Deep Gravity Interpretation by Stripping

Abstract

“Old gravity data never die.” Review interpretations of gravity surveys can be made whenever warranted by new geological concepts, development information, or improved techniques. Important additional uses can be gained by extending the interpretation to deeper horizons by calculating and subtracting the gravity effects of overlying strata whose structure becomes known in detail from shallower development. This constitutes the new technique reported in this paper. An essential new factor which makes gravity “stripping” practicable is the advent of the gamma‐gamma density log which determines subsurface density relations in strata penetrated by development drilling. Combined stratigraphic and density information defines the mass anomalies in the upper strata. Subtracting the calculated shallower gravity influences improves the definition of the deeper gravity prospects. Applications of the method are illustrated by selected examples.

Mantle origin of the Emeishan large igneous province (South China) from the analysis of residual gravity anomalies

“…Therefore, although the topography and free-air effects have been removed from the Bouguer gravity, in order to isolate the gravity response of Emeishan LIP we have to remove other gravitational effects, in particular those caused by the sedimentary cover, crystalline basement, the undulation of the upper crust, Moho and the lithosphere. This sequential procedure, referred to as stripping, was first described by Hammer (1963) and later developed by other authors (Bielik, 1988;Bielik et al, 2013a, b;Mooney and Kaban, 2010). Low-density sediments result in a negative gravity anomaly relative to the crystalline crust.…”

Un modelo gravimétrico 3D de la profunda cuenca sedimentaria de Ischigualasto-Villa Unión (San Juan y La Rioja)-Argentina

“…Con el propósito de normalizar la respuesta gravimétrica de la corteza superior, se efectuó una corrección geológica tentativa (Hammer, 1963;Introcaso, 1989). Esta consistió en descontar de la Carta de Anomalías de Bouguer (Fig.…”

Bathymetric stripping corrections to gravity gradient components

“…In geophysics, this step is well known as gravity stripping (e.g., Hammer, 1963). The gravitational field generated by the ocean density contrast (relative to an adopted mean Earth's density) represents a significant amount of the gravitational signal to be modeled and subsequently removed from observed gravity data.…”