Deep-Sea Deposits in But Not on the Continents

Abstract

The early principle of geology that deep-sea deposits do not occur on continents has been seriously challenged by both paleontologists and marine geologists. So, in turn, has the dependent Doctrine of Vertical Permanency, according to which elevator tectonics with relative changes between ocean basin and continental levels do not take place. (Other aspects of permanency, such as permanency of continents in position as opposed to drift, or of their areal plan as opposed to accretion, are independent questions.) The writers agree with those who ascribe a deep-sea (>2,000 meters) environment to radiolarian cherts, graptolite shales, and graywackes. Recognition of the role of turbidity-current emplacement has altered the interpretation of much of the evidence for these lithofacies being shallow-water beds, e.g., sandstone layers, current ripples, neritic faunal remains, and plants. From a world-wide review of the well-known localities, the writers find, however, that such hemipelagic deep-water deposits are confined uniquely to the eugeosynclinal facies. It is suggested that this facies is deposited originally at the base of the continental slope as a continental-rise prism; hence, it is ensimatic rather than ensialic as are other marine deposits found on continents. Subsequently, landward t rusting causes continental accretion and orogeny. The collapsed eugeosynclinal prism thus becomes a part of the deep continental fabric. The incorporated deep-sea sediment may be considered conveniently as being in the continent. By this proposed process, the Doctrine of Vertical Permanency is sustained even though deep-sea deposits do bulk large in eugeosynclinal flysch.