The Effect of Magmatic Activity on Hydrothermal Venting Along the Superfast-Spreading East Pacific Rise

Abstract

A survey of hydrothermal activity along the superfast-spreading (approximately 150 millimeters per year) East Pacific Rise shows that hydrothermal plumes overlay approximately 60 percent of the ridge crest between 13 degrees 50' and 18 degrees 40'S, a plume abundance nearly twice that known from any other rige portion of comparable length. Plumes were most abundant where the axial cross section is inflated and an axial magma chamber is present. Plumes with high ratios of volatile ((3)He, CH(4), and H(2)S) to nonvolatile (Mn and Fe) species marked where hydrothermal circulation has been perturbed by recent magmatic activity. The high proportion of volatile-rich plumes observed implies that such episodes are more frequent here than on slower spreading ridges.

Origin of native sulfur ball from the Kueishantao hydrothermal field offshore northeast Taiwan: Evidence from trace and rare earth element composition

“…) in the native sulfur ball are likely to be sourced from a deeper magma chamber, from where they are transported by high-temperature fluids during degassing (e.g. Fleet and Wu, 1993;Tsunogai et al, 1994;Ballhaus et al, 1994;Urabe et al, 1995;Scott, 1996, 2002;Herzig et al, 1998). Most of the volatiles and metals could be carried directly into hydrothermal fluids flowing onto the sea floor (Yang and Scott, 2002).…”

Co-diagenesis of iron and phosphorus in hydrothermal sediments from the southern East Pacific Rise: Implications for the evaluation of paleoseawater phosphate concentrations

“…Pyrite is a relatively inefficient scavenger of oxyanions such as phosphate, and the region to the south of 17°20 0 S on the SEPR is characterised by the highest discharges of H 2 S yet seen on the global ridge crest system (Urabe et al, 1995;Feely et al, 1996). This results in high S/Fe ratios in the plume particles (0.5-4.1) relative to those found at more northern sites (S/Fe = $0.18).…”

Hydrothermal activity in the Northwest Lau Backarc Basin: Evidence from water column measurements

“…As shown in Figure 7b, Lobster Caldera has an estimated end-member 3 He/Mn of 1.3 Â 10 À7 , while Central Caldera has 3 He/Mn of 8.8 Â 10 À9 , a factor of 15 lower. These 3 He/Mn values fall within the range of typical MOR hydrothermal plumes, which vary from 6 Â 10 À9 up to 2 Â 10 À7 [e.g., Urabe et al, 1995]. It is notable that Lobster Caldera has 3 He/Mn similar to that at the 9 45′ N East Pacific Rise site ( 3 He/Mn = 1.2 Â 10 À7 ), which is known to have been perturbed by magma input [Lupton et al, 1993], while the 3 He/Mn at Central Caldera is similar to that at longer-lived mature sites [e.g., Lupton et al, 1993;Massoth et al, 1994].…”