Evolution of the Pacific Margin: Progress and Future Jeremy Hourigan, Yale University

Evolution of the Pacific Margin: Progress and Future

• Jeremy Hourigan, Yale University

• Sergei D. Sokolov, GIN-RAS Moscow

• Aleksandr I. Khanchuk, FEGI-RAS, Vladivostok

Outline of Progress

• Pre-Late Cretaceous Pacific Convergent Margin

• Sea of Okhotsk

• Olyutorsky Arc-Collision zone, Kamchatka

• Neotectonics - upper crustal response to plate margin processes

• Geophysics - structure of the modern subduction zone

Terrane Map: Nokleberg et al, 1998

Progress: Pre-Late Cretaceous Convergent Margin evolution

• Laboratory of Tectonics of Oceanic and Perioceanic zones (Sokolov)

• Pekul’ney Range
• Koryak Highlands
• Taigonos Peninsula

• Transform-margin evolution in Primoriye (Khanchuk)

Outline of Progress

• Uda-Murgal Arc evolution

• Improved understanding of Pacific plate geometry and kinematics from the record far-traveled material in accretionary prism (geochemistry, radiolarian stratigraphy, and paleomagnetic)
• Tectonic reconstruction of Pre-mid Cretaceous NE Russian Margin

Modern extent of the Uda-Murgal Arc

Okhotsk-Chukotka Volcanic Belt

Okhotsk Chukotka Volcanic Belt

Outline of Progress

• Sea of Okhotsk

• Sredinniy Range (eastern edge of Okhotsk Sea microplate?)
• Seasat gravity dataset
• Analog modeling asymmetric back arc extension
• S-wave tomography of sub-Okhotsk mantle
• Thermochronologic constraints for extension in the Magadan Basin

Existing models for the origin of the Okhotsk Sea Basement

Structure of the Exterior OCVB

Reconstruction of the Late Cretaceous – Early Tertiary margin

Surface Wave Diffraction Tomography

Outline of Progress

• Olyutorsky arc-continent collision zone

• New timing constraints for arc-continent collision (Soloviev, Garver and Brandon)
• High-grade roots of the Collision zone in the Sredinniy Range

Arc-continent collision between Late K – Paleocene Olyutorsky Arc and the northeast Russian continental margin

• Arc-continent collision between Late K – Paleocene Olyutorsky Arc and the northeast Russian continental margin

• Timing constrained by fission-track grain-age stratigraphy and biostratigraphy from marginal sandstone units in the lower plate

• Timing estimates: 55 – 45 Ma

• Cross-cutting granite and overlapping Kinkil volcanic rocks of the West Kamchatka Belt: 45 Ma (U/Pb zircon TIMS, Garver, 2001)

Simplified geologic map of the Sredinniy Range

Kolpakova Gneiss: migmatite

Accumulation of protoliths

Outline of Progress

• Neotectonics

• Tephrachronologic, marine terrace record of vertical motion along coastal Kamchatka (Bourgeois group)
• Accretion history of Cape Terranes (Mann and co-workers; Gaedicke and others)

Outline of Progress

• Geophysics – Modern subduction zone structure

• SEKS experiment (Side-Edge of the Kamchatka Slab)
• Crustal Structure of Kamchatka and Mainland Russia
• Mantle velocity structure beneath the Sea of Okhotsk

Workshop objective

• Establish links between geodetic, neotectonic, structural, thermochronologic, and geophysical disciplines to understand the evolution of the Pacific margin at a range of time and length scales.

Discussion objectives

• Establish links between geodetic, neotectonic, structural, thermochronologic, and geophysical disciplines to understand the evolution of the Pacific margin at a range of time and length scales  cross-disciplinary approach.

Discussion objectives

• The southern continuation  Understanding linkages with Mongol-Okhotsk Belt and Sikhote-Alin Margin

• Radiation of angiosperms – climatic and paleobotanical implications (EARTHTIME Iniative)

• The Sea of Okhotsk

• Origin of basement

• Time-space patterns of extensional basin formation and strike-slip faulting

• Role of Pacific plate roll-back, strike-slip modification, and Asian extrusion

• If the Sea of Okhotsk is a microplate, when did it achieve the microplate character?

Discussion objectives

• Kamchatka

• Cross disciplinary projects that address the evolution of the Aleutian Kamchatka junction
• Evolution of high grade metamorphic rocks in a collage of low-grade accreted terranes (Sredinniy, Ganal and Khavyven Ranges)