Geodynamics and slip rates of the Ulakhan fault and northwestern Okhotsk plate, Northeast Russia

• Applicant: Dr. David Hindle
• Subject Area: Palaeontology
• Term: from 2012 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 207575714

The relative motion of the Eurasian (Eur) and North American (NAm) plates, responsible for North Atlantic opening, takes place about a pole of rotation very close to their mutual plate boundary, located within Northeast Asia. The result is a scissors type motion between the two plates with a transition from extension in the Arctic ocean along the Gakkel ridge to transpression / contraction in Northeast Russia. This has also led to the development of several, smaller plates with slow rates of relative motion and uncertain geometries, within the Eur-NAm plate boundary zone. Better understanding these is key to improving global plate tectonic models and the interpretation of a host of geological and geophysical data. The Okhotsk plate (Okh) is one such example and is effectively a crustal sliver caught in the jaws of converging Eur and NAm. It is an example of embryonic oblique convergence and extrusion. Many processes within Okh are poorly understood, including the rate of extrusion along its plate boundaries, and the style and amount of internal deformation it undergoes. Even more fundamentally, whilst we suspect that we know where the plate boundaries of Okh are, their location and identities have still not been scientifically verified. This proposal is to carry out initial research on the Ulakhan fault, very probably the boundary between NAm and Okh, using modern, neotectonic analyses to determine rates of slip and paleoseismological investigations to study its seismic cycle, and thus, its seismic hazard for the region. We will also attempt to examine the broader uplift of the landscape within the plate boundary zone using novel dating techniques of spectacular abandoned meanders which can potentially yield erosion/uplift rates. Based on our new data, we will build and calibrate a variety of numerical models to study the different possible processes driving deformation of the Okhtosk plate and surrounding area.

• DFG Programme: Research Grants
• International Connection: Russia, USA
• Participating Persons: Larissa Gunbina; Professor Kevin Mackey