Modern and ancient hiatuses in the pelagic caps of Pacific guyots and seamounts and internal tides

Abstract

Incidences of nondeposition or erosion at the modern seabed and hiatuses within the pelagic caps of guyots and seamounts are evaluated along with paleotemperature and physiographic information to speculate on the character of late Cenozoic internal tidal waves in the upper Pacific Ocean. Drill-core and seismic reflection data are used to classify sediment at the drill sites as having been accumulating or eroding or not being deposited in the recent geological past. When those classified sites are compared against predictions of a numerical model of the modern internal tidal wave field (Simmons, 2008), the sites accumulating particles over the past few million years are found to be away from beams of the modeled internal tide, while those that have not been accumulating are in internal tide beams. Given the correspondence to the modern internal wave field, we examine whether internal tides can explain ancient hiatuses at the drill sites. For example, late Cenozoic pelagic caps on guyots among the Marshall Islands contain two hiatuses of broadly similar age, but the dates of the first pelagic sediments deposited following each hiatus do not correlate between guyots, suggesting that they originate not from ocean chemical changes, but from physical processes, such as erosion by internal tidal waves. We investigate how changing conditions such as ocean temperature and basin physiography may have affected internal tides through the Cenozoic. Allowing for subsequent rotation or uplift by plate tectonics, ancient submarine ridges among the Solomon, Bonin, and Mariana island chains may have been responsible for some sediment hiatuses at these distant guyot sites.

Stratigraphic evolution and karstification of a Cretaceous Mid‐Pacific atoll (Resolution Guyot) resolved from core‐log‐seismic integration and comparison with modern and ancient analogues

“…The very high amplitude of SF1 could be explained by the underlying iron‐manganese encrusted limestone (lithostratigraphic Unit II; Figure 2) representing a drowning succession similar to those identified by Eberli et al (2010) on the Marion Plateau. Similar seismic facies was described by Mitchell et al (2015) in other Pacific guyots.…”

Observed Deep Anticyclonic Cap Over Caiwei Guyot

“…When the ocean flow impinges on a seamount, a series of complex dynamic responses are generated that modulate local and large‐scale circulation (Lavelle & Mohn, 2010; Perfect et al, 2018, 2020a, 2020b; Robertson et al, 2017; White & Mohn, 2004). These dynamic processes around the seamount also contribute to local biological and geological distribution (Boehlert & Genin, 1987; Genin, 2004; Mitchell et al, 2015; Stashchuk et al, 2018; Vlasenko et al, 2018; White & Mohn, 2004; White et al, 2007). Hence, local circulation induced by the seamount topography is important to the energy and material exchanges in the deep ocean.…”

Wave‐influenced deposition of carbonate‐rich sediment on the insular shelf of Santa Maria Island, Azores

“…Sandy clinoforms could be used to reconstruct the palaeo‐hydrodynamic conditions and processes in the geological record at positions where waves in the past are difficult to assess (Mitchell et al ., 2015). For example, the boomer data in Fig.…”