Generation and preservation of continental crust in the Grenville Orogeny

Abstract

a b s t r a c tDetrital zircons from modern sediments display an episodic temporal distribution of U-Pb crystallization ages forming a series of 'peaks' and 'troughs'. The peaks are interpreted to represent either periods of enhanced generation of granitic magma perhaps associated with mantle overturn and superplume events, or preferential preservation of continental crust during global collisional orogenesis. The close association of those peaks with the assembly of supercontinents implies a causal relationship between collisional orogenesis and the presence of zircon age peaks. Here these two end-member models (episodic periodicity of increased magmatism versus selective preservation during collisional orogenesis) are assessed using U-Pb, Hf, and O analysis of detrital zircons from sedimentary successions deposited during the w1.3e1.

Breaking the Grenville–Sveconorwegian link in Rodinia reconstructions

“…An extensional depositional environment with intervening compressional phases was active until at least ca. 590 Ma (Cutts et al, ; Kirkland et al, ), covering large tracts of Baltica (Sparagmite Basin, Nystuen, ), Laurentia (Spencer et al, ), exotic entities including the Pearya terrane (Estrada et al, ; Malone, McClelland, Gosen, & Piepjohn, ; Trettin, ), domains of northeastern Russia (Lorenz, Gee, Larionov, & Majka, ), the Moine and Dalradian supergroups (Kirkland, Strachan, & Prave, ; Strachan, Prave, Kirkland, & Storey, ), the Kalak Nappe Complex in northern Norway (Kirkland, Daly, & Whitehouse, ), Krummedal succession on Greenland (Kalsbeek, Thrane, Nutman, & Jepsen, ), and terranes on Svalbard (Johansson, Gee, Larionov, Ohta, & Tebenkov, ) (Figure ). This series of linked basins received detrital input from the eroding Sveconorwegian orogen and other, older and younger continental sources.…”

TTG‐Adakitic‐Like (Tonalitic‐Trondhjemitic) Magmas Resulting From Partial Melting of Metagabbro Under High‐Pressure Condition During Continental Collision in the North Qaidam UHP Terrane, Western China

“…Alternatively, it has been argued that continental collision zones are primary sites for preserving juvenile crust and maintaining net continental crustal growth in the Phanerozoic (Niu et al, ; Song et al, ). In this model, the juvenile crust is dominated by syncollisional granitoids such as the voluminous batholiths along many orogenic belts on the greater Tibetan Plateau (Mo et al, ; Niu et al, ), and continental collision with juvenile crust formation/preservation and supercontinent amalgamation explains the episodic growth of the continental crust (Spencer et al, ). The combined field, petrological, geochemical, and isotopic data in our study together suggest that TTG‐like magmas were possibly produced through partial melting of newly emplaced metagabbros with arc affinity and that the melting was triggered by the breakdown of amphibole and rare zoisite under HP granulite facies conditions during continental collision and amalgamation of juvenile marginal arc rocks that formed in the active continental margin before collision.…”

Implications of erosion and bedrock composition on zircon fertility: Examples from South America and Western Australia

“…Preservation and fertility bias has been considered as an important aspect of the global zircon age record (e.g. Hawkesworth et al., ; Puetz et al., ; Spencer et al., ). Hawkesworth et al.…”