Recent advances in the understanding of mid-ocean ridge tectonics and volcanism using swath-mapping tools

摘要: New swath mapping sonar systems have revealed the structure of mid-ocean ridge (MOR) and sunounding deep ocean floor with unprecedent clarity. These images show that MOR is partitioned into segments by a variety offsets such as transform faults, overlapping spreading centers very fine scale discontinuities which are barely detectable. The smallest fundamental building blocks for creation new oceanic crust. They only 2-20 km long active, distinct units =100-10,000 years. At fast centers, axial neovolcanic zone persistent 300-400 m high elevation produced bouyancy hot rock magma; it not volcanic construction (most time in most plac e ~ )so there almost no vestige off-axis. Along ~60%of its length, center characterized an summit caldera inflation collapse. size shape sensitive indicators relatively steady robust magma supply at fast-spreading ndges, been used successfuliy to predict location chambers forecast recent emptions including one witnessed from ALVIN March-Apnl 1991. intermediate rates, region cools sufficiently constructional edifice develop episodically normal faulting occur along graben. Under these conditions volcanoes split two graben rernnants can be found on flanks centers. slow-spreading ridges, budget starved indicated nft valley highly discontinuous zone, strong asymmetry profiles across strike ridge.