Polyphase Magmatism During the Formation of the Northern East Greenland Continental Margin

D Franke,P Klitzke,M Thorwart,M Schnabel,W Geissler,T Funck,Per Trinhammer,U Barckhausen,V Damm,C Berndt,M Engels,K Berglar,A Dannowski,A Ehrhardt

doi:10.1029/2019tc005552

Abstract

AbstractNew marine geophysical data acquired across the partly ice‐covered northern East Greenland continental margin highlight a complex interaction between tectonic and magmatic events. Breakup‐related lava flows are imaged in reflection seismic data as seaward dipping reflectors, which are found to decrease in size both northward and southward from a central point at 75°N. We provide evidence that the magnetic anomaly pattern in the shelf area is related to volcanic phases and not to the presence of oceanic crust. The remnant magnetization of the individual lava flows is used to deduce a relative timing of the emplacement of the volcanic wedges. We find that the seaward dipping reflectors have been emplaced over a period of 2–4 Ma progressively from north to south and from landward to seaward. The new data indicate a major post‐middle Eocene magmatic phase around the landward termination of the West Jan Mayen Fracture Zone. This post‐40‐Ma volcanism likely was associated with the progressive separation of the Jan Mayen microcontinent from East Greenland. The breakup of the Greenland Sea started at several isolated seafloor spreading cells whose location was controlled by rift structures and led to the present‐day segmentation of the margin. The original rift basins were subsequently connected by steady‐state seafloor spreading that propagated southward, from the Greenland Fracture Zone to the Jan Mayen Fracture Zone.

Highlights

Information on the continental breakup and opening of the Norwegian-Greenland Sea in the North Atlantic Ocean is preserved along the continental margins off northern East Greenland and Norway
We present an interpretation of the seaward dipping reflectors (SDRs) along the northern East Greenland margin
Volcanism in the vicinity of the West Jan Mayen Fracture Zone is shown to differ from the SDRs stage and is suggested to originate from a late Oligocene/early Miocene magmatic phase

Summary

Introduction

We focus on the northern East Greenland margin, between the West Jan Mayen and the Greenland Fracture Zones (Fig. 1) This margin is well known to originate from volcanic rifting. Based on the same data set, Tsikalas et al [2005] proposed conjugate sets of transfer zones on the NE Greenland shelf and the Vøring Plateau, which are thought to have segmented the rift before breakup occurred. This has been challenged based on new magnetic data by Olesen et al [2007]. Most structural interpretations on the NE Greenland shelf and margin are derived from potential field data or extrapolation of conjugate structures [e.g. Tsikalas et al, 2002]

Results

Discussion

Conclusion