The location and evolution of the tectonic boundary between the Paleoproterozoic Jiao-Liao-Ji Belt and the Longgang Block, northeast China

• Tectonic boundary between the Jiao-Liao-Ji Belt and the Longgang Block is identified.
• The basin-controlling boundary fault indicates a continental rift or rift-and-collision belt.
• The Lianshanguan rock mass contains Archean TTG gneiss and Paleoproterozoic granite.
• The Eastern Block can be regarded as a micro-block.

In this paper we discuss the location, nature, and evolution of the tectonic boundary between the Jiao-Liao-Ji Belt and the Longgang Block, northeast China. The boundary in terms of paleogeography, which involves a study of the Liaohe Group, or tectonics. Employing non-seismic geophysical data (e.g., gravity data and magnetotelluric soundings), existing geological data, and the differences in physical properties between the Jiao-Liao-Ji Belt and the Longgang Block, we clarified the spatial distribution of the tectonic boundary, and characterized the geological bodies at different depths on either side of the boundary. We analyzed the most recently updated Bouguer gravity anomaly, gravity, magnetic, and electrical profile data, as well as comprehensive data on the physical properties of the rocks in the research area, thus providing information on the geological nature of the boundary at deep levels. The results indicate that during the early period of formation of the Jiao-Liao-Ji Belt, a basin-controlling boundary fault developed that constituted the original tectonic boundary between the Jiao-Liao-Ji Belt and the Longgang Block. This fault extended from Shuangtaling to Sandaoling, Lian Shanguan, Dawanggou, Balidianzi, and Erhulai to Guaimozi, following a roughly east–west trend. Most previous studies have considered that the Liaohe Group, which extends from Benxi City to Benxi County and Huanren County, is the paleo-geographic boundary of the Jiao-Liao-Ji Belt.

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