Observation of ferromanganese crusts on lava deposits recovered near the Galapagos spreading center area, supplement to: Christie, David M; Sinton, John M (1981): Evolution of abyssal lavas along propagating segments of the Galapagos spreading center. Earth and Planetary Science Letters, 56, 321-335


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.

DOI https://doi.org/10.1594/PANGAEA.882395
Related Identifier https://doi.org/10.1016/0012-821X(81)90137-0
Related Identifier https://doi.org/10.7289/V52Z13FT
Related Identifier https://doi.org/10.7289/V53X84KN
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.882395
Creator Christie, David M; Sinton, John M
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 1981
Rights Creative Commons Attribution 3.0 Unported
OpenAccess true
Language English
Resource Type Supplementary Dataset
Format text/tab-separated-values
Size 138 data points
Discipline Earth System Research
Spatial Coverage (-95.670W, 1.384S, -86.523E, 3.897N); Pacific Ocean
Temporal Coverage Begin 1979-05-02T00:00:00Z
Temporal Coverage End 1979-06-11T00:00:00Z