Re: [meteorite-list] Portales Valley: Not Just Another Ordinary Chondrite
In Roberl Woolard site its write this: H7, Metallic Melt Breccia (Primitive Achondrite) Its ok? Matteo --- Frank Cressy [EMAIL PROTECTED] ha scritto: Matteo and all, I believe it is now classified as a Metallic-melt Meteorite Breccia. Cheers, Frank M come Meteorite Meteorites [EMAIL PROTECTED] wrote: ok...in conclusion what new classification is portales valley? Matteo --- Ron Baalke ha scritto: http://www.psrd.hawaii.edu/Sept05/PortalesValley.html Portales Valley: Not Just Another Ordinary Chondrite Planetary Science Research Discoveries September 30, 2005 --- A melted meteorite gives a snapshot of the heat and shock that wracked an asteroid during the first stages of differentiation. Written by Alex Ruzicka and Melinda Hutson Department of Geology, Portland State University Soon after the Portales Valley meteorite fell in 1998, it was classified as one of the most common types of meteorites, an H6 ordinary chondrite. Although researchers quickly recognized that Portales Valley is not a typical H6 chondrite, there was little agreement about how the meteorite formed. A recent study of Portales Valley by Ruzicka and colleagues suggests that the textures, mineralogy, and chemistry of the meteorite are best explained as the first good example of a metallic melt breccia. This meteorite represents a transitional stage between chondrites and various classes of differentiated meteorites, and offers clues as to how differentiation occurred in early-formed planetary bodies. Reference: * Ruzicka, A., Killgore, M., Mittlefehldt, D.W. and Fries, M.D (2005) Portales Valley: Petrology of a metallic-melt meteorite breccia. Meteoritics Planetary Science, v. 40, p. 261-295. Differentiation: a widespread but poorly-understood process Most solar system material underwent differentiation, a process involving melting and separation of liquids and solids of varying density and chemical composition. However, chondritic meteorites escaped this process and are believed to be pieces of undifferentiated asteroids. All other meteorites, and probably all rocks from planets and large moons, melted when the parent bodies differentiated to form cores, mantles, and crusts. The heat source for differentiation is uncertain, as are the exact physical processes and conditions that allowed differentiation to proceed in small planetary bodies with weak gravity. Proposed sources of heat include internally-generated heat from short-lived radioactive materials such as aluminum-26 (26Al), external heating from our young active Sun, and heating resulting from collisions between planetary bodies (shock heating). A detailed study of the Portales Valley meteorite suggests that differentiation of small planetary bodies involved a combination of an internal heat source and shock. Shock heating was not the major heat source involved in differentiation, but the stress waves associated with even modest shock events played a critical role in helping materials to separate and reconfigure during differentiation. illustration of differentiation by Granshaw A sequence of images showing stages in the differentiation of a planetesimal, an early-formed planetary body. The image in the left hand side shows a chondritic planetesimal becoming hot enough for melting to begin. The middle image shows that the heavier metallic liquid sinks toward the center, while the less dense rocky material rises toward the surface. The result is a differentiated object with a crust, mantle and core, as shown in the image in the right hand side. (Images created by Frank Granshaw of Artemis Software for the Cascadia Meteorite Laboratory, Portland State University.) Not an ordinary H6 ordinary chondrite Three features link Portales Valley to H-group ordinary chondrites. These are (1) the presence of rare chondrules with a rather typical chondritic texture present in silicate-rich areas, (2) the compositions of most minerals, and (3) the bulk oxygen isotopic composition of the meteorite. Nonetheless, Portales Valley contains unusual features that distinguish it from any other ordinary chondrite. Even in a cut section, the differences between Portales Valley and a typical H-chondrite are readily apparent (see figures below). comparison to H chondrite A comparison of a typical H-chondrite and Portales Valley. Bright areas are mainly metallic; dark areas are mainly silicates. Left: A slice of a meteorite that is paired with the Franconia (H5) chondritic meteorite. The small lines on the ruler are one
Re: [meteorite-list] Portales Valley: Not Just Another Ordinary Chondrite
Anotherthe probably H7, Metallic Melt Breccia (Primitive Achondrite) classification its for the pieces with metal veins...but for the normaly portales valley without any veins the classification its a H6? The matrix its paired to a normaly ordinary chondrite. Matteo --- Frank Cressy [EMAIL PROTECTED] ha scritto: Matteo and all, I believe it is now classified as a Metallic-melt Meteorite Breccia. Cheers, Frank M come Meteorite Meteorites [EMAIL PROTECTED] wrote: ok...in conclusion what new classification is portales valley? Matteo --- Ron Baalke ha scritto: http://www.psrd.hawaii.edu/Sept05/PortalesValley.html Portales Valley: Not Just Another Ordinary Chondrite Planetary Science Research Discoveries September 30, 2005 --- A melted meteorite gives a snapshot of the heat and shock that wracked an asteroid during the first stages of differentiation. Written by Alex Ruzicka and Melinda Hutson Department of Geology, Portland State University Soon after the Portales Valley meteorite fell in 1998, it was classified as one of the most common types of meteorites, an H6 ordinary chondrite. Although researchers quickly recognized that Portales Valley is not a typical H6 chondrite, there was little agreement about how the meteorite formed. A recent study of Portales Valley by Ruzicka and colleagues suggests that the textures, mineralogy, and chemistry of the meteorite are best explained as the first good example of a metallic melt breccia. This meteorite represents a transitional stage between chondrites and various classes of differentiated meteorites, and offers clues as to how differentiation occurred in early-formed planetary bodies. Reference: * Ruzicka, A., Killgore, M., Mittlefehldt, D.W. and Fries, M.D (2005) Portales Valley: Petrology of a metallic-melt meteorite breccia. Meteoritics Planetary Science, v. 40, p. 261-295. Differentiation: a widespread but poorly-understood process Most solar system material underwent differentiation, a process involving melting and separation of liquids and solids of varying density and chemical composition. However, chondritic meteorites escaped this process and are believed to be pieces of undifferentiated asteroids. All other meteorites, and probably all rocks from planets and large moons, melted when the parent bodies differentiated to form cores, mantles, and crusts. The heat source for differentiation is uncertain, as are the exact physical processes and conditions that allowed differentiation to proceed in small planetary bodies with weak gravity. Proposed sources of heat include internally-generated heat from short-lived radioactive materials such as aluminum-26 (26Al), external heating from our young active Sun, and heating resulting from collisions between planetary bodies (shock heating). A detailed study of the Portales Valley meteorite suggests that differentiation of small planetary bodies involved a combination of an internal heat source and shock. Shock heating was not the major heat source involved in differentiation, but the stress waves associated with even modest shock events played a critical role in helping materials to separate and reconfigure during differentiation. illustration of differentiation by Granshaw A sequence of images showing stages in the differentiation of a planetesimal, an early-formed planetary body. The image in the left hand side shows a chondritic planetesimal becoming hot enough for melting to begin. The middle image shows that the heavier metallic liquid sinks toward the center, while the less dense rocky material rises toward the surface. The result is a differentiated object with a crust, mantle and core, as shown in the image in the right hand side. (Images created by Frank Granshaw of Artemis Software for the Cascadia Meteorite Laboratory, Portland State University.) Not an ordinary H6 ordinary chondrite Three features link Portales Valley to H-group ordinary chondrites. These are (1) the presence of rare chondrules with a rather typical chondritic texture present in silicate-rich areas, (2) the compositions of most minerals, and (3) the bulk oxygen isotopic composition of the meteorite. Nonetheless, Portales Valley contains unusual features that distinguish it from any other ordinary chondrite. Even in a cut section, the differences between Portales Valley and a typical H-chondrite are readily apparent (see figures below). comparison to H chondrite A comparison of a typical H-chondrite and Portales Valley. Bright areas are mainly metallic;
Re: [meteorite-list] Portales Valley: Not Just Another Ordinary Chondrite
Obviously there is disagreement among scientists on what to call PV. I personally see no reason to call it type 7, a primitive achondrite, an achondrite OR to coin a new term. If I take the conclusions of the Ruzicka study as a given, that you had H6 material near its peak metamorphic temperature, which additional shock heating and mobilization of metal-rich melt, then I see no reason not call it an H chondrite impact melt breccia in which the clasts are dominantly type 6. jeff At 12:15 PM 10/5/2005, M come Meteorite Meteorites wrote: In Roberl Woolard site its write this: H7, Metallic Melt Breccia (Primitive Achondrite) Its ok? Matteo --- Frank Cressy [EMAIL PROTECTED] ha scritto: Matteo and all, I believe it is now classified as a Metallic-melt Meteorite Breccia. Cheers, Frank M come Meteorite Meteorites [EMAIL PROTECTED] wrote: ok...in conclusion what new classification is portales valley? Matteo --- Ron Baalke ha scritto: http://www.psrd.hawaii.edu/Sept05/PortalesValley.html Portales Valley: Not Just Another Ordinary Chondrite Planetary Science Research Discoveries September 30, 2005 --- A melted meteorite gives a snapshot of the heat and shock that wracked an asteroid during the first stages of differentiation. Written by Alex Ruzicka and Melinda Hutson Department of Geology, Portland State University Soon after the Portales Valley meteorite fell in 1998, it was classified as one of the most common types of meteorites, an H6 ordinary chondrite. Although researchers quickly recognized that Portales Valley is not a typical H6 chondrite, there was little agreement about how the meteorite formed. A recent study of Portales Valley by Ruzicka and colleagues suggests that the textures, mineralogy, and chemistry of the meteorite are best explained as the first good example of a metallic melt breccia. This meteorite represents a transitional stage between chondrites and various classes of differentiated meteorites, and offers clues as to how differentiation occurred in early-formed planetary bodies. Reference: * Ruzicka, A., Killgore, M., Mittlefehldt, D.W. and Fries, M.D (2005) Portales Valley: Petrology of a metallic-melt meteorite breccia. Meteoritics Planetary Science, v. 40, p. 261-295. Differentiation: a widespread but poorly-understood process Most solar system material underwent differentiation, a process involving melting and separation of liquids and solids of varying density and chemical composition. However, chondritic meteorites escaped this process and are believed to be pieces of undifferentiated asteroids. All other meteorites, and probably all rocks from planets and large moons, melted when the parent bodies differentiated to form cores, mantles, and crusts. The heat source for differentiation is uncertain, as are the exact physical processes and conditions that allowed differentiation to proceed in small planetary bodies with weak gravity. Proposed sources of heat include internally-generated heat from short-lived radioactive materials such as aluminum-26 (26Al), external heating from our young active Sun, and heating resulting from collisions between planetary bodies (shock heating). A detailed study of the Portales Valley meteorite suggests that differentiation of small planetary bodies involved a combination of an internal heat source and shock. Shock heating was not the major heat source involved in differentiation, but the stress waves associated with even modest shock events played a critical role in helping materials to separate and reconfigure during differentiation. illustration of differentiation by Granshaw A sequence of images showing stages in the differentiation of a planetesimal, an early-formed planetary body. The image in the left hand side shows a chondritic planetesimal becoming hot enough for melting to begin. The middle image shows that the heavier metallic liquid sinks toward the center, while the less dense rocky material rises toward the surface. The result is a differentiated object with a crust, mantle and core, as shown in the image in the right hand side. (Images created by Frank Granshaw of Artemis Software for the Cascadia Meteorite Laboratory, Portland State University.) Not an ordinary H6 ordinary chondrite Three features link Portales Valley to H-group ordinary chondrites. These are (1) the presence of rare chondrules with a rather typical chondritic texture present in silicate-rich areas, (2) the compositions of most minerals, and (3) the bulk oxygen isotopic composition of the meteorite. Nonetheless, Portales Valley
Re: [meteorite-list] Portales Valley: Not Just Another Ordinary Chondrite
Hello Matteo and List, Matteo had written: In Roberl Woolard site its write this: H7, Metallic Melt Breccia (Primitive Achondrite) Its ok? Matteo Just to make it perfectly clear, what I say on the site, in context, is: (Capitalization and spacing added here for emphasis): POSSIBLE New Classification for Portales Valley ! H7, Metallic Melt Breccia (Primitive Achondrite) And further, in the text: From the very start, PV proved to be very puzzling. It simply did not appear to resemble any other known meteorite. Was it a stone, an iron, or a stony-iron? Even today, almost every reference to PV includes phrases such as unique, never before seen, first time ever, puzzling, one of a kind, etc. Some of the reasons for these claims are that this is the first time for a stone meteorite to exhibit Thomson (Widmanstatten) figures, incredibly large veins and even sheets of metal, and graphite nodules up to one inch in diameter. Seven years and literally dozens of research papers later, the complete story of the formation of Portales Valley is still unknown, and continues to be debated. Current research MAY lead to the reclassification of this unique and intriguing meteorite as an H7, Metallic Melt Breccia (primitive achondrite). http://www.portalesvalleymeteorites.com I am encouraged to see that the debate/questioning appears to still be ongoing, and I'm hopeful that one of these days, the COMPLETE formation history of PV will be understood and agreed on by all WHATEVER that final understanding is. Best wishes, Robert __ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Portales Valley: Not Just Another Ordinary Chondrite
http://www.psrd.hawaii.edu/Sept05/PortalesValley.html Portales Valley: Not Just Another Ordinary Chondrite Planetary Science Research Discoveries September 30, 2005 --- A melted meteorite gives a snapshot of the heat and shock that wracked an asteroid during the first stages of differentiation. Written by Alex Ruzicka and Melinda Hutson Department of Geology, Portland State University Soon after the Portales Valley meteorite fell in 1998, it was classified as one of the most common types of meteorites, an H6 ordinary chondrite. Although researchers quickly recognized that Portales Valley is not a typical H6 chondrite, there was little agreement about how the meteorite formed. A recent study of Portales Valley by Ruzicka and colleagues suggests that the textures, mineralogy, and chemistry of the meteorite are best explained as the first good example of a metallic melt breccia. This meteorite represents a transitional stage between chondrites and various classes of differentiated meteorites, and offers clues as to how differentiation occurred in early-formed planetary bodies. Reference: * Ruzicka, A., Killgore, M., Mittlefehldt, D.W. and Fries, M.D (2005) Portales Valley: Petrology of a metallic-melt meteorite breccia. Meteoritics Planetary Science, v. 40, p. 261-295. Differentiation: a widespread but poorly-understood process Most solar system material underwent differentiation, a process involving melting and separation of liquids and solids of varying density and chemical composition. However, chondritic meteorites escaped this process and are believed to be pieces of undifferentiated asteroids. All other meteorites, and probably all rocks from planets and large moons, melted when the parent bodies differentiated to form cores, mantles, and crusts. The heat source for differentiation is uncertain, as are the exact physical processes and conditions that allowed differentiation to proceed in small planetary bodies with weak gravity. Proposed sources of heat include internally-generated heat from short-lived radioactive materials such as aluminum-26 (26Al), external heating from our young active Sun, and heating resulting from collisions between planetary bodies (shock heating). A detailed study of the Portales Valley meteorite suggests that differentiation of small planetary bodies involved a combination of an internal heat source and shock. Shock heating was not the major heat source involved in differentiation, but the stress waves associated with even modest shock events played a critical role in helping materials to separate and reconfigure during differentiation. illustration of differentiation by Granshaw A sequence of images showing stages in the differentiation of a planetesimal, an early-formed planetary body. The image in the left hand side shows a chondritic planetesimal becoming hot enough for melting to begin. The middle image shows that the heavier metallic liquid sinks toward the center, while the less dense rocky material rises toward the surface. The result is a differentiated object with a crust, mantle and core, as shown in the image in the right hand side. (Images created by Frank Granshaw of Artemis Software for the Cascadia Meteorite Laboratory, Portland State University.) Not an ordinary H6 ordinary chondrite Three features link Portales Valley to H-group ordinary chondrites. These are (1) the presence of rare chondrules with a rather typical chondritic texture present in silicate-rich areas, (2) the compositions of most minerals, and (3) the bulk oxygen isotopic composition of the meteorite. Nonetheless, Portales Valley contains unusual features that distinguish it from any other ordinary chondrite. Even in a cut section, the differences between Portales Valley and a typical H-chondrite are readily apparent (see figures below). comparison to H chondrite A comparison of a typical H-chondrite and Portales Valley. Bright areas are mainly metallic; dark areas are mainly silicates. Left: A slice of a meteorite that is paired with the Franconia (H5) chondritic meteorite. The small lines on the ruler are one millimeter apart. Right: A slice of the Portales Valley meteorite showing that the chondritic, silicate-rich material occurs as angular clasts floating in metallic veins. Tiny bright spots in silicate-rich clasts consist of troilite (FeS) and smaller amounts of fine-grained metal. A large graphite nodule is visible. Besides the obvious differences between Portales Valley and a typical H chondrite, Portales Valley is also unusual in several other ways. It is the only known ordinary chondrite that contains coarse (cm-sized) graphite nodules as well as metal that shows a Widmanstätten texture (an intergrowth of high- and low-Ni metal, see left image below), both of which are common in iron meteorites.
Re: [meteorite-list] Portales Valley: Not Just Another Ordinary Chondrite
ok...in conclusion what new classification is portales valley? Matteo --- Ron Baalke [EMAIL PROTECTED] ha scritto: http://www.psrd.hawaii.edu/Sept05/PortalesValley.html Portales Valley: Not Just Another Ordinary Chondrite Planetary Science Research Discoveries September 30, 2005 --- A melted meteorite gives a snapshot of the heat and shock that wracked an asteroid during the first stages of differentiation. Written by Alex Ruzicka and Melinda Hutson Department of Geology, Portland State University Soon after the Portales Valley meteorite fell in 1998, it was classified as one of the most common types of meteorites, an H6 ordinary chondrite. Although researchers quickly recognized that Portales Valley is not a typical H6 chondrite, there was little agreement about how the meteorite formed. A recent study of Portales Valley by Ruzicka and colleagues suggests that the textures, mineralogy, and chemistry of the meteorite are best explained as the first good example of a metallic melt breccia. This meteorite represents a transitional stage between chondrites and various classes of differentiated meteorites, and offers clues as to how differentiation occurred in early-formed planetary bodies. Reference: * Ruzicka, A., Killgore, M., Mittlefehldt, D.W. and Fries, M.D (2005) Portales Valley: Petrology of a metallic-melt meteorite breccia. Meteoritics Planetary Science, v. 40, p. 261-295. Differentiation: a widespread but poorly-understood process Most solar system material underwent differentiation, a process involving melting and separation of liquids and solids of varying density and chemical composition. However, chondritic meteorites escaped this process and are believed to be pieces of undifferentiated asteroids. All other meteorites, and probably all rocks from planets and large moons, melted when the parent bodies differentiated to form cores, mantles, and crusts. The heat source for differentiation is uncertain, as are the exact physical processes and conditions that allowed differentiation to proceed in small planetary bodies with weak gravity. Proposed sources of heat include internally-generated heat from short-lived radioactive materials such as aluminum-26 (26Al), external heating from our young active Sun, and heating resulting from collisions between planetary bodies (shock heating). A detailed study of the Portales Valley meteorite suggests that differentiation of small planetary bodies involved a combination of an internal heat source and shock. Shock heating was not the major heat source involved in differentiation, but the stress waves associated with even modest shock events played a critical role in helping materials to separate and reconfigure during differentiation. illustration of differentiation by Granshaw A sequence of images showing stages in the differentiation of a planetesimal, an early-formed planetary body. The image in the left hand side shows a chondritic planetesimal becoming hot enough for melting to begin. The middle image shows that the heavier metallic liquid sinks toward the center, while the less dense rocky material rises toward the surface. The result is a differentiated object with a crust, mantle and core, as shown in the image in the right hand side. (Images created by Frank Granshaw of Artemis Software for the Cascadia Meteorite Laboratory, Portland State University.) Not an ordinary H6 ordinary chondrite Three features link Portales Valley to H-group ordinary chondrites. These are (1) the presence of rare chondrules with a rather typical chondritic texture present in silicate-rich areas, (2) the compositions of most minerals, and (3) the bulk oxygen isotopic composition of the meteorite. Nonetheless, Portales Valley contains unusual features that distinguish it from any other ordinary chondrite. Even in a cut section, the differences between Portales Valley and a typical H-chondrite are readily apparent (see figures below). comparison to H chondrite A comparison of a typical H-chondrite and Portales Valley. Bright areas are mainly metallic; dark areas are mainly silicates. Left: A slice of a meteorite that is paired with the Franconia (H5) chondritic meteorite. The small lines on the ruler are one millimeter apart. Right: A slice of the Portales Valley meteorite showing that the chondritic, silicate-rich material occurs as angular clasts floating in metallic veins. Tiny bright spots in silicate-rich clasts consist of troilite (FeS) and smaller amounts of fine-grained metal. A large graphite nodule is visible. Besides the obvious differences between Portales Valley and a typical H chondrite, Portales Valley is also unusual in
