Reply to: Frisch and Dawes (DOI 10.1007/s00531-013-0980-7) discussion on The rotations opening the Central and Northern Atlantic Ocean: compilation, drift lines, and flow lines (DOI 10.1007/s00531-012-0860-6)
Greenland and Ellesmere Island across the Nares Strait based on the field data. As a proof of the “mismatch” resulting from the assumption of a transform fault (fig. 1a), they insert in our paleographic map (fig. 9, situation before 175 Ma) the recent geologic boundaries according to the map of Dawes (2009, see fig. 1b). We will discuss the arguments for and against the transform fault. Frisch and Dawes consider our paper as a “laboratorybased tectonic model with scant regard for the geology in the field.” They disregard that the oceanic magnetic anomalies (figs. 1–4), on which our reconstructions of the flow lines and drift lines rest, are field data though of different type. In addition, we constantly controlled the feasibility of our reconstructions on geological maps (in this region, chiefly on the “Geological Map of the Arctic 1:5,000,000” of Harrison et al. (2008, as shown in Fig. 2). We start with the analysis of the drift lines in Fig. 1. Their course exhibits three segments of time: the third and youngest segment shows the rotation between anomaly C 13–C 24 (33.27–52.65 Ma). This segment is well based by magnetic anomalies from the North Atlantic and the labrador Sea (see figs. 1–4 or the map of Asch 2007). The Eocene convergence between Greenland on the SE side of the northern Nares Strait and the opposite situated part of Ellesmere Island is calculated from these data. This part of Ellesmere Island moved together with the North American plate at this time. The direction of the movement was about NW–SE. The outcome is the Eocene fold-and-thrust belt (Eurekan orogeny). The localization of this contraction in the region from the NW margin of the Nares Strait to the northernmost Ellesmere Island is not possible using our method. For this reason, we follow lawver et al. (1990) and distribute the contraction schematically on three well-known thrust groups. The southernmost is the “Judge Daly Fault System Remark for distinguishing different figures of the same name: we call a figure in our original paper and in papers of other authors a “fig,” in the discussion of Frisch and Dawes a “fig” (italic), and in this reply a “Fig” (capital). Greiner and Neugebauer (2013) consider Greenland as an independent plate (microplate) separated from the North American plate in the southwest by the labrador Sea/Baffin Bay and from the Ellesmere Island in the northwest by the Nares Strait. The labrador Sea is to a large extent underlain by oceanic crust, the Baffin Bay by extended continental crust and serpentinitic mantel, oceanic crust is also considered as possible (Harrison 2006). The Nares Strait is seen as a transform fault formed by the separation of the microplate. This interpretation is the view of many earth scientists since Wegener (1915) or Wilson (1965) and has been disputed since these authors. The amount of the rotation of the Greenland plate is calculated from the magnetic anomalies of the contiguous oceanic regions in the North Atlantic and in the labrador Sea (Srivastava and Tapscott 1986; Roest and Srivastava 1989; Srivastava and Roest 1999, see Table 1 in our paper). We illustrate the movements by drift lines (examples: Fig. 1). Frisch and Dawes doubt the existence of a transform fault in the Nares Strait following Dawes and Kerr (1982). The authors assume a continuity of the geologic units of