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Magmatic Response To Subduction Initiation, Part Ii: Boninites And Related Rocks Of The Izu‐Bonin Arc From Iopd Expedition 352, John W. Shervais, Mark K. Reagan, Marguerite Godard, Julie Prytulak, Jeffrey G. Ryan
Magmatic Response To Subduction Initiation, Part Ii: Boninites And Related Rocks Of The Izu‐Bonin Arc From Iopd Expedition 352, John W. Shervais, Mark K. Reagan, Marguerite Godard, Julie Prytulak, Jeffrey G. Ryan
School of Geosciences Faculty and Staff Publications
International Ocean Discovery Program Expedition 352 to the Izu‐Bonin forearc cored over 800 m of basement comprising boninite and boninite‐series lavas. This is the most extensive, well‐constrained suite of boninite series lavas ever obtained from in situ oceanic crust. The boninites are characterized as high‐silica boninite (HSB), low‐silica boninite (LSB), or basaltic boninite based on their SiO2‐MgO‐TiO2 relations. The principal fractionation products of all three series are high‐Mg andesites (HMA). Lavas recovered >250 meters below seafloor (mbsf) erupted at a forearc spreading axis and are dominated by LSB and HMA. Lavas recovered fromoff‐axis and are dominated by …
Magma Source Evolution Following Subduction Initiation: Evidence From The Element Concentrations, Stable Isotope Ratios, And Water Contents Of Volcanic Glasses From The Bonin Forearc (Iodp Expedition 352), Daniel A. Coulthard, Mark K. Reagan, Kenji Shimizu, Ilya N. Bindeman, Maryjo Brounce, Renat R. Almeev, Jeffrey Ryan, Timothy Chapman, John Shervais, Julian A. Pearce
Magma Source Evolution Following Subduction Initiation: Evidence From The Element Concentrations, Stable Isotope Ratios, And Water Contents Of Volcanic Glasses From The Bonin Forearc (Iodp Expedition 352), Daniel A. Coulthard, Mark K. Reagan, Kenji Shimizu, Ilya N. Bindeman, Maryjo Brounce, Renat R. Almeev, Jeffrey Ryan, Timothy Chapman, John Shervais, Julian A. Pearce
School of Geosciences Faculty and Staff Publications
International Ocean Discovery Program Expedition 352 to the Bonin forearc drilled the sequence of volcanic rocks erupted in the immediate aftermath of subduction initiation along the western margin of the Pacific Plate. Pristine volcanic glasses collected during this expedition were analyzed for major and trace elements, halogens, sulfur, and H and O isotopes with goals of characterizing the fluids and melts of subducted materials that were involved in generating the nascent upper plate crust. Incompatible trace element compositions of the oldest lavas (forearc basalts [FAB]) are similar to those of the most depleted mid‐ocean ridge basalts globally. Most FAB were …
Magmatic Response To Subduction Initiation: Part 1. Fore‐Arc Basalts Of The Izu‐Bonin Arc From Iodp Expedition 352, John W. Shervais, Mark Reagan, Emily Haugen, Renat R. Almeev, Julian A. Pearce, Julie Prytulak, Jeff Ryan
Magmatic Response To Subduction Initiation: Part 1. Fore‐Arc Basalts Of The Izu‐Bonin Arc From Iodp Expedition 352, John W. Shervais, Mark Reagan, Emily Haugen, Renat R. Almeev, Julian A. Pearce, Julie Prytulak, Jeff Ryan
School of Geosciences Faculty and Staff Publications
The Izu‐Bonin‐Mariana (IBM) fore arc preserves igneous rock assemblages that formed during subduction initiation circa 52 Ma. International Ocean Discovery Program (IODP) Expedition 352 cored four sites in the fore arc near the Ogasawara Plateau in order to document the magmatic response to subduction initiation and the physical, petrologic, and chemical stratigraphy of a nascent subduction zone. Two of these sites (U1440 and U1441) are underlain by fore‐arc basalt (FAB). FABs have mid‐ocean ridge basalt (MORB)‐like compositions, however, FAB are consistently lower in the high‐field strength elements (TiO2, P2O5, Zr) and Ni compared to MORB, with Na2O at the low …