NONDESTRUCTIVE IMAGING OF FRAGILE SEA-FLOOR VENT DEPOSIT SAMPLES

X-ray computed tomography was used to detail the internal structure of sea-floor hydrothermal vent samples. A third-generation industrial co mputed tomography (CT) scanner with a microfocus tube was used to scan a black smoker chimney and cores taken from a white smoker chimney an d a block of Fe-rich sulfide. Images of the black smoker chimney clear ly show sulfide-versus anhydrite-dominated areas. Display of pore spac e in three dimensions shows the complex geometry of the main flow cond uit, and also much smaller (2-3 mm diameter) conduits within the chimn ey wall that parallel the main flow conduit, Images of the white smoke r sample document the continuity of an anastomosing similar to 1-mm-di ameter flow conduit, and the pronounced anisotropy of porosity. Tube s tructures presumed to be casts of worm tubes are clearly evident in im ages of the Fe-rich sulfide sample. X-ray CT is an excellent technique for rapidly identifying the internal structure of porosity and minera logy of fragile hydrothermal precipitates on scales of tens of microns to hundreds of millimeters, and data can be used to deduce styles of fluid flow and other processes involved in vent deposit formation.