Mechanism for three types of mafic dyke swarms

Abstract

This study proposes three models to explain the mechanism of the three major types of mafic dyke swarms. Parallel dyke swarms form in response to a regional stress field, e.g. the mafic dyke swarms in the North China Craton, whereas small radiating dyke swarm forms due to stress constructions around a plutonic or volcanic edifice, such as the dyke swarm at Spanish Peak, USA. The third type of radiating dyke swarm is giant fan-shaped dyke swarm such as the Mackenzie dyke swarm. Fractures that formed prior to magmatism may play a vital role in dictating the dyke swarm geometry. In most of the cases, the pre-existing fractures are induced by tectonic stresses and not by magma injection though magma injection can increase the fracture size by propagation at the dyke tip. ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

Geochemistry of metamafic dykes from the Quanji massif: Petrogenesis and further evidence for oceanic subduction, Late Paleoproterozoic, NW China

“…Giant radiating dyke swarms have been frequently related to mantle plume activities, typically linked with the breakup of the supercontinents (Ernst et al, 2013;Hou, 2012;Goldberg, 2010;Zhang et al, 2009;Ernst et al, 2008Ernst et al, , 1995Peng et al, 2007;Mayborn and Lesher, 2004;Ernst and Buchan, 2001a;Park et al, 1995). Smaller scale metamafic dyke swarms can be related to volcanic edifices in subduction settings, in back-arc environments or as one component of oceanic crustal complex (Peng et al, 2007;Ernst et al, 1995).…”

“…Recently, Liao et al (2014) reported metamafic dyke swarms that intruded into the east Delingha region in the central east portion of the Quanji massif at ~1.85-1.83 Ma (Lu et al, 2008). Their study revealed that these dyke swarms have small-scale outcrops and limited distribution, and thus they cannot be regarded as giant mafic dike-swarms that are usually related to continental rifting or breakup of the supercontinents (Liao et al, 2014;Ernst et al, 2013Ernst et al, , 2008Ernst et al, , 1995Hou, 2012;Goldberg, 2010;Zhang et al, 2009;Peng et al, 2007;Mayborn and Lesher, 2004;Ernst and Buchan, 2001a). Combination of the affinity of backarc settings for their precursor magma at ~1.85-1.83 Ga and the medium-P/T type metamorphism of the dyke swarms at ~1.82 Ga (Chen et al, 2013a), Liao et al (2014) firstly proposed that an oceanic subduction process was going on before ~1.85 Ga. Our study reveals that the metamafic dykes within the paragneiss suite in the Delingha region carry even stronger signature of subduction-related volcanic arc setting, thus indicative of an oceanic lithosphere subduction process for generation of their precursor magma.…”

“…The QM exposes a variety of Precambrian metamorphosed metamafic dykes, lithologically dominated by amphibolites with minor granulites. Metamafic dykes commonly occur in extensional tectonic environments (e.g., Ernst et al, 2013;Goldberg, 2010;Harlan et al, 2008;Buchan, 2001a, 1997;Allen, 2000), and have been widely employed to address the tectonic process of specific geological events (Hou, 2012;Piper et al, 2011;Peng et al, 2007;Sklyarov et al, 2003). Recently, Liao et al (2014) suggested that the ~1.85-1.83 Ga metamafic dykes within the Early Paleoproterozoic monzo-granitic gneiss among those occur in the QM, were generated in a back arc setting based on field occurrence and geochemical data, supporting a subduction process in the very Late Paleoproterozoic period.…”

Late Paleoproterozoic rift-related magmatic rocks in the North China Craton: Geological records of rifting in the Columbia supercontinent

“…Kusky and Santosh, 2009;Rogers and Santosh, 2009;Santosh et al, 2009a,b,c;Santosh, 2010b;Santosh et al, 2010;Meng et al, 2011;N. Li et al, 2011;Yang et al, 2011;Zhai and Santosh, 2011;Zhao et al, 2011;Hou, 2012;Deng et al, 2013) (Figs. 1 and 2).…”

“…Zhang et al, 2007;Xu et al, 2007;Wang et al, 2007aWang et al, ,b, 2008He et al, 2008;Hou et al, 2008a,b;Peng et al, 2008;He et al, 2009;T.P. Zhao et al, 2009;He et al, 2010a,b;Peng, 2010;Wang et al, 2010;Cui et al, 2011;Hou, 2012).…”