Reply

The South Anyui suture zone (SASZ) is a key tectonic boundary for paleo­geographic reconstructions of the Arctic region prior to the opening of the Amerasia basin. Sokolov et al. (2009, p. 201) noted that “many aspects of the geological setup of the [South Anyui suture] remain poorly understood and there are dissenting viewpoints on the following issues”, and then listed the following: the location of the boundaries of the SASZ, the origin and age of the oceanic basin, its tectonic history, and the timing of the onset and termination of collision. Thus, it is not surprising that workers in this remote area with poor exposure (Fig. 1) will come to differing conclusions about the significance of the rocks and structures of the region.

It has been difficult for geologists outside of Russia to understand the geol­ogy of the SASZ because of the limited availability of published material in English. Some data referred to by Sokolov (2017) in his Comment on our paper (Amato et al., 2015) remain unpublished in the form of a Ph.D. thesis at the University of Moscow (Bondarenko, 2004). Dr. Sokolov has been publishing for years on the geology of the region (e.g., Sokolov et al., 2002, 2009, 2015), but many questions remain concerning the geology of the region.

Our paper (Amato et al., 2015) had the following goals: (1) to provide a concise overview of this geologically complex region highlighting the known versus speculative aspects of existing models, relying on easily obtained published works; (2) to publish new data on the depositional age and provenance of key sedimentary units using detrital zircon ages, sedimentology, and point-counting data from sandstones; (3) to publish new data on the ages of igneous rocks in the SASZ, as well as from volcaniclastic rocks that help establish the age of volcanism; (4) to evaluate structural relationships, a challenge given the poor outcrop (particularly of major faults) and locally intense deformation; (5) to interpret a seismic reflection line that passes through the field area; and (6) to present a tectonic model that incorporates our new data, existing published data, and a GPlates (www.gplates.org) animation. We have never claimed to have resolved all of the SASZ controversies and appreciate that Sokolov (2017) has highlighted some remaining uncertainties. We would like to point out that we all are interested in reaching a better understanding of this complex area that is an important piece of the tectonic puzzle in the Arctic region. Below we respond to the some of his major concerns and highlight existing problems in the region that can be evaluated with additional data.