DOI: 10.5061/dryad.280gb5mx9
title: Data for: Cross-folding in the North Singhbhum Mobile Belt by tectonic relaxation: insights from scaled laboratory modelling

description: Mechanism of formation of  'cross folds' in orogenic
 belts is still unclear. In this study we focus on cross- folds (Ft) from
 North Singhbhum Mobile Belt (NSMB), India and try to understand the
 kinematics of their formation through structural mapping and laboratory
 modelling. The  outcrop scale Ft folds and associated fabric (St)
 show a NE-SW trend in the eastern flank of NSMB. Analogue experiments were
 also conducted to replicate the Proterozoic southward convergence in NSMB.
 To quantitatively understand the deformation in the laboratory model, we
 analyzed the strain and model upper surface topography at different stages
 of the experiment. The data collected in field and during the analysis of
 experiments are presented in the current data repository along with one
 video of the experiment.
description: For analysing the field structures, orientation of
 the cross-folds and fabrics was collected using clinometer.
 We use a high-resolution camera for collecting the experimental
 photos at regular intervals. The velocity field of the model was
 calculated using particle image velocimetry technique in PIVLab software.
 The velocity data was further processed in grid_strain MATLAB toolbox to
 get the eigenvalues of the deformation matrix. The
 topography of the model upper surface was analyzed using a laser
 scanner.
description: # Data for: Cross-folding in the North Singhbhum Mobile Belt by tectonic
 relaxation: insights from scaled laboratory modelling Provenance for this
 README --- * Authors: Ayan Patsa * Other contributors: Nandini Choudhury,
 Atin Kumar Mitra, Nibir Mandal * Date created: 2024-02-21 * Date modified:
 2024-02-21 Dataset Version and Release History --- * Current Version: *
 Number: 1.0.0 * Date: 2024-02-21 * Persistent identifier:
 [https://doi.org/10.5061/dryad.280gb5mx9](https://doi.org/10.5061/dryad.280gb5mx9) * Summary of changes: n/a Dataset Attribution and Usage --- * Dataset Title: Data depository of manuscript titled "Cross-folding in the North Singhbhum Mobile Belt by tectonic relaxation: insights from scaled laboratory modelling" * Persistent Identifier: [https://doi.org/10.5061/dryad.280gb5mx9](https://doi.org/10.5061/dryad.280gb5mx9) * Dataset Contributors: * Creators: Ayan Patsa, Nandini Choudhury, Atin Kumar Mitra, Nibir Mandal * Date of Issue: 2024-02-21 * License: CC0 1.0 Universal (CC0 1.0) Public Domain Dedication * Citation: Patsa, Ayan; Choudhury, Nandini; Mitra, Atin Kumar; Mandal, Nibir (2024), Data for: Cross-folding in the North Singhbhum Mobile Belt by tectonic relaxation: insights from scaled laboratory modelling, Dryad, Dataset, [https://doi.org/10.5061/dryad.280gb5mx9](https://doi.org/10.5061/dryad.280gb5mx9) Contact Information --- * Name: Ayan Patsa ([https://orcid.org/0009-0007-3386-2060](https://orcid.org/0009-0007-3386-2060)) * Affiliations: Department of Geological Sciences, Jadavpur University, Kolkata, India 700032 * ORCID ID: 0009-0007-3386-2060 * Email: [ayan1166@gmail.com](mailto:ayan1166@gmail.com) Acknowledgements --- Authors acknowledge The DST-SERB for supporting this work through the J.C.Bose fellowship (SR/S2/JCB-36/2012) to NM. Files Overview --- * File count: Data file: 3, Supplemental Files: 1 * File formats: .xlsx, .mp4 * Range of individual file size: 10 KB to 25 MB Table of Content --- Data files --- 1. Foliation_data.xlsx 11 KB - provides the orientation of the orogen-transverse foliation (St) from four different locations of the study area. 2. Foldaxes_data.xlsx 10 KB -provides the orientation of the fold axes of the orogen-transverse folds (Ft) from four different locations of the study area. 3. Principalstrainvalues.xlsx 12 KB -provides the temporal variation of the principal stretching rates and directions of five different points (A-E) of the Exp-1 model. Supplemental Files 1 --- 1. Exp1video.mp4 25 MB -shows the video of the whole model during experimental run in Exp-1. * Recommended software/tools: Microsoft excel 2021, Windows Media Player Data Types --- Two types of data sets (a) *Field data of foliation and fold axes , (b) *Experimental model data of principal strain rate values*. (a) *Field data*: We measured the orientations of orogen-transverse foliation (St) and fold axes (Ft) from different locations of the eastern flank of the North Singhbhum Mobile Belt using clinometer and Brunton compass. Orientation of the foliation (strike, dip, dip quadrant) and fold axes (trend, plunge) are provided in the two separate .xlsx files . (b) *Experimental data* We performed scaled analogue model experiments to understand the strain evolution in the eastern flank of the North Singhbhum Mobile belt. The NSMB model was shortened in three stages (Stage I (2.6 cm/yr), II (1.56 cm/yr) and III (0.16 cm/yr)). To derive the velocity and strain field, successive top-view photographic images of the models were captured at a regular time intervals. The principal strain rate values and their orientations at five different points in the model (A,B,C,D and E, shown in the main manuscript and coordinates (x, y) provided in the table) is given as table. One video of the experiment (Exp-1) is also provided. To work with the provided data sets one can directly use the .xlsx files to plot or analyze. Description of the Data and file structure --- Data files --- 1.Details for: Foliation_data.xlsx --- * Description: a Microsoft Excel spreadsheet file containing the orientation of orogen-transverse fabric (St) from different locations of the study area. St strike, St dip and St dip quad represents the strike, dip and dip quadrant of the orogen-transverse fabric. * Format(s): .xlsx * Size(s): 11 KB * Dimensions: 105 rows x 4 columns * Variables: Location, St strike, St dip, St dip quad Location: This shows the places of our geological field observations in and around Ghatsila, India (22.5862° N, 86.4773° E). St strike: It represents the trend of orogen-transverse foliation (St) at different locations. Strikes are measured using clinometer and brunton compass. St dip: It represents the dip amount of orogen-transverse foliation (St) at different locations. Dips are mostly measured using clinometer. St dip quad: This shows the direction of dip of St foliation planes. 2.Details for: Foldaxes_data.xlsx --- * Description: a Microsoft Excel spreadsheet file containing the orientation of orogen-transverse folds (Ft) from different locations of the study area. Ft trend and Ft plunge represents the plunge direction and plunge amount of the orogen-transverse fold axes. * Format(s): .xlsx * Size(s): 10 KB * Dimensions: 70 rows x 3 columns * Variables: Location, Ft trend, Ft plunge * Location: It shows the places of our geological field observations in and around Ghatsila, India (22.5862° N, 86.4773° E). Ft trend: This represents the trend of orogen-transverse folds (Ft) at different locations. Trends are measured using clinometer and brunton compass. Ft plunge: It represents the plunge amount of orogen-transverse folds (Ft) at different locations. Plunges are mostly measured using clinometer. 3.Details for: Principalstrainvalues.xlsx * Description: a Microsoft Excel spreadsheet file showing the evolution of principal stretching rates (ISAHmax and ISAHmin) and the orientations of ISAHmax with time at five different points (A-E, coordinates (x, y) provided in the table) in the eastern flank of the model S-NSMB. * Format(s): .xlsx * Size(s): 12 KB * Dimensions: 96 rows x 8 columns * Variables: Exp. time (s), Time (Ma), Points, x (m), y (m), ISAHmax (1/s),ISAHmin (1/s), ISAHmax trend Exp. time (s): It shows the time passed (in seconds) since the start of the experiment. The values represent different stages of the experiment. Time (Ma): It represents the upscaled natural values of the time passed (in Ma) since the start of the experiment. Points: This represents the names of five points, whose movement and strain field were tracked during the experiment. x (m): It represents the x-coordinates (in meter) of the five points at different stages of the experiment. y (m): It represents the y-coordinates (in meter) of the five points at different stages of the experiment. ISAHmax (1/s): This represents the maximum horizontal stretching rates (in 1/s) at the points (A-E) at different times. These values were measured by Particle Image Velocimetry (PIV) analysis of the experimental photos. ISAHmin (1/s): This represents the minimum horizontal stretching rates (in 1/s) at the points (A-E) at different times. ISAHmax trend: It shows the trend of maximum stretching rates at the points (A-E) at different stages of the experiment. The trends are measured with respect to the longitudinal direction of the experimental box. Supplemental Files --- Details for: Exp1video.mp4 --- *Description: a MPEG-4 AVC ( advanced video coding) file showing the video of Exp-1. The experimental box is 34 cm in length and 31 cm in width. The model is shortened at three stages with varying shortening velocities. During the initial stages (Stage I & II) the model develops grossly southward flow. However, reduction in shortening velocity in stage III causes a southeastward flow from the northwestern part of the model (north is towards the upper side of the model). *Format(s): .mp4 * Size(s): 25 MB