The Dabie–Sulu continental collision zone: A comprehensive review

Diverse P–T paths of the northern Dabie complex in central China and its reworking in the early Cretaceous

“…1). Although oriented exsolution textures have been commonly considered as evidence for peak UHP metamorphism Zhang and Liou, 1999;Ye et al, 2000b;Chopin, 2003;Zhang et al, 2003), they have recently come under scrutiny as to their suitability as unambiguous marker for peak UHP conditions (Page et al, 2005;Hwang et al, 2007;Yang and Powell, 2008;Zheng, 2008;Liou et al, 2009;Zhang et al, 2009). However, the UHP metamorphic microdiamonds in retro-eclogite relics from Raobazhai, Huangweihe and Baizhangyan (Xu et al, 2003 and UHP microdiamond inclusions in zircon in gneiss from Ta'erhe and in the eclogite relic from Luotian (Liu et al, 2007a,b) (Fig.…”

“…As the largest ultrahigh-pressure (UHP) metamorphic belt recognized in the world, the Dabie-Sulu orogenic belt in east-central China is thought to have formed by continental subduction and collision between the North China and Yangtze blocks in the Triassic (240-220 Ma) (Li et al, , 1996Ames et al, 1996;Chavagnac and Jahn, 1996;Cong, 1996;Liou et al, 1996Liou et al, , 2004Liou et al, , 2009Hacker et al, 1998Hacker et al, , 2006Jahn, 1998;Jahn et al, 2003;Zheng et al, 2003;Liu et al, 2006;Zhang et al, 2009). The discovery of UHP metamorphic coesite and microdiamond in eclogite of the Dabie orogenic belt over 20 years ago (Okay et al, 1989;Wang et al, 1989;Xu et al, 1992), has led to extensive studies of the orogen.…”

“…The intensity of this event masked possible earlier metamorphic events. Thus, until recently, the tectonic nature of the NDC in particular whether Triassic subduction and HP/UHP metamorphism played a role has been an issue (Ernst et al, 2007;Jahn and Chen, 2007;Zhang et al, 2009). Different proposals have been put forward for the NDC such as: (1) it is the upper part of the subducted plate (Maruyama et al, 1994;Ernst and Liou, 1995); (2) it belongs to a Palaeozoic magmatic arc complex (Zhai et al, 1995) or part of the hanging wall of the North China block without UHP metamorphism; (3) it represents a Cretaceous extensional magmatic complex (Hacker et al, 1998Ratschbacher et al, 2000); (4) it represents a Jurassic migmatite dome (metamorphic core complex) involving Triassic subduction and UHP metamorphism (Faure et al, 1999;Zhong et al, 1999); (5) it is an extension of the Yangtze craton unaffected by the Triassic UHP metamorphism (Bryant et al, 2004); or (6) it belongs to part of the Yangtze plate that experienced Triassic deep subduction and UHP metamorphism Xu et al, 2000Xu et al, , 2005Liu et al, 2001cLiu et al, ,d, 2005Liu et al, , 2007aMalaspina et al, 2006).…”

Revealing the climate of snowball Earth from Δ 17 O systematics of hydrothermal rocks

“…We use the triple oxygen isotope composition ( 17 O/ 16 O, 18 O/ 16 O) of Proterozoic rocks to reconstruct the 18 O/ 16 O ratio of ancient meteoric waters. Some of these waters have originated from snowball Earth glaciers and thus give insight into the climate and hydrology of these critical intervals in Earth history.…”

“…For a Paleoproterozoic [∼2.3-2.4 gigayears ago (Ga)] snowball Earth, δ 18 O = −43 ± 3‰ is estimated for pristine meteoric waters that precipitated at low paleo-latitudes (≤35°N). Today, such low 18 O/ 16 O values are only observed in central Antarctica, where long distillation trajectories in combination with low condensation temperatures promote extreme 18 O depletion. For a Neoproterozoic (∼0.6-0.7 Ga) snowball Earth, higher meltwater δ 18 O estimates of −21 ± 3‰ imply less extreme climate conditions at similar paleolatitudes (≤35°N).…”