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• 1. [Article] Elemental and isotopic abundance of noble gases in formation fluids recovered in situ from the Chile Triple Juction

  Sedimentary pore fluids from the Chile Triple Junction were sampled in situ, and analyzed for their noble gas composition. ³He/⁴He and ⁴He/Ne ratios were used to evaluate the fraction of helium in the ...

  Citation × Citation Citation Abstract Copy Title: Elemental and isotopic abundance of noble gases in formation fluids recovered in situ from the Chile Triple Juction Author: Torres, Marta E., Winckler, Gisela, Suckow, Axel, Bayer, Reinhold, Froelich, Philip N. Sedimentary pore fluids from the Chile Triple Junction were sampled in situ, and analyzed for their noble gas composition. ³He/⁴He and ⁴He/Ne ratios were used to evaluate the fraction of helium in the samples that originated from mantle and radiogenic sources. The results show no primordial helium in samples recovered from Sites 860 and 861. In contrast, a primordial component is present in two samples from a depth interval in Site 863 that corresponds to a zone of tectonic discontinuity. A decrease in the concentration of dissolved K, Sr, Mg, and SO₄ in this interval is consistent with the presence of a fluid which has been altered by basalt-seawater reactions. These results indicate lateral fluid migration from a hydrothermal source which is probably associated with the recently subducted Chile Ridge axis. Title: Elemental and isotopic abundance of noble gases in formation fluids recovered in situ from the Chile Triple Juction Author: Torres, Marta E., Winckler, Gisela, Suckow, Axel, Bayer, Reinhold, Froelich, Philip N. Sedimentary pore fluids from the Chile Triple Junction were sampled in situ, and analyzed for their noble gas composition. ³He/⁴He and ⁴He/Ne ratios were used to evaluate the fraction of helium in the samples that originated from mantle and radiogenic sources. The results show no primordial helium in samples recovered from Sites 860 and 861. In contrast, a primordial component is present in two samples from a depth interval in Site 863 that corresponds to a zone of tectonic discontinuity. A decrease in the concentration of dissolved K, Sr, Mg, and SO₄ in this interval is consistent with the presence of a fluid which has been altered by basalt-seawater reactions. These results indicate lateral fluid migration from a hydrothermal source which is probably associated with the recently subducted Chile Ridge axis. Close