Elevated turbidity and dissolved manganese in deep water column near 10°47’S Central Indian Ridge: studies on hydrothermal activities

Volatile‐Rich Hydrothermal Plumes Over the Southern Central Indian Ridge, 24°49’S: Evidence for a New Hydrothermal Field Hosted by Ultramafic Rocks

“…A sharp increase in dissolved trace metals and gas concentrations of plumes layers 1 and 2 at P8, and P5 indicate the possibility of nearby venting. These values are comparable to concentrations reported for hydrothermal plumes found in the Indian Ocean and elsewhere in global oceans (Boulart et al, 2017;Fang & Wang, 2021;Gamo et al, 2015;Gharib et al, 2005;González-Santana et al, 2020;Haalboom et al, 2019;Kawagucci et al, 2008;Ray et al, 2012Ray et al, , 2020Resing et al, 2009;Schmid et al, 2019;Wang et al, 2012;You et al, 2014;Zhu et al, 2008 and references therein). The δ 3 He (88%) at 2570 m at P5 is the highest reported hydrothermal plume value in the Indian Ocean (Table 1) when compared to hydrothermal plumes above Solitaire vent field (δ 3 He = ∼56%; Kawagucci et al, 2008).…”

“…In plume layer 2, the concentrations (plume maxima) of CH 4 , DMn, DFe and δ 3 He value vary from 32 to 246 nM, 19–112 nM, 33–85 nM, and 28%–88%, respectively (Table 1), with maximum concentrations at 2570 m of P5 (Figure 3). Very high δ 3 He of 88% is observed at 2570 m of P5 and is the largest anomaly observed in the Indian Ocean (Gamo et al., 2015; Kawagucci et al., 2008; Ray et al., 2008, 2012, 2020; Takahata et al., 2018). In addition, background concentrations (below plume layer 2 and above the seafloor; 50–80 m) were found to be high for P5 (13.94% of δ 3 He; 4.7 nM of CH 4 ; 5.4 nM of DMn and 24.57 nM of DFe when compared to P8.…”

“…The Central Indian Ridge (CIR) has been better explored for hydrothermal plumes in the water‐column compared to the other parts of the Indian mid‐oceanic ridge system such as the Carlsberg, Southeast, and Southwest Indian Ridges. Numerous studies have focused on identification of hydrothermal plume signatures in the water column and ultimately led to the discovery of vent fields (Gamo et al., 1996; Jean‐Baptiste et al., 1992; Kawagucci et al., 2008; Nakamura et al., 2012; Ray et al., 2020; Son et al., 2014; You et al., 2014). In continuation of these studies, hydrothermal vent fields have been discovered at eight different sites, between 8° and 27°S, ranging from basaltic to ultramafic hosted systems (Gamo et al., 2001; Kawagucci et al., 2008, 2016; Kim et al., 2020; Nakamura et al., 2012; Ryu et al., 2019; Van Dover et al., 2001).…”

Identification of Two New Hydrothermal Fields and Sulfide Deposits on the Mid-Atlantic Ridge as a Result of the Combined Use of Exploration Methods: Methane Detection, Water Column Chemistry, Ore Sample Analysis, and Camera Surveys

“…CTD sounding was carried out by the SBE 911 plus probe at point stations from the ocean surface to the bottom and back, with a discreteness of 24 measurements per second to identify anomalous structures of ocean waters associated with modern hydrothermal activity and geoecological monitoring [43]. The coordinates of the hydrological sounding complex were determined using the low-frequency ultra-deep water positioning system Kongsberg HiPAP 101.…”

Observing the full ocean volume using Deep Argo floats

“…Emerging plans involve testing the performance of pilot optical scattering sensors (Gardner et al, 2018) on Deep Argo floats to measure the concentration of particles present in deep-sea water. Deeprated optical scattering sensors are commercially available and have been field tested to 6000 m (e.g., Gardner et al, 2018;Ray et al, 2020), but have not yet been implemented on Deep Argo floats. The high sensitivity of optical scattering to minerals and large particles (Briggs et al, 2020) implies that no increase in sensor sensitivity nor accuracy is needed to quantitatively resolve the deep-ocean signal.…”