Inputs from deep-sea hydrothermal vents influence ocean geochemical budgets worldwide.
Hydrothermal vents produce buoyant and chemically dynamic plumes that are rich in trace
seawater elements. The mineral diversity in lower plumes is a direct result of interactions
between local geology, hydrology, and biology. Because of this, differences in geochemical
trends among naturally occurring plumes are detectable. Past studies have focused on geologic
and bulk-chemistry differences between hydrothermal vents (Ferrini et al. 2008; Baker et al.
2005; Pearce et al. 1995; Tivey et al. 2005), while mineral differences among individual plumes
remain poorly understood. This study examines and compares lower plume geochemistry of
three hydrothermal vents located along the Eastern Lau Spreading Center (ELSC). Deep-sea
hydrothermal plumes were sampled by in-situ filtration using ROV Jason2 and the SUPR
Sampler (Breier et al. 2009). Samples were collected 0.5 meters above each vent onto
polycarbonate membrane filters. Plume particles on the filters were examined by synchrotron
radiation X-ray fluorescence (XRF) mapping. Subsequently, a total of 67 filter-bound particles
underwent X-ray ray diffraction (XRD) to define the crystalline minerals. Differences among
sites are compared and discussed regarding: (1) geologic setting; (2) vent fluid chemistry; and (3)
lower-plume mineral species. Reduced metal polysulfides were detected in concentrations that
coincide with previous bulk-chemistry studies (Mottl et al., 2011; Tivey et al., 2007; Ishibashi
and Urabe, 1995). In addition, this study will introduce a new method to rate confidence levels
associated with the identification of mineral species using X-ray microprobe XRD and XRF
Geochemical Profiles of Three Deep-sea Hydrothermal Plumes of the Eastern Lau Spreading Center.
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