Figure 5: Geological maps (and stratigraphic column) of the North Atlantic region highlighting the position of DSDP Hole 418A within the context of regional patterns of lithospheric age and seafloor spreading magnetic anomalies. (a) Bathymetry, seafloor spreading magnetic anomalies (pink lines), and fault/fracture zones (green lines) of the southwestern North Atlantic Ocean (after [160, 177]). HAP denotes Hatteras Abyssal Plain. Fracture zones (FZ) include the Atlantis (AFZ), Delaware Bay (DBFZ), Norfolk (NFZ), Kane (KFZ), Carolinas (CFZ), Blake Spur (BSFZ), Jacksonville (JFZ), and 15°20′N FZ. (b) Stratigraphic column for DSDP 418A (after [160162]) showing the locations of basaltic glass pillow margin samples in which classic “tubular” () and “granular” () alteration microtextures have been documented at the glass-palagonite interface in this (black) and previous studies (red). The black dashed line demarcates the top of volcanic basement, and zigzags represent interbedding of lithologic units. The volcanostratigraphic zone in which glass group “J” occurs [161, 162] is denoted in purple (g.g. “J”) and corresponds to a geochemically coherent volcanic (glass) interval from which all three glass samples were collected in this study. Samples a–l from previous studies (shown in red) correspond to a—418A-30-3-[4–6] in Furnes and Staudigel [33] and Furnes et al. [59]; b—418A-43-1-[80–82] in Fliegel et al. [100]; c—418A-49-2-[41–45] in Staudigel et al. [27] and Furnes et al. [59]; d—418A-52-5-[75–80] in Furnes et al. [11] and Furnes et al. [59]; e—418A-55-4-[112–114] in Furnes et al. [11], Staudigel et al. [27], Furnes et al. [59], and Fliegel et al. [100]; f—418A-56-5-[129–132] in McLoughlin et al. [28] and Furnes et al. [59]; g—418A-57-5-[12-13] in Furnes et al. [59]; h—418A-59-3 in Furnes et al. [59]; i—418A-62-4-[64–70] in Furnes et al. [11], Staudigel et al. [27], McLoughlin et al. [28], McLoughlin et al. [31], Furnes et al. [59], and Furnes et al. [61]; j—418A-68-3-[32–38] in Furnes et al. [59]; k—418A-76-1-[4–7] in Furnes et al. [59]; l—418A-86-5-[24–32] in Furnes et al. [59]. (c) Map showing lithospheric age in the North Atlantic Ocean, highlighting the location of DSDP 418A and Chron “M0” on which it lies (after Müller et al. [167]). Tectonic plates: AP: African Plate; EP: Eurasian Plate; NAP: North American Plate. (d) Close-up geological/geophysical map showing the location of DSDP 418A (and other nearby holes) in the context of local patterns of seafloor spreading magnetic anomalies and fracture/fault zones [160, 171]. The age intervals for geomagnetic isochrons M0, M2, and M4 are from Channell et al. [176].