Crustal reflection structure in the uplifting zone of Songliao Basin and disconnecting Moho interface

In order to obtain the fine structure of Songliao Basin, four nearly vertical reflection profiles were acquired and then processed so as to get the poststack migration sections with two-way travel of 15s. In this paper, we study the reflection characteristics in the southeastern and northeastern uplifting zones of Songliao Basin, discovering that the structure within the uplifting zones has the following features: (i) The sedimentary thickness decreases from west to east and increases from north to south. (ii) In the northeastern and southeastern uplifting zones, the crustal reflection image varies remarkably along east-west or south-north direction. (iii) In the northeastern uplifting zone, the two-way travel time of Moho interface ranges within 9.6–11.0 s (the depth range of 30–34 km). (iv) In the southeastern uplift, the two-way travel time of Moho interface ranges within 9.7–10.4 s (the depth range of 30–32 km). The poststack migration sections manifest the peculiar phenomenon of the disconnecting Moho reflection phases in Songliao Basin with two-way travel time difference of 0.1–0.5 s (2 km or so). In the vicinity of disconnecting zone, there are several shear faults, which are wide within the uplifting zone and become narrow at the intersection of two uplifting zones. It can be inferred that these reflection images and peculiar reflections from Moho interface are attributed to the coupling of the following dynamic factors: multi-phase weak collision of Heilongjiang micro-continents, westward under-thrusting of Pacific plate and so on.