Meeting

The InterRidge cruise bursary is aimed at post graduate students seeking cruise experience. This provides a vital opportunity for training in data collection and experience of scientific principles in action.  The bursary allowed me to join Dr. R. Hobbs’ JC114 cruise to the Panama basin to study the Costa Rica and Ecuador ridges. Subsequently after the cruise I became involved in the OSCAR project, ‘Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge’.

Abyssal peridotites are of great interest to geoscientists because they provide direct information about the present-day Earth's mantle. Os isotope systems in abyssal peridotites are also interesting because Os is a highly siderophile and compatible element and so concentrates in the core in preference to the mantle, and in the mantle in preference to the crustal materials. In addition, Os in abyssal peridotites is not susceptible to metasomatism and alteration by sea water.

We quantify systematic variations in morphological characteristics of global transform faults and investigate their dependence on spreading rate, local magma supply, and other tectonic variables. Detailed analyses were conducted on 78 transform faults where high-resolution multibeam bathymetry and other geophysical data are available.

Jinchang Zhang^1,2, William W. Sager^2,3, Jun Korenaga⁴

¹South China Sea Institute of Oceanology, Chinese Academy of Sciences, China

²Texas A&M University, College Station, Texas, USA

³University of Houston, Houston, Texas, USA

We applied the maximum offset of sound velocity algorithm to sound velocity profile streamlining and optimization to overcome multi-beam survey and data processing efficiency problems. The impact of sound velocity profile streamlining on sounding data accuracy is evaluated. By automatically optimizing the threshold, the reduction rate of sound velocity profile data can reach over 90% and the standard deviation percentage error of sounding data can be controlled to within 0.1%.

 A new method is proposed to identify automatically the foot of the continental slope (FOS) based on the integrated analysis of topographical profiles. First, it simplifies the topographic profiles based on second derivative extremum points and the Douglas-Peucker algorithm, and calculates a second-order derivative of the original profiles and the D-P profiles. Then, seven steps are used to simplify the original profiles and determine the slope gradient, water depth and second derivative values of data points.

With a systematic study on mineralogy of the three stations’ sulfide samples dredged from the seafloor hydrothermal field near 15°S Southern Mid-Atlantic Ridge, geochemical features of these sulfides are also described in detail. Bulk chemical analyses of sulfide samples were obtained using X-ray Fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The sulfides on the Southern Mid-Atlantic Ridge (SMAR) near 15°S can be divided into three types: Fe-rich sulfide, Fe-Cu-rich sulfide and Fe-Zn-rich sulfide, and enrich Fe, Zn and Cu concentrations successively.

In recent years, Sub-Committee on Undersea Feature Names (SCUFN) has been conducting deliberations on naming undersea features that are entirely or mainly (more than 50%) outside the external limits of the territorial sea, adhering to the principles of not involving sovereignty dispute between countries. In order to participate in undersea feature naming and embody the international responsibility, obligation and influence of the State, Chinese State Oceanic Administration submitted seven undersea name proposals to SCUFN in 2011 for the first time.

Hydrothermal systems play an important role on the oceanic biogeochemical cycles of Zn and its isotopes. However, for the Zn isotopic systems in hydrothermal systems we know too little of the distribution of Zn isotopes in variable hydrothermal products and its impact on modern oceanic mass balance. We have measured Zn isotopes in hydrothermal products such as oxidation products of chimney sulfides and hydrothermal sediments from the active hydrothermal field on the Mid-Atlantic Ridge in order to better understand the oceanic biogeochemical cycles of Zn isotopes.

Seafloor polymetallic sulfide resources exhibit significant development potential. In 2011, the China Ocean Mineral Resources Research and Development Association (COMRA) and International Seabed Authority (ISA) signed a contract for the exploration of 10,000 km2 of a hydrothermal sulfide area located on the Southwest Indian Ridge (SWIR). According to the Regulations, China will have to relinquish, respectively, 50 % and 75 % of the contract area within 8 and 10 years. However, an exploration of the seafloor hydrothermal sulfide deposits in China remains in the initial stage.

Real-time, continuously recording observatory technologies are now installed at three mid-ocean ridge locations, serving disciplines from geophysics to biology.  All three observatories provide power and communications to seafloor networks of sensors, with data being transmitted to land via long-distance cables or a satellite link. Two observatories have been operating since 2010 (EMSO Açores and NEPTUNE Endeavour), and the third (OOI Axial Volcano) went online in 2015.

Increasing commercial interest in mining of seafloor massive sulfides and the political will to secure metal supply for global industries has led to an ongoing debate about their possible resource potential. The need for such assessments is now more urgent, as a number of countries and international consortia have begun to invest in intensive exploration campaigns. A growing database of global SMS occurrences is providing clues to the likely distribution, size and grade of the deposits. More than 330 sites of seafloor mineralization are now known on the ocean floor.

Deep-sea hydrothermal systems and associated biota have long attracted interest of many researchers (e.g., Humphris et al., 1995; Van Dover, 2000; Wilcock et al., 2004). In the past few decades, particular attention has been paid to chemolithoautotrophic microorganisms that sustain the hydrothermal vent-endemic animal communities as the primary producer.

Marcia Maia¹, Susanna Sichel²,Anne Briais³, Daniele Brunelli^4,5, Nicolas Ferreira¹, Marco Ligi⁵, Thomas Campos⁶

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Europe, and the world in general, need new sources of base and strategic metals, given a growing global population, with growing effluence, which will reach ten billion human beings before (slowly) decreasing. One of the new, global scale sources of mineral resources is the deep seafloor, and there are 25 exploration concessions already granted by ISA (International Seabed Authority) in the Area, mostly for polymetallic nodules and sms deposits, and still others in waters under national jurisdiction.