Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean
Basalts from DSDP Site 417 (109 Ma) exhibit the effects of several stages of alteration reflecting the evolution of seawater-derived solution compositions and control by the structure and permeability of the crust. Characteristic secondary mineral assemblages occur in often superimposed alteration z...
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1984
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ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.667336 2023-05-15T17:37:02+02:00 Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean Alt, Jeffrey C Honnorez, Jose J MEDIAN LATITUDE: 25.111250 * MEDIAN LONGITUDE: -68.045450 * SOUTH-BOUND LATITUDE: 25.111000 * WEST-BOUND LONGITUDE: -68.046800 * NORTH-BOUND LATITUDE: 25.111500 * EAST-BOUND LONGITUDE: -68.044100 * DATE/TIME START: 1976-12-02T00:00:00 * DATE/TIME END: 1976-12-30T00:00:00 1984-11-02 application/zip, 8 datasets https://doi.pangaea.de/10.1594/PANGAEA.667336 https://doi.org/10.1594/PANGAEA.667336 en eng PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.667336 https://doi.org/10.1594/PANGAEA.667336 CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess CC-BY Supplement to: Alt, Jeffrey C; Honnorez, Jose J (1984): Alteration of the upper oceanic crust, DSDP site 417: mineralogy and chemistry. Contributions to Mineralogy and Petrology, 87(2), 149-169, https://doi.org/10.1007/BF00376221 51-417_Site 52-417D COMPCORE Composite Core Deep Sea Drilling Project DRILL Drilling/drill rig DSDP Glomar Challenger Leg51 Leg52 North Atlantic/CONT RISE Dataset 1984 ftpangaea https://doi.org/10.1594/PANGAEA.667336 https://doi.org/10.1007/BF00376221 2023-01-20T07:31:05Z Basalts from DSDP Site 417 (109 Ma) exhibit the effects of several stages of alteration reflecting the evolution of seawater-derived solution compositions and control by the structure and permeability of the crust. Characteristic secondary mineral assemblages occur in often superimposed alteration zones within individual basalt fragments. By combining bulk rock and single phase chemical analyses with detailed mineralogic and petrographic studies, chemical changes have been determined for most of the alteration stages identified in the basalts. 1) Minor amounts of saponite, chlorite, and pyrite formed locally in coarse grained portions of massive units, possibly at high temperatures during initial cooling of the basalts. No chemical changes could be determined for this stage. 2) Possible mixing of cooled hydrothermal fluids with seawater resulted in the formation of celadonite-nontronite and Fe-hydroxide-rich black halos around cracks and pillow rims. Gains of K, Rb, H20, increase of Fe 3 +/FeT and possibly some losses of Ca and Mg occurred during this stage. 3a) Extensive circulation of oxygenated seawater resulted in the formation of various smectites, K-feldspar, and Fe-hydroxides in brown and light grey alteration zones around formerly exposed surfaces. K, Rb, H20, and occasionally P were added to the rocks, Fe3+/FeT increased, and Ca, Mg, Si and occasionally Al and Na were lost. 3 b) Anoxic alteration occurred during reaction of basalt with seawater at low water-rock ratios, or with seawater that had previously reacted with basalt. Saponite-rich dark grey alteration zones formed which exhibit very little chemical change: generally only slight increases in Fe 3 +/FeT and H20 occurred. 4) Zeolites and calcite formed from seawater-derived fluids modified by previous reactions with basalt. Chemical changes involved increases of Ca, Na, H20 , and CO2 in the rocks. 5) A late stage of anoxic conditions resulted in the formation of minor amounts of Mn-calcites and secondary sulfides in previously oxidized rocks. No ... Dataset North Atlantic PANGAEA - Data Publisher for Earth & Environmental Science ENVELOPE(-68.046800,-68.044100,25.111500,25.111000) |
institution |
Open Polar |
collection |
PANGAEA - Data Publisher for Earth & Environmental Science |
op_collection_id |
ftpangaea |
language |
English |
topic |
51-417_Site 52-417D COMPCORE Composite Core Deep Sea Drilling Project DRILL Drilling/drill rig DSDP Glomar Challenger Leg51 Leg52 North Atlantic/CONT RISE |
spellingShingle |
51-417_Site 52-417D COMPCORE Composite Core Deep Sea Drilling Project DRILL Drilling/drill rig DSDP Glomar Challenger Leg51 Leg52 North Atlantic/CONT RISE Alt, Jeffrey C Honnorez, Jose J Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean |
topic_facet |
51-417_Site 52-417D COMPCORE Composite Core Deep Sea Drilling Project DRILL Drilling/drill rig DSDP Glomar Challenger Leg51 Leg52 North Atlantic/CONT RISE |
description |
Basalts from DSDP Site 417 (109 Ma) exhibit the effects of several stages of alteration reflecting the evolution of seawater-derived solution compositions and control by the structure and permeability of the crust. Characteristic secondary mineral assemblages occur in often superimposed alteration zones within individual basalt fragments. By combining bulk rock and single phase chemical analyses with detailed mineralogic and petrographic studies, chemical changes have been determined for most of the alteration stages identified in the basalts. 1) Minor amounts of saponite, chlorite, and pyrite formed locally in coarse grained portions of massive units, possibly at high temperatures during initial cooling of the basalts. No chemical changes could be determined for this stage. 2) Possible mixing of cooled hydrothermal fluids with seawater resulted in the formation of celadonite-nontronite and Fe-hydroxide-rich black halos around cracks and pillow rims. Gains of K, Rb, H20, increase of Fe 3 +/FeT and possibly some losses of Ca and Mg occurred during this stage. 3a) Extensive circulation of oxygenated seawater resulted in the formation of various smectites, K-feldspar, and Fe-hydroxides in brown and light grey alteration zones around formerly exposed surfaces. K, Rb, H20, and occasionally P were added to the rocks, Fe3+/FeT increased, and Ca, Mg, Si and occasionally Al and Na were lost. 3 b) Anoxic alteration occurred during reaction of basalt with seawater at low water-rock ratios, or with seawater that had previously reacted with basalt. Saponite-rich dark grey alteration zones formed which exhibit very little chemical change: generally only slight increases in Fe 3 +/FeT and H20 occurred. 4) Zeolites and calcite formed from seawater-derived fluids modified by previous reactions with basalt. Chemical changes involved increases of Ca, Na, H20 , and CO2 in the rocks. 5) A late stage of anoxic conditions resulted in the formation of minor amounts of Mn-calcites and secondary sulfides in previously oxidized rocks. No ... |
format |
Dataset |
author |
Alt, Jeffrey C Honnorez, Jose J |
author_facet |
Alt, Jeffrey C Honnorez, Jose J |
author_sort |
Alt, Jeffrey C |
title |
Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean |
title_short |
Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean |
title_full |
Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean |
title_fullStr |
Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean |
title_full_unstemmed |
Mineralogy and chemistry of basalts and secondary minerals from DSDP Site 417, Atlantic Ocean |
title_sort |
mineralogy and chemistry of basalts and secondary minerals from dsdp site 417, atlantic ocean |
publisher |
PANGAEA |
publishDate |
1984 |
url |
https://doi.pangaea.de/10.1594/PANGAEA.667336 https://doi.org/10.1594/PANGAEA.667336 |
op_coverage |
MEDIAN LATITUDE: 25.111250 * MEDIAN LONGITUDE: -68.045450 * SOUTH-BOUND LATITUDE: 25.111000 * WEST-BOUND LONGITUDE: -68.046800 * NORTH-BOUND LATITUDE: 25.111500 * EAST-BOUND LONGITUDE: -68.044100 * DATE/TIME START: 1976-12-02T00:00:00 * DATE/TIME END: 1976-12-30T00:00:00 |
long_lat |
ENVELOPE(-68.046800,-68.044100,25.111500,25.111000) |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Supplement to: Alt, Jeffrey C; Honnorez, Jose J (1984): Alteration of the upper oceanic crust, DSDP site 417: mineralogy and chemistry. Contributions to Mineralogy and Petrology, 87(2), 149-169, https://doi.org/10.1007/BF00376221 |
op_relation |
https://doi.pangaea.de/10.1594/PANGAEA.667336 https://doi.org/10.1594/PANGAEA.667336 |
op_rights |
CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1594/PANGAEA.667336 https://doi.org/10.1007/BF00376221 |
_version_ |
1766136744299724800 |