Deformed River Sediments, High Himalaya Crystalline, Alakhnanda Valley, Gahrwal Himalaya
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| A psammitic sequence in the Pandukeshwar Fm, in the High Himalayan Crystalline sequence in the Alakhnanda valley shows an interesting sequence of sediments that underwent thrusting to the south and southwest accompanied by folding and anatexis, and still preserve numerous primary structures such as cross-bedding and possible channel scour and infill. |
Folded, distorted cross-bedding features
Cross-bedding in quartzite with little obvious distortion of the original beds. Younging downwards. Pandukeshwar Fm on the way to Malari, HHC. |
Cross-bedding in quartzite. Younging downwards. Note in situ partial melting on the lower left of the photograph forming a speckled Bt-leucosome. Pandukeshwar Fm on the way to Malari, HHC. |
Folded cross-bedding in quartzite. Younging downwards. Pandukeshwar Fm on the way to Malari, HHC. |
Cross-bedding in quartzite with distortion of the original beds to nearly perpendicular to the main layer. Younging downwards. Pandukeshwar Fm on the way to Malari, HHC. |
Cross-bedding in quartzite with distortion of the original beds to nearly perpendicular to the main layer. Younging downwards. Pandukeshwar Fm on the way to Malari, HHC. |
Folded cross-bedding in quartzite. Younging to right. Pandukeshwar Fm on the way to Malari, HHC. |
Folded cross-bedding in quartzite. Folds develop from right to left, notice tight folds in the far left. Pandukeshwar Fm on the way to Malari, HHC. |
 Metasomatic alteration around a band of possible calc-silicate comprising garnet, biotite, possible diopside in a quartz matrix. The alteration overprints pre-existing beds that are partly preserved as ghosts. Pandukeshwar Fm on the way to Malari, HHC. |
Folded cross-bedding in quartzite. Notice truncation of layers on the left by the darker layer. Pandukeshwar Fm on the way to Malari, HHC. |
 Folded cross-bedding in quartzite. Notice truncation of layers on the left by the darker layer. Pandukeshwar Fm on the way to Malari, HHC. |
Complex patterns: interaction between primary features and deformation
Possible example of a channel scour and fill, marked by the truncation of layers on the right, younging to the left. |
 Complex patterns: notice a possible change in the younging direction marked by cross-bedding from up at the bottom to downa at the top of the photograph. |
 Cross-bedding, younging downwards, plus complex patterns due to scour-and-fill. Bt-leucosomes sub-parallel to main bedding. |
 Detail. |
 Complex patterns due deformation, cut effects and in situ melting. |