Observation of ferromanganese crusts on lava deposits recovered near the Galapagos spreading center area
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| Main Authors: | , |
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| Format: | Dataset Open Access |
| Language: | en |
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PANGAEA
1981
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| _version_ | 1867169122861711360 |
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| author | Christie, David M Sinton, John M |
| author_facet | Christie, David M Sinton, John M |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | The unusual petrological diversity of abyssal lavas erupted along some segments of the Galapagos spreading center is a direct consequence of the propagation (elongation) of these segments into older oceanic crust. With increasing distance behind propagating rift tips, relatively unfractionated MORB erupted close to the tips are joined first by FeTi basalts (bimodal assemblage) and then by a wide range of basaltic and siliceous lavas. Further behind propagating rift tips, this broad range diminishes again, approaching the narrow compositional range of adjacent normal ridge segments. These compositional variations reflect the evolution of the subaxial magmatic system beneath the newly forming spreading center as it propagates through a pre-existing plate. We envisage this evolution as proceeding from small, isolated, ephemeral magma chambers through increasing numbers of larger, increasingly interconnected chambers to the steady-state buffered system of a normal ridge. Throughout this evolution, magma supply rates gradually increase and cooling rates of crustal magma bodies decrease. High degrees of crystal fractionation are favored only when a delicate balance between cooling rate and resupply rate of primitive magma is achieved. At other propagating and non-propagating ridge-transform intersections the degree to which the balance is achieved and the length of ridge over which it evolves control the distribution of fractionated lavas. These effects may be evaluated provided a number of tectonic variables including transform length, spreading and propagation rates are taken into account. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_882395 |
| institution | PANGAEA |
| language | en |
| publishDate | 1981 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Observation of ferromanganese crusts on lava deposits recovered near the Galapagos spreading center area Christie, David M Sinton, John M Deposit type; DEPTH, sediment/rock; Description; Dredge, rock; DRG_R; Elevation of event; Event label; Identification; Kana Keoki; KK781230; KK78-12-RD10; KK78-12-RD12; KK78-12-RD12B; KK78-12-RD14; KK78-12-RD16; KK78-12-RD17; KK78-12-RD2; KK78-12-RD20; KK78-12-RD21; KK78-12-RD24; KK78-12-RD25; KK78-12-RD26; KK78-12-RD27; KK78-12-RD29; KK78-12-RD32; KK78-12-RD4; Latitude of event; Longitude of event; Method/Device of event; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; Pacific Ocean; Position; Quantity of deposit; Sediment type; Size; Station 107; Station 109; Station 8; Station 80; Station 83; Station 85; Station 86; Station 88; Station 89; Station 91; Station 93; Station 94; Station 95; Station 96; Substrate type; Uniform resource locator/link to image; Visual description The unusual petrological diversity of abyssal lavas erupted along some segments of the Galapagos spreading center is a direct consequence of the propagation (elongation) of these segments into older oceanic crust. With increasing distance behind propagating rift tips, relatively unfractionated MORB erupted close to the tips are joined first by FeTi basalts (bimodal assemblage) and then by a wide range of basaltic and siliceous lavas. Further behind propagating rift tips, this broad range diminishes again, approaching the narrow compositional range of adjacent normal ridge segments. These compositional variations reflect the evolution of the subaxial magmatic system beneath the newly forming spreading center as it propagates through a pre-existing plate. We envisage this evolution as proceeding from small, isolated, ephemeral magma chambers through increasing numbers of larger, increasingly interconnected chambers to the steady-state buffered system of a normal ridge. Throughout this evolution, magma supply rates gradually increase and cooling rates of crustal magma bodies decrease. High degrees of crystal fractionation are favored only when a delicate balance between cooling rate and resupply rate of primitive magma is achieved. At other propagating and non-propagating ridge-transform intersections the degree to which the balance is achieved and the length of ridge over which it evolves control the distribution of fractionated lavas. These effects may be evaluated provided a number of tectonic variables including transform length, spreading and propagation rates are taken into account. |
| title | Observation of ferromanganese crusts on lava deposits recovered near the Galapagos spreading center area |
| topic | Deposit type; DEPTH, sediment/rock; Description; Dredge, rock; DRG_R; Elevation of event; Event label; Identification; Kana Keoki; KK781230; KK78-12-RD10; KK78-12-RD12; KK78-12-RD12B; KK78-12-RD14; KK78-12-RD16; KK78-12-RD17; KK78-12-RD2; KK78-12-RD20; KK78-12-RD21; KK78-12-RD24; KK78-12-RD25; KK78-12-RD26; KK78-12-RD27; KK78-12-RD29; KK78-12-RD32; KK78-12-RD4; Latitude of event; Longitude of event; Method/Device of event; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; Pacific Ocean; Position; Quantity of deposit; Sediment type; Size; Station 107; Station 109; Station 8; Station 80; Station 83; Station 85; Station 86; Station 88; Station 89; Station 91; Station 93; Station 94; Station 95; Station 96; Substrate type; Uniform resource locator/link to image; Visual description |
| url | https://doi.org/10.1594/PANGAEA.882395 |