hide
Free keywords:
Anabar Shield; seismic structure; gravity field; heat flow
Abstract:
In terms of the Anabar Shield investigation the authors studied seismic, gravity, and thermal characteristics of granulitic zones in the earth crust. Lower crustal complexes of the Anabar shield uplifted to the Earth surface are subdivided into passive (terranes) and active (collision zones) tectonic unites. The detailed structure of the SE zone of the Anabar Shield and the adjacent zones, which are characterized by vertical and lateral heterogeneity, was created along the DSS profile «Shpat» (Vp and Vs waves). Gravity field of the crust within the Anabar Shield is characterized by linear maxima of NW–SE course and coinciding maxima with zones of granulitic terranes. Special analysis of gravity field gives the same direction of inclination of high-density blocks in the crust as that found from the surface geology and seismic crustal model. The Anabar Shield is characterized by very low measured heat flow density: 20 to 25 mW/m2. We estimate deep heat flow on Anabar as minima ~30±(5–7) mW/m2. The average crustal heat production in the Anabar Shield was estimated to be 0.36 mkW/m3, this value is tipical for the lower crust. Mantle heat flow density is 10–16 mW/m2. Moho temperature on the Anabar Shield is about 330±20 °С. Spatial relationship between high permafrost thickness (up to 1500m) on the Anabar Shield and its slope is caused by anomalous low heat flow and glacial epoch.
