A novel regional-residual separation approach for gravity data through crustal modeling

Abstract

Gravity anomalies normally contain information of all sources beneath Earth’s surface. Once residual anomalies exhibit information about the main target, the knowledge of this specific residual signal is extremely important to interpretation. To find this signal, it’s necessary to perform regional-residual separation. We present here a new approach of separation by using gravity crustal modeling. We divide the surface in prisms, with density given by GEMMA. We calculate the regional signal, assuming Earth’s crust can be the source of observed anomaly. This methodology was applied on Barreirinhas basin-Brazil. Its formation is related to geologic events in South America-Africa break. Besides, the complex geology is the main obstacle on finding the residual anomaly. We compare our methodology with robust-polynomial fitting and spectral analysis. They were not able to identify the residual anomaly. Main trouble relies on absence of crust information. Those kind of environment usually requires forward modeling and/or gravity inversion. On the other hand, our approach considers all crust’s parameters. Then the difficulty on choosing the residual no longer exists. The residual anomaly follows a geologic pattern. The crustal depocenter was mapped between structural faults. Therefore, our results satisfies the main expectation and are extremely linked to Barreirinhas basin’s geological background. We recommend this separation procedure, once Earth’s crustal model and gravity data are available for all planet.