Subsurface structure of the Tecocomulco sub-basin (northeastern Mexico basin), and its relationship to regional tectonics

Abstract

Gravity, magnetics, DC resistivity, VLF profiles, geologic mapping, and analysis of regional lineaments in the Tecocomulco sub-basin of the northeastern Mexico Basin were carried out. To the south, the structure is of the half-graben type. To the north, the basin gets wider. Three NW-SE faults bound the half-graben to the E while only one delimits it to the W. Faults delimiting the halfgraben, as well as several cinder cones and the neighboring ranges delimiting the basin, have a NE-SW orientation. The halfgraben structure is due to tilting towards the NW of regional shallow crustal blocks. A chain of cinder cones interrupts the southward surficial drainage towards the neighboring Apan Basin, but we infer a communication at depth between these two subbasins through a narrow graben. The faults in the Tecocomulco basin might still be active, as inferred by low-level seismic activity. DC resistivity helped to characterize the stratigraphic sequence of the volcano-sedimentary infill. The Acoculco caldera is not a piston-like caldera but a collapsed graben caldera. The Chichicuautla caldera has been downfaulted to the south by a NWSE fault. The gravity signature of the southern half of this caldera is masked by the presence of a structural high, or by mafic bodies.