In March 2022, we conducted a fieldwork at the islands of San Benedicto and Socorro, two volcanoes of the Revillagigedo Archipelago that is located ~500 km west of the Mexian mainland. These are active volcanoes that have formed since the Pleistocene on a mid-oceanic ridge that has been extinct for about 2 million years. I assembled a team of 10 outstanding geologists to turn these islands inside out. The primary idea – the source of the funding – was to test the longevity of former mantle wedges, which form above subduction zones, after subduction stops. At a depth of 1500 km in the lower mantle below the Revillagigedo Islands, a slab is located that sudbucted 180 million years ago, during which time an arc formed that we believe is the Bonanza Arc of Vancouver Island. We have sampled sandstones from the Bonanza arc to test what the signature of zircons is that were transported to the trench at that time, and we sampled volcanic rocks and river and beach sands of Socorro and San Benedicto to test whether the geochemical subduction signature and the zircon signature are still detectable. If so, we obtain a surprising, and important constraint on the rate of upper mantle convection. In addition, we took samples for, and studied the explosiveness of the eruptions for volcanic and tsunami hazard assessment, as well as to study the intensity of the Earth’s magnetic field. Below you will find a picture impression of the most amazing fieldwork I have done to date – the people, the scenery, the activities, and the amazing wildlife.
The team: Janne Koornneef, isotope geochemist and associate professor at the VU University of Amsterdam, the NetherlandsYamirka Rojas-Agramonte, geochronolist and zircon specialist at the University of Kiel, Germany
Pablo Davila-Harris, a volcanologist from the Instituto Potosino de Investigación Científica y Tecnológica, San Luis, Mexico
Romy Meyer, PhD student in paleomagnetism at Utrecht University
Christian Winter, coastal geologist and beach specialist, Kiel University, Germany
Mélody Philippon, tectonicist, associate professor at the University of the Antilles at Guadeloupe
Pete Lippert, paleomagnetist and associate professor at the University of Utah at Salt Lake City, USARoberto Hassán Téllez Vizcaíno, volcanologist and prospective PhD student from Colima, MexicoLaurens Tromp. MSc student in isotope geochemistry, VU University, the Netherlands…and meWe did fieldwork using the ship the Quino el Guarian, on which we slept and ate with an amazing crew.The Quino was equipped with two dingies that we used for beach landingsThe Quino with the dingies, ready to go to shoreReady for a field day!And off we goApproaching Socorro’s Playa NortePablo, Janne, Romy, and Roberto, looking forward to some ignimbrites and basaltsMélo, arriving after some recon
Beach landing on Playa Norte, Socorro. Well, beach…mostly us standing up to our chin in the waves.
We had four targets during fieldwork: Janne and Laurens were hunting for olvine basalts to constrain the geochemistry of the mantle below the islands…Yamirka was huntng for zircons on beaches and in rivers, together with Christian. Here, she’s washing those samples with Mélo on the back of the boat, to get the heavy mineral fraction
Yami, panning on Playa Blanco, Socorro
San Benedicto volcano, with a major ash cone that formed in 1952
Pablo and Roberto, sampling ashes and obsidian
Roberto, hiking on San BenedictoThrough the edge of San Benedicto burst a basaltic lava that formed a lava deltaRomy, hiking the lava delta…which is not easy to walk with a blocky lavaRomy and Mélo, samping for paleomag in the San Benedicto lava deltaMélo on the lava deltaLaurens, Mélo and the rest of the team, on SocorroYami, having some fun in the fieldHiking northern SocorroThe team, happy to have the first landing on San Benedicto!Geologist hunting for olivineDiscussion on Playa NorteFumaroles at the top of Mt Evermann volcano, SocorroCrystalline sulphur at the fumarolesBoiling mud!Fumaroles and happy geologistsJanne, studying basaltsOn to the next landing!Back at the boat, discussing the field resultsA blocky lava flow from the Pleistocene, SocorroRpmy and Pete, cleaning up the – by now inevitable – plastic debris on Playa Norte, SocorroPete, finding plastic bottles that came all the way from AsiaRomy and Mélo, drillingReady for a next field day!Roberto, studying rocks in the fieldPete and Romy, on their way back from the field in SocorroPete, Romy, and me, having some fun in the fieldJanne, Roberto, and Pablo on the rocksView of Socorro’s west coastYami and Mélo, discussing on Playa NortePete, Mélo, and me, at the truck of the Mexican navy – they helped us tremendously in reaching our desired sampling locations!Mélo, hiking SocorroJanne, in her comfort zone
Janne and Pablo, after landing on Paya Norte
Janne, searching for olivineLaurens and Janne with the results of their hunts
Me, sampling sand for Yami
In the back of the navy truck!Sampling in the gulliesArch next to Playa Blanca, Socorro
Roberto, pointing at beautiful ignimbrites!
Mélo and Romy with the local taxi on SocorroJanne, om the move between the turtle tracksYamirka on Playa BlancaSocorro and San Benedicto have a beautiful wildlife, mostly endemic. This is the Socorro wrenSocorro Tropical ParulaSocorro TowheeSocorro Red-Tailed HawkSocorro ParakeetSocorro MockinbirdSocorro landcrabSocorro Blue LizardSan Benedicto has colonies of seabirds. It is a breeding place for the Laysan Albatross!Laysan Albatross chicks!Magnificent FrigateBrown boobyBrown boobies on the boatMasked boobiesGreat FrigateTurtle tracks, on their way to and from their nestsRemains of a turtleThis little fella didn’t make itFlying fishLanded fishManta ray!Silky shark behind the boatHumpback whales!Every day, within a few hundred yards from the boat, the humpbacks were playing. Mother and calfOn their way down……and up!Bottlenose dolphins, behind the boat!Romy, mesmerizing ainthe sunsetThis was the best fieldtrip ever……and I wanna go back!…but if this worked, the future is bright!
