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Sharkov, E V; Shatagin, K N; Krassivskaya, I S; Chernyshev, I V; Bortnikov, Nikolay S; Chistyakov, A V; Trubkin, N V; Kramchaninov, A Yu (2008): Chemical and isotopic compositions of basalts and glasses from lavas of the Sierra Leone fault site [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.744586, Supplement to: Sharkov, EV et al. (2008): Pillow lavas of the Sierra Leone test site, Mid-Atlantic Ridge, 5°-7°N: Sr-Nd isotope systematics, geochemistry, and petrology. Petrologiya, 16(4), 356-375

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Abstract:
According to detailed petrological, geochemical, and isotope-geochemical study, fragments of fresh pillow lavas with chilled glass margins dredged at the Sierra-Leone test site in the axial rift zone of the MAR between 5° and 7°N correspond to MORB tholeiites, which are not primitive mantle melts, but were differentiated in intermediate magmatic (intrusive) chambers. Small-scale geochemical and Sr-Nd isotope heterogeneities were established for the first time in basalts and their glasses. It was shown that some samples have significant nonsystematic differences in the 87Sr/86Sr ratio between basalts and their chilled glasses and less significant difference in e-Nd; higher Sr ratios can be observed both in glasses and basalts of the same lava fragments. No significant correlation is observed between isotope characteristics of samples and their geochemistry; it was also shown that seawater did not affect Sr and Nd isotope compositions of the chilled glasses from the studied pillow lavas. It is suggested that such differences in isotope ratios are related to small-scale heterogeneity of melts owing to incomplete homogenization during their rapid ascent to the surface. Heterogeneity of basaltic melts is explained by their partial contamination by older plutonic rocks (especially gabbroids) of the lower oceanic crust, through which they ascended to the surface of the ocean floor. The wider scatter of the Sr isotopic ratios relative to Nd ones is related to presence of xenocrysts of calcic plagioclase; correspondingly, absence of a Nd mineral carrier in the rocks results in less distinct Nd isotope variations. It was shown that all studied basalts define a single trend along the mantle correlation array in the Sr-Nd isotope diagram. Causes of this phenomenon remain unclear.
Project(s):
Archive of Ocean Data (ARCOD)
Coverage:
Median Latitude: 6.308638 * Median Longitude: -33.697606 * South-bound Latitude: 5.375000 * West-bound Longitude: -34.588300 * North-bound Latitude: 7.296700 * East-bound Longitude: -32.975000
Event(s):
I1003 * Latitude Start: 7.248300 * Longitude Start: -34.585000 * Latitude End: 7.255000 * Longitude End: -34.588300 * Elevation Start: -4800.0 m * Elevation End: -5000.0 m * Location: Mid-Atlantic Ridge * Campaign: Ioffe-10 * Basis: Akademik Ioffe * Method/Device: Dredge (DRG)
I1011 * Latitude Start: 7.290000 * Longitude Start: -33.961700 * Latitude End: 7.296700 * Longitude End: -34.000000 * Elevation Start: -3500.0 m * Elevation End: -3220.0 m * Location: Mid-Atlantic Ridge * Campaign: Ioffe-10 * Basis: Akademik Ioffe * Method/Device: Dredge (DRG)
I1016 * Latitude Start: 6.615000 * Longitude Start: -34.100000 * Latitude End: 6.616700 * Longitude End: -34.090000 * Elevation Start: -2800.0 m * Elevation End: -2700.0 m * Location: Mid-Atlantic Ridge * Campaign: Ioffe-10 * Basis: Akademik Ioffe * Method/Device: Dredge (DRG)
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
4 datasets

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Datasets listed in this publication series

  1. Sharkov, EV; Shatagin, KN; Krassivskaya, IS et al. (2008): (Table 2) Compositions of basalts and their chilled glasses from pillow lavas of the Sierra Leone fault site, MAR 5-7°N. https://doi.org/10.1594/PANGAEA.744582
  2. Sharkov, EV; Shatagin, KN; Krassivskaya, IS et al. (2008): (Table 3) REE contents in basalts from pillow lavas of the Sierra Leone fault site, MAR 5-7°N. https://doi.org/10.1594/PANGAEA.744583
  3. Sharkov, EV; Shatagin, KN; Krassivskaya, IS et al. (2008): (Table 4) Trace element contents in basalts and plutonic rocks from pillow lavas of the Sierra Leone fault site, MAR 5-7°N. https://doi.org/10.1594/PANGAEA.744584
  4. Sharkov, EV; Shatagin, KN; Krassivskaya, IS et al. (2008): (Table 5) Rb-Sr and Sm-Nd isotopic systems in pillow lavas, their chilled glasses, and underlying holocrystalline rocks dredged from the Markov Deep, Sierra Leone Site, MAR 5-7°N. https://doi.org/10.1594/PANGAEA.744585