Articles
Bagherpour, B.,
Faghih, A.,
Vaziri moghaddam, H.,
Mehrabi, H.,
Zare, M.,
Immenhauser, A. Sedimentary Geology (00370738)486
Basement highs and adjacent basins are significant structural elements controlling regional facies architecture. Overprinted by fluctuating sea-levels, the correlation of facies units from the crest into the flank environments is often challenging. Here, a case example of an upper Turonian–lower Campanian palaeohigh on the northeastern margin of the Arabian Plate is presented. Two stratigraphic sections (Jarhum and Qazi, respectively) compare the depositional dichotomy between crest and flank. The palaeohigh Jahrum section documents a deepening upward succession that includes brackish carbonates at the base, followed by shallow–marine carbonates, and culminates in basinal deposits. The sedimentary record of Santonian deposits in the Qazi section (flank) comprises stratigraphically thick calciturbidites, calcidebrites, slump folding, clinoforms, and channel-fill deposits, which conformably overlie deep-water deposits. This case study provides insights into processes that are rarely documented in the Tethyan realm. Data shown here exemplify the interaction between regional uplift (related to tectonic inversion) and eustatic sea–level changes. The regional correlation of the facies architecture highlights important lateral variations in facies and stratigraphic thickness controlled by bathymetry and seafloor inclination related to the geometry of the palaeohigh. We suggest that the redeposited carbonates described here are characteristic of tectonically active intervals along slope settings. Furthermore, we demonstrate that sustained carbonate production on unrimmed, distally steepened ramps supports the deposition of calciclastics. The data presented are crucial for understanding redeposition processes in Cretaceous carbonate systems along the Arabian margin and beyond. © 2025 The Author(s)
Rajabi A.,
Mahmoodi P.,
Alfonso P.,
Canet C.,
Andrew C.,
Azhdari S.,
Rezaei S.,
Alaminia, Z.,
Tamarzadeh S.,
Yarmohammadi A.,
Khan Mohammadi G.,
Saeidi R.,
Sattari, E.,
Bahrami, A.,
Vaziri moghaddam, H.,
Taheri a., A. Minerals (2075163X)(7)pp. 1-25
Iran hosts more than 350 Precambrian to Cenozoic sediment-hosted Zn-Pb±Ba and barite-sulfide deposits, including shale-hosted massive sulfide (SHMS, also called SEDEX) and Irish-type and Mississippi Valley-type (MVT) mineralization, and barite is a common mineral in these deposits. In the SHMS deposits, barite is typically found as fine-grained disseminations in thin laminae. In these deposits, the sulfide laminae often occur as diagenetic replacements and as bands containing authigenic and diagenetic barite and pyrite framboids. In the Irish-type Zn-Pb-Ba and stratabound barite-sulfide deposits, barite exhibits various textures, including fine-grained disseminated barite, banded zebra textures, veins, and massive barite lenses. In some of the giant Irish-type deposits, as well as in the stratabound barite-sulfide mineralization, the main stratabound sulfide ore is developed within a barite envelope and is characterized by the replacement of barite and pyrite by chalcopyrite, galena, and sphalerite. In the MVT deposits, the formation of barite is often related to dolomitization, and sulfide mineralization involves the replacement of the dolomitized carbonate rocks, as well as associated barite. Fluid inclusion studies on the Irish-type deposits indicate that the temperatures and salinities of the sulfide-forming fluids are higher compared to those of the barite-forming fluids. Fluid inclusion analyses of coarse-grained barites from Irish and MVT deposits reveal their hydrothermal origin. The δ3⁴S values of sulfide minerals (pyrite, sphalerite, and galena) in Irish-type deposits exhibit a broad range of low values (mostly −28 to +5‰), primarily revealing a process of bacterial sulfate reduction (BSR). However, the textures (replacement, colloform, and banded) and more positive sulfur isotope values (+1 to +36‰) in the SHMS Zn-Pb deposits suggest that bacterial sulfate reduction (BSR) plays a less significant role. We suggest that thermochemical sulfate reduction (TSR) connected to the direct replacement of barite plays a more relevant role in providing sulfur for the sulfide mineralization in the SHMS, barite-sulfide, and MVT deposits. Based on the textual evidence, sulfur isotopic data, and fluid inclusion studies, barite has been identified as a key controller for the subsequent Zn-Pb mineralization by providing a suitable host and significant sulfur contribution in the sediment-hosted Zn-Pb and stratabound barite-sulfide deposits. This implies that diagenetic barite might be a precursor to all types of sediment-hosted Zn-Pb mineralization. © 2024 by the authors.
