# Diagenetic Study of Marron Emperador Ornamental Stone (Upper Cretaceous, SE Spain)
## 5 Discussion
### Breccitation Processes  
The brecciated bodies are stratiform on a large scale, with irregular limits and a great spatial continuity. The main types of breccias identified (crackle- and mosaic-clast-supported breccias and chaotic or rubble matrix-supported breccias) are widely represented in all sectors of the study area. These types are generally spatially associated at different scales and, in most cases (when more than two of these types coexist in an outcrop), it has not been possible to delimit separate geometric distributions. A main characteristic of these rocks, which even contributes to their aesthetic value as an ornamental rock, is that calcite crystalline cement surround the clasts. The formation of calcitic (and, to a lesser extent, dolomitic) fills in the form of venules reflects an extensive circulation of fluids through fractures that can occur in various phases of the genetic history of the materials, reflecting the origin and geochemical evolution of the materials and fluids during the thermotectonic evolution of the sedimentary basin [88, 89]. The existence and predominance (in 'crackle' and mosaic-type brecciated facies) of calcite venules and veins and the texture of their fillings (equidimensional or 'blocky' mosaics) provide data on the genesis of these materials:  
* In facies where cement dominate, regardless of the type of brecciation mechanism considered, a dilation process has occurred during fragmentation. In this sense, we could take into account the concept of dilation breccias [90]. * Blocky textures imply a filling of a pre-existing hole, contrary to the fibrous textures in venules that are indicative of filling during the opening of the fractures [91]. * Blocky textures also tend to indicate rapid brecciation [92]. The fibrous textures would be more indicative of a slow opening of holes or brecciation. * All textures are phreatic. Only textures that can be interpreted as vadose have been recognised in complex breccia types (e.g., Mv). * The predominant existence of a single cementation phase in all types of venules (different sizes and orientations, for example) favours the existence of a single and probably rapid fracturing phase (brecciation). However, by cathodoluminescence, it has been possible to observe some venules with more than one cementation phase. * Locally, transgranular fractures have been observed parallel to venules filled by one or more cement phases that could be related to crack-seal processes in which fluid overpressure plays a major role in their genesis [93, 94]. However, other typical textures, such as fibrous cements, calcite bridges, etc., have not been observed [95, 96, 97, 98]. Multiple phases of calcitic cementation are recognised, in some cases taking advantage of or leaning on previous dolomitic cements. Figure 2D-G illustrate smaller calcite venules arranged parallel to the main dolomitic-calcitic vein. All types of breccias recognised in this study have been described in different contexts and attributed to various genetic mechanisms, from intraformational breccias by the dissolution of interbedded evaporites in the series, to fault breccias or breccias of hydrothermal origin [9, 46]. In themselves, these typologies, based mainly on the degree of concentration of clasts and the degree of fit between them, do not indicate a specific origin for each one of them. However, the high degree of clast fit and gradation between types is a clear argument for a diagenetic origin [99]. The lack of evidence of evaporite dissolution, the nonstratiform geometry of the breciated bodies or the compositional homogeneity of the matrix in the breciated facies exclude a penecontemporaneous origin, by collapse (evaporite dissolution) or karstic dissolution, for the breciated dolostones.