Duration measurement in geological sciences — A geophysical approach

There are two ways of measuring the time structure of geological events: the time-point at which an event occurred and its duration. Although the isotopic geochronological method, after nearly a century of development, is now a mature approach to the time-point measurement of a geological event (generally with a precision of a millions years error), it is incapable of measuring its duration. The measurement of a geological event from beginning to end requires an insight into structural geochronology, a new field at the forefront of international research. A geophysical approach was thus proposed (generally with a precision of 104 years error ). The approach can be divided into four steps: tectonic-geological work — observation of order and intensity of tectonic reworking; tectonic-physical work — measurement of differential stress and strain rates, a basic component in geological dating; tectonic-chemical work — calculating volumetric factors of deformed geological bodies; and tectonic-mathematical work — calculating the duration of structure formation. The approach has been applied to the study of the ductile zone in East and Southwest China and some results have been achieved. The approach is not yet mature and further improvement is needed for it to qualify as an effective theory of structural geochronology. The prospects of structural geochronology were given and its application limitations were pointed out.