Marchena

This is my only picture of Marchena: me in the foreground (beside marijuana-looking bush). Caldera in background. Hill is a kipuka of palagonite tuff surrounded by caldera-filling eruptions.

Marchena is a wonderful volcano, with a large caldera, prominent pyroclastic deposits, and an eruption in 1991. Unfortunately, it has no public landing site and is truly a wilderness island. Ed Vicenzi did a great M.S. thesis on the island and condensed that into a paper:

Vicenzi EP, McBirney AR, White WM, Hamilton M (1990) The geology and geochemistry of Isla Marchena, Gal·pagos Archipeligo: an ocean island adjacent to a mid-ocean ridge. J Volcanol Geotherm Res 40: 291-315
McBirney AR, Williams H (1969) Geology and petrology of the Gal·pagos Islands. Geol Soc Am Mem 118, pp 1-197.

Here is his geologic map of the island.

Check out the excellent analyses from Marchena - OR-

Download an Excel file of geochemical data.

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