In South Asia, a region facing rapid economic growth, immense population pressure, and high climate vulnerability, the circular economy (CE) has become a critical imperative for sustainable development. This study provides a comparative overview of the CE landscape across eight South Asian countries: Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. The analysis reveals the CE transition is nascent region-wide, though India has advanced its policy landscape through a comprehensive suite of rules and missions and Pakistan is developing a national policy. The primary focus remains on waste management, evidenced by programs like Bhutan’s ‘Zero Waste by 2030’ vision, the Maldives’ Single-Use Plastic Phase-Out Plan, and Sri Lanka’s Clean Sri Lanka Programme. While Extended Producer Responsibility (EPR) is emerging for plastics and e-waste in India, Bangladesh, Sri Lanka, and Pakistan, a significant “policy-practice gap” persists, undermined by weak enforcement and governance fragmented across priority sectors like plastics, food systems, and textiles. Most major CE initiatives are catalyzed by international development partners, with regional programs playing a key role in funding innovation. Finally, while the informal sector is the backbone of material recovery, ensuring a just transition that improves working conditions and secures livelihoods remains a critical challenge. The absence of a cohesive regional framework limits collaboration. Scaling the circular economy in South Asia requires integrated national strategies, prioritizing a just transition for the informal sector, and establishing a regional platform for policy harmonization to create self-sustaining system through multi-sectoral involvement, including the business sector.

Porosity serves as a critical parameter in shale oil reservoir evaluation and resource quantification. Limitations in evaluation principles and shale heterogeneity lead to varying effectiveness among different methods. Moreover, solvent extraction may cause fluid retention, toxicity risks, and data distortion, compromising the accuracy of shale oil resource assessment. This study proposes the Shale-ΦT1/T2 (a nuclear magnetic resonance (NMR) method combining longitudinal relaxation and transverse relaxation for shale porosity) porosity evaluation methodology for conventional core shales as an innovative approach, using sealed core samples from the fourth member of the Shahejie Formation, Dongying sag as the study object. A NMR-based NMR-ΦT1/T2 model was established to characterize sealed core shale fluid porosity (Φtotal1), residual fluid porosity (Φ1) in conventional cores after surface exposure, and saturation-fluid porosity (Φ2) in pressurized-saturated shales. Total porosity (Φtotal2) is obtained by summing the two-stage results (Φ1 + Φ2). Results demonstrate high consistency between sealed core porosity (Φtotal1) and Shale-ΦT1/T2-derived porosity (Φtotal2), with error coefficients systematically decreasing as porosity increases. This method avoids core extraction and solvent-induced pore distortion, significantly improving detection efficiency. As an eco-friendly solution addressing fidelity challenges in shale porosity assessment, it can be rapidly adopted as a primary method for porosity determination in shale oil reserve evaluation and resource quantification.

Porosity serves as a critical parameter in shale oil reservoir evaluation and resource quantification. Limitations in evaluation principles and shale heterogeneity lead to varying effectiveness among different methods. Moreover, solvent extraction may cause fluid retention, toxicity risks, and data distortion, compromising the accuracy of shale oil resource assessment. This study proposes the Shale-ΦT1/T2 (a nuclear magnetic resonance (NMR) method combining longitudinal relaxation and transverse relaxation for shale porosity) porosity evaluation methodology for conventional core shales as an innovative approach, using sealed core samples from the fourth member of the Shahejie Formation, Dongying sag as the study object. A NMR-based NMR-ΦT1/T2 model was established to characterize sealed core shale fluid porosity (Φtotal1), residual fluid porosity (Φ1) in conventional cores after surface exposure, and saturation-fluid porosity (Φ2) in pressurized-saturated shales. Total porosity (Φtotal2) is obtained by summing the two-stage results (Φ1 + Φ2). Results demonstrate high consistency between sealed core porosity (Φtotal1) and Shale-ΦT1/T2-derived porosity (Φtotal2), with error coefficients systematically decreasing as porosity increases. This method avoids core extraction and solvent-induced pore distortion, significantly improving detection efficiency. As an eco-friendly solution addressing fidelity challenges in shale porosity assessment, it can be rapidly adopted as a primary method for porosity determination in shale oil reserve evaluation and resource quantification.

Astronomically forced climate cycles and hyperpycnal flow deposits are the forefront of contemporary geological research. Climate significantly influences the formation of hyperpycnal flows, with these changes being driven by astronomical cycles. However, the relationship between astronomical cycles and hyperpycnal flows has not been sufficiently explored. Additionally, although hyperpycnal flows can transport terrigenous clastic particles to the deep-water areas of basins, their impact on organic matter enrichment remains inadequately studied. Therefore, this study analyzed the characteristics of hyperpycnal flow deposits within the Chang 7 Oil Member (Chang 7 Member) in the southern Ordos Basin, assessed their frequency of occurrence, and investigated their correlation with long-eccentricity cycles. By examining the geochemical signatures and sedimentary accumulation rates (SARs) of different genetic types of deposits, this study also explored the controlling factors of hyperpycnal flows on organic matter enrichment. The analysis indicates that hyperpycnal flows within the Chang 7 Member exhibit periodic development, significantly influenced by long-eccentricity cycles. Hyperpycnal flows not only transport nutrients into the lake basin but also increase SARs, thereby facilitating the rapid burial of organic matter and promoting its enrichment. These findings underscore the significant role of astronomical cycles in governing the development of hyperpycnal flows and highlight their positive influence on organic matter enrichment.

Astronomically forced climate cycles and hyperpycnal flow deposits are the forefront of contemporary geological research. Climate significantly influences the formation of hyperpycnal flows, with these changes being driven by astronomical cycles. However, the relationship between astronomical cycles and hyperpycnal flows has not been sufficiently explored. Additionally, although hyperpycnal flows can transport terrigenous clastic particles to the deep-water areas of basins, their impact on organic matter enrichment remains inadequately studied. Therefore, this study analyzed the characteristics of hyperpycnal flow deposits within the Chang 7 Oil Member (Chang 7 Member) in the southern Ordos Basin, assessed their frequency of occurrence, and investigated their correlation with long-eccentricity cycles. By examining the geochemical signatures and sedimentary accumulation rates (SARs) of different genetic types of deposits, this study also explored the controlling factors of hyperpycnal flows on organic matter enrichment. The analysis indicates that hyperpycnal flows within the Chang 7 Member exhibit periodic development, significantly influenced by long-eccentricity cycles. Hyperpycnal flows not only transport nutrients into the lake basin but also increase SARs, thereby facilitating the rapid burial of organic matter and promoting its enrichment. These findings underscore the significant role of astronomical cycles in governing the development of hyperpycnal flows and highlight their positive influence on organic matter enrichment.

Quaternary sequence stratigraphy, supported by an exceptional abundance of proxy data and well-constrained boundary conditions, provides an unprecedented opportunity to bridge the gap between quantified modern processes and the interpretation of the ancient sedimentary record. High-resolution subsurface data sets capture the complex interplay between sea-level changes and tectonic activity at subseismic scales, with temporal resolutions rarely achievable in older strata, revealing a largely unexplored hierarchy of hiatal surfaces and condensed intervals spanning 102- to 104-yr timescales within stratigraphic successions generally assumed to be continuous. Quaternary sequence stratigraphy not only provides a robust chronostratigraphic framework to serve as the basis for paleogeographic maps, but also delivers accurate three-dimensional reconstructions of shallow-subsurface stratigraphic architecture. Beyond its traditional applications in hydrocarbon exploration, Quaternary data sets support a wide range of practical applications, including carbon capture and storage site selection, groundwater reservoir characterization, reconstruction of contaminant migration pathways, seismic-hazard assessment, and infrastructure development, demonstrating their relevance for both geoscience research and societal challenges. GRAPHICAL ABSTRACT View largeDownload slide View largeDownload slide

We introduce a new rule-based algorithm called GEOPARD, which models shoreface deposits by following geological principles. In this algorithm, the outcomes of geological processes are represented as rules that are integrated into the core of a standard geostatistical modeling framework. The GEOPARD builds on the stochastic object-based facies modeling technique and incorporates a Bayesian framework for conditioning to data and reducing uncertainty. This paper outlines the geological prior model of the GEOPARD algorithm, which generates facies geometries and controls object placement using geological rules. Specifically, the algorithm builds up a parasequence by stacking a succession of prograding shoreface bedsets, bounded by small-scale hiatus, until a final point of maximum shoreline advance. Model parametrization closely follows the geological conceptual model. The rules are implemented as a series of fully automated modeling steps, mapping the wide variety of facies geometries typically associated with shallow-marine deposits. The functionality of GEOPARD is demonstrated through a series of scenarios, including the reproduction of features observed in an outcrop analogue and benchmarking against the truncated Gaussian simulation method. Key modeled features include sand-body thickness, lateral extent of facies, overall parasequence geometry, and the spacing and dip of bedset bounding surfaces.