Magmatic plumbing system through shallow sills characterization in a sector of Guaymas rift basin, Gulf of California

We interpret eleven two-dimensional multichannel seismic reflection profiles across the Northern Trough of the Guaymas Basin, grouped into three sectors: north, intermediate, and south. Using seismic facies and geometry, we map and correlate sills across adjacent seismic profiles. Three intrusion series are defined in the north and intermediate sectors (deep, middle, and shallow), and a 3D visualization derived from the 2D interpretations is used to illustrate spatial distribution and emplacement trends. In the north sector, located toward the northwest, deep sills redistribute magma upward into the shallow series, together with intrusive series that enter from the northeast and are interpreted to be associated with the Guaymas Transform Fault. Emplacement steps upward and propagates toward the southwest, and there is an increase in shallow-series emplacement along the northwest–southeast direction toward the axial trough, although coverage limits prevent tracking this trend farther. In the intermediate sector, southeast of Isla Tortuga, two intrusive series converge from opposite directions: one from the northeast margin, likely related to the transform system, and one from the southwest, likely from the Isla Tortuga side. Petrographic inspection and whole-rock geochemistry of IODP Expedition 385 sills from Guaymas basin, compared with Isla Tortuga lavas, reveal comparable inherited anomalies consistent with an arc-derived parental magma, suggesting that the island and basin sills may be connected in the subsurface by a common plumbing system. Along the axial system, long complexes of shallow intrusions are more common toward the northwest, whereas deeper and larger intrusions occur toward the southeast. This contrast matches sector-scale differences in sediment delivery, with thicker terrigenous input favoring deeper emplacement, and thinner cover favoring shallower levels. Finally, the close spacing of profiles in the north sector enabled sill correlation and definition of a coherent, stepped emplacement pattern; in the intermediate sector, the shorter lateral extent of individual bodies limited correlation across adjacent 2D profiles, but the emplacement trend could still be tracked, clarifying the magmatic plumbing architecture of the Northern Trough. • Spatial pattern of sill intrusions along the northern Guaymas Basin spreading axis from seismic reflection data. • Magmatic plumbing system in the northern spreading axis constrained by 2D interpretations and 3D visualization. • Differences in sill geometry, width, and emplacement depth between the NW and SE portions of the northern trough. • Relative chronology of sill emplacement across the northern spreading axis