experts on this subject based on the ideXlab platform.
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noble gases in cm carbonaceous chondrites effect of parent body aqueous and Thermal Alteration and cosmic ray exposure ages
Geochimica et Cosmochimica Acta, 2021Co-Authors: Daniela Krietsch, H Busemann, M E I Riebe, A J King, Conel Od M Alexander, C MadenAbstract:Like most primitive carbonaceous chondrites, the CM chondrites experienced varying degrees of asteroidal aqueous Alteration, which may have overprinted pre-accretionary processing. Several aqueous Alteration scales for CM chondrites (and other carbonaceous chondrites) have been proposed based on Alteration-dependent changes in various petrological and geochemical characteristics. Given the possibility that the intensity of aqueous Alteration could be recorded in the primordial noble gas compositions, we test potential correlations between petrologic, geochemical and noble gas characteristics in a detailed study on 39 CM chondrites, including some of the most pristine CM chondrites identified to date, and 4 CM-related carbonaceous chondrites. We mainly compare our noble gas data with the Alteration schemes proposed by Alexander et al. (2013) and Howard et al. (2015). In addition to the noble gas analyses, we determined the phyllosilicate fractions of 17 of the CM chondrites using X-ray diffraction (XRD) to complement missing data points in the Howard Alteration scheme. The influence of post-hydration Thermal modification on noble gases in CM chondrites is investigated by comparison of heated and unheated samples. Cosmic-ray exposure (CRE) ages are determined for all samples in this study as well as for 26 more samples based on CM chondrite literature noble gas data. The noble gas inventory in CM chondrites represents a mixture of cosmogenic, radiogenic, and abundant primordially trapped noble gases. Additionally, about 50 % of our CM bulk samples contain detectable solar wind (SW), which implies that many but not all CM chondrites are regolith breccias or carry SW from a pre-accretion irradiation phase. Aqueous Alteration affects primordial noble gas abundances and elemental and isotopic compositions in CM chondrites. In particular, the process causes loss of an Ar-rich component, different in elemental and isotopic composition to known noble gas components. This component is lost during the early stages of aqueous Alteration until complete degassing of its carrier material (possibly upon at least partial destruction) below petrologic type of ∼1.5 on the Howard et al. (2015) scale. Likely, small amounts of Q gases were additionally released by aqueous Alteration. Strong Thermal modification at >750 °C results in a significant additional loss of noble gases, whereas peak temperatures <500 °C likely have minor effects on the noble gas inventories of CM chondrites. Some of the described trends of noble gas contents and elemental and isotopic ratios in this study are observable across multiple carbonaceous chondrite groups, in particular also the CR chondrites. Hence, these carbonaceous chondrites may have started with similar initial noble gas inventories due to accretion of material from a common reservoir. The CRE ages of most of our CM samples fall within the typical range of <10 Myr previously observed for CM chondrites. A few CM chondrites, however, show longer CRE ages, with the longest CRE age of ∼20 Myr determined for the SW-rich CM Allan Hills (ALH) 85013. The degree of aqueous and Thermal Alteration is variable among CM chondrites with similar CRE ages.
