230Th/238U dating of hydrothermal sulfides from Duanqiao hydrothermal field, Southwest Indian Ridge

Abstract

Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones at the central volcano, at 50°28 0 E in the ultraslow-spreading Southwest Indian Ridge (SWIR). Twenty-eight subsamples from a relict chimney and massive sulfides were dated using the 230 Th/ 238 U method. Four main episodes of hydrothermal activity were determined according to the restricted results: 68. 9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. The periodic character of hydrothermal activity may be related to the heat source provided by the interaction of local magmatism and tectonism. The estimated mean growth rate of the sulfide chimney is \0.02 mm/yr. This study is the first to estimate the growth rate of chimneys in the SWIR. The maximum age of the relict chimney in Duanqiao hydrothermal filed is close to that of the chimneys from Mt. Jourdanne (70 kyrs). The hydrothermal activity in Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. The preliminarily estimated reserves of sulfide ores of Duanqiao are approximately 0.5-2.9 million tons.

He–Ar–S Isotopic Compositions of Polymetallic Sulphides from Hydrothermal Vent Fields along the Ultraslow-Spreading Southwest Indian Ridge and Their Geological Implications

“…Two mineralisation stages were also recognised by previous researchers [26,27]. Similarly, ore samples recovered from the adjacent Duanqiao and Yuhuang hydrothermal fields also include Fe-rich relict sulphide talus or clasts (20V-S32-TVG14 and 21VII-S35-TVG22) consisting mostly of pyrite/marcasite with minor chalcopyrite and sphalerite ( Figure 2D,E), which might be derived from the recent collapse of inactive chimney edifices [24,29,80]. By contrast, the mineralisation style is somewhat unique at the Tianzuo field, which reflects complex ore-forming processes related to ultramafic-hosted hydrothermal environments of the ultraslow-spreading SWIR [86].…”

“…The Duanqiao (50.5 • E) field lies on an axial highland with a shallow depth of~1700 m. Seafloor morphology of the surrounding terrain is relatively flat [79]. Hydrothermal precipitates, including silica-rich metalliferous sediments (mostly amorphous opal), relict chimneys, and massive sulphide talus, are pervasive in this inactive field [23,80]. The Yuhuang (49.2 • E) field is situated on the south rift wall of segment 29, approximately 7.5 km from the ridge axis with a water depth ranging from 1400 to 1600 m. Its surrounding terrain exhibits NEE-striking highland features, with an elevation of~1500 m to the bottom of the rift valley [76].…”

“…Inset shows regional setting of the ultraslow-spreading SWIR. For more detailed bathymetry and topography data on each of these six hydrothermal fields (marked with red circles), please see the previously published literature [23,24,29,[78][79][80][81][82][83]]. With the aim of exploring the SWIR hydrothermal systems, the Chinese research cruises DY115-19, DY115-20, and DY115-21 have been successfully carried out by China Ocean Mineral Resources Research & Development Association (COMRA) during 2007-2010 [23,24,76].…”

Mineralogy and Geochemistry of Deep-Sea Sediments from the Ultraslow-Spreading Southwest Indian Ridge: Implications for Hydrothermal Input and Igneous Host Rock

“…However, it was not much related to rock debris or biological shells. Previous studies have revealed that Pb in massive sulfides from the Duanqiao Hydrothermal Field was chiefly leached from host rock (basalt), and the Pb contribution of seawater was negligible [19]. Through correlation analysis between Pb and HFSE and LILE (large ion lithophile element), in S25-21 plus S32-14ABC, r (Pb/Nb) = 0.427, r (Pb/Zr) = 0.012, r (Pb/Hf) = 0.056, r (Pb/Cs) = 0.872, r (Pb/Rb) = 0.616, and in S23-12, S17-4, S7-7 plus S37-21, r (Pb/Nb) = 0.880, r (Pb/Zr) = 0.008, r (Pb/Hf) = -0.019, r (Pb/Cs) = 0.259, r (Pb/Rb) = 0.437.…”

230Th/238U Dating of Sulfide Chimneys in the Longqi‐1 Hydrothermal Field, Southwest Indian Ridge

“…However, the hiatuses of almost 40kyrs from the inactive chimney collected in M zone, indicate venting continuous may not be integrated. Multi-stage of deposition have been reported widely for many conduits of the relict chimney samples (Wang et al, 2012;Yang et al, 2016).…”