Abstract

With respect to weathering, erosional processes, and sediment transport, quartz is one of the most stable minerals and makes up to 98% of the mineral volume of siliciclastic sands (Pettijohn et al. 1987). Although a major component in a wide variety of rocks, quartz has almost no characteristic properties that allow determining parent rock types. Quartz does not contain characteristic cleavage planes, and quartz grains react to impact or collision with other sediment particles by producing conchoidal fractures very similar to those observed for broken glass. For sedimentologists, physical geographers, and soil scientists, detrital quartz grains are poor in characteristic features except for a suite of surface features that may be indicative of various transport environments or even climate-related alterations. One of these surface features are chattermark trails.

Chattermark trails are a series of linearly arranged, rune-like grooves on surfaces of minerals grains, such as quartz and garnet, lacking any type of cleavage. These trails have been described from many unconsolidated sediments and are attributed mostly to glacial sediments. Laboratory experiments on polished quartz beads reveal that chattermark trails are not primary surface features, but become visible after etching by dilute hydrofluoric acid. Comparison of the etched and non-etched surface of the same quartz bead reveals that mechanically produced invisible cracks, related to blunt collisions with other polished quartz beads, became visible only after chemical etching. Chattermark trails on detrital quartz grains are the product of two processes: the dynamic one is an invisible, transport-related blunt collision, followed by a second, stationary process, which enables quartz dissolution to make the chattermarks visible. In the broad field of laterite research it is well accepted that quartz dissolution in surface or near-surface deposits is restricted to stationary chemical weathering in a wet tropical or at least subtropical climate. Drawing on this information, chattermark trails are no longer considered a product of a specific sedimentary environment, but reveal a distinct history of the quartz grain: they are formed by blunt collisions in a sediment transport stage before experiencing some dissolution during a depositional stage in a tropical climate. Grains can be remobilized in an active sediment transport system. Collectively, the results reveal that chattermark trails on quartz grains provide unique insights into the transport and climate history of sediments.

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