Sand spikes pinpoint powerful palaeoseismicity

Elmar Buchner,Volker J Sach,Martin Schmieder

doi:10.1038/s41467-021-27061-6

Elmar Buchner, Volker J Sach + Show 1 more

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https://doi.org/10.1038/s41467-021-27061-6

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Journal: Nature Communications	Publication Date: Nov 18, 2021
Citations: 2	License type: open-access

Affiliation: Neu Ulm University of Applied Sciences

Abstract

Sand spikes, pin-shaped, carbonate-cemented sandstone bodies of variable size widely interpreted as sedimentary concretions, have been enigmatic for nearly two centuries. We here present a high-energy mechanism for their formation. Two classic sand spike occurrences are found in the North Alpine Foreland Basin of Central Europe and at Mount Signal in southern California, USA. A distinct seismite horizon in Mid-Miocene Molasse sediments of southern Germany, genetically linked with the Ries impact event, exhibits dewatering structures and contains numerous sand spikes with tails systematically orientated away from the Ries crater. Sand spikes at Mount Signal, strikingly similar in shape to those found in Germany, have tails that point away from the nearby San Andreas Fault. Based on their structural and stratigraphic context, we interpret sand spikes as a new type of seismite and a promising tool to identify strong impact-induced or tectonic palaeo-earthquakes and their source regions in the geologic record.

Highlights

Sand spikes, pin-shaped, carbonate-cemented sandstone bodies of variable size widely interpreted as sedimentary concretions, have been enigmatic for nearly two centuries
The NAFB and Mount Signal sand spikes are strikingly similar in their appearance, structure, composition, and internal texture[1,2,3,4,5,6,7,8,9]
Sand spikes are found in the area around Ravensburg[15,16,24], in ravines and gullies in the Hochgeländ plateau[15,16], at Ochsenhausen near Biberach an der Riss

Summary

Introduction

Pin-shaped, carbonate-cemented sandstone bodies of variable size widely interpreted as sedimentary concretions, have been enigmatic for nearly two centuries. Fine-grained and internally featureless sand- and siltstone bodies of irregular shape, similar in appearance to sand spikes in the NAFB and their associated dikes and sills, are found, e.g., in the Paraná Basin of Brazil, where widespread seismites were linked to the large Permotriassic Araguainha impact[11].

Results

Conclusion