Coastal Boulder Deposits of the Neogene World: A Synopsis

Dmitry A Ruban

doi:10.3390/jmse7120446

Abstract

Modern geoscience research pays significant attention to Quaternary coastal boulder deposits, although the evidence from the earlier geologic periods can be of great importance. The undertaken compilation of the literature permits to indicate 21 articles devoted to such deposits of Neogene age. These are chiefly case studies. Such an insufficiency of investigations may be linked to poor preservation potential of coastal boulder deposits and methodological difficulties. Equal attention has been paid by geoscientists to Miocene and Pliocene deposits. Taking into account the much shorter duration of the Pliocene, an overemphasis of boulders of this age becomes evident. Hypothetically, this can be explained by more favorable conditions for boulder formation, including a larger number of hurricanes due to the Pliocene warming. Geographically, the studies of the Neogene coastal boulder deposits have been undertaken in different parts of the world, but generally in those locations where rocky shores occur nowadays. The relevance of these deposits to storms and tsunamis, rocky shores and deltas, gravity processes, and volcanism has been discussed; however, some other mechanisms of boulder production, transportation, and accumulation (e.g., linked to seismicity and weathering) have been missed.

Highlights

Modern marine sedimentology grows rapidly, and new research directions have strengthened in the past two decades
Boulders are regarded as precious evidence of present and ancient rocky shore facies and extreme events
The devastating catastrophes like the 2004 Indian Ocean tsunami [34] and the 2011 Tohoku tsunami [35] have fueled the interest of researchers in coastal sedimentology and, large clasts [36]

Summary

Introduction

Modern marine sedimentology grows rapidly, and new research directions have strengthened in the past two decades. An ancient coastal boulder-bearing deposit may be legacy of the really existed boulder-dominated deposit Until these problems are resolved and the nomenclature of large-clast deposits is fixed, it is possible to apply the general term “coastal boulder deposit” broadly, but preferably in those cases when boulders tend to concentrate. The both modern and ancient deposits of this type are called as boulderites [41] It is the right of the noted authors to use it so, one may question whether the term “boulderite” can be used for only ancient boulder-dominated deposits, i.e., sedimentary rocks, not recent sediments

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Further Inferences