What Is a Dissolvable Suture?

A special planar structure in rocks produced by pressure-dissolution. Under the action of pressure, the soluble matter of the rock migrates with the fluid, and the insoluble residual matter precipitates along the pressure-dissolved surface. Because the pressure-dissolved surface is in an obvious state of unevenness, the suture line, which looks like a skull, is also called a stylolite when viewed from the side. The tapered or cylindrical fine teeth on the suture surface are generally 3 to 10 mm high, and the direction of the fine teeth is parallel to the direction of the maximum principal stress. Based on this, the direction of the principal compressive stress can be judged. The rocks prone to suture structures are mainly carbonates. Undoubtedly, volume loss occurred in the jointed rock along the suture line, and sometimes the lost volume (thickness) can be estimated based on the residual part of the fossil after pressure dissolution. ^[1]

The so-called suture joint is an irregular, jagged discontinuous surface in some rocks. Its contour is similar to a meridian line. It is often clearly visible because of the concentration of chlorite minerals and some opaque minerals on it. This structure is particularly found in limestone, because after a new stress increase occurs, limestone is prone to dissolve, resulting in relative enrichment of residual minerals. Sawtooth may be the product of differences in dissolution rate, which in turn depends on the uneven distribution of poorly soluble impurities.

The cause of suture-like joints is relatively special, and it is mostly perpendicular to the stress 1 direction, that is, the sawtooth in the suture points. Therefore, suture-like joints often appear perpendicular to the tensile rupture, but this is not always the case, especially when the suture develops along the fault, and its zigzag direction indicates the direction of displacement, that is, the rubbing on the fault direction. ^[2]