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Vertical movements of ocean island volcanoes: Insights from a stationary plate environment

May 10, 2010

Uplift reconstructions based on the Cape Verde's geological record provide a unique opportunity to study the long-term isostatic movements associated with hotspot activity on a stationary plate environment. The archipelago is considered stationary with respect to its melting source so the hotspot-driven isostatic effects affecting the ocean islands are expected to be enhanced. In this study, Ar–Ar and U–Th geochronology techniques were used to date a set of palaeo-markers of sea-level from Santiago's and São Nicolau's edifices, two of the main Cape Verde Islands. A comparison between relative sea-level and eustatic sea-level (from a modern eustatic curve) was established to extract the vertical displacement undergone by the markers, and to reconstruct the uplift/subsidence history of each island. The resulting uplift reconstructions confirm that both Santiago and São Nicolau experienced a general uplift trend over the last 6 Ma, seemingly synchronous with the vigorous volcanic activity that built their exposed edifices. These islands, however, exhibit different uplift histories despite their common uplift trend. Several uplift mechanisms were tested and a local rather than regional mechanism is proposed as the main cause of uplift, generally unrelated with far-field effects of surface loading. This mechanism is probably associated with magmatic additions at crustal level.

Publication Year 2010
Title Vertical movements of ocean island volcanoes: Insights from a stationary plate environment
DOI 10.1016/j.margeo.2010.04.009
Authors Ricardo Ramalho, George Helffrich, Michael A Cosca, D. Vance, D. Hoffman, Daniela N. Schmidt
Publication Type Article
Publication Subtype Journal Article
Series Title Marine Geology
Index ID 70211110
Record Source USGS Publications Warehouse
USGS Organization Central Mineral and Environmental Resources Science Center; Geology, Geophysics, and Geochemistry Science Center