Origin of the Neoproterozoic Baijianshan banded iron formation at the southeastern margin of the Tarim Block in NW China: implication for an extremely reducing ocean

Author(s):  
Xiao-Shu Hao ◽  
Chuan-Lin Zhang ◽  
Hui-Chao Zhang ◽  
Teng Ding ◽  
Xian-Tao Ye
2016 ◽  
Vol 66 (4) ◽  
pp. 313-334 ◽  
Author(s):  
Xiangdong Wang ◽  
Xinbiao Lv ◽  
Xiaofeng Cao ◽  
Qian Yuan ◽  
Yifan Wang ◽  
...  

Author(s):  
Donald Eugene Canfield

This chapter considers the aftermath of the great oxidation event (GOE). It suggests that there was a substantial rise in oxygen defining the GOE, which may, in turn have led to the Lomagundi isotope excursion, which was associated with high rates of organic matter burial and perhaps even higher concentrations of oxygen. This excursion was soon followed by a crash in oxygen to very low levels and a return to banded iron formation deposition. When the massive amounts of organic carbon buried during the excursion were brought into the weathering environment, they would have represented a huge oxygen sink, drawing down levels of atmospheric oxygen. There appeared to be a veritable seesaw in oxygen concentrations, apparently triggered initially by the GOE. The GOE did not produce enough oxygen to oxygenate the oceans. Dissolved iron was removed from the oceans not by reaction with oxygen but rather by reaction with sulfide. Thus, the deep oceans remained anoxic and became rich in sulfide, instead of becoming well oxygenated.


Author(s):  
Peter R. Dawes ◽  
Bjørn Thomassen ◽  
T.I. Hauge Andersson

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Dawes, P. R., Thomassen, B., & Andersson, T. H. (2000). A new volcanic province: evidence from glacial erratics in western North Greenland. Geology of Greenland Survey Bulletin, 186, 35-41. https://doi.org/10.34194/ggub.v186.5213 _______________ Mapping and regional geological studies in northern Greenland were carried out during the project Kane Basin 1999 (see Dawes et al. 2000, this volume). During ore geological studies in Washington Land by one of us (B.T.), finds of erratics of banded iron formation (BIF) directed special attention to the till, glaciofluvial and fluvial sediments. This led to the discovery that in certain parts of Daugaard-Jensen Land and Washington Land volcanic rocks form a common component of the surficial deposits, with particularly colourful, red porphyries catching the eye. The presence of BIF is interesting but not altogether unexpected since BIF erratics have been reported from southern Hall Land just to the north-east (Kelly & Bennike 1992) and such rocks crop out in the Precambrian shield of North-West Greenland to the south (Fig. 1; Dawes 1991). On the other hand, the presence of volcanic erratics was unexpected and stimulated the work reported on here.


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