Geodynamic implications of paleomagnetic data from Tertiary sediments in Sakhalin, Russia (NW Pacific)

Abstract

N‐S trending right‐lateral strike‐slip faults, which were active in the Tertiary, transect Sakhalin, Russia, while Mesozoic forearc and accretionary rocks testify to an earlier period of subduction. Several kinematic models have been proposed for the region, but the details required to constrain these models, such as the timing of the transition from subduction to strike‐slip tectonics in Sakhalin, are still unknown. Even first‐order tectonic features, such as the boundaries of the plates with which Sakhalin evolved during the Tertiary, are poorly known. Paleomagnetic results from around Sakhalin were obtained to constrain the geodynamic evolution of the region. Comparison of paleomagnetic inclination data with the apparent polar wander paths for the Eurasian, Pacific, and North American Plates suggests that Sakhalin probably evolved with the North American Plate, although a history including the Eurasian Plate cannot be ruled out. Paleomagnetic declination data suggest that significant clockwise vertical axis rotation has occurred in Sakhalin since the mid‐Paleocene. It is likely that this rotational deformation was accommodated by Tertiary activity on right‐lateral strike‐slip faults, which may be associated with the opening of the Japan Sea, Tatar Strait, and Kuril Basin. These data contradict a published kinematic model for eastern Sakhalin, where counterclockwise vertical axis rotations were predicted for Neogene basins in the East Sakhalin Mountains. Agreement is better, however, with published paleomagnetic data from southern Sakhalin, where clockwise vertical axis rotations were documented.

Magnetic mineral diagenesis

“…Jackson et al (1991) proposed a method based on measurement of the anisotropy of remanence. It is effective and has been widely used (e.g., Tan and Kodama, 1998;Weaver et al, 2003;Bilardello and Kodama, 2010), but it is labour-intensive and time-consuming. Tauxe and Kent (2004) proposed an alternative method that makes use of the different properties of expected distributions for geomagnetic field directions and flattened inclinations.…”

Evolution of collision-related basins in the eastern end of the Kurile Basin, Okhotsk Sea, Northwestern Pacific

“…The geology of Hokkaido is closely related to that of Sakhalin (Rozhdestvenskiy, 1982;Kharakhinov et al, 1985;Kimura et al, 1992a,b;Natal'in, 1993;Dobretsov et al, 1994;Fournier et al, 1994;Weaver et al, 2003). The tectonic belts on Central Hokkaido extend to Sakhalin.…”

“…Fournier et al (1994) suggested that counter-clockwise rotations would be expected for Neogene basins in eastern areas of Sakhalin. Takeuchi et al (1999) and Weaver et al (2003) suggested that clockwise rotations have occurred, accommodated by 100 km scale crustal blocks, which were part of a domino system that may have extended southward to Hokkaido, based on palaeomagnetic data from Hokkaido and Sakhalin. The edges of crustal blocks should be expected to sustain tectonic deformation.…”

Cenozoic basin-forming processes along the northeastern margin of Eurasia: Constraints determined from geophysical studies offshore of Hokkaido, Japan

“…50 km within the northern part of the island since the Miocene. Based on paleomagnetic data, Weaver et al (2003) argued that fault motion in Sakhalin had begun in the Eocene and was associated with clockwise rotation. As for the southern extension, Kurita and Yokoi (2000) found a pull-apart basin in southcentral Hokkaido that formed as a result of Oligocene right-lateral slip on the Umaoi-Iburi Fault Zone (Fig.…”

“…1), as the northern extension of the tectonic zone, with the back-arc opening of the Japan Sea. However, their structural interpretation must be refined considering the discordant mode of block rotation detected by Weaver et al (2003). A paleoreconstruction proposed by Itoh and Tsuru (2006) suggested considerable dextral displacement on the tectonic zone but did not constrain Eocene and older relative motions because coeval sediments were lacking, because of the intense deformation of the forearc.…”