The relationship between depth and age and heat flow and age in the western North Atlantic

Abstract

There are two simple models, compatible with the theory of plate tectonics, that can account for the observed relations between depth and age and between heat flow and age for oceanic crust. The first is the cooling plate model (Langseth and others, 1966; McKenzie, 1967; Sclater and others, 1971), which has been best matched to the depth and heat flow observations by Parsons and Sclater (1977). The second is that of a growing boundary layer (Turcotte and Oxburgh, 1967; Parker and Oldenburg, 1973) that has been matched to the depth and heat flow data by Davis and Lister (1974) and Lister (1977). Both models give good agreement with observations in the range 0–80 Ma. At greater ages the observations of average depth and mean heat flow are best matched by the plate model. The models are similar in that thermal cooling is the dominant mechanism. The difference between them results from concentrating on two different aspects of the observations. In the plate model, emphasis is placed on matching the exponential decay of heat flow and depth at older ages, whereas the boundary layer model was developed to explain the relation between subsidence and the square root of time on young ocean floor. Though the predictions of the plate model best match the average observations there is a problem with this model in that the constant temperature bottom boundary condition is physically unrealistic. Parsons and McKenzie (1978) have reconciled the two models and also developed

The geological record of oceanic crustal accretion and tectonism at slow-spreading ridges

“…The crest of the rift mountains represents the maximum elevation (-2000 m) of the ridge at -15 to 35 km off-axis (-1.5-3.5 m.y.). From there, crust progressively deepens with age, following a square-root of age relationship predicted by plate cooling models (Parsons and Sclater, 1977;Sclater and Wixon, 1986).…”

“…Crust older than the crests of the rift mountains is considered to be the ridge flank and deepens by following a square-root-of-age relation (cf. Sclater and Wixon, 1986).…”

“…Older seafloor is considered to be the "ridge flank" , and it progressively deepens with age, roughly following a squareroot-of-age relation (cf. Sclater and Wixon, 1986). The detailed fault analysis in Chapter 3…”

Origin of the Bermuda volcanoes and the Bermuda Rise: History, observations, models, and puzzles

“…1700-2000 km, from about 25-27º N to 37-38º N (Figs. 9 and 10 of Sclater and Wixon, 1986). The depth anomaly is somewhat asymmetrical in transverse section, with steeper southeastern vs. northwestern slopes.…”

“…Of the many plumes that have been postulated, Bermuda, although throughout the last 30 years appearing in most "hotspot catalogues" (Steinberger (2000) is a rare exception), rates practically at the bottom in terms of consistency with the deep mantle plume hypothesis (e.g., Anderson and Schramm, 2005;Courtillot et al, 2003). Is the Bermuda Rise an expression of thermal expansion of hot underlying mantle, low density materials intruded into the plate, a low density buoyant root of partial melt residue, dynamic uplift maintained by convection, or some combination (e.g., Sclater and Wixon, 1986;Detrick et al, 1986;Louden et al, 1987;Sheehan and McNutt, 1989;Sleep, 1990;? There are troubling inconsistencies between data and any of these mechanisms, and even problems with the data themselves, specifically heat flow measured from shallow penetration deep-sea probes (e.g., Ruppel, 1996;.…”