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This study reveals the morphological transformations of a deep-water channel system within the Rakhine Basin in the northeastern Bay of Bengal through a comprehensive analysis of high-resolution 3D seismic data integrated with drilling logs. Employing the "source-channel-sink" paradigm, this investigation examined the impact of various factors, including tectonic transformations, sediment influx, slope dynamics, climatic changes, and relative sea-level fluctuations, on the evolutionary trajectory of these channel systems. Applying precise time-slicing techniques integrating root-mean-square amplitude attributes, coherent amplitude attributes, and horizontal amplitudes on seismic profiles, this investigation recognized three distinct stages in the evolution of channel-levee complexes (CLCs): the Middle Miocene erosional deep-water channel-levee complex (CLC-1), the Pliocene erosional-depositional deep-water channel-levee complex (CLC-2), and the Pleistocene depositional deep-water channel-levee complex (CLC-3). Comparative analysis revealed that the CLC-3 exhibits unique characteristics, including shallower channel depth (D), wider channel width (W C), extensive U-shaped cross-sectional area (S), broader natural levee width (W L) and height (H), and the highest tortuosity coefficient (L C /L S) when contrasted with the other two CLCs. Furthermore, this study substantiated how tectonic processes, primarily the collision between the Indo-Eurasian plates, resulting in the Himalayan and Indo-Burma Range orogenies, have shaped the region's geological and climatic framework, thereby influencing monsoon circulation and precipitation patterns, which in turn augmented detrital material influx into the basin. Moreover, this tectonic collision has led to gradual changes in the slope gradient of the Rakhine Basin and its deep-water areas, impacting internal flow velocities and channel curvature, thus governing deep-water channel systems' development and spatial distribution. Also, episodic sea level fluctuations were identified as significant contributors to sediment transport from shelves to deep-water regions and sediment deposit reworking. Overall, this study underscores the role of tectonic changes after the Eocene in driving the evolutionary dynamics of the deep-water channel system within the Rakhine Basin, Myanmar. [Display omitted] • Indo-Eurasian plate collision shaped the deep-water channel systems in the Rakhine Basin. • 3D seismic data reveals three evolutionary stages in these deep-water channel systems. • Pleistocene depositional channel-levee complex exhibits unique physical characteristics. • Tectonically affected slope dynamics have directed the channels' evolutionary dynamics. • Episodic sea level fluctuations have also supported these morphological transformations. [ABSTRACT FROM AUTHOR]

Four southern California beaches were nourished with offshore sand placed as subaerial pads several meters thick, ∼ 50 m wide, and spanning between 500 and 1500 m alongshore. Three nourishments constructed with coarser than native sand, placed in 2012 at Imperial, Cardiff and Solana Beaches, elevated subaerial sand volumes for several years even when exposed to the energetic winter waves of the 2015-16 El Niño, followed by a stormy 2016-17 winter. As these relatively resilient pads were overwashed, landward tilted subaerial profiles (accretionary crowns) formed at the eroding front face of the originally flat-topped pads and pooling occurred in the backbeach. At Imperial Beach, nourishment sand helped prevent waves from directly impacting riprap fronting houses, while groundwater flooding behind the pad was observed at a location where the pad was elevated ∼ 1.6 m above the street. As the nourishments retreated, alongshore oriented spits grew downdrift from the eroding face. The alongshore displacement of the subaerial center of mass of the 2012 nourishments is positively correlated with the seasonally varying S x y (the alongshore radiation stress component). After four years, the net southward drift of the Imperial Beach nourishment contributed to the winter 2016 closure of the Tijuana River mouth and the associated hyper-polluted and anoxic estuary conditions. Nourishment impacts on sand levels on rocky reefs were not unambiguously detectable in the background of natural variability. Over several years, gains or losses in the total sand volume (integrated from the back beach to 8 m depth, over the few km alongshore survey spans) are sometimes comparable to nourishment volumes, suggesting relatively large interannual sediment fluxes across the control volume boundaries. The clearest trend in total volume is at Torrey Pines; during 16 years since the 2001 nourishment, about 300,000 m 3 of sand has been lost. If the trend continues, the thinning veneer of sand will be removed more often from the subaerial winter beach, exposing rocks and cobbles. [ABSTRACT FROM AUTHOR]

As a part of the Bangong-Nujiang suture, the Shiquanhe-Namco ophiolite mélange belt (SNM), together with the Bangong-Nujiang ophiolite mélange belt (BNM), records the evolutionary history of the Mesotethys. In terms of the closure of the Mesotethys, previous sedimentological research has focused on the BNM, while the SNM remains insufficient. On the basis of detrital zircon dating and sedimentologic data, in this study, we determined the existence of Aptian deep-marine turbidites in the Zhongcang and Lhakorco areas of the SNM. Sandstone petrographic and detrital zircon analysis combine to show that the Zhongcang turbidites provide records of the recycled from the accretionary complex and Triassic-Jurassic strata in the southern Qiangtang margin, with the minor addition of Qiangtang magmatic arc rocks, while sediments in the Lhakorco turbidites were derived mainly from recycled orogen source and Late Jurassic-Early Cretaceous magmatic arc in the Lhasa Terrane. Further analysis suggests that the Aptian turbidites were deposited in a deep-marine oceanic basin of Mesotethys and this oceanic basin prevented Qiangtang-derived sediments transported onto the Lhasa terrane. The Mesotethys experienced diachronic closure from east to west during the Early Cretaceous, and the final closure was most likely completed along the SNM after Aptian. • Discovery of the Aptian deep-marine fan turbidities in SNM • Featuring the Aptian Qiangtang and Lhasa source separation along SNM • Implications for diachronous closure of the Mesotethys [ABSTRACT FROM AUTHOR]