Fig 1.
A map of the studied area illustrating locations, sampling sites, stratigraphic and structural characteristics.
Fig 2.
Schematic representation of studied weathering profiles showing the sectional structure and sampling depth.
Fig 3.
XRD patterns of selected Fe nodule and soil samples from profiles XY and PG.
G–gibbsite, Go–goethite, H–hematite, I–illite, K–kaolinite, Or–orthoclase, P–pyrophyllite, Q–quartz, S–smectite, C–calcite.
Fig 4.
Distributions of selected major elements and changes of several relevant physicochemical parameters along with the vertical sampling depth.
Table 1.
Selected major and trace element concentrations, 87Sr/86Sr ratios and physicochemical parameters of bulk samples of weathering profile XY in the study area.
Table 2.
Selected major and trace element concentrations, 87Sr/86Sr ratios and physicochemical parameters of bulk samples of weathering profile PG in the study area.
Fig 5.
PAAS (Post–Archean Australian Shale) normalized REE distribution patterns of profiles XY and PG.
Table 3.
Rare earth element concentrations and relevant parameters of bulk samples in weathering profiles XY in the study area.
Table 4.
Rare earth element concentrations and relevant parameters of bulk samples in weathering profiles PG in the study area.
Fig 6.
Distributions of 87Sr/86Sr ratio with (A) K2O, (B) CIA value, (C) CaO, (D) Fe2O3, and (F) P2O5 and relationships between (E) Fe2O3 and P2O5. Significant correlations are shown in the plots. CaO refers to the total content.
Fig 7.
87Sr/86Sr ratio trends as function of Nb/Sr ratio in profiles XY and PG.
Fig 8.
Relationships between 87Sr/86Sr and Rb/Sr ratios.
(A) Weathering profiles in the studied area. (B) cited profiles in Guizhou province. (Data of profiles PB were derived from Ji and Wang [93]; data of profiles QZ–I, QZ–II, QZ–III and BY are from Liu et al. [62]).
Fig 9.
Global paleogeographic reconstruction in the Permian and the Late Triassic.
NC: North China, SC: South China (after Scotese and Ziegler [96]).