Are magnetite spherules capable of carrying stable magnetizations?
To determine if magnetite spherules extracted from ancient carbonate rocks can carry ancient remanent magnetizations, electron microscope observations and magnetic data have been obtained for more than 100 individual spherules extracted from the Jurassic Twin Creek limestone, Wyoming, and the Missis...
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Veröffentlicht in: | Geophysical research letters 1994-04, Vol.21 (7), p.517-520 |
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description | To determine if magnetite spherules extracted from ancient carbonate rocks can carry ancient remanent magnetizations, electron microscope observations and magnetic data have been obtained for more than 100 individual spherules extracted from the Jurassic Twin Creek limestone, Wyoming, and the Mississippian Leadville limestone, Colorado. Two categories of surface textures (smooth and patterned) correlate with different hysteresis parameters. Spherules with patterned surfaces (Group A) have ratios of saturation remanent magnetization to saturation magnetization (Msr/Ms) < 0.1 and ratios of remanent coercive force to coercive force (Hcr/Hc) mostly > 3. Most spherules with smooth surfaces (Group B) have 0.1 < Msr/Ms < 0.3 and Hcr/Hc< 3. The patterned surfaces consist of (1) parallel dendritic nets with units ≈ 1 μm wide, (2) platelets with widths of 1 to 3 μm, (3) mosaic surface units with diameters between 2 and 5 μm; each of these surface elements consists of a single crystal, as verified by selected‐area electron diffraction patterns showing sharp spots, whereas the spherules as a whole show multicrystalline patterns by X‐ray diffraction. The Msr/Ms and Hc values of group A increase with decrease in grain size; these Group A magnetite spherules are undoubtedly multi‐domain in character and are unlikely to carry stable ancient remanences. The smooth‐surfaced Group B spherules are not very abundant (< 8% of the entire population) and have pseudo‐single‐domain (PSD) or multi‐domain (MD) magnetic properties; they may carry ancient remanences, although we infer that single‐domain (SD), non‐spherical, submicrometer magnetite is the principal carrier of remanence in most carbonates. |
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Two categories of surface textures (smooth and patterned) correlate with different hysteresis parameters. Spherules with patterned surfaces (Group A) have ratios of saturation remanent magnetization to saturation magnetization (Msr/Ms) < 0.1 and ratios of remanent coercive force to coercive force (Hcr/Hc) mostly > 3. Most spherules with smooth surfaces (Group B) have 0.1 < Msr/Ms < 0.3 and Hcr/Hc< 3. The patterned surfaces consist of (1) parallel dendritic nets with units ≈ 1 μm wide, (2) platelets with widths of 1 to 3 μm, (3) mosaic surface units with diameters between 2 and 5 μm; each of these surface elements consists of a single crystal, as verified by selected‐area electron diffraction patterns showing sharp spots, whereas the spherules as a whole show multicrystalline patterns by X‐ray diffraction. The Msr/Ms and Hc values of group A increase with decrease in grain size; these Group A magnetite spherules are undoubtedly multi‐domain in character and are unlikely to carry stable ancient remanences. The smooth‐surfaced Group B spherules are not very abundant (< 8% of the entire population) and have pseudo‐single‐domain (PSD) or multi‐domain (MD) magnetic properties; they may carry ancient remanences, although we infer that single‐domain (SD), non‐spherical, submicrometer magnetite is the principal carrier of remanence in most carbonates.</description><identifier>ISSN: 0094-8276</identifier><identifier>EISSN: 1944-8007</identifier><identifier>DOI: 10.1029/94GL00366</identifier><identifier>CODEN: GPRLAJ</identifier><language>eng</language><publisher>Washington, DC: Blackwell Publishing Ltd</publisher><subject>Carbonates ; Categories ; Coercive force ; Earth sciences ; Earth, ocean, space ; Exact sciences and technology ; Geophysics: general, magnetic, electric and thermic methods and properties ; Internal geophysics ; Limestone ; Magnetite ; Spherules ; Surface layer ; Texture</subject><ispartof>Geophysical research letters, 1994-04, Vol.21 (7), p.517-520</ispartof><rights>Copyright 1994 by the American Geophysical Union.</rights><rights>1994 INIST-CNRS</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-a4247-60374585b9d54245b2fbac5fd19e3b13eacd81d4c068ab6a44303567534159a23</citedby><cites>FETCH-LOGICAL-a4247-60374585b9d54245b2fbac5fd19e3b13eacd81d4c068ab6a44303567534159a23</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://onlinelibrary.wiley.com/doi/pdf/10.1029%2F94GL00366$$EPDF$$P50$$Gwiley$$H</linktopdf><linktohtml>$$Uhttps://onlinelibrary.wiley.com/doi/full/10.1029%2F94GL00366$$EHTML$$P50$$Gwiley$$H</linktohtml><link.rule.ids>314,780,784,1417,27924,27925,45574,45575</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=4177601$$DView record in Pascal Francis$$Hfree_for_read</backlink></links><search><creatorcontrib>Xu, Weixin</creatorcontrib><creatorcontrib>Van der Voo, Rob</creatorcontrib><creatorcontrib>Peacor, Donald R.</creatorcontrib><title>Are magnetite spherules capable of carrying stable magnetizations?</title><title>Geophysical research letters</title><addtitle>Geophys. Res. Lett</addtitle><description>To determine if magnetite spherules extracted from ancient carbonate rocks can carry ancient remanent magnetizations, electron microscope observations and magnetic data have been obtained for more than 100 individual spherules extracted from the Jurassic Twin Creek limestone, Wyoming, and the Mississippian Leadville limestone, Colorado. Two categories of surface textures (smooth and patterned) correlate with different hysteresis parameters. Spherules with patterned surfaces (Group A) have ratios of saturation remanent magnetization to saturation magnetization (Msr/Ms) < 0.1 and ratios of remanent coercive force to coercive force (Hcr/Hc) mostly > 3. Most spherules with smooth surfaces (Group B) have 0.1 < Msr/Ms < 0.3 and Hcr/Hc< 3. The patterned surfaces consist of (1) parallel dendritic nets with units ≈ 1 μm wide, (2) platelets with widths of 1 to 3 μm, (3) mosaic surface units with diameters between 2 and 5 μm; each of these surface elements consists of a single crystal, as verified by selected‐area electron diffraction patterns showing sharp spots, whereas the spherules as a whole show multicrystalline patterns by X‐ray diffraction. The Msr/Ms and Hc values of group A increase with decrease in grain size; these Group A magnetite spherules are undoubtedly multi‐domain in character and are unlikely to carry stable ancient remanences. The smooth‐surfaced Group B spherules are not very abundant (< 8% of the entire population) and have pseudo‐single‐domain (PSD) or multi‐domain (MD) magnetic properties; they may carry ancient remanences, although we infer that single‐domain (SD), non‐spherical, submicrometer magnetite is the principal carrier of remanence in most carbonates.</description><subject>Carbonates</subject><subject>Categories</subject><subject>Coercive force</subject><subject>Earth sciences</subject><subject>Earth, ocean, space</subject><subject>Exact sciences and technology</subject><subject>Geophysics: general, magnetic, electric and thermic methods and properties</subject><subject>Internal geophysics</subject><subject>Limestone</subject><subject>Magnetite</subject><subject>Spherules</subject><subject>Surface layer</subject><subject>Texture</subject><issn>0094-8276</issn><issn>1944-8007</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>1994</creationdate><recordtype>article</recordtype><recordid>eNp1kD9PwzAUxC0EEqUw8A0yMMCQYsf_4glBgRQpLVIFYrReEqcE0qTYqaB8egypujG90-l3p6dD6JTgEcGRulQsSTGmQuyhAVGMhTHGch8NMFZeR1IcoiPn3rBnMCUDdHNtTbCERWO6qjOBW70au66NC3JYQVaboC29tHZTNYvAdX_WFv-Grmobd3WMDkqonTnZ3iF6vr97Gk_C9DF5GF-nIbCIyVBgKhmPeaYK7g2eRWUGOS8LogzNCDWQFzEpWI5FDJkAxvyHXEhOGeEKIjpE533vyrYfa-M6vaxcbuoaGtOunSacYqUiSYVHL3o0t61z1pR6Zasl2I0mWP_upHc7efZsWwsuh7q00OSV2wUYkVJg4rFRj31Wtdn836eTeSoZkz4Q9oHKdeZrFwD7roWkkuuXWaLn04ma3s64HtMfgQmCtw</recordid><startdate>19940401</startdate><enddate>19940401</enddate><creator>Xu, Weixin</creator><creator>Van der Voo, Rob</creator><creator>Peacor, Donald R.</creator><general>Blackwell Publishing Ltd</general><general>American Geophysical Union</general><scope>BSCLL</scope><scope>IQODW</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>8FD</scope><scope>FR3</scope><scope>H8D</scope><scope>KR7</scope><scope>L7M</scope></search><sort><creationdate>19940401</creationdate><title>Are magnetite spherules capable of carrying stable magnetizations?</title><author>Xu, Weixin ; Van der Voo, Rob ; Peacor, Donald R.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-a4247-60374585b9d54245b2fbac5fd19e3b13eacd81d4c068ab6a44303567534159a23</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>1994</creationdate><topic>Carbonates</topic><topic>Categories</topic><topic>Coercive force</topic><topic>Earth sciences</topic><topic>Earth, ocean, space</topic><topic>Exact sciences and technology</topic><topic>Geophysics: general, magnetic, electric and thermic methods and properties</topic><topic>Internal geophysics</topic><topic>Limestone</topic><topic>Magnetite</topic><topic>Spherules</topic><topic>Surface layer</topic><topic>Texture</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Xu, Weixin</creatorcontrib><creatorcontrib>Van der Voo, Rob</creatorcontrib><creatorcontrib>Peacor, Donald R.</creatorcontrib><collection>Istex</collection><collection>Pascal-Francis</collection><collection>CrossRef</collection><collection>Technology Research Database</collection><collection>Engineering Research Database</collection><collection>Aerospace Database</collection><collection>Civil Engineering Abstracts</collection><collection>Advanced Technologies Database with Aerospace</collection><jtitle>Geophysical research letters</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Xu, Weixin</au><au>Van der Voo, Rob</au><au>Peacor, Donald R.</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Are magnetite spherules capable of carrying stable magnetizations?</atitle><jtitle>Geophysical research letters</jtitle><addtitle>Geophys. Res. Lett</addtitle><date>1994-04-01</date><risdate>1994</risdate><volume>21</volume><issue>7</issue><spage>517</spage><epage>520</epage><pages>517-520</pages><issn>0094-8276</issn><eissn>1944-8007</eissn><coden>GPRLAJ</coden><abstract>To determine if magnetite spherules extracted from ancient carbonate rocks can carry ancient remanent magnetizations, electron microscope observations and magnetic data have been obtained for more than 100 individual spherules extracted from the Jurassic Twin Creek limestone, Wyoming, and the Mississippian Leadville limestone, Colorado. Two categories of surface textures (smooth and patterned) correlate with different hysteresis parameters. Spherules with patterned surfaces (Group A) have ratios of saturation remanent magnetization to saturation magnetization (Msr/Ms) < 0.1 and ratios of remanent coercive force to coercive force (Hcr/Hc) mostly > 3. Most spherules with smooth surfaces (Group B) have 0.1 < Msr/Ms < 0.3 and Hcr/Hc< 3. The patterned surfaces consist of (1) parallel dendritic nets with units ≈ 1 μm wide, (2) platelets with widths of 1 to 3 μm, (3) mosaic surface units with diameters between 2 and 5 μm; each of these surface elements consists of a single crystal, as verified by selected‐area electron diffraction patterns showing sharp spots, whereas the spherules as a whole show multicrystalline patterns by X‐ray diffraction. The Msr/Ms and Hc values of group A increase with decrease in grain size; these Group A magnetite spherules are undoubtedly multi‐domain in character and are unlikely to carry stable ancient remanences. The smooth‐surfaced Group B spherules are not very abundant (< 8% of the entire population) and have pseudo‐single‐domain (PSD) or multi‐domain (MD) magnetic properties; they may carry ancient remanences, although we infer that single‐domain (SD), non‐spherical, submicrometer magnetite is the principal carrier of remanence in most carbonates.</abstract><cop>Washington, DC</cop><pub>Blackwell Publishing Ltd</pub><doi>10.1029/94GL00366</doi><tpages>4</tpages><oa>free_for_read</oa></addata></record> |
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subjects | Carbonates Categories Coercive force Earth sciences Earth, ocean, space Exact sciences and technology Geophysics: general, magnetic, electric and thermic methods and properties Internal geophysics Limestone Magnetite Spherules Surface layer Texture |
title | Are magnetite spherules capable of carrying stable magnetizations? |
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