Imaging of a coimmobilized diaphorase and albumin surface was investigated by scanning electrochemical microscopy (SECM) with shear force based tip-substrate distance control. A microelectrode tip was attached to a commercially available tuning fork to detect the shear force between the microelectrode tip and the surface. We used the standing approach mode, which repeats an approach and retraction at each data point of the surface to obtain simultaneous current and topographic images. To check the performance of our SECM system, we imaged a platinum-patterned array electrode and a diaphorase/albumin coimmobilized glass surface. Since the system acquires current when the tip is retracted to a desired distance, this mode is useful for a relatively large microelectrode (approximately 10 microm) and for scanning a large area (few hundreds of micrometers). Furthermore, by retracting the tip when the tip moves laterally to the next data point to avoid contact between the tip and sample surface, we successfully imaged the surface without destroying its morphology.

Mineralogically investigated were massive sulfide samples of chimneys and mounds collected during the "SHINKAI 6500" dives (Dive 562 and Dive 567) from two basalt-hosted hydrothermal ore deposits, being at a short distance of about 1 km, occurring in the eastern end of the Yaeyama Central Graben, the Southern Okinawa Trough. In both sample series (#562-and #567-series), ore minerals are dominated by low-iron sphalerite with small amounts of chalcopyrite and galena. Sphalerite in the #567-series samples shows somewhat wide compositional variation, ranging from 0.4 to 3.8 mole%FeS, with the highest mode of about 1 to 2 mole%FeS. Significant amounts of pyrite and secondary marcasite are present in the #562-series samples with subordinate bornite, while in the #567-series samples, they are lacking, but instead tetrahedrite-tennantite series with atomic ratios of Sb/(Sb+As) being 0.2 to 0.8 is abundant and contains Ag up to 0.7wt% with mostly less than 0.5 wt%. Neither pyrrhotite nor isocubanite is encountered in the two sample series. Microthermometries of two-phase (liquid + gas) fluid inclusions trapped in calcite (#567-series) have revealed the following results: homogenization temperatures (not corrected for pressure) of 242 to 317 °C and salinities of 5.1 to 7.6 wt.%NaCl equiv., being a little more saline than the seawater. The observed mineral assemblages and sphalerite compositions obtained for the Yaeyama Central Graben deposits lead us to indicate that the basalt-hosted mineralizations might have occurred under rather higher sulfidation state. From the mineral associations observed, it is also indicated that both hydrothermal deposits are characterized by a metal association of essentially Zn-Pb-Cu. The mineral assemblages and ore textures observed are similar to those of the Kuroko deposits rather than the Besshi-type deposits, as well as their metal association (Cu-Pb-Zn).

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