Reinterpretation of morphology and crustal structure in the Central Arctic Ocean Basin

Abstract

Ice station bathymetric profiles and submarine echograms reveal a steep escarpment at least 200 km long with up to 1700 m of relief subparallel to the Lomonosov Ridge. This feature, formerly called the Marvin Spur, is here interpreted as the Makarov‐facing flank of the Alpha Ridge. East of the 160°W meridian the intervening Makarov Basin is a narrow grabenlike trough between 25 and 60 km wide filled with horizontally stratified sediments that were deposited largely after the Marvin Seamounts were constructed along the basin axis. The association of basement relief with geomagnetic field variations within the trough plus evidence of normal faulting on the Lomonosov Ridge suggest that this segment of the Makarov Basin is an extensional feature produced by other than typical seafloor‐spreading processes. Gravity models indicate that the crust below the Makarov flank of the Alpha Ridge ranges in thickness between 16 and 20 km, considerably less than the 26 km known from seismic refraction work to exist below the Lomonosov Ridge. It is argued, on the basis of gravity data, that adjacent to the Lomonosov Ridge the Fram Basin crust, which is probably truly oceanic, is 3–4 km thinner than that of the Makarov Basin.

Canadian expedition to study the Alpha Ridge complex: results of the seismic refraction survey

“…The overly thick crust beneath this southern flank of the Makarov Basin is probably related to its proximity to the anamalous Alpha Ridge complex. Weber & Sweeney (1985) and Weber (1986) have suggested that the northern flank of the Alpha Ridge complex extends well into the bathymetrically defined Makarov Basin, and that the true Makarov Basin occurs as a narrow deep trough approximately 100 km to the north of our seismic line.…”

Chapter 49 A first look at the petroleum geology of the Lomonosov Ridge microcontinent, Arctic Ocean

“…Seismic refraction and gravity experiments show that the Lomonosov Ridge is the surface expression of a sliver of continental crust having a Moho at a depth of 25-28 km (Forsyth & Mair 1984;Weber & Sweeney 1985;Lebedeva-Ivanova et al 2006a). Although the Lomonosov Ridge is a prominent bathymetric feature adjacent to the Eurasia Basin, the continental crust on the Amerasia Basin side of the microcontinent extends beneath the lower-lying parts of the adjacent Podvodnikov Basin (Jokat 2005).…”

Expedition 302 geophysics: integrating past data with new results

“…F1). The conclusion from these data was that the Ridge consisted of a series of tilted en-echelon fault blocks with their crests covered by thin (<75 m thick) drapes of unconsolidated sediments (Weber and Sweeney, 1985) (Fig. F2).…”

“…Further along the oblique drift track across the Ridge (Fig. F1), the thickness of the conformably draped and well-stratified sediments increased to >850 m on the Ridge's flat-topped crest (Weber and Sweeney, 1985).…”

“…The scientific program included bathymetric measurements, gravity observations, and continuous seismic reflection profiling. Reprocessing of the seismic reflection data (Weber and Sweeney, 1985) resulted in the interpretation of a 60 m thick section of conformable sediments draping the Lomonosov Ridge plateau along the ARLIS II's first crossing of the ridge plateau from the Makarov Basin side. Further along the oblique drift track across the Ridge (Fig.…”