Integrated calcareous nannofossils and planktonic foraminifera biostratigraphy as tool to date serpentinite mud production for Fantangisña seamount on the Mariana forearc (IODP Expedition 366)
Del Gaudio, Arianna V.; Piller, Werner E.; Auer, Gerald; Kurz, Walter
Newsletters on Stratigraphy Volume 55 Number 3 (2022), p. 255 - 284
veröffentlicht: Jun 15, 2022
Online veröffentlicht: Nov 19, 2021
Manuskript akzeptiert: Aug 31, 2021
finale Ms. Revision erhalten: Aug 2, 2021
Manuskript-Revision angefordert: Mar 22, 2021
Manuskript erhalten: Jan 29, 2021
Open Access (Arbeit kann kostenlos heruntergeladen werden)
Abstract
The Izu-Bonin-Mariana (IBM) arc-system, located in the NW Pacific (12° N to 35° N), represents one of the most intensively studied convergent margins as it is so far the only known setting of recently active serpentinite mud volcanism. Its formation started at around 50–52 Ma and is linked to the subduction of the Pacific plate underneath the eastern Eurasian Margin and Philippine Plate. On the southern segment of the IBM (the Mariana forearc system), several large and active serpentinite mud volcanoes originated when serpentinite mud and fluids along with materials from the upper mantle, the Philippine and the Pacific plates arise episodically to the sea floor through a series of faults and extrude, forming the seamount edifices. International Ocean Discovery Program (IODP) Expedition 366 cored three serpentinite mud volcanoes at increasing distances from the Mariana trench subduction zone: Yinazao (Blue Moon), Fantangisña (Celestial), and Asùt Tesoru (Big Blue). Recovered material includes serpentinite mud with lithic clasts derived from the slab as well as from the forearc mantle and the overriding plate. Furthermore, lithologies at all sites include a pelagic cover and nannofossil rich volcanic forearc deposits overlying and underlying the serpentinite mud flows, respectively. In our study, integrated calcareous nannofossils and planktonic foraminifera biostratigraphy was conducted on Site U1497, drilled on top of Fantangisña serpentinite mud volcano and Site U1498 cored on its southern flank. Selected bioevents allow to construct a reliable age-depth model for Site U1498A as well as to provide valuable information on the latest phase of the seamount activity in the Mariana region. Specifically, the onset of the latest stage of the serpentinite mud production was recorded between 6.10 Ma (late Miocene, Messinian) and 4.20 Ma (early Pliocene, Zanclean) as indicated by the LO of Reticulofenestra rotaria and the FO of Discoaster asymmetricus, respectively. This time interval is approximately 4 Ma younger than the previously proposed age of 10.77 Ma. The emplacement of the serpentinite mud production has been found to concur with the inception of the rifting in the Mariana Trough dated at 7–6 Ma. An abrupt change in the sedimentation rates (11.80 to 94.71 m/Myr) between different mud deposits was later observed in the Middle Pleistocene, possibly related to regionally occurring tectonic processes (variation of forearc extension due to the slab rollback and/or phases of seamount accretion and subduction).
Schlagworte
biostratigraphy • age-depth model • calcareous nannofossils • planktonic foraminifera • serpentinite mud volcanism • northwestern Pacific Ocean