Site U1565

Abstract

Contents 1 Background and objectives 3 Operations 5 Lithostratigraphy 9 Biostratigraphy 12 Paleomagnetism 17 Geochemistry 21 Physical properties 24 References

Site U1566

“…The liner correction of 66/58 = 1.138 should be applied to the WRMSL GRA bulk densities (see Physical properties in the Expedition 396 methods chapter [Planke et al, 2023a]). The value of the liner correction was confirmed for the granitic cores recovered at Site U1565 (see Physical properties in the Site U1565 chapter [Planke et al, 2023b]).…”

“…Site U1566 is a companion site to Site U1565. Both sites are located on the western flank of the Kolga High (see Figure F1 in the Site U1565 chapter [Planke et al, 2023b]) about 1 km apart at a water depth just above 2000 m. The Kolga High is one of several areas along the rifted margin characterized by a thin sediment cover above the top basalt surface and a rapidly westward shoaling of the Base Cretaceous Unconformity (BCU) (Zastrozhnov et al, 2020) (for a summary, see Background and objectives in the Site U1565 chapter [Planke et al, 2023b]).…”

“…The primary objective of Site U1566 was to sample the lowermost part of the SDR on the Kolga High (see Figure F3 in the Site U1565 chapter [Planke et al, 2023b]). If possible, we would also try to drill through the entire basalt sequence, but this was not a key target because the primary target of the nearby Site U1565 was to recover the subbasalt units.…”

“…Although Site U1566 was placed only 1 km away from Site U1565, the seismic data are inconclusive about the dip of the basal surface of the lava pile and hence the depth to this interface. Although high-resolution seismic data (see Figure F3 in the Site U1565 chapter [Planke et al, 2023b]) may indicate that this base basalt is as shallow as 200 meters below seafloor (mbsf ) (depending on the choice of seismic velocity), 3-D exploration seismic data suggest that the basal surface may be as deep as 400 mbsf and out of reach of the planned 200 m hole.…”

Understanding volcanic margin evolution through the lens of Norway's youngest granite

“…Pre‐drilling seismic interpretation suggested that the volcanic rocks might be retained on top of thick Cretaceous‐Palaeocene sedimentary layers (Gernigon et al., 2021; Manton et al., 2018; Millett et al., 2022; Zastrozhnov et al., 2020). The IODP Expedition 396 revealed, however, the unexpected presence of altered granitic ‘basement rocks’ beneath Quaternary sediments in Holes U1565A/B and beneath older basaltic cover in Hole U1566A (Figure 1) (Planke et al., 2023a, 2023b).…”