Hydrothermal venting and the apparent magmatic budget of the Juan De Fuca Ridge
摘要：
The fact that vigorous hydrothermal discharge occurs on ridge segments with a variety of spreading rates and morphological characteristics makes it difficult to discern the large-scale geological controls on the distribution of hydrothermal venting along the mid-ocean ridge. We undertook to simplify this problem by mapping the distribution of hydrothermally produced thermal and light attenuation anomalies along the crest of the Juan de Fuca Ridge, a medium-rate spreading center with segments of markedly differing morphology. Hydrothermal anomalies were detected by towing a high-precision conductivity-temperature-depth-transmissometer (CTDT) package in a sawtooth pattern through the lowermost 1000 m of the water column above each segment. These surveys, conducted between 1985 and 1989, have produced the first quantitative and continuous visualizations of hydrothermal plumes along a multisegment portion of the mid-ocean ridge. Hydrothermal discharge is strongest on those segments, or portions of segments, where the apparent magmatic budget is highest, as indicated by the degree of along-axis inflation and other morphological characteristics. This correspondence implies that magma is episodically delivered in small and spatially discontinuous bodies of melt rather than by the constant resupply of a steady state magma chamber. We propose that the probability of discharge occurring at any point on the mid-ocean ridge is proportional to the spreading rate. This probability, scaled by the observation that significant plumes presently emanate from 20% of the Juan de Fuca Ridge, is expected to range from 5% on the slowest-spreading ridge to 50% on the fastest-spreading ridge.
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关键词：
Bibliography, Experimental/ oceanic crust seawater tectonics terrestrial heat volcanology/ seafloor spreading rate hydrothermal venting seawater thermal anomalies mid-ocean ridge segments hydrothermal discharge probability plate tectonics small discontinuous melt bodies ocean floor morphology magma episodic delivery NE Pacific Ocean vertical temperature profiles AD 1985 to 1989 apparent magmatic budget Juan de Fuca Ridge light attenuation anomalies high-precision conductivity-temperature-depth-transmissometer along-axis inflation morphological characteristics mid-ocean ridge slowest-spreading ridge fastest-spreading ridge 2000 to 2450 m/ A9150E Seafloor processes A9135D Terrestrial heat A9140 Volcanology A9330P Pacific Ocean A9145B Sub-plate scale tectonics (faults, folds, rifts, etc.) A9145D Plate tectonics A9210M Thermohaline structure and circulation of the oceans A9150G Bathymetry and seafloor topography A9210P Optical aspects of oceanography/ depth 2.0E+03 to 2.45E+03 m
DOI：
10.1029/91JB02671
被引量：
年份：
1992
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