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[The Andean cordillera, the Himalayan collisionorogen, and the Apennine thrust belt are archetypes of different orogens associatedwith different sedimentary basins. Sediment storage capacity, maximum inforedeeps where slab retreat induces rapid subsidence of the downgoing plate, isminimum in broken retroarc basins where flat‐slab subduction leads to basininversion and uplift of basement blocks on the overriding plate. , Abstract Central Argentina from the Pampean flat‐slab segment to northern Patagonia (27°–41°S) represents a classic example of a broken retroarc basin with strong tectonic and climatic control on fluvial sediment transport. Combined with previous research focused on coastal sediments, this actualistic provenance study uses framework petrography and heavy‐mineral data to trace multistep dispersal of volcaniclastic detritus first eastwards across central Argentina for up to ca. 1,500 km and next northwards for another 760 km along the Atlantic coast. Although detritus generated in the Andes is largely derived from mesosilicic volcanic rocks of the cordillera, its compositional signatures reflect different tectono‐stratigraphic levels of the orogen uplifted along strike in response to varying subduction geometry as well as different character and crystallization condition of arc magmas through time and space. River sand, thus, changes from feldspatho‐litho‐quartzose or litho‐feldspatho‐quartzose in the north, where sedimentary detritus is more common, to mostly quartzo‐feldspatho‐lithic in the centre and to feldspatho‐lithic in the south, where volcanic detritus is dominant. The transparent‐heavy‐mineral suite changes markedly from amphibole ≫ clinopyroxene > orthopyroxene in the north, to amphibole ≈ clinopyroxene ≈ orthopyroxene in the centre and to orthopyroxene ≥ clinopyroxene ≫ amphibole in the south. In the presently dry climate, fluvial discharge is drastically reduced to the point that even the Desaguadero trunk river has become endorheic and orogenic detritus is dumped in the retroarc basin, reworked by winds and temporarily accumulated in dune fields. During the Quaternary, instead, much larger amounts of water were released by melting of the Cordilleran ice sheet or during pluvial events. The sediment‐laden waters of the Desaguadero and Colorado rivers then rushed from the tract of the Andes with greatest topographic and structural elevation, fostering alluvial fans inland and flowing in much larger valleys than today towards the Atlantic Ocean. Sand and gravel supply to the coast was high enough not only to promote rapid progradation of large deltaic lobes but also to feed a cell of littoral sediment transport extending as far north as the Rio de la Plata estuary.]

This Nile Delta case study provides quantitative information on a process that we must understand and consider in full before attempting provenance interpretation of ancient clastic wedges. Petrographic and heavy-mineral data on partly lithified sand, silt, and mud samples cored from the up to 8.5 km-thick post-Eocene succession of the offshore Nile Delta document systematic unidirectional trends. With increasing age and burial depth, quartz increases at the expense of feldspars and especially of mafic volcanic rock fragments. Heavy-mineral concentration decreases drastically, transparent heavy minerals represent progressively lower percentages of the heavy fraction, and zircon, tourmaline, rutile, apatite, monazite, and Cr-spinel relatively increase at the expense mainly of amphibole in Pliocene sediments and of epidote in Miocene sediments. Recent studies have shown that the entire succession of the Nile Delta was deposited by a long drainage system connected with the Ethiopian volcanic highlands similar to the modern Nile since the lower Oligocene. The original mineralogy should thus have resembled that of modern Delta sand much more closely than the present quartzose residue containing only chemically durable heavy minerals. Stratigraphic compositional trends, although controlled by a complex interplay of different factors, document a selective exponential decay of non-durable species through the cored succession that explains up to 95% of the observed mineralogical variability. Our calculations suggest that heavy minerals may not represent >20% of the original assemblage in sediments buried less than ~1.5 km, >5% in sediments buried between 1.5 and 2.5 km, and >1% for sediments buried >4.5 km. No remarkable difference is detected in the intensity of mineral dissolution in mud, silt, and sand samples, which argues against the widely held idea that unstable minerals are prone to be preserved better in finer-grained and therefore presumably less permeable layers. Intrastratal dissolution, acting through long periods of time at the progressively higher temperatures reached during burial, can modify very drastically the relative abundance of detrital components in sedimentary rocks. Failure to recognize such a fundamental diagenetic bias leads to grossly mistaken paleogeographic reconstructions, as documented paradigmatically by previous provenance studies of ancient Nile sediments.

The Nicobar Fan and Bengal fans can be considered as the eastern and western parts, respectively, of the largest submarine-fan system in the world. This study presents the integrated results of petrographic and provenance studies from the Nicobar Fan and evaluates these in the context of controls on sedimentation. Both fans were predominantly supplied by Himalaya-derived material from the main tectono-stratigraphic sequences as well as the Gangdese arc. A lack of volcanic material in the Nicobar Fan rules out sources from the Sumatra magmatic arc. Overall, the petrographic data shows a progressive decrease in sedimentary detritus and corresponding increase of higher-grade metamorphic detritus up-section. Changes in sediment provenance and exhumation rates in the Himalaya are seen to track changes in sediment accumulation rates. High sediment accumulation rates in the Bengal Fan occurred at ∼13.5–8.3 Ma, and in the Nicobar Fan from ∼9.5–5 Ma. Both fans show peak accumulation rates at 9.5–8.3 Ma (but with the Nicobar Fan being about twice as high), and both record a sharp drop from ∼5.5–5.2 Ma, that coincided with a change in river drainage associated with the Brahmaputra River diverting west of the uplifting Shillong Plateau. At ∼5 Ma, the Nicobar Fan was supplied by an eastern drainage route that finally closed at ∼2 Ma, when sediment accumulation rates in the Nicobar Fan significantly decreased. Sediment provenance record these changes in routing whereby Bengal Fan deposits include granitoid sources from the Namche Barwa massif in the eastern syntaxis that are not seen in the Nicobar Fan, likely due to a more localised eastern drainage that included material from the Indo-Burman wedge. Prior to ∼3 Ma, source exhumation rates were rapid and constant and the short lag-time rules out significant intermediate storage and mixing. In terms of climate versus tectonic controls, tectonically driven changes in the river network have had most influence on fan sedimentation.

The highest peaks in Europe are found in the central Greater Caucasus, an orogenic belt characterized by extremely active tectonic and sedimentary processes. In this rugged mountain region, we have investigated sand generation and erosion patterns by using high-resolution petrographic and heavy-mineral data on river sands complemented by detailed morphometric analysis of 9 major mountain branches of the Terek River. Also presented is an extensive review of sediment-transport data available in the Russian literature on glacial-lake outburst floods and rainfall-triggered debris flows, which owing to global warming and glacier retreat have afflicted the Greater Caucasus with increasing frequency in the last 50 years. The accurate definition of mineralogical signatures characterizing detritus derived from six end-member volcanic, metamorphic basement, and sedimentary/metasedimentary rock units allowed us to calculate the relative contribution of each to the sand load, with particular precision for the Baksan River draining Mt. Elbrus. Results clearly indicate that volcanic and basement rocks supply a disproportionate amount of sand relatively to their outcrop area, testifying to strongly focused erosion in the high-relief axial part of the range. River channels here display extreme steepness (ksn up to 200–300) and low concavity indices (θ 0.15 - 0.35) typical of thalwegs shaped by debris flows. Average erosion rates reach as high as 2–4 mm/a, which is explained by the frequency of catastrophic mass-transport events able to mobilize in one single episode between 106 and 107 tons of detritus, corresponding to 10–50 mm of erosion distributed across the catchment upstream. On 20 September 2002, the Kolka “glacier disaster” mobilized 2 × 108 tons of debris, corresponding to ≥ 400 mm of erosion in the upper Genaldon valley. To quantify the intrinsic capacity of different bedrock types to generate sand isolated from such a strong focused-erosion effect, we used the normalized steepness index ksn as a proxy of erosion rate and thus redefined the sand generation index as S G I * = S A S A A A k s n k s n A . More realistic values are thus obtained, although far more comprehensive data on sediment load than those presently available are required to discriminate robustly between the effect of focused-erosion versus lithological control on sand generation.

The Bangladesh lowlands are traversed by the largest sediment flux on the planet. Detritus generated mostly in Himalayan highlands and conveyed through the Ganga&ndash, Brahmaputra rivers and Meghna estuary reaches the Bay of Bengal, where it forms a composite deltaic system. This study integrates the vast existing database on Ganga&ndash, Brahmaputra sediments of all grain sizes from clay to sand with new petrographic, mineralogical, and geochemical data on estuarine and shallow-marine sands. A large spectrum of compositional signatures was used to: (i) assess the relative supply of the Ganga and Brahmaputra rivers to estuarine and shelfal sediments, (ii) define the compositional variability of estuarine sediments and the impact exerted by hydraulic sorting and climate-related chemical weathering on provenance signals, (iii) define the compositional variability of shelf sediments and the potential hydrodynamic segregation of fast-settling heavy minerals in coastal environments and of slow-settling platy micas on low-energy outer-shelf floors, (iv) consider the potential additional mud supply from the western subaerial part of the delta formerly built by the Ganga River, and (v) draw a preliminary mineralogical comparison between fluvio-deltaic sediments and turbidites of the Bengal&ndash, Nicobar deep-sea fan, thus tracing sediment dispersal across the huge sedimentary system extending from Tibet to the equatorial Indian Ocean. All investigated mineralogical and geochemical parameters, as well as Sr and Nd isotope ratios and clay&ndash, mineral assemblages, showed a clear prevalence in sediment supply from the Brahmaputra (60&ndash, 70%) over the Ganga (30&ndash, 40%). Heavy-mineral suites and Sr and Nd isotope fingerprints of Bengal shelf sediments are nearly identical to those of the Brahmaputra River and Meghna estuary, also because the Brahmaputra carries almost twice as many Ca-plagioclase grains and heavy minerals including epidote than the Ganga, and these minerals control the large majority of the Sr and Nd budgets. The experience gained in modern settings can be directly extrapolated only to the recent past, because sediments older than the late Pleistocene and buried more than a few hundred meters begin to lose less durable ferromagnesian minerals by selective chemical dissolution, which makes quantitative estimates progressively less robust in more deeply buried older strata.

The Changjiang, the fourth longest river on Earth and the largest in Eurasia, has a complex sediment-routing system presently interrupted by the Three Gorges Dam, the world's largest hydroelectric engineering project. To study sediment-generation processes in the huge catchment and compare the different erosion patterns obtained by different methodological approaches, high-resolution petrographic and heavy-mineral analyses were performed on sands from the trunk river and its major tributaries. The frequency distributions of diverse groups of detrital amphiboles were also investigated. Rigorous statistical methods were used to define end-members, evaluate mineralogical variability, assess similarities among samples, and eventually calculate the relative contributions from each major tributary to the trunk river by forward end-member modelling of integrated compositional data. The litho-quartzose sand with few heavy minerals generated in Tibetan headwaters evolves downstream to feldspatho-litho-quartzose with medium-rank metamorphic rock fragments and moderately rich amphibole-epidote suites. Sand across the Sichuan basin and as far as the Three Gorges Dam is enriched in mafic volcanic, clinopyroxene, and carbonate grains eroded from Permian basalts and Paleozoic strata of the South China Block. The final (Yangtze) tract is characterized by litho-feldspatho-quartzose sand with moderately poor, amphibole-dominated suites with epidote, clinopyroxene, and garnet. The orogenic compositional signature acquired in the upper part of the basin is thus carried all the way to the Chinese passive margin, as observed also for the Yellow River in the north. Even after long-distance transport across wide continental areas, detrital modes thus reveal the tectonic character of the source rather than the geodynamic environment of the sink. Quantitative provenance analysis indicates that left-bank tributaries draining the Longmen and Qinlin mountains supply most of the sand reaching the East China Sea. Contributions from Tibetan headwaters are negligible, as those from right-bank tributaries in the middle-lower part of the basin. Sediment budgets and erosion patterns inferred from our integrated petrographic and heavy-mineral data set contrast with those based on detrital-zircon geochronology but agree with stream-profile analysis, revealing close correspondence with slope steepness, precipitation, stream power, tectonic activity, and frequency of major earthquakes. Sediment budgets based on amphibole groups are poorly constrained. We conclude that provenance budgets based on single-mineral species are typically unrobust, particularly because they suffer from inaccurate estimates of mineral concentration in the end-member sources. Exploring in detail a millesimal part of the sediment (typically 1/5000 in the case of zircon) is a risky strategy that may return a distorted picture of reality.

This study focuses on the causes, modalities and obstacles of sediment transfer in the longest cell of littoral sand drift documented on Earth so far. Sand derived from the Orange River is dragged by swell waves and persistent southerly winds to accumulate in four successive dunefields in coastal Namibia to Angola. All four dunefields are terminated by river valleys, where aeolian sand is flushed back to the ocean; and yet sediment transport continues at sea, tracing an 1800Âkm long submarine sand highway. Sand drift would extend northward to beyond the Congo if the shelf did not become progressively narrower in southern Angola, where drifting sand is funnelled towards oceanic depths via canyon heads connected to river mouths. Garnet–magnetite placers are widespread along this coastal stretch, indicating systematic loss of the low-density feldspatho-quartzose fraction to the deep ocean. More than half of Moçamedes Desert sand is derived from the Orange River, and the rest in similar proportions from the Cunene River and from the Swakop and other rivers draining the Damara Orogen in Namibia. The Orange fingerprint, characterized by basaltic rock fragments, clinopyroxene grains and bimodal zircon-age spectra with peaks at ca 0·5ÂGa and ca 1·0ÂGa, is lost abruptly at Namibe, and beach sands further north have abundant feldspar, amphibole-epidote suites and unimodal zircon-age spectra with a peak at ca 2·0ÂGa, documenting local provenance from Palaeoproterozoic basement. Along with this oblique-rifted continental margin, beach placers are dominated by Fe–Ti–Cr oxides with more monazite than garnet and thus have a geochemical signature sharply different from beach placers found all the way along the Orange littoral cell. High-resolution mineralogical studies allow us to trace sediment dispersal over distances of thousands of kilometres, providing essential information for the correct reconstruction of ‘source to sink’ relationships in hydrocarbon exploration and to predict the long-term impact of man-made infrastructures on coastal sediment budgets.

Subduction complexes large enough to be exposed subaerially and become significant sources of terrigenous detritus are formed by tectonic accretion above trenches choked with thick sections of remnant-ocean turbidites. They thus need to be connected along strike to a major collision zone, where huge volumes of orogenic detritus are produced and conveyed via a major fluvio-deltaic system to the deep sea. In this article we investigate sediment generation and recycling in the archetype of such settings, the eastern prolongation of the Himalayan collisional system. We illustrate the petrographic and heavy-mineral suites of modern sands produced all along the Indo-Burman-Andaman-Nicobar subduction complex, which includes accreted abyssal-plain sediments overthrust by ophiolites and unconformably overlain by volcaniclastic forearc strata. "Subduction Complex Provenance" is thus composite, and overwhelmingly consists of detritus recycled from largely turbiditic parent rocks (Recycled Clastic Provenance), with local supply from obducted ultramafic and mafic rocks of forearc lithosphere (Ophiolite Provenance) or recycled paleovolcanic to neovolcanic sources (Volcanic Arc Provenance). In order to specifically investigate the effect of recycling, we characterize the diverse detrital signatures of Cenozoic sandstones originally deposited during subsequent stages of "soft" and "hard" Himalayan collision and presently exposed from Bangladesh to the Andaman Islands, and discuss the reasons for compositional discrepancies between parent sandstones and their recycled daughter sands. Long-distance, multistep and multicyclic sediment transfer along and across convergent plate boundaries follows complex trajectories in space and time, which must be resolved whenever we want to obtain a reasonably faithful paleogeographic reconstruction for the recent and less recent geological past. © 2013 Elsevier B.V.

We used petrographic, heavy-mineral, and geochronological signatures of sand-sized grains to document an exceptional case of long-distance sediment transport dominated by eolian processes in a hyperarid climate. Feldspatho-quartzo-lithic orogenic detritus shed by the Anatolia Plateau and Zagros Mountains-including carbonate, chert, volcanic, metabasite, and ultramafic lithic grains with a rich epidote-amphibole-pyroxene-garnet heavy-mineral suite-was carried to the Arabian-Gulf foreland basin via the Euphrates-Tigris-Karun fluvial system and other rivers draining the Zagros, and blown inland by dominant Shamal winds to reach well into the Arabian foreland. Sediment dispersal over a cumulative distance of up to 4000 km took place in multiple steps, involving extensive eolian reworking of older deposits during lowstand stages of the Pleistocene before final accumulation in the Rub' al Khali sand sea. The siliciclastic fraction of Gulf beaches changes southeastwards from litho-quartzose carbonaticlastic and quartzose north of Qatar to quartzo-lithic carbonaticlastic along the Trucial Coast, but invariably contains chert, volcanic, and metabasite lithics, together with epidote, pyroxene, amphibole, and garnet. Dune sand inland is progressively enriched in quartz until composition becomes feldspatho-quartzose, whereas the heavy-mineral assemblage remains virtually unchanged. Beach and dune sands of the Gulf and northeastern Rub' al Khali were derived from Arabia, Anatolia, and the Zagros in varying proportions, with only local contribution from ophiolites of the northern Oman Mountains as revealed by cellular serpentinite and enstatite grains. In all samples detrital zircons yielded mostly Cambrian to Neoproterozoic ages reflecting "Pan-African" crustal growth and amalgamation of the Arabian shield, but several upper Paleozoic, Mesozoic, and Cenozoic zircons with ages as young as 5 Ma in northeastern Rub' al Khali dunes document ultimate provenance from the Anatolia-Zagros orogen. Quartzose dune sand of the southwestern Rub' al Khali, containing a moderately poor, amphibole-rich heavy-mineral assemblage and very few young zircons, is dominantly Arabian-derived. Relatively soft carbonate grains are typically concentrated in finer sand classes, which is ascribed to both mixing with coarser quartz recycled from Arabian siliciclastic covers and selective mechanical wear during multicyclic long-distance transport in high-energy eolian environments. Understanding the complex transfer of huge detrital masses on the Earth's surface, and mixing of sediments derived from different sources along successive tracts of a composite routing system that may cover cumulative distances of thousands of kilometers across climatic and tectonic boundaries over time periods of millions of years, is essential to enhance the resolution of source-to-sink studies and avoid gross oversimplifications in paleogeographic reconstructions.

We present a detailed sediment-provenance study on the modern Euphrates-Tigris-Karun fluvial system and Mesopotamian foreland basin, one of the cradles of humanity. Our rich petrographic and heavy-mineral dataset, integrated by sand geochemistry and U–Pb age spectra of detrital zircons, highlights the several peculiarities of this large source-to-sink sediment-routing system and widens the spectrum of compositions generally assumed as paradigmatic for orogenic settings. Comparison of classical static versus upgraded dynamic petrologic models enhances the power of provenance analysis, and allows us to derive a more refined conceptual model of reference and to verify the limitations of the approach. Sand derived from the Anatolia-Zagros orogen contains abundant lithic grains eroded from carbonates, cherts, mudrocks, arc volcanics, obducted ophiolites and ophiolitic melanges representing the exposed shallow structural level of the orogen, with relative scarcity of quartz, K-feldspar and mica. This quartz-poor petrographic signature, characterizing the undissected composite tectonic domain of the entire Anatolia-Iranian plateau, is markedly distinct from that of sand shed by more elevated and faster-eroding collision orogens such as the Himalaya. Arid climate in the region allows preservation of chemically unstable grains including carbonate rock fragments and locally even gypsum, and reduces transport capacity of fluvial systems, which dump most of their load in Mesopotamian marshlands upstream of the Arabian/Persian Gulf allochemical carbonate factory. Quartz-poor sediment from the Anatolia-Zagros orogen mixes with quartz-rich recycled sands from Arabia along the western side of the foreland basin, and is traced all along the Gulf shores as far as the Rub' al-Khali sand sea up to 4000 km from Euphrates headwaters.

We use quantitative provenance analysis (geochemical analysis; high- resolution bulk-petrography and heavy-mineral analysis, exploratory compositional data analysis and Aitchison distance) on present-day river sediments of the Changjiang (Yangtze) River to quantify the contributions of each tributary to the Changjiang River Delta, and thus to evaluate sediment provenance in the distinct p arts of the drainage basin.

Marine accumulations of terrigenous sediment are widely assumed to accurately record climatic- and tectonic-controlled mountain denudation and play an important role in understanding late Cenozoic mountain uplift and global cooling. Underpinning this is the assumption that the majority of sediment eroded from hinterland orogenic belts is transported to and ultimately stored in marine basins with little lag between erosion and deposition. Here we use a detailed and multi-technique sedimentary provenance dataset from the Yellow River to show that substantial amounts of sediment eroded from Northeast Tibet and carried by the river's upper reach are stored in the Chinese Loess Plateau and the western Mu Us desert. This finding revises our understanding of the origin of the Chinese Loess Plateau and provides a potential solution for mismatches between late Cenozoic terrestrial sedimentation and marine geochemistry records, as well as between global CO2 and erosion records., Theories of Cenozoic mountain uplift and associated global cooling assume that eroded mountain sediments are stored in marine basins. Here, based on detailed provenance data, Nie et al. show that Northeast Tibetan sediments are in fact stored inland, in the Chinese Loess Plateau and Mu Us desert.

The Indus River, one of Asia’s premier rivers, drains the western Tibetan Plateau and the Nanga Parbat syntaxis. These two areas juxtapose some of the lowest and highest topographic relief and commensurate denudation rates in the Himalaya-Tibet orogen, respectively, yet the spatial pattern of denudation rates upstream of the syntaxis remains largely unclear, as does the way in which major rivers drive headward incision into the Tibetan Plateau. We report a new inventory of ^(10)Be-based basinwide denudation rates from 33 tributaries flanking the Indus River along a 320 km reach across the western Tibetan Plateau margin. We find that denudation rates of up to 110 mm k.y.^(–1) in the Ladakh and Zanskar Ranges systematically decrease eastward to 10 mm k.y.^(–1) toward the Tibetan Plateau. Independent results from bulk petrographic and heavy mineral analyses support this denudation gradient. Assuming that incision along the Indus exerts the base-level control on tributary denudation rates, our data show a systematic eastward decrease of landscape downwearing, reaching its minimum on the Tibetan Plateau. In contrast, denudation rates increase rapidly 150–200 km downstream of a distinct knickpoint that marks the Tibetan Plateau margin in the Indus River longitudinal profile. We infer that any vigorous headward incision and any accompanying erosional waves into the interior of the plateau mostly concerned reaches well below this plateau margin. Moreover, reported long-term (>10^6 yr) exhumation rates from low-temperature chronometry of 0.1–0.75 mm yr^(–1) consistently exceed our ^(10)Be-derived denudation rates. With averaging time scales of 10^3–10^4 yr for our denudation data, we report postglacial rates of downwearing in a tectonically idle landscape. To counterbalance this apparent mismatch, denudation rates must have been higher in the Quaternary during glacial-interglacial intervals.