ABSTRACT During the Late Miocene and Pliocene, northern Belgium and the Netherlands occupied the southern margin of the North Sea Basin, which was progressively infilled by a (north‐)westward migrating deltaic system. To date, the regional evolution and continuity of this system—transitioning from northern Belgium during the Late Miocene to the central Netherlands in the Pliocene—remain poorly constrained. This study clarifies this spatio‐temporal transition utilizing a well‐log correlation panel tied to biostratigraphically calibrated wells. The transect demonstrates that Upper Miocene successions, which attain thicknesses of up to 60 m in northernmost Belgium, pinch out northward and are completely absent in the southern Netherlands. Regional mapping reveals that the Upper Miocene deltaic progradation terminated just north of the Belgian–Dutch border along a roughly E‐W‐trending line. During the early Zanclean (Early Pliocene) transgression, a thin (5–10 m) sequence of Lower Pliocene fine‐grained sands was deposited above the relict delta topsets in northern Belgium. Northward and distal to this relict delta system, the Lower Pliocene units exhibit higher glauconite concentrations, probably reflecting increased depositional depths. Although these distal units locally thicken to 20–30 m, they failed to completely consume the available accommodation space. Complete infilling occurred during the late Zanclean to early Piacenzian, when deltaic progradation resumed with the deposition of highly bioclastic, coarsening‐upward sands. This shell‐rich unit remains thin (~4 m) where it overlies the relict Upper Miocene delta topsets in the south, but rapidly thickens to over 70 m as it filled the residual accommodation space further north. Because the residual accommodation space was largely filled by the early Piacenzian, subsequent younger Piacenzian sequences are significantly thinner and register a transition to a shallower‐marine depositional environment that covered a vast area across northern Belgium and the southern Netherlands.
ABSTRACT Surma Basin in northeastern Bangladesh contains a thick Cenozoic sedimentary rock succession, offering a valuable record of the tectono‐sedimentary evolution from the Eocene to Mio‐Pliocene. This study combines lithology, organic matter (OM) geochemistry and elemental composition of sedimentary rocks to assess sediment and OM sources, depositional environments and tectonic influences. Geochemical proxies, including TOC (0.02%–2.68%), C/N (0.15–26.34), C/S (0.36–11.36) and δ 13 C (−26.50‰ to −23.42‰), indicate variable depositional settings and OM sourced from both marine to terrestrial origins. MFW and A–CN–K diagrams, along with weathering indices (CIA: 62.2%–89.7%, ICV: 0.32–1.16, K 2 O/Na 2 O: 1.36–7.50), reveal moderate to intense chemical weathering and sedimentary rocks form primarily from felsic to intermediate rock in humid climatic conditions. Tectonic discrimination diagrams show a transition from passive to active continental margin settings, linked to the Himalayan uplift and evolving monsoonal regimes. Lithological and geochemical records indicate that Sylhet Limestone Formation was deposited in a stable shallow shelf, the Kopili Shale Formation in an outer continental shelf to deltaic environment and OM originating from nearby landmasses. Subsequent basin subsidence adjacent to the uplifted Himalayas resulted in rapid deltaic to fluvial sedimentation of the Barail (Renji) Sandstone Formation. Global sea‐level changes along with continued Himalayan uplift, intensified monsoonal activity, influenced the deposition of the Bhuban and Boka Bil formations, Tipam Sandstone Formation and Girujan Clay Formation in outer shelf deltaic to fluvial–lacustrine systems. Tectonics, monsoonal activity and sea‐level fluctuations collectively affected basin evolution, sedimentation and OM preservation over time.
ABSTRACT The Wangmushan mining district (WMD) in the Southeast Coastal Volcanic Belt (SCVB) of South China provides an excellent natural laboratory to constrain Late Mesozoic crustal architecture and tectonomagmatic evolution. Here, we present zircon U–Pb geochronology, whole‐rock geochemistry and Sr–Nd–Pb–Hf isotopic data for ore‐bearing rhyolitic ignimbrite (RI) and barren K‐feldspar granite porphyry (KGP) from the WMD to explore their petrogenesis and tectonic setting. Zircon U–Pb dating yields ages of 173.8 ± 0.8 Ma for the RI and 102.6 ± 0.4 Ma for the KGP, recording two distinct magmatic episodes. Both suites show enrichments in large‐ion lithophile elements (Rb, U, Th, K, Pb) and light rare earth elements, coupled with depletions in Nb, Ta, Ti, P and heavy rare earth elements, indicating subduction‐zone/arc geochemical affinities. The Middle Jurassic RI displays enriched Sr–Nd–Pb–Hf isotopes ( ε Nd (t) = −13.3 to −11.3; zircon ε Hf (t) = −22.5 to −10.8) with crustal Pb isotopic signatures. In comparison, the Early Cretaceous KGP has less negative ε Nd (t) (−9.2 to −8.3) and zircon ε Hf (t) (−9.6 to −6.5), alongside more radiogenic Pb isotopes trending toward EMII. The RI originated mainly from partial melting of Early Paleoproterozoic Cathaysia basement under continental extension, whereas the KGP formed via melting of Paleo–Mesoproterozoic basement mixed with significant juvenile lower‐crustal melts in a comparable extensional regime. Combined with the spatial–temporal pattern of Jurassic–Cretaceous arc magmatism across the SCVB, we suggest that RI magmatism relates to the breakup and foundering of a Middle Jurassic flat slab, and the KGP formed during enhanced lithospheric extension driven by Paleo‐Pacific slab rollback.
ABSTRACT The well‐exposed Middle Miocene reefal carbonates of Wadi Kharaza (Gebel Abu Shaar), along the southwestern coast of the Gulf of Suez, Egypt, provide an excellent outcrop analogue for investigating the development and distribution of porosity in the subsurface Nullipore reservoir. Field observations and petrographic analyses reveal that secondary porosity varies considerably within the reef framework and represents an important contributor to reservoir heterogeneity. Among the recognized biogenic features, bioerosion—predominantly represented by the Trypanites Ichnofacies—appears to have played a significant role in porosity development through the generation of secondary voids and the modification of the primary skeletal framework. In addition, dissolution of coral colonies and molluscan shells contributed to secondary porosity, although some dissolution cavities were subsequently partially or completely occluded by calcite cement, locally reducing reservoir quality and pore connectivity. These findings highlight the interplay between reservoir‐enhancing processes, particularly bioerosion and dissolution and reservoir‐deteriorating processes such as calcite cementation, which together control porosity development and reservoir heterogeneity. The correlation between the Middle Miocene reefal carbonates of the surface outcrops and the Nullipore reservoir of the Gulf of Suez may act as a framework for evaluating how the observed surface facies and pore‐system characteristics may help constrain the subsurface reservoir architecture and heterogeneity.
ABSTRACT Accurate landslide susceptibility assessment in mountainous regions is often constrained by the reliance on static environmental factors and by spatial discontinuities in SBAS‐InSAR‐derived deformation caused by decorrelation. To address this widely encountered problem in vegetated and topographically complex landslide‐prone regions, this study proposes a potentially transferable workflow for static‐deformation‐informed landslide susceptibility assessment that integrates SBAS‐InSAR deformation reconstructed using a standard random forest (RF) regression model with ensemble machine learning. Wanzhou District, Chongqing, China, located within the Three Gorges Reservoir Area, was selected as a representative mountainous study area influenced by reservoir‐related hydrological processes. Mean line‐of‐sight deformation rates were retrieved from ascending Sentinel‐1A SAR images acquired between January 2020 and December 2024. Fifteen static conditioning factors and a historical landslide inventory were compiled, and RF regression was used to reconstruct deformation in low‐coherence areas. The reconstructed deformation field was then incorporated as a multi‐year deformation‐based conditioning factor into landslide susceptibility modelling. Four models, including RF, XGBoost, LightGBM, and Stacking, were developed under static‐only and static‐deformation‐informed scenarios. The results show that incorporating InSAR‐derived deformation generally improved model performance, with the InSAR–Stacking model achieving the highest AUC of 0.9082. Frequency ratio analysis indicated that historical landslides were more strongly concentrated in high‐ and very‐high‐susceptibility classes under the static‐deformation‐informed framework. SHAP analysis further confirmed that deformation provides complementary information beyond conventional static factors. Overall, the proposed framework improves susceptibility mapping accuracy and can be adapted as a methodological reference for dynamic landslide hazard identification and risk management in mountainous and reservoir‐bank environments.
