Fig. 3: The relationships between Ni concentration, Ni isotopes, and rare earth element pattern of the Nantuo pyrite samples.
From: Active methanogenesis during the melting of Marinoan snowball Earth
a Cross-plot of Ni concentration versus δ60Ni. There is an anticorrelation between Ni concentrations and δ60Ni values. Dash lines represent the relationship between Ni concentration and isotopes in a theoretical mixing model. Here, δ60Ni values of the two end-members are −0.5‰ and +1.5‰, respectively. The Ni concentration of the high-δ60Ni end-member is fixed to 20 p.p.m., while that of low-δ60Ni end-member is assigned to 50, 100, and 250 p.p.m., respectively. The anticorrelation between Ni concentration and δ60Ni could be explained by a binary mixing model. b Cross-plot of Ni concentration versus SmN/YbN. Here, Sm and Yb are used to represent middle rare earth element (MREE) and heavy REE (HREE) respectively. An anticorrelation is shown between Ni concentration and MREE/HREE. REE data are normalized to post-Archean Australian shale (PAAS). Green triangles, red circles, red squares, and red diamonds represent the Huakoushan, Tongle, Yazhai, and Datan sections, respectively.
