georefid:2006-008647SEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=2006-008647<gco:CharacterString>Effect of compositional and structural variations on log responses of igneous and metamorphic rocks; I, Mafic rocks</gco:CharacterString>2005-01-01publicationgeorefid:2006-008647Bartetzko, A.RWTH Aachen University of Technology, Applied Geophysics, Aachen, Federal Republic of GermanyauthorDelius, H.Universite de Montpellier II, FranceauthorPechnig, R.Russian Academy of Sciences, Russian FederationauthorGeological Society of London, London, United KingdompublisherdocumentHardcopyIn: Harvey, Peter K. (editor), Brewer, Tim S. (editor), Pezard, Phillipe A. (editor), Petrov, Vladislav A. (editor), Petrophysical properties of crystalline rocks240255-278Well logging has become a standard method in the oil industry for the investigation of subsurface geology. Accordingly, interpretation techniques have been mainly developed for use in sedimentary rocks, and the log responses of sediments are well known. However, this is not the case for igneous and metamorphic rocks. We present a compilation of log responses for mafic rocks from drill-holes in oceanic and continental basement. The holes cover a variety of mafic rocks: mid-ocean ridge basalt (MORB), gabbro, basalt and andesitic basalt from back-arc basins, flood basalt from large igneous provinces (LIPs), and continental metamorphic rocks. The comparison of log responses shows that rocks from the same geological setting have similar in situ physical properties. Differences in physical properties between rocks from different geological setting are mainly related to variations in the structure of the rocks, while variations in composition have only a minor effect on the in situ physical properties. In volcanic rocks, variations in fracturing and vesicularity related to cooling of the lava strongly influence log responses. Mafic rocks from continental drill-holes were enriched in radioactive elements during regional metamorphism, resulting in higher values in the total gamma-ray compared to the oceanic rocks.completedIgneous and metamorphic petrologyApplied geophysicsacoustical loggingAtlantic OceanAtlantis II fracture zonebasaltsBermuda Risebody wavesboreholeschemical compositioncrustdensityDSDP Site 395DSDP Site 418DSDP Site 504elastic waveselectrical logginggabbrosgamma-ray methodsigneous rocksIndian Oceanlarge igneous provincesLeg 102Leg 111Leg 148Leg 174BLeg 179mafic compositionmetamorphic rocksMid-Atlantic Ridgemid-ocean ridge basaltsneutron methodsNorth AtlanticOcean Drilling Programoceanic crustODP Site 1105P-wavesphysical propertiesplutonic rocksporosityseismic wavesultramaficsvelocityvolcanic rockswell-loggingurn:org.iodp:exp:102urnlargerWorkCitationcampaignurn:org.iodp:exp:111urnlargerWorkCitationcampaignurn:org.iodp:exp:148urnlargerWorkCitationcampaignurn:org.iodp:exp:174BurnlargerWorkCitationcampaignurn:org.iodp:exp:179urnlargerWorkCitationcampaignurn:org.iodp:exp:102:site:418urnlargerWorkCitationstudyurn:org.iodp:exp:102urnlargerWorkCitationcampaignurn:org.iodp:exp:111:site:504urnlargerWorkCitationstudyurn:org.iodp:exp:111urnlargerWorkCitationcampaignurn:org.iodp:exp:137:site:504urnlargerWorkCitationstudyurn:org.iodp:exp:137urnlargerWorkCitationcampaignurn:org.iodp:exp:140:site:504urnlargerWorkCitationstudyurn:org.iodp:exp:140urnlargerWorkCitationcampaignurn:org.iodp:exp:148:site:504urnlargerWorkCitationstudyurn:org.iodp:exp:148urnlargerWorkCitationcampaignurn:org.iodp:exp:179:site:1105urnlargerWorkCitationstudyurn:org.iodp:exp:179urnlargerWorkCitationcampaignEnglishgeoscientificInformation-83.435757.1639-32.430825.0207