Magmatic-tectonic response of the South China Craton to the Paleo-Pacific subduction during the Triassic: a new viewpoint based on Well NK-1

The Nansha Block (NB) is one of the blocks separated from the southern margin of the South China Craton (SCC) by the western Pacific subduction, which contains rich information of geodynamic and tectonic transformation. To reveal the essence of western Paleo-Pacific subduction during the Triassic period, Well NK-1 in this block was selected for petrographic study, and published research data from other cooperative teams were compared. A double-cycle pattern of basic to neutral magmatic volcanism was established, and 36 lithological rhythmic layers and representative cryptoexplosive breccia facies and welded tuff bands were identified. Combined with a reanalysis of published geochronological data, geochemical elements, and isotope geochemistry, we found that the rock assemblages could be divided into an intermediate-acid dacite (DA) series (SiO 2 >65%) and basaltic (BA) series (Co