The initial break-up of Pangæa elicited by Late Palæozoic deglaciation

Abstract

The break-up of Pangæa was principally facilitated by tensional plate stress acting on pre-existing suture zones. The rifting of Pangæa began during the Early Permian along the southern Tethys margin and produced the lenticular-shaped continent known as Cimmeria. A mantle-plume model is ascribed to explain the rift-related volcanism but the NW-SE oriented Cimmerian rifts do not correlate well with pre-existing suture zones or ‘structural heterogeneities’ but appear to have a pertinent spatial and temporal association with Late Palæozoic glacial-interglacial cycles. Mantle potential temperature estimates of Cimmerian rift-related basalts (1410 °C ± 50 °C) are similar to ambient mantle conditions rather than an active mantle-plume rift as previously suggested. Moreover, we find that the distribution of glacial deposits shows significant temporal and spatial concurrence between the glacial retreat margins and rifting sites. We conclude that the location and timing of Cimmerian rifting resulted from the exploitation of structural heterogeneities within the crust that formed due to repeated glacial-interglacial cycles during the Late Palæozoic. Such effects of continental deglaciation helped to create the lenticular shape of Cimmeria and Neotethys Ocean suggesting that, in some instances, climate change may directly influence the location of rifting.

Improving global paleogeography since the late Paleozoic using paleobiology

“…Only during the time interval of 323-296 Ma are landmass and shallow marine areas nearly equal at about 14.0 %, and only during 359-285 Ma do ice sheet areas exceed mountain areas, but ice sheets only exist during 380-285, 81-58 and 37-2 Ma. With Pangea formation during the latest Carboniferous or the Early Permian and breakup initiation in the Early Jurassic (Blakey, 2003;Domeier et al, 2012;Lenardic, 2016;Stampfli et al, 2013;Vai, 2003;Veevers, 2004;Yeh and Shellnutt, 2016), these paleogeographic feature areas significantly change over time (Fig. 8).…”

Permian felsic magmatism in the Neoproterozoic Nagar Parkar Igneous Complex of the Malani Igneous Suite: Evidence from zircon U–Pb age

“…However, we propose that the rift extended to the western Indian Shield, and possibly produced the Permian dyke swarm that intruded the Neoproterozoic granites and the porphyritic felsic dykes. Our inference is consistent with the interpretation of the presence of rift‐related magmatism during the Permian (269 to 272 Ma) to the west of NPIC as shown in Figure (modified and reproduced from the Figure of Yeh & Shellnutt, ). Literature review provides supporting evidence for the occurrence of extensive magmatism in the Permian along the Neotethyan margins (Figure ): the 315 to 297 Ma Peshawar Plain Alkaline Igneous Province (marked P) in northern Pakistan (Ahmad et al, ; Jan & Karim, ), the 289 to 260 Ma Panjal Traps continental flood basalts (marked K) of bimodal magmatism (Rehman et al, ; Rehman et al, ; Shellnutt, , ), the 284 Ma granitic dykes in Lahul and SE Zanskar, Indian Himalaya (marked Z) (Spring, Bussy, Vannay, Huon, & Cosca, ), the 279 to 285 Ma mafic dyke swarm in the Woniusi and Qiangtang (marked W and Q) in Tibet and southeastern China (Garzanti et al, ; Zhai et al, ), Lower Permian basalts in Arunachal Pradesh in India (marked A) (Garzanti et al, ), and the Middle Permian basalts in Oman (marked O) (Chauvet et al, ; Chauvet et al, ; Lapierre et al, and references therein).…”

“…Older subduction zone along the northern periphery of the Palaeotethys is also shown (blue line). Structural features are modified from past publications (Chauvet et al, ; Chauvet, Dumont, & Basile, ; Garzanti et al, ; Lapierre et al, ; Metcalfe, ; Yeh & Shellnutt, )…”

Publisher’s Note

“…The processes that initiate the dispersal of these large continental accumulations remain controversial (Santosh et al, 2009;Audet and Bürgmann, 2011;Murphy and Nance, 2013;Nance et al, 2014;Petersen and Schiffer, 2016;Peace et al, 2017a;Petersen et al, 2018;Schiffer et al, 2018;Olierook et al, 2019). The debate primarily revolves around whether continental dispersal is driven by deep-rooted thermal anomalies (Morgan-type mantle plumes) or shallow plate tectonic processes (Storey, 1995;Dalziel et al, 2000;Beutel et al, 2005;Frizon De Lamotte et al, 2015;Pirajno and Santosh, 2015;Yeh and Shellnutt, 2016;Keppie, 2016;Petersen et al, 2018;Heron, 2018).…”