Density structure characteristics of the aldan-stanovoy shield lithosphere
© Podgornyi V.Ya., Malyshev Yu.F.
The models of density distribution in the double-layered and multilayered lithosphere of the Aldan-Stanovoy Shield have been constructed by the results of calculations passing to its southern and northern framing by the seismic profile Djalinda-Ulu along the Aldan-Yakutsk main line. Based on the peculiarities of the density section of the double-layered model (the crust and lithospheric mantle underlied by the asthenosphere) the lithospheric block which practically encloses the structures of the Aldan-Stanovoy Shield composed of the granulite-gneiss complexes of the Aldan mega block and the granite and greenstone rocks of the Stanovoy has been distinguished. The area of the abnormal density decrease was established in the lithosphere mantle and the asthenosphere in the central part beneath the crust of the Chulman depression. The density increases step-like to the both sides towards the periphery of the profile. This regularity is not so clearly displayed in the crustal strata. Density distribution in the seismically layered model of the crust is a complicated one. The compressional and extensional zones are distinguished by the peculiarities of the density section. According to the character of distribution of the density inhomogeneities and manifestation of faults in the lithosphere of the Aldan-Stanovoy Shield three blocks are distinguished to which the lithosphere of the Stanovoy mega block, of the Chulman depression and the northern part of the Aldan mega block correspond. The southwestern boundary of the shield in the crust is displayed by the Djeltulaksky fault, gently dipping beneath the shield; the northern boundary is associated with a set of faults, controlling the gold and uranium ore areas.