Morphometric analysis of Proterozoic stromatolites from India — preliminary report on testing of a new technique

Abstract

A recent technique of image analysis of stromatolite laminae has been tested on Proterozoic stromatolitic assemblages in the Aravalli dolomite of Udaipur and Jhabua, the Bhagwanpura limestones of Chittorgarh, the Bilara carbonates of Jodhpur and the Raipur limestones of the Chattisgarh region. The technique involves tracing of the upper lamina boundary of each stromatolite column which permits measurements of different profile shape attributes such as area, length, width, vertical and horizontal intercepts and profile inclination. The numerical data so generated were subjected to statistical analysis. Cluster analysis by the pair group method shows mutually correlatable cluster centres. Dendrograms based thereon have been drawn to depict the nature of correlation. Four major groupings of lamina shape have been recognized: (1) highly convex, (2) flattened convex and irregular shape, (3) erect, highly convex to conical, and (4) horizontal development of flattened laminae. Successful correlation between stromatolites of the Bhagwanpura limestone (Chittorgarh), the Bilara Formation (Jodhpur) and Raipur (Chattisgarh) and negative correlation between the Aravalli stromatolites of Udaipur (Rajasthan) and Jhabua (Madhya Pradesh) clearly indicate the biostratigraphic utility of morphometric analysis.