Abstract
Nighttime transient geomagnetic variations recorded by an array of 29 magnetometers in the equatorial region of north-northeast Brazil have been subjected to robust regression analysis in order to derive transfer functions as a diagnostic indication of lateral conductivity variations. A thin sheet conductance model was developed to explain and interpret the variety of conductive anomalies evidenced by the induction arrow maps. The two main structures revealed by the present study are: a large NE-SW trending conductive anomaly with an embedded resistive zone in the central part of the Parnaiba Basin (Parnaiba Basin Conductive Anomaly-PBCA) and a relatively weaker anomaly branching off from the northwestern corner of the PBCA and extending towards the Marajo basin (LINK anomaly). The major PBCA anomaly is provisionally interpreted as a graben in the Precambrian basement filled with carbonaceous carbonates. The embedded resistive body, also characterized by a high density, is shown to be consistent with the presence of a diabase intrusive related to a magmatic event. The LINK anomaly is tentatively considered to be the relics of a sedimentary channel connecting the Parnaiba and Marajo basins.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
