Origin and Characterization of Joints in Sedimentary Rocks: A Review

Discontinuities are ubiquitous in all rocks at different scales. Their characterization occupies a high ground in the field of geological research. Discontinuity abundance, strength, flow and frictional properties are matters of great interest to structural geologists, petroleum engineers (mostly in unconventional shale gas a nd oil production) , and civil engineers. Joints (opening mode fractures) are some of the most commonly observed rock discontinuities among others. Understanding joint origins from outcrops and other directly visible sources explain the presence of certain joints in the near and deep subsurface. We have summarized several tectonic and non - tectonic drivers behind joint origins and suggested the use of multiple supporting evidence while timing and causal interpretations are made. If particular subsurface joint sets may be traced back to the outcrops through the knowledge of their origins, the ir characteristics (length, aperture, height, abundance and interrelationships between these parameters) may be measured at the outcrops or using other data sources such as cores and image logs. Additionally, it is important to understand several non - visual data sources aiding in joint parameterization. This paper discusses the strengths and limitations of these direct (visual) and indirect (infere nce) data sources. In addition, we have summarized different methods for the quantification of the aforementioned joint related geometric and abundance parameters.