Tuzo Wilson Seamounts numerous smaller vents, with a total edifice volume of about 12 km. The lava emitted in eruptions at the Tuzo Wilson Seamounts is made of basalt, a common gray to black or dark brown extrusive volcanic rock low in silica content (the lava is mafic) that is usually fine-grained due to rapid cooling of lava. Glassy pillow lava is found at the seamounts, a type of rock typically formed when basaltic lava emerges from a submarine volcanic vent. The viscous lava gains a solid crust on contact with the water, and this crust cracks and oozes additional large blobs or
Chinchillas (lava dome) Chinchillas (lava dome) Chinchillas is a lava dome complex in the northern Puna of the Andes, in the Sierra de Rinconada. The complex is constructed on an Ordovician basement called the Acoite Formation. In addition to the dacitic lava dome on the southern end of the complex it also contains small volume massive pyroclastic flows and ash-and-block flows. The complex has a volume of . The complex was formed 13±1 mya over a fault zone. Hydrothermal Ag-Pb-Zn deposits found there in breccia were mined occasionally. According to Coira "et al." (1996) it, Cerro Redondo and Pan de Azúcar may be