Eurasia spreading basin to Laptev Shelf transition: structural pattern and heat flow

Abstract

SUMMARY New geophysical data have become available from shipborne and satellite measurements allowing a re‐evaluation of the largely unknown junction of the Arctic spreading centre and the northeastern Siberian continental margin where the transpolar mid‐ocean Gakkel Ridge abuts against the continental slope of the Laptev Sea. Based on multichannel seismic reflection and gravity data, this sediment‐covered spreading axis can be traced to the continental rise where it is cut‐off by a transcurrent fault. Further continuation of the extensional axis into the continental slope can be attributed to two asymmetric grabens, which terminate against the prominent Khatanga–Lomonosov Fracture. Remnants of hydrothermal fauna and high heat‐flow values of approximately 100 mW m−2 documented around these grabens in the up‐slope area are typical for an oceanic spreading axis. Thus we consider these grabens to be morphotectonic termination of the global Atlantic–Arctic spreading system with plate motions shifting to the Khatanga–Lomonosov Fracture. The high heat flow and the distribution of earthquake epicentres allow us to assume that the present‐day divergent plate tectonic boundary passes from the Gakkel Ridge to the eastern part of Laptev Sea with an offset of initial rifting along the Bel'kov–Svyatoi Nos Rift to the projected prolongation of the buried spreading axis by 140–150 km.

Expanding the Cenozoic paleoceanographic record in the Central Arctic Ocean: IODP Expedition 302 Synthesis

“…O'Regan et al [79] show that basinwide compression occurred in two stages: the first phase was caused by a northward movement of the Greenland micro-plate during Eocene times and terminated when Greenland joined the North American plate during Chron C13 [14,81]; The second phase occurred along the Laptev Sea margin and was initiated by plate re-organization during Chron C13. This lasted until Chron C6 at about 19 Ma and resulted in the structural evidence observed on the New Siberian Islands and the northern Verkhoyansk Range, as well as the prominent hiatuses on the Laptev and Siberian shelves [82][83][84]. O'Regan et al [79] argue that the end of the long lasting (56-19 Ma) basin-wide compression occurred shortly prior to, or in conjunction with, the observed onset of early Miocene subsidence of the Lomonosov Ridge, thus permitting post-rifting lithospheric thermal cooling to begin.…”

“…The Amerasian Basin was the only deep basin in the Arctic Ocean for about [80][81][82][83][84][85][86][87][88][89][90] Myr. The Lomonosov Ridge separates the older Amerasian Basin from the younger Eurasian Basin (Figure 1).…”

Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

“…Heat flow in rift zones also provides geologic control (Drachev et al, 2003;Nicolsky et al, 2012). High heat flow areas include relic thaw lakes and river valleys that were submerged during the Holocene inundation.…”

“…The outer Laptev Sea is one of the few places where active oceanic spreading approaches a continental margin (Drachev et al, 2003) and correlates with the "hot" area crossed by the Ust' Lensky Rift and KhatangaLomonosov Fracture (Drachev et al, 2003;Nicolsky et al, 2012). Evidence of rifting is provided by hydrothermal fauna remnants documented around grabens (dropped blocks between faults) in the up-slope area that typically occurs along oceanic divergent axes (Drachev et al, 2003).…”

Coastal permafrost landscape development since the Late Pleistocene in the western Laptev Sea, Siberia

“…It has not escaped our attention that the presence of non-marine interglacial sediments in core C1 (suggested by palynological data and OSL ages) and of marine interglacial sediments in core C2 suggests, when considered in the context of the IR-OSL ages, that the maximum extent of the associated transgression is between the borehole positions of cores C1 and C2. Environmental changes resulting from sea-level fluctuation might have been accompanied by glacioisostatic adjustments in the study area after the deglaciation of the Late Saalian ice sheet, which still covered parts of the Taymyr Peninsula , and seismo-tectonic movement, which also occurs today at the eastern boundary of the Eurasian plate owing to rift-zone fracturing across the Laptev Sea (Drachev et al 1998(Drachev et al , 2003Franke et al 2004). An improved understanding of glacio-and seismo-tectonic processes in the western Laptev Sea is necessary to evaluate the current low-elevation position of Unit I and the likelihood of higher sea-floor altitudes during its accumulation.…”