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The Origin of Carbonate Veins Within the Sedimentary Cover and Igneous Rocks of the Cocos Ridge : Results From IODP Hole U1414A

Brandstätter, Jennifer; Kurz, Walter; Richoz, Sylvain LU ; Cooper, Matthew J. and Teagle, Damon A.H. (2018) In Geochemistry, Geophysics, Geosystems 19(10). p.3721-3738
Abstract

Carbonate veins in the igneous basement and in the lithified sedimentary cover of the Cocos Ridge at International Ocean Discovery Program (IODP) Hole 344-U1414A reveal the hydrologic system and fluid-rock interactions. IODP Hole 344-U1414A was drilled on the northern flank of the Cocos Ridge and is situated 1 km seaward from the Middle America Trench offshore Costa Rica. Isotopic and elemental compositions were analyzed to constrain the fluid source of the carbonate veins and to reveal the thermal history of Hole 344-U1414A. The formation temperatures (oxygen isotope thermometer) of the carbonate veins in the lithified sedimentary rocks range from 70 to 92 °C and in the basalt from 32 to 82 °C. 87Sr/86Sr ratios of... (More)

Carbonate veins in the igneous basement and in the lithified sedimentary cover of the Cocos Ridge at International Ocean Discovery Program (IODP) Hole 344-U1414A reveal the hydrologic system and fluid-rock interactions. IODP Hole 344-U1414A was drilled on the northern flank of the Cocos Ridge and is situated 1 km seaward from the Middle America Trench offshore Costa Rica. Isotopic and elemental compositions were analyzed to constrain the fluid source of the carbonate veins and to reveal the thermal history of Hole 344-U1414A. The formation temperatures (oxygen isotope thermometer) of the carbonate veins in the lithified sedimentary rocks range from 70 to 92 °C and in the basalt from 32 to 82 °C. 87Sr/86Sr ratios of the veins in the altered Cocos Ridge basalt range between 0.707307 and 0.708729. The higher ratios are similar to seawater strontium ratios in the Neogene. 87Sr/86Sr ratios lower 0.7084 indicate exchange of Sr with the igneous host rock. The calcite veins hosted by the sedimentary rocks are showing more primitive 87Sr/86Sr ratios <0.706396. The isotopic compositions indicate seawater, modified into a hydrothermal fluid by subsequent heating, as the main fluid source. Low-temperature alteration and the presence of a high-temperature fluid resulted in different carbonate precipitates forming up to several cm thick veins. The geochemical data combined with age data of the sedimentary rocks suggest intraplate seamount volcanism in the area between the Galapagos hot spot and the Cocos Island as an additional heating source, after the formation of the Cocos Ridge at the Galapagos hot spot.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
carbonate veins, Cocos Ridge, elemental composition, fluid-rock interaction, IODP, isotope geochemistry
in
Geochemistry, Geophysics, Geosystems
volume
19
issue
10
pages
3721 - 3738
publisher
American Geophysical Union
external identifiers
  • scopus:85054836212
ISSN
1525-2027
DOI
10.1029/2018GC007729
language
English
LU publication?
yes
id
a54f6eef-2b1c-4daf-90b9-f7a88b28a90f
date added to LUP
2018-11-13 10:42:52
date last changed
2019-02-20 11:35:27
@article{a54f6eef-2b1c-4daf-90b9-f7a88b28a90f,
  abstract     = {<p>Carbonate veins in the igneous basement and in the lithified sedimentary cover of the Cocos Ridge at International Ocean Discovery Program (IODP) Hole 344-U1414A reveal the hydrologic system and fluid-rock interactions. IODP Hole 344-U1414A was drilled on the northern flank of the Cocos Ridge and is situated 1 km seaward from the Middle America Trench offshore Costa Rica. Isotopic and elemental compositions were analyzed to constrain the fluid source of the carbonate veins and to reveal the thermal history of Hole 344-U1414A. The formation temperatures (oxygen isotope thermometer) of the carbonate veins in the lithified sedimentary rocks range from 70 to 92 °C and in the basalt from 32 to 82 °C. <sup>87</sup>Sr/<sup>86</sup>Sr ratios of the veins in the altered Cocos Ridge basalt range between 0.707307 and 0.708729. The higher ratios are similar to seawater strontium ratios in the Neogene. <sup>87</sup>Sr/<sup>86</sup>Sr ratios lower 0.7084 indicate exchange of Sr with the igneous host rock. The calcite veins hosted by the sedimentary rocks are showing more primitive <sup>87</sup>Sr/<sup>86</sup>Sr ratios &lt;0.706396. The isotopic compositions indicate seawater, modified into a hydrothermal fluid by subsequent heating, as the main fluid source. Low-temperature alteration and the presence of a high-temperature fluid resulted in different carbonate precipitates forming up to several cm thick veins. The geochemical data combined with age data of the sedimentary rocks suggest intraplate seamount volcanism in the area between the Galapagos hot spot and the Cocos Island as an additional heating source, after the formation of the Cocos Ridge at the Galapagos hot spot.</p>},
  author       = {Brandstätter, Jennifer and Kurz, Walter and Richoz, Sylvain and Cooper, Matthew J. and Teagle, Damon A.H.},
  issn         = {1525-2027},
  keyword      = {carbonate veins,Cocos Ridge,elemental composition,fluid-rock interaction,IODP,isotope geochemistry},
  language     = {eng},
  month        = {09},
  number       = {10},
  pages        = {3721--3738},
  publisher    = {American Geophysical Union},
  series       = {Geochemistry, Geophysics, Geosystems},
  title        = {The Origin of Carbonate Veins Within the Sedimentary Cover and Igneous Rocks of the Cocos Ridge : Results From IODP Hole U1414A},
  url          = {http://dx.doi.org/10.1029/2018GC007729},
  volume       = {19},
  year         = {2018},
}