Detrital zircon multi‐chronology, provenance, and low‐grade metamorphism of the <scp>C</scp>retaceous <scp>S</scp>himanto accretionary complex, eastern <scp>S</scp>hikoku, <scp>S</scp>outhwest <scp>J</scp>apan: <scp>T</scp>ectonic evolution in response to igneous activity within a subduction zone

<jats:title>Abstract</jats:title><jats:p>Detrital zircon multi‐chronology combined with provenance and low‐grade metamorphism analyses enables the reinterpretation of the tectonic evolution of the <jats:styled-content style="fixed-case">C</jats:styled-content>retaceous <jats:styled-content style="fixed-case">S</jats:styled-content>himanto accretionary complex in <jats:styled-content style="fixed-case">S</jats:styled-content>outhwest <jats:styled-content style="fixed-case">J</jats:styled-content>apan. Detrital zircon <jats:styled-content style="fixed-case">U</jats:styled-content>–<jats:styled-content style="fixed-case">P</jats:styled-content>b ages and provenance analysis defines the depositional age of trench‐fill turbidites associated with igneous activity in provenance. Periods of low igneous activity are recorded by youngest single grain zircon <jats:styled-content style="fixed-case">U</jats:styled-content>–<jats:styled-content style="fixed-case">P</jats:styled-content>b ages (<jats:styled-content style="fixed-case">YSG</jats:styled-content>) that approximate or are older than the depositional ages obtained from radiolarian fossil‐bearing mudstone. Periods of intensive igneous activity recorded by youngest cluster <jats:styled-content style="fixed-case">U</jats:styled-content>–<jats:styled-content style="fixed-case">P</jats:styled-content>b ages (<jats:styled-content style="fixed-case">YC</jats:styled-content>1σ) that correspond to the younger limits of radiolarian ages. The <jats:styled-content style="fixed-case">YC</jats:styled-content>1σ <jats:styled-content style="fixed-case">U</jats:styled-content>–<jats:styled-content style="fixed-case">P</jats:styled-content>b ages obtained from sandstones within mélange units provide more accurate younger depositional ages than radiolarian ages derived from mudstone. Determining true depositional ages requires a combination of fossil data, detrital zircon ages, and provenance information. Fission‐track ages using zircons estimated <jats:styled-content style="fixed-case">YC</jats:styled-content>1σ <jats:styled-content style="fixed-case">U</jats:styled-content>–<jats:styled-content style="fixed-case">P</jats:styled-content>b ages are useful for assessing depositional and annealing ages for the low‐grade metamorphosed accretionary complex. These new dating presented here indicates the following tectonic history of the accretionary wedge. Evolution of the <jats:styled-content style="fixed-case">S</jats:styled-content>himanto accretionary complex from the <jats:styled-content style="fixed-case">A</jats:styled-content>lbian to the <jats:styled-content style="fixed-case">T</jats:styled-content>uronian was caused by the subduction of the <jats:styled-content style="fixed-case">I</jats:styled-content>zanagi plate, a process that supplied sediments via the erosion of <jats:styled-content style="fixed-case">P</jats:styled-content>ermian and <jats:styled-content style="fixed-case">T</jats:styled-content>riassic to <jats:styled-content style="fixed-case">E</jats:styled-content>arly <jats:styled-content style="fixed-case">J</jats:styled-content>urassic <jats:styled-content style="fixed-case">g</jats:styled-content>ranitic rocks and the eruption of minor amounts of <jats:styled-content style="fixed-case">E</jats:styled-content>arly <jats:styled-content style="fixed-case">C</jats:styled-content>retaceous intermediate volcanic rocks. The complex subsequently underwent intensive igneous activity from the <jats:styled-content style="fixed-case">C</jats:styled-content>oniacian to the early <jats:styled-content style="fixed-case">P</jats:styled-content>aleocene as a result of the subduction of a hot and young oceanic slab, such as the <jats:styled-content style="fixed-case">K</jats:styled-content>ula–<jats:styled-content style="fixed-case">P</jats:styled-content>acific plate. Finally, the major out‐of‐sequence thrusts of the <jats:styled-content style="fixed-case">F</jats:styled-content>ukase <jats:styled-content style="fixed-case">F</jats:styled-content>ault and the <jats:styled-content style="fixed-case">A</jats:styled-content>ki <jats:styled-content style="fixed-case">T</jats:styled-content>ectonic <jats:styled-content style="fixed-case">L</jats:styled-content>ine formed after the middle <jats:styled-content style="fixed-case">E</jats:styled-content>ocene, and this reactivation of the <jats:styled-content style="fixed-case">S</jats:styled-content>himanto accretionary complex as a result of the subduction of the <jats:styled-content style="fixed-case">P</jats:styled-content>acific plate.</jats:p>