Fold interference patterns in Meso-Proterozoic Champaner fold belt (CFB) Gujarat, western India

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This paper documents three phases of folding within the Meso-Proterozoic Champaner Fold Belt (CFB) located at the eastern part of Gujarat, western India. The first phase ( $$\hbox {F}_{1})$$ displays WNW plunging $$\hbox {F}_{1}$$ fold of moderately inclined nature in the schists of the Khandia Formation. The second phase ( $$\hbox {F}_{2})$$ refolded $$\hbox {F}_{1}$$ along a similar trend to produce folds of tight isoclinal nature in the Khandia and Narukot quartzites. Additionally, these $$\hbox {F}_{1}$$ folds depict second-order tight, and $$\hbox {F}_{2}$$ folds as first-order open type in the younger sequences of the CFB with varying amplitude vs. wavelength ratio. The ratio for $$\hbox {F}_{1}$$ folds ranges from 2:1 to 3:1, obtained along 3–4 m length across 3–6 $$\hbox {m}^{2}$$ area, whereas for $$\hbox {F}_{2}$$ folds the ratio ranges from 1:4 to 1:5 and is obtained along 1–2.5 km length across 0.5–1.5 km $$^{2}$$ area. The fold interference pattern developed on account of $$\hbox {F}_{1}$$ and $$\hbox {F}_{2 }$$ folds has resulted into Type-III or hook-shaped geometry regionally. The last phase of folding is characterised by N–S trending $$\hbox {F}_{3}$$ folds of open type over kilometre long limbs of $$\hbox {F}_{1}$$ and $$\hbox {F}_{2}$$ folds. The superposition of $$\hbox {F}_{1-3 }$$ folds developed map scale Type-I or Dome and Basin geometry over Type-III superposed folds. The overall compressional direction for $$\hbox {F}_{1}$$ and $$\hbox {F}_{2}$$ folds ranges from N–S to NNE–SSW and for $$\hbox {F}_{3}$$ ranges from E–W to ESE–WNW.