Exploration of Shallow-Marine Carbonate Micritization Styles: Arabian Plate Coasts (Red Sea, Arabian Sea, and Arabian Gulf) Available to Purchase

In numerous Middle Eastern carbonate reservoirs, peloidal wackestone–packstone–grainstone facies deposited in shallow-marine environments are rock types with excellent pore storage potential in microporous and micritic/micritized grains. While the origin of microporosity has been extensively studied, the process of early marine micritization remains unclear. One hypothesis suggests that early marine micritization first alters carbonate microtextures, which then facilitates the formation of micro-spar and micropores in the micritized sediments during subsequent diagenetic processes in the subsurface. Therefore, a better understanding of the origin and spatial distribution of micritized sediments is essential for accurately predicting the distribution of microporosity in limestones. This study examines micritization products in shallow-marine carbonate sediments from four lagoons on the Arabian plate coast: the Red Sea, Arabian Sea, and Arabian/Persian Gulf. Micritized grains are identified and char acterized using optical and backscattered scanning electron microscopy. Petrographic observations are compared and correlated with oceanographic and environmental parameters to identify micritization styles and environmental conditions at a regional scale. The findings present several key insights: (i) cryptocrystalline micritic microtextures are heterogeneous, characterized by a combinations of microborings and various microboring infill materials, (ii) Red Sea and Arabian Gulf sediments are predominantly composed of micritized grains (60% of the grains are micritized grains/peloids), whereas Arabian Sea coast sediments are primarily microbored with minimal infill of endolithic tunnels and rare cryptocrystalline microtextures; and (iii) the arid climate and warm, restricted oligotrophic seawater of the Red Sea and Arabian Gulf promote micritization processes. Conversely, the relatively cooler seawater of the Arabian Sea, largely open to the Indian Ocean and influenced by the Southeast Asian monsoon and associated upwelling currents, promotes intense endolithic activity but limited boring infilling (incomplete micritization). Hence, we show for the first time that the early marine and microbial diagenetic process of micritization relate to a well-defined set of regional environmental and oceanographic settings parameters, corresponding to those that also promote the tropical-biochemical carbonate factory.