Early cretaceous extensional structures in the Liaodong Peninsula: Structural associations, geochronological constraints and regional tectonic implications

Abstract

Various extensional structures, e.g., half grabens, detachment faults, and metamorphic core complexes, were formed in the Liaodong Peninsula. There are two metamorphic core complexes (mcc's) in the western part of the Peninsula, i.e. the Liaonan mcc and the Wanfu mcc. They share the same lower plate and constitute a conjugate mcc pair. The Dayingzi detachment fault system and the three half grabens are exposed in the central and eastern parts, respectively. U-Pb dating of zircons from syntectonic plutons in the lower plates of the detachment faults and volcanic rocks from half graben basins indicates that their formation spans from 135 to 106 Ma, although the individual structure may be formed at a particular stage. Despite the differences in age of formation, in the regional attitudes, and in rooting depths, the extensional structures have great similarities in their kinematics, geometrical asymmetry, and coeval tectono-magmatic activities etc. Macroscopically, the extensional structures constitute conjugate associations, but a particular one generally has asymmetric patterns. Early Cretaceous extensional structures extend from the Liaodong Peninsula to North China, Northeast China, South China, and eastern Mongolia and Transbaikal area in Russia. The extensional structures from different areas share many common features. The Liaodong Peninsula is the miniature of the East Asia with respect to the formation of extensional structures in Early Cretaceous. It is suggested that the interaction of the Izanagi Plate with Eurasia Plate is responsible for the extension of crust. The structural mobility of the lithosphere, partly attributed to the fluid flow at the depth, and detachment faulting in both the crustal and mantle lithosphere provide important constraints on the development of Early Cretaceous extensional structures in the East Asia. Liaodong Peninsula, Cretaceous extension, geochronology, East Asia, the North China Craton Citation:Liu J L, Ji M, Shen L, et al. Early Cretaceous extensional structures in the Liaodong Peninsula: Structural associations, geochronological constraints and regional tectonic implications.

Late Mesozoic compressional to extensional tectonics in the Yiwulüshan massif, NE China and their bearing on the Yinshan–Yanshan orogenic belt

“…Traynor and Sladen, 1995;Chough et al, 2000;Mazukabzov et al, 2006;Erdenetsogt et al, 2009;Andryushchenko et al, 2010;Chough and Sohn, 2010;Metelkin et al, 2010;Daoudene et al, 2011) and several national and international conferences have been organized on this topic, the tectonic evolution and geodynamics of the different tectonic events are still hotly debated (e.g. Davis et al, 2001;Darby and Ritts, 2002;Liu et al, 2005;Lin et al, 2007Lin et al, , 2008Vergely et al, 2007;Davis and Darby, 2010;Liu et al, 2011;Zhang et al, 2011a).…”

Evolving magma sources during continental lithospheric extension: Insights from the Liaonan metamorphic core complex, eastern North China craton

“…Combining structural and microstructural analysis and geothermobarometry data, it is suggested that the Zhaotun monzogranite emplaced and deformed at a relatively deep crustal level during detachment faulting. Liu et al (2011Liu et al ( , 2013. 40 Ar/ 39 Ar ages of hornblende, muscovite, biotite and K-feldspar are from Yang et al (2007a), Yang et al (2007b) and Lin et al (2011) Wu et al, 2005;Guo et al, 2004;Ji et al, 2009;Liu et al, 2013).…”

“…The zircon U-Pb (SHRIMP and LA-ICPMS) ages of the plutonic rocks range from 130 ± 5 Ma to 113 ± 2 Ma Wu et al, 2005). However, the Zhaofang granodioritic porphyry, was suggested to be a typical postkinematic intrusion ), but the others were suggested to be syn-kinematic intrusions during regional extension Liu et al, 2011Liu et al, , 2013Wu et al, 2005). In addition, the trachy-dacite at Yuhuangding in the supradetachment basin was also related to the formation of the basin during extension.…”

“…A thick layer of trachy-dacites crop-outs in the central part of the Cretaceous Wafangdian supradetachment basin, i.e., the Yuhuangding trachy-dacite (SL0577, SL0581, SL0583, SL0585, 126 ± 6 Ma; Liu et al, 2011). The volcanics are embedded in lacustrine sediments in the middle section of the basin fill.…”

“…Late Mesozoic metamorphic core complexes, mostly with volcanics in their supradetachment basins and synkinematic granitic plutons in their lower plates, are widespread in the eastern North China craton (Lin et al, 2008;Liu et al, 2006Liu et al, , 2011Liu et al, , 2013Wang et al, 2011). They provide a basis for understanding of the essential relationships between continental lithospheric extension, mcc exhumation and magmatism, and the major causes of thinning of the cratonic lithosphere.…”