[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-154912-105":59,"doc-detail-154912-en":131},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":124,"head_meta":126,"extra_data":128,"updated_unix":130},105,"en","15ocean-crust-geothermal-processes-a-perspective-from-the-vantage-of-leg-54-drilling","15.OCEAN CRUST GEOTHERMAL PROCESSES - A PERSPECTIVE FROM THE VANTAGE OF LEG 54 DRILLING","","Two sedimentary facies formed by seafloor hydrothermal activity were recovered during Deep Sea Drilling Project Leg 54. One facies consists of basal iron- and manganese-rich clayey mud dispersed across cores near the East Pacific Rise, inferred to originate from iron hydroxides vent-derived and later diagenetically transformed with siliceous microfossils and detrital clays into K- and Fe-rich clays. The second facies comes from the active Galapagos Mounds field, characterized by Mn oxide caps and green nontronitic mud with distinct SiO2/Fe2O3 and Fe2O3/FeO features.",{"@graph":69,"@context":123},[70,84,106],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":40,"@type":76,"position":81},"https://docshare.wps.com/document/research-report/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/15ocean-crust-geothermal-processes-a-perspective-from-the-vantage-of-leg-54-drilling/154912/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/15ocean-crust-geothermal-processes-a-perspective-from-the-vantage-of-leg-54-drilling/154912.png","ImageObject",300,407,{"name":92,"@type":93},"Rowan","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-29","2026-08-28",true,{"@type":102,"interactionType":103,"userInteractionCount":105},"InteractionCounter",{"@type":104},"ViewAction",11,{"@type":107,"mainEntity":108},"FAQPage",[109,115,119],{"name":110,"@type":111,"acceptedAnswer":112},"What two sedimentary facies were recovered during DSDP Leg 54?","Question",{"text":113,"@type":114},"The recovery includes a basal iron- and manganese-rich clayey mud facies typical of many DSDP sites, and a second facies from the active Galapagos Mounds hydrothermal field with Mn-oxide capping and green nontronitic mud.","Answer",{"name":116,"@type":111,"acceptedAnswer":117},"How is the East Pacific Rise iron-hydroxide-related facies interpreted to have formed?",{"text":118,"@type":114},"It is inferred that iron hydroxides dispersed from high-temperature vents over the axial magma chamber were deposited first, and then diagenetically reacted with siliceous microfossil tests and detrital clays to form K- and Fe-rich clays.",{"name":120,"@type":111,"acceptedAnswer":121},"Why are the Galapagos Mounds nontronites considered distinct from East Pacific Rise clays?",{"text":122,"@type":114},"The mounds nontronites show geochemical traits—such as appreciable SiO2 and MgO, a high Fe2O3/FeO ratio, nearly no Al2O3, and a relatively fixed SiO2/Fe2O3 ratio—that differ from the compositionally variable K-Fe montmorillonite produced diagenetically at the East Pacific Rise.","https://schema.org",{"og:url":83,"og:type":125,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":127,"canonical":83},"index,follow",{"doc_id":129,"site_id":62},154912,1787900857,{"code":4,"msg":5,"data":132},{"doc_id":129,"user_id":133,"nickname":92,"user_avatar":134,"doc_module":4,"category_id":39,"category_name":40,"doc_title":65,"doc_description":67,"doc_content":135,"file_id":136,"file_url":137,"file_type":138,"file_size":139,"view_count":105,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":140,"language":141,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":142,"faqs":143,"seo_title":144,"seo_description":67,"update_tm":130,"read_time":145,"preview_page_count":4},1099514067415,"https://ap-avatar.wpscdn.com/avatar/100002539d78ffe74a7?x-image-process=image/resize,m_fixed,w_180,h_180&k=1779092875211072502","# 15.OCEAN CRUST GEOTHERMAL PROCESSES:A PERSPECTIVEFROM THE VANTAGE OF LEG 54 DRILLING\n\nRoger Hekinian,Centre Oceanologique de Bretagne,29273 Brest,FranceBruce R.Rosendahl,Department of Geology,Duke University,Durham,North CarolinaandJames H.Natland,Deep Sea Drilling Project,Scripps Institution of Oceanography,La Jolla,California  \n## ABSTRACT\n\nTwo distinct sedimentary facies produced by sea-floor hydrother-mal activity were cored during Deep Sea Drilling Project Leg 54.Thefirst is equivalent to the typical basal iron-and manganese-rich,clayeymud recovered at many DSDP sites.It was sampled as a dispersedcomponent throughout the cores taken in small sediment ponds inseveral sites within 120 km of the East Pacific Rise at 9°N.We inferthat this component was originally deposited as iron hydroxides dis-persed from high-temperature vents over the axial magma chamberof the East Pacific Rise.In the sediments,the iron hydroxides havereacted diagenetically with siliceous microfossil tests and detritalclays to form K-and Fe-rich clays with variable SiO₂/Fe₂O₃andFe₂O₃/Al₂O₃ratios.  \nThe second facies was cored in the active Galapagos Mounds hy-drothermal field 21 km south of the Galapagos Rift.Mounds sedi-ments consist of a capping of Mn oxides and up to 15 meters of greennontronitic mud overlying about 10 meters of carbonate ooze andfresh basalt.The green muds and Mn oxides were precipitated fromfluids carrying components derived from alteration of solid basalticrocks during the early cooling of a consolidated,but thin,oceaniclithosphere.The nontronite has appreciable SiO₂and MgO notfound in the axial iron-hydroxide facies,a high Fe₂O₃/FeO ratio,vir-tually no Al₂O₃,and a comparatively fixed SiO₂/Fe₂O₃ratio ofabout 2:1.These geochemical features allow it to be distinguishedfrom the compositionally more variable K-Fe montmorillonite of theEast Pacific Rise sites which forms diagenetically.On this basis,mounds-type nontronites occur in both Bauer Deep and DOMESSite C sediments,on the flanks of the East Pacific Rise.The con-trasts with the diagenetically produced clays also support the conclu-sion that the mounds nontronites are direct precipitates from hydro-thermal solutions encountering sea water,rather than the productsof diagenetic reactions between the solutions and components of thesediments.  \n# INTRODUCTION\n\nDuring Leg 54,the Glomar Challenger cored a seriesof holes in two regions of the tropical eastern Pacific,one near 9N on the flanks of the East Pacific Rise,in-cluding a site in the Siqueiros fracture zone,the other onthe flanks of the Galapagos Rift near the equator atabout 86°W(Table 1 and Figure 1).The purposes of allthese sites were to explore the origin of intermediate andfast-spreading segments of non-rifted oceanic crust,andtheir subsequent modification by physical and chemicalprocesses at low or high temperatures.At Sites 424 and425 on the Galapagos Rift,the primary objectives ofdrilling were geothermal,and site selection was basedprimarily on measurements of heat flow and near-bot-tom observations of geothermal phenomena.  \nIn this chapter,we summarize the post-eruptive his-tory of all the sites drilled on Leg 54.This includes thesedimentary history of the sites and the modification ofbasement basaltic rocks by interaction with sea water,pore fluids,and possible hydrothermal fluids.The per-spective of this report is that oceanic crust,sediments,sea water,and pore fluids constitute a complex systemof components that interact to varying degrees depend-ing on such factors as heat flow,sedimentation rate,bottom current activity,structural setting,and depthbelow the calcite compensation depth.We examined aspectrum of sites in two contrasting settings where thevarious geothermal phenomena are quite different.Im-portant features of these settings are as follows:  \n1)Most of the East Pacific Rise sites are thinly sedi-mented ponds or shallow structural depressions on the  \nTABLE1  \nSite Locations  \n\n| Hole   | Latitude   | Lon","cbCaijzrQFfe31RU","https://ap.wps.com/l/cbCaijzrQFfe31RU","pdf",7579766,28,"English","# Abstract\n# Introduction\n## Regional drilling objectives (Leg 54 sites)\n## Geothermal focus at the Galapagos Rift and East Pacific Rise\n## Post-eruptive and hydrothermal modification framework\n## Site setting characteristics\n## Table 1: Site locations","[{\"question\":\"What two sedimentary facies were recovered during DSDP Leg 54?\",\"answer\":\"The recovery includes a basal iron- and manganese-rich clayey mud facies typical of many DSDP sites, and a second facies from the active Galapagos Mounds hydrothermal field with Mn-oxide capping and green nontronitic mud.\"},{\"question\":\"How is the East Pacific Rise iron-hydroxide-related facies interpreted to have formed?\",\"answer\":\"It is inferred that iron hydroxides dispersed from high-temperature vents over the axial magma chamber were deposited first, and then diagenetically reacted with siliceous microfossil tests and detrital clays to form K- and Fe-rich clays.\"},{\"question\":\"Why are the Galapagos Mounds nontronites considered distinct from East Pacific Rise clays?\",\"answer\":\"The mounds nontronites show geochemical traits—such as appreciable SiO2 and MgO, a high Fe2O3/FeO ratio, nearly no Al2O3, and a relatively fixed SiO2/Fe2O3 ratio—that differ from the compositionally variable K-Fe montmorillonite produced diagenetically at the East Pacific Rise.\"}]","15.OCEAN CRUST GEOTHERMAL PROCESSES - A PERSPECTIVE FROM THE VANTAGE OF LEG 54 DRILLING | PDF",71]