265 Structural Geology: Active and Ancient Deformation in North America and around the World (Posters)

Tuesday, 27 September 2016
9:00 AM - 6:30 PM
Exhibit Hall E/F

STRUCTURAL ANALYSIS AND DETRITAL ZIRCON (U-TH)/HE AGES FROM PALEOZOIC STRATA OF THE NW NOVAYA ZEMLYA ARCHIPELAGO (RUSSIAN HIGH ARCTIC)

Paper number: 265-40
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Regional structural analysis and detrital zircon (U-Th)/He (ZHe) ages from the Northern part of Novaya Zemlya Archipelago (Russian High Artic) suggest two stages of deformation since the Paleozoic. The structural style of the region is dominated by NW-striking folds, which is clearly recognized on the ground and in geological maps. The folds are typically overturned to the northwest and a southeast-dipping axial-plane cleavage is widely distributed. Tectonic transportation is directed from southeast to northwest and the bedding-cleavage intersection lineation plunges to the southeast and southwest; parallel to the axes of large and small folds. The dip angle of the lineation is high, commonly up to 30o and occasionally higher. Dip angles of intersection lineations are highly variable over a short distance, pointing to the occurrence of several stages of deformation. The intersection lineation plunge angles are likely close to the dip angles of bedding on the early-stage fold limbs, most of which were gentle to open.

Six samples from Paleozoic successions of the NW Novaya Zemlya Archipelago were analyzed for ZHe analysis. The obtained ZHe ages are younger than the depositional age of the studied strata, indicating the ages have been reset since deposition. The ZHe data constrain the minimum burial depth of the studied succession to >~7 km and provide information on the exhumation history of the NW Novaya Zemlya Archipelago. ZHe ages from Cambrian to Devonian strata yield two age peaks at ca. 218 and 180 Ma, pointing to significant uplift and erosion in the Late Triassic and Early Jurassic.

The two stages of deformation revealed from the structural studies are attributed to two separate episodes of orogenic activity within the study region. We speculative assume that the first stage of folding is likely related to the Caledonian or Ellesmerian orogenies. The second stage of deformation, with significant Late Mesozoic uplift as suggested by the ZHe ages, is related to the latest stages of the Uralian Orogeny.

This research was supported by RFBR grant 16-55-20012 & The Research Council of Norway grant 254962/H30.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-285900

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