Supplementary for FcIM3D
Description
We introduce a novel algorithm, termed the "Forward Calculation of the Intelligent Mesh Grid-FcIM3D" designed to unveil intricate deep-density structures by modeling Bouguer gravity data with minimal prior constraints. The algorithm employs upward continuation to decompose the gravity field into signals at various levels, spanning a range of wavelengths from short to long. Subsequently, it analyzes the amplitude of the real part for each level and utilizes the results to estimate the dimensions of the geometric underground 3D mesh. This involves the application of radially averaged power spectrum moving windows. Ultimately, a forward formulation is employed to compute the 3D density for the subsurface 3D mesh grid. To assess the algorithm's efficacy, several synthetic tests were conducted, demonstrating its capability to recover complex anomalous features. Subsequently, we applied the algorithm to a combination of satellite and ground gravity data in northwestern Iran. Through a comparative analysis with a high-resolution velocity cross-section obtained from ambient noise tomography, we demonstrate the algorithm's effectiveness. Our findings confirm that the uppermost mantle of the Arabian plate in the Zagros collision zone and South Caspian basin exhibit higher density, in contrast to the lower density uppermost mantle beneath Central Iran. Additionally, we uncover a crustal-scale low-density shear zone between the underthrusting Arabian plate and the overriding Central Iran, a feature notably challenging to identify using previous methods. The FcIM3D Matlab Code is located in the folder named "FcIM3D Matlab Code" This folder encompasses the comprehensive Matlab code for FcIM3D, along with both real and synthetic gravity data. Within the "GCBSatGround2670Vox" folder, you'll find the 3D model representing knitted Bouguer ground gravity data (NCC), coupled with Bouguer gravity data sourced from global 1-minute grids (https://topex.ucsd.edu/cgi-bin/get_data.cgi). Output figures generated by the FcIM3D Matlab code for knitted Bouguer ground gravity data (NCC), integrated with Bouguer gravity data from global 1-minute grids (https://topex.ucsd.edu/cgi-bin/get_data.cgi), located in the "OutputGCBSatGround2670" folder. The "RealData" folder contains "GCBSatGround2670.mat," a dataset that includes knitted Bouguer ground gravity data (NCC) and satellite Bouguer gravity data (https://topex.ucsd.edu/cgi-bin/get_data.cgi). For synthetic testing purposes, you can explore the "SyntheticTest 1, 2, and 3" folders, each housing 3D models for synthetic tests 1, 2, and 3.