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Studying the origin of rivers, the development of drainage through geological time, and the multiple processes that affect the composition of the sediment is a fascinating scientific adventure. This article probes into modern sedimentary processes in the Orange River catchment, which covers much of South Africa, and monitors changes in petrographic, mineralogical, geochemical, and geochronological signatures along the ∼4000 km-long fluvial and coastal conveyor belt that transferred pyroxene-rich and diamond-bearing sand from Lesotho to Angola.The Orange River, established as early as the Early Jurassic as a classic example of dome-flank drainage, is perhaps the oldest river on our planet. A quarter of Orange sand is supplied by the erosion of Lesotho basaltic highlands, reaching 3482 m a.s.l. and representing a remnant of one of the most extensive magmatic effusions of Phanerozoic history, the Lower Jurassic Karoo lavas. Basaltic lavas, dolerite sills and dykes shed rock fragments and clinopyroxenes that constitute the unique fingerprint of Orange River sand. Only a tenth of the sediment is supplied by the Vaal River, the longest Orange tributary that drains siliciclastic and volcanic units ranging in age from Neoarchean in the Transvaal to early Mesozoic in the Karoo Basin. In the arid middle and lower reaches, the Orange River carves its course into the Namaqua Belt and receives the Molopo River flowing only episodically across the vast Kalahari Desert and the Fish River draining sedimentary rocks of the Nama Group and Karoo Supergroup. Fragile sedimentary rock fragments do not survive high-energy wave transport, but basaltic rock fragments and pyroxenes do, allowing us to trace sand transport for ∼1800 km all along the Atlantic coast of Namibia to as far as southern Angola. Understanding sediment mass transfer has scientific as well as practical interest, being a prerequisite for effective fluvial and coastal management, with particular economic significance in the special case of diamond-bearing Orange sand.

We investigate the Palaeocene succession of the Hazara Basin (Northern Pakistan) to better understand the impact of climate change on marine carbonate-producing organisms. These shallow-water carbonates, deposited during the Late Palaeocene, before the onset of the Palaeocene-Eocene Thermal Maximum, were studied using a quantitative approach to highlight changes in the skeletal assemblage. We recognise a decrease in the abundance of colonial corals and green calcareous algae and an increase in larger benthic foraminifera and red calcareous algae from the early Thanetian to the late Thanetian. Increasing temperatures may represent a plausible cause for the decline of the more sensitive colonial corals in favor of the more tolerant larger benthic foraminifera. A similar pattern is observed in most successions deposited along the margins of the Neotethys Ocean, suggesting a connection with the Late Palaeocene environmental changes that heralded the PETM hyperthermal event. Our stratigraphic analysis of the Hazara Basin strata suggests that the biotic turnovers occurred during the Palaeocene – Eocene transition started already before the onset of the Palaeocene Eocene Thermal Maximum as recorded by the geochemical proxies.

Abstract The controversial history of Indian subduction beneath Asia is crucial to understand the Himalayan orogeny and more in general the geodynamic process of continental subduction. New key information is here presented from the Oligocene‐Pliocene Shiquanhe Basin located in the southwestern Tibetan Plateau. The alluvial‐fan, lacustrine, and braided‐river sediments of the Oligocene Rigongla Formation were non‐conformably deposited onto the Upper Cretaceous Gangdese granitoid rocks and fed from erosion of the batholith itself and of associated Paleogene Linzizong volcanic rocks. Stratigraphic evidence testifies to the development of an orogen‐parallel intracontinental rift along the retro‐side of the Gangdese arc in the Oligocene, at the same time as the Kailas basin formed along the pro‐side of the Gangdese arc. The subsidence of these twin basins may have been caused by steepening of the subducting Indian continental slab or by the passage of a wave of dynamic topography during continuing subduction.

The major facies changes documented in shallow-marine sediments of the northern Indian passive margin of Neo-Tethys throughout the Jurassic, from widespread platform carbonates in the Early Jurassic to organic-rich black shales in the Late Jurassic, imply a substantial turnover in oceanic conditions. All along the Tethys (Tibetan) Himalaya, from the Zanskar Range to southern Tibet, a peculiar interval characterized by ooidal ironstones of Dingjie Formation (Ferruginous Oolite Formation, FOF) marks the base of the organic-rich Spiti Shale. This laterally-extensive ooidal ironstone interval is a fundamental testimony of the mechanisms that led to major paleoceanographic changes that occurred in the eastern Neo-Tethys during the Middle Jurassic. In this article, we illustrate in detail the petrology, mineralogy, and geochemistry of ooidal ironstones and the major element contents of the entire Lanongla section. The FOF is characterized by significantly high contents of Fe2O3 (56.80% ± 9.07%, n = 7) and P2O5 (1.72% ± 1.19%, n = 7). In contrast, the Fe2O3 and P2O5 contents average 3.58% and 0.15% in the overlain carbonates of Lanongla Fm., and 5.55% and 0.16% in the overlying Spiti Shale. The ooidal ironstones are mainly composed of iron ooids with a few quartz grains and bioclasts cemented by sparry calcite. The iron ooids consist of concentric dark layers of francolite (carbonate fluorapatite), hence enriched in Ca, P, and F, and bright layers of chamosite, enriched in Fe, Si, Al, and Mg. Precipitation of francolite ensued from oversaturation of phosphorous ascribed to intensified upwelling, high biogenous productivity, and degradation of organic matter, whereas the formation of chamosite reflects enhanced continental weathering and erosion leading to increased Fe input to the ocean during transgressive stages characterized by low sedimentation rate and scarce oxygenation at the seafloor. Modern upwelling zones in outer shelf or slope areas perform similar geochemical characteristics to those as observed in this study. Under the Mesozoic greenhouse background, fluctuating redox conditions induced the alternate growth of francolite under anoxic conditions and of chamosite under suboxic conditions. Ooids were thus formed on the seafloor during continued resuspension and vertical oscillations of the chemocline rather than from interstitial waters after burial. The mineralogy of iron ooids indicates mainly reducing conditions in the water column, suggesting that extensive upwelling along the continental margin of eastern Neo-Tethys contributed significantly to the transition from carbonate deposits to organic-rich black shales during the Jurassic, as testified by the transition from well-oxygenated in Lanongla Fm. To a reduceing condition in Spiti Shale indicated by the Mn/Al ratios compared to PAAS.

The 3-D seismic dataset is a key tool to analyze and understand the mechanism of structural and stratigraphic hydrocarbon (HC) trapping in the subsurface. Conventionally used subsurface seismic characterization methods for fractures are based on the theory of effective anisotropy medium. The aim of this work is to improve the structural images with dense sampling of 3-D survey to evaluate structural and stratigraphic models for reservoir development to predict reservoir quality. The present study of the Gullfaks Field, located in the Norwegian North Sea Gullfaks sector, identifies the shallowest structural elements. The steepness of westward structural dip decreases eastward during the Upper Jurassic to Lower Cretaceous deposition. Reservoir sands consist of the Middle Jurassic deltaic deposits and Lower Jurassic fluvial channel and delta plain deposits. Sediment supply steadily prevails on sea-level rise and the succession displays a regressive trend indicated by a good continuous stacking pattern. The key factor for the development of reservoirs in the Gullfaks Field is fault transmissibility with spatially distributed pressure. The majority of mapped faults with sand-to-sand contacts are non-sealing, which provide restriction for the HC flow between the fault blocks. The traps for HC accumulation occur between the post-rift and syn-rift strata, i.e. antiform set by extensional system, unconformity trap at the top of syn-deposition, and structural trap due to normal faults. Overall reservoir quality in the studied area is generally excellent with average 35% porosity and permeability in the Darcy range. Our findings are useful to better understand the development of siliciclastic reservoirs in similar geological settings worldwide.

Epidote group minerals are one of the three most abundant kinds of heavy minerals in orogenic sediments, the other two being amphibole and garnet. They resist diagenesis better than amphibole and resist weathering in soils better than garnet. Their chemical composition and optical properties vary markedly and systematically with temperature and pressure conditions during growth. Useful information on the metamorphic grade of source rocks can thus be obtained by provenance analysis. In this study, we combine optical, SEM–EDS, and Raman analyses of nine standard crystals of epidote group minerals collected from different rock units exposed in the European Alps and Apennines and develop a Raman library for efficient discrimination of epidote, clinozoisite, zoisite, and allanite by establishing clear user-oriented relationships among optical properties, chemical composition, and Raman fingerprint. This new library allows us to distinguish and reliably determine, directly from their Raman spectrum, the chemical compositions of epidote group minerals during routine heavy mineral analyses of sand/sandstone and silt/siltstone samples down to the size of a few microns. The validity of the approach is illustrated by its application to 41 Bengal Fan turbidites collected from five cores during IODP Expedition 354 and ranging in grain size from medium sand to fine silt.

Aeolian sedimentary processes and corresponding facies shape the Earth’s surface and control the evolution of dune fields. The Namib Sand Sea with its Sossusvlei playa-lake is a perfect example to investigate the spatial distribution of fluvially influenced aeolian deposits. Remote sensing in combination with ground observations allowed for mapping of the facies distribution pattern of associated fluvial and aeolian sediments. Laboratory spectral signature measurements were used to further improve the separation between six groups of facies: modern aeolian sand, deflation surface, mud pool/mud drapes, heavy mineral lag, reworked fluvial–aeolian sediments, and fossil dune remnant. The best results were achieved through a supervised classification algorithm trained by field observations, a combination of Principal Component Analysis, band ratios, texture and geomorphologic indices. Consequently, a map outlining the facies distribution pattern of the Sossusvlei area at a scale of 1:10,000 was created. We propose this as a possible workflow to efficiently map and monitor desert environments and to investigate the interplay of aeolian and fluvial sediments.

A detailed Upper Cretaceous/Paleocene stratigraphic section was measured from the Spanboth Chu Valley, High Himalaya Nappes. Placement Of the Cretaceous—Tertiary boundary was refined, but some uncertitudes still remain because of poor exposure in this portion of the sequence. The Maastrichtian is characterized by floral and faunal assemblages consisting of Cymopolia, Ornphalocyclus, Siderolites and Odon togryphaea. The Lower Paleocene seems to be missing, whilst the Middle to Upper Paleocene is characterized by Rotalia, Daviesina, Lockhartia and Furcoporella assemblages. Sandstone petrography and carbonate microfacies were analyzed for environmental interpretation. Moreover, a reconsideration of the recent published data on the Upper Cretaceous/ Paleocene from the Zanskar mountains allows us to delineate a tentative depositional history of this part of the Indian continental margin during the considered time.

The results of several—year stratigraphic researches on the Northwestern Himalaya Late Cretaceous—Early Tertiary succession are here presented. New biostratigraphic data allowed to recognize several benthic foraminiferal assemblages in five measured stratigraphic sections and to reconsider the position of the Cretaceous—Tertiary boundary. Refined chronostratigraphic calibration and assessment of sedimentation rates were obtained through correlation between benthic and planktonic biozones. Petrographical analysis of sandstones allowed to tentatively put forward a sedimentological model, to give rough estimates for temperatures of anchimetamorphic deformation in the different thrust sheets of the Tethys Himalaya zone and to shed new light on the genesis of superstable and supermature quartzarenites. Integrated sedimentological—petrographical studies allowed to distinguish at least three depositional sequences separated by major unconformities in the previously undifferentiated succession, and to put further constraints to the dating of the India—Asia collision.

Studies on the most southern and complete Carnian sequence of the Bergamasc Alps (S. Gallo well) and of several exposed stratigraphic sections throw new light on the paleogeographic evolution and the metallogenesis of the Pb—Zn—Fluorite—Barite Gorno district. In the Early Carnian (Calcare Metallifero Bergamasco and Basal Tongue of the Gorno Fm.) , an open lagoon with mixed calcareous—terrigenous sedimentation passed northward to carbonate tidal flats and was fringed by karstified carbonate paleo—highs. Next, the great supply of terrigenous detritus from a southern volcanic belt brought about the progradation of a fluviodeltaic body (Val Sabbia Sandstone) and confined carbonate sedimentation to an outer zone.

During Serravallian time, a shallow—water shelf mantled by northward migratine sand waves occupied the eastern part of the Tertiary Piedrnont Basin (Serravalle Sandstone, Gavi area). Towards the west, the shelf graded into a basinal zone through a series of steps probably controlled by synsedimentary faults. The autochthonous sediments of the shelf—basin transition were sandy siltstones, which are interbedded in the stratigraphical column with sands carried from near—shore arcas by tectonically—triggered sediment gravity flows. On the Proxima] "steps traction currents could rework these sands and re—form sand waves, while in deeper water they were buried without further reworking. Finally, at the western edge of the study area (Cassinasco), "high—dcnsity" turbidity currents flowing towards the ENE depositcd the sands of the Cassinasco Fm. onto the deep bottoni of the basmal zone. Riv. IC. Paleont. Strat. 90 pp. 545—564 Marzo 1985 Two distinct petrofacies characterize the Serravalle hybrid arenites (bioclastic lithic arkoses) and the Cassinasco sandstones (litharenites), pointing to different source terranes. The Cassinasco Fm. was fed by the Alpine fold—thrust belt, comprising Carboniferous metasediments, Permlan igneous rocks, Mesozoic sediments and the Ligurid Allochthon. The paragencsis of lithic fragrnents and the heavy mineral assemblage show that the source rocks bave undergone blueschist facies (eoalpine) and greenschist facies (rnesoalpine) polyphase rnetarnurpllism. The Serravalle arenites bave a similar "aphanite" rock fragment population, but detritus frorn granitoid bodies is prominent and the detrital modes are closer to the Tertiary clastic units of the Apennines.

The preliminary results of the 1984 Italian Geological Expedition to Zanskar are given as a general account of the stratigraphy of the Tethys Himalaya succession. The sedimentary sequence has been subdivided in three parts, from Late Precambrian to Eocene.

Major deserts do not necessarily consist of eolian dunes as quartz-rich as those of the Great Nafud, Rub’ al Khali, Sahara, and Mega-Kalahari sand seas accumulated in anorogenic settings of Arabia and Africa. The Karakum dune field of Turkmenistan is one of the several examples of central Asian deserts bound by recent or recently reactivated orogenic belts where eolian sand includes abundant sedimentary and subordinately metamorphic and volcanic lithic fragments. Feldspatho-litho-quartzose detrital modes and epidote-amphibole-garnet heavy-mineral suites of southern Karakum dune sand compare well with those in mountain branches of the Amu Darya, indicating provenance from the western Pamir mountains of Tajikistan in the east. Dunes closer to the Caspian Sea in the west contain additional carbonate or felsic volcanic grains which, together with decreasing heavy-mineral concentration and increasing ZTR indices, reveals local recycling of cover strata exposed in the Kopeh-Dagh and Balkhan zone. Our data suggest that the huge Amu Darya River, which in Plio-Pleistocene to historical times has repeatedly changed its course across Turkmenistan from westward toward the Caspian Sea to northward toward the Aral Sea, represents the major sediment source for the Karakum Desert. Together with the Taklamakan sand sea of the Tarim basin, the Ordos and adjacent deserts of northern China, and the Thal and Thar deserts of the western Himalayan foreland basin, the Karakum would thus represent another example of large dune field principally fed by one major fluvial feeder system.

The Upper Triassic-Lower Jurassic sedimentary succession of the Zanskar Tethys Himalaya (Ladakh, India) can be subdivided into three stratigraphic units: the Zozar Formation (Late Garnian), the Quartzite Series (Norian) and the Kioto Group (Rhaetian to Early Dogger).

The Bangladesh lowlands are traversed by the largest sediment flux on the planet. Detritus generated mostly in Himalayan highlands and conveyed through the Ganga−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−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−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−mineral assemblages, showed a clear prevalence in sediment supply from the Brahmaputra (60−70%) over the Ganga (30−40%). 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.

This article illustrates a multi-technique frontier approach for the provenance study of silt-size sediments. The mineralogical composition of low-density and heavy-mineral fractions of four samples of fine to very coarse silt deposited on the Bengal shelf was analyzed separately for six different grain-size classes by combining grain counting under an optical microscope, Raman spectroscopy, and X-ray diffraction. The geochemical composition was determined on both bulk-sediment samples and on their

The age range of the major intra-plate volcanic event that affected the northern Indian margin in the Early Cretaceous is here defined precisely by detrital zircon geochronology. U–Pb ages of Early Cretaceous detrital zircons found in the Cretaceous to the Paleocene sandstones cluster mainly between 142 Ma and 123 Ma in the northern Tethys Himalayan unit, and between 140 Ma and 116 Ma in the southern Tethys Himalayan unit. The youngest and oldest detrital zircons within this group indicate that volcanism in the source areas started in the latest Jurassic and ended by the early Albian. Stratigraphic data indicate that volcaniclastic sedimentation began significantly earlier in southern Tibet (Tithonian) than in Nepal (Valanginian), and considerably later in Spiti and Zanskar (Aptian/Albian) to the west. This apparent westward migration of magmatism was explained with progressive westward propagation of extensional/transtensional tectonic activity and development of fractures cutting deeply across the Indian continental margin crust. However, detrital zircon geochronology provides no indication of heterochroneity in magmatic activity in the source areas from east to west, and thus lends little support to such a scenario. Westward migration of volcaniclastic sedimentation may thus reflect instead the westward progradation of major drainage systems supplying volcanic detritus sourced from the same volcanic centers in the east. Development of multiple radial drainage away from the domal surface uplift associated with magmatic upwelling, as observed for most large igneous provinces around the world, may also explain why U–Pb ages of detrital zircons tend to cluster around 133–132 Ma (the age of the Comei igneous province) in Tethys Himalayan units, but around 118–117 Ma (the age of the Rajmahal igneous province) in Lesser Himalayan units.

Detailed biostratigraphic study of mid-Cretaceous Tethys Himalayan pelagic units shed new light on the evolution of the northern India passive continental margin. After a major episode of alkaline magmatism recorded from Zanskar to Nepal in the Early Cretaceous, condensed glauco-phosphorites were deposited during the Rotalipora subticinensis Subzone, and were overlain unconformably by pelagic mudstones during the Rotalipora ticinensis to Rotalipora appenninica Zones (Fatu La Formation in Zanskar and Muding Formation in Nepal). Throughout the Tethys Himalaya drowning of clastic shelves thus occurred with the same modalities and synchronously in Late Albian time. The base of the Chikkim Formation in Zanskar is younger, and overlies palimpsest arenites and reworked glauco-phosphorires deposited during the latest Cenomanian Whiteinella archaeocretacea Zone. Hiatuses several million years long, mainly coeval and similar in duration in the Chikkim and Fatu La Formations, characterize the Cenomanian and the Late Turonian to Campanian sections throughout the Zanskar Range. These hiatuses are ascribed to continuous resuspension of pelagic sediments on the upper slope, caused by the action of strong eastbound oceanic currents. Much higher accumulation rates were recorded in the early-middle Turonian, when deposition occurred at grearer depths below the mudline. Accumulation rates increased greatly in the Maastrichtian, when offshore marls with sparsc phosphate nodules were gradually rcplaced by inner shelf carbonate facies at the close of the Cretaceous. The studied succession shows a mirrorlike repetition of sedimentary facies, interpreted as part of a 65 to 70 my long Cretaceous supersequence. Sedimentary evolution reflected a complex interplay of global and regional phenomena, including the extensional and magmatic episodes leading to thc final fragmentarion of Gondwana-Land and opening of the Indian Ocean, a long-term tendency to eustatic rise, changing paleooceanographic circulation, and oceanic anoxic events.

The Carnian sedimentary succession of the Lierna area, more than 4OO m thick and belonging to the Coltignone tectonic unit (Grigne Group), has considerable paleogeographic significance, for it documents the western termination of the deltalagoon-carbonate platform depositional system of the Lombard Prealps. The Carnian succession, directly overlying basinal (Perledo-Varenna Formation) to shallow-marine (Lierna Formation) carbonates of Ladinian age, is characterized by deltaic terrigenous deposits (Val Sabbia Sandstone), progressively replaced by lagoonal (Gorno Formation) to peritidal (Breno Formation) limestones. In the studied stratigraphic sections these three lithofacies alternate vertically at decametric scale, and are each characterized by different types of cyclothems at metric scale. High-frequency "punctuated aggradational cycles" (PAC) are best recognized at the top of the Val Sabbia clastic body, where the final transition to the Gorno lagoon is marked by arenite layers containing ferruginous ooids. Grains of this type have nor been previously reported from Southalpine arenites. The petrographic composition of the Val Sabbia Sandstone points to provenance from an active volcanic chain, but abundance of quartzose detritus and occurrence of perthitic K-feldspar and sedimentary rock fragments suggest extensive erosion of the Hercynian basement and Upper Carboniferous to Ladinian sedimentary cover. These peculiar characteristics confirm the existence of a small "Lierna lobe" separated from the deltaic systems of central Lombardy, and fed by a basement- high located southwest of Como lake.

The stratigraphic succession of central Dolpo (Tarap-Atali area) begins with thick calcsilicate marbles of inferred Cambrol-Ordovician age, injected by pegmatitic dykes. The strongly deformed mid-Paleozoic sequence comprises fossiliferous marls, dolomitic quartzarenites and dolomites. The latter are unconformably followed by earliest Late Devonian biocalcarenites, capped by a maior ironstone layer. The overlying offshore black pelites contain quanzose sandstones and bioclastic limestones at several intervals, indicating deposition in shelfal environments at latest Devonian times. The Carboniferous is poorly represented in the surveyed area. A major disconformity, cutting deep into Early? Carboniferous fenestellid-rich biocalcarenites at Tarap, is overlain by white quartzarenites interbedded with dark pelites, sharply followed by a fossiliferous marker horizon yielding a large brachiopod fauna of mid-Permian age (Costiferina arenites); the overlying fossiliferous shelfal pelites are unconformably followed by coarsening-upward quartzarenite sequences deposited in estuarine environments (Thini Chu Formation). In the Late Permian, another disconformity is overlain by conglomeratic to glauconitic arenites and shelfal pelites (Kuling Formation). The Triassic Tamba Kurkur Formation, with dolomitic subarkoses ar the base, consists of two condensed pelagic carbonate horizons of Dienerian and Smithian age, separated by dark pelites. Marly limestones and marls were deposited from the Spathian through the Carnian (Mukut Formation), and are overlain by the thick Tarap Shale. A thin basal condensed bed is followed by dark pelites yielding Early Norian ammonoids, by thick siltstones with phosphatic nodules and next by dark shales and calcareous siltstones with large Zoophycos-type burrows. The upper part of the unit contains up to fine-grained quartzo-feldspathic sandstones, nodular marly limestones and ironstone horizons ("upper assemblage"). The Late Triassic shallowing- upward succession is capped by dolomitic and oolitic quartzarenites with spectacular herringbone structures (Quartzite Series). The largely Lower Jurassic shallow-water Kioto Limestone, still containing metric intervals of up to medium-grained hybrid quartzarenites in the lower part, is followed by Middle Jurassic lumachelles (Laptal Formation). Younger terms of the succession are not exposed in Dolpo.

Detailed stratigraphic work in the course of four geologic expeditions has allowed refinement of the Early Cretaceous stratigraphy of the Zanskar Range. The Giumal Sandstone, which is comprised between the Late Jurassic to earliest Cretaceous? Spiti Shale and the mid-Cretaceous Chikkim and Fatu La pelagic limestones, is formally elevated to Group rank and subdivided into two new formations, both capped by laterally continuous condensed sections here considered as formal stratigraphic horizons. The Takh Formation, overlying the Spiti Shale stratigraphically in the Zumlung Unit and commonly with tectonic contact in the Zangla Unit, is in turn subdivided into two parts. The lower part (62 to 86 m thick in the Zumlung Unit) is characterized by very fine to fine-grained subarkoses and medium to very coarse-grained quartzarenites derived from the rejuvenated Indian continental block. In the upper part (103 to 117 m thick), deeper-water dark pelites locally yielding ill-preserved faunas probably Aptian in age become more important. The formation is capped by a glauconitic marker horizon (Labar La Arenite), testifying to a major starved transgressive stage possibly close to the Aptian/Albian boundary. The Pingdon La Formation (214 to 240 m thick in the southwestern part of the Zangla Unit and only 92 to 130 m thick in the Nerak area and Zumlung Unit) is characterized by the sudden appearance of up to medium-grained volcanic detritus. Decametric intervals of up to very coarse-grained quartzo-feldspathic sandstones characterize the middle part of the formation in proximal areas, whereas more monotonous distal sections contain only up to lower fine-grained volcanic arenites. In the upper part, volcanic arenite layers are interbedded with glaucony-rich or bioclastic sediments yielding sporadic foraminifers of Late Albian age. The formation is capped by a condensed horizon (Nerak Glauco-phosphorite) of Late Albian age (R. subticinensis Subzone), which in distal areas is overlain by latest Albian multicolored pelagic limestones of the Fatu La Formation. In the western part of the Zangla Unit, another condensed horizon rich in phosphates, glaucony and bioclasts (Oma Chu Glauco-phosphorite), reaching up to the Late Cenomanian (W. archaeocretacea Zone), is followed by Early Turonian grey pelagic limestones of the Chikkim Formation. Final drowning of the Zanskar shelf occurred through successive episodes of starvation and deepening, related to a complex interplay of geodynamic, eustatic and paleoceanographic processes.

The stratigraphic succession of the Thakkhola region (central Nepal) begins in the Cambro-Ordovician with thick shallow-water carbonates, followed in the Siluro-Devonian by pelitic units deposited in deeper-water environments and at much higher accumulation rates with respect to the northwestern Himalaya sequence. During Carboniferous and Permian times, shallow-water limestones and coarse quartzose arenites were deposited, with major unconformities related to the initial opening of Neotethys. The following Triassic to Jurassic sedimentary units display comparable features all along the Tethys Himalaya. Owing to strong thermo-tectonic subsidence, the newly-formed Indian margin was rapidly drowned in the Early Triassic, and covered by thick marly limestones in Anisian to Carnian times. The Norian was characterized by very fine- grained quartzo-feldspathic detritus derived from the rejuvenated Indian foreland, while exclusive quartzose detritus suggests latitudinal drift towards more humid climates or more subdued relief in the Rhaetian. Shallow subtidal Early Jurassic limestones were covered in the Bajocian- Bathonian by bioclastic hybrid arenites, capped by a widespread condensed ironstone in the Early Callovian. In the Late Jurassic, black shales were deposited in outer shelf-slope conditions. The Cretaceous sedimentary evolution was related to the final fragmentation of Gondwanaland and initial opening of the Indian Ocean. Renewed quartzose detritus in the early? Neocomian was followed by deposition of thick deltaic to shallow-marine sandstones invariably characterized by abundant volcanic rock fragments. The northward-prograding deltaic complexes were overlain by a glauconitic condensed section, followed by late Albian pelagic marls. After the onset of collision berween India and Asia, the sedimentary units were involved in fold-thrust deformation at pre-anchimetamorphic to medium metamorphic grade, followed by uplift, formation of the Thakkhola graben and deposition of thick fluviolacustrine sediment in the Plio-Pleistocene.

In the Manang area (north Annapurna Range; Nepal Himalaya), the Permo-Carboniferous succession is 1000 to 1500 m thick. Crinoidal biocalcarenites (Tilicho Lake Fm.) pass upward to alternating black shales and sharp-based white quartzose sandstones (Thini Chu Group). Detailed stratigraphic analysis of this unit allowed us to recognize and establish 5 new formations and 8 new members. The Marsyandi Fm., of Visean age, records an increase of subarkosic terrigenous detritus during the initial stage of Neotethyan rifting, and is capped by two sequences "Syringotbyris beds") characterized by transgressive sandstones rich in Serpukhovian brachiopods. The overlying black shales with subordinate quartzarenites (Col Noir Shale) are followed in the more proximal Bangba section by diamictites yielding dolostone rock fragments, documenting the first advance of glacial ice on rift shoulders, actively uplifted since the Bashkirian-Moscovian (Bangba Fm.). Next, glaciomarine to transgressive shelfal deposits are enriched first in igneous detritus and then in arenaceous rock fragments (Braga Fm.). Mafic to felsic magmatism during the climax of rifting was thus followed by active erosion of sedimentary successions, probably around the Carboniferous/Permian boundary. A major Early Permian transgression, coinciding with ameliorating climates at the end of the Gondwana glaciation, was followed by mainly estuarine chert-bearing quartzose pebbly sandstones capped by richly bioclastic shelfal deposits (Puchenpra Fm.). This second major transgression, associated with quartzose sandstones documenting subdued rift reliefs, is dated as Bolorian at Bangba, as Murgabian-Midian at Col Noirand as Djulfian at Tilicho. The base of the condensed outer shelf/upper slope carbonates capping the Thini Chu Group ("topmost biocalcarenites") is also strongly heterochronous, being dated as Bolorian to Kubergandian-Murgabian at Bangba and as Djulfian-Dorashamian at Col Noir and Tilicho. Thermal subsidence associated with the opening of Neotethys thus began as early as the Early Permian.

The stratigraphical data collected during four geological expeditions to the Northern Karakorum (1996,1991,1992a,1992b) are discussed. The sedimentary succession has been classified by 9 formations, here formalised, and subdivided into members and lithozones. The biochronology has been established on fusulinids, brachiopods, and conodonts. Several plates illustrate the most significant fossil species as well as the litho- and microfacies. The sedimentary succession may be roughly subdivided into three parts. The lower part consists of terrigenous rocks, mostly pelitic and less frequently arenaceous(quartzarenites with thick arkose intervals during the latest Asselian-early Sakmarian). They are evidence of a continental to coxtal environment, with short term marine ingressions. The second part begins with the Sakmarian, when the marine environment spread over most of the studied area. Bioclastic sand bars with brachiopods and crinoids at the base are followed by huge fusulinid packages. In Hunza oolitic bars and dolostone peritidal cycles also follow. The carbonate ramp is often polluted by terrigenous sediments, especially westwards. Temporary arenaceous spillovers (quartzarenites), often linked to minor sedimentation gaps, occur both westwards in the Baroghil area, and eastwards in the Hunza-Shimshal area. In the centre, in the Upper Karambar valley, a large gap most probably occurs, with reappearance of the sedimentation only with the dolostones of the Upper Permian. These erosional episodes with arenaceous spillovers are interpreted as being linked to rifting events of the Neotethys opening, active southwards. The third part of rhe succession concerns the Late Permian. Towards the end at the Murgabian or at the beginning of the Midian, the Northern Karakorum is subdivided into two major areas. To the west, after a transgressive episode with ironstone deposition, a wide peritidal carbonate platform spread over from Baroghil to Chillinji in Karambar and the Pasu area in Hunza. This palaeogeographic pattern extends up to the Triassic. However, biostratigraphic control is poor. Instead to the north-east, a progressive sinking of the slope is observed, with spreading of deeper environments and cherty limestone deposition. The down-warping is activated by block-faulting resulting in huge megabreccia bodies interbedded with the cherty limestones. During the Dzhulfian, significant clay inputs dilute the carbonate mud accumulation and shales are dominant around the Permian-Triassic boundary. Pelagic carbonate sedimentation gradually recovers from the Smithian onward. The Permian of the Karakorum is the sedimentary evidence of the passive margin of a lithospheric block, detached from the Gondwana continent during the Permian, that will later migrate towards the centre of the Paleo-Tethys, along with other lithospheric blocks of the Mega Lhasa plate.

The mixed terrigenous-carbonate-evaporitic S.Giovanni Bianco Formation and dolomitic Campolungo Tongue (upper part of the Breno Formation), generally 2OO to 3OO m thick, are assigned to the Late Carnian. They respectively overlie lagoonal limestones (Gorno Fm.) and peritidal carbonates (Annunciata Member of the Breno Fm.), and underlie intraformational breccias and recrystallized limestones (Castro Fm.). Recognition of an unconformity, ascribed to a relative fall of sea-level (sequence boundary), allowed us to subdivide the Upper Carnian succession into two parts. ln the lower part (SGBL), six lithosomes were recognized. Red to green alluvial clastics in the south-east and south-west pass northward to mixed terrigenous-carbonate coastal sediments and finally to dolostones deposited in carbonate tidal flats. In the proximal sections of the Brescia Prealps, renewed north-westward progradation of alluvial redbeds with intercalated calclithite conglomerates points to a stage of teconic uplift. A distinct increase in quartz, representing a regional petrographic marker followed all across Lombardy, indicates deepening of erosion into the metamorphic wallrocks of the volcanic belt. A major hiatus at the top of the SGB1 is best documented in the northern Presolana area by a silcrete crust directly overlying the Julian Annunciata Member of the Breno Formation. In the Brembana Valley area, the discontinuity occurs within a greenish siliciclastic coastal plain succession, and may be traced at the top of a marker interval of interbedded reddish siltstones and sandstones. The upper part (SGB2) consists of four lithosomes. Greenish sandstones and siltstones, accumulating in coastal plains in the south-west, passed northward to mudrocks and dolostones. In the southernmost Camonica Valley area, mudrocks are locally interbedded with calcarenites containing bored or pedogenized lithoclasts ripped from the underlying sequence and varied bioclasts, restifiying to relatively open shallow-marine conditions during transgression. Next, thick gypsum accumulated in coasral salinas barred by locally oolitic platform carbonates to the north. Rare sandstone lenses occurring in the Brembana Valley at the top of the unit conrain exclusive rhyolitic detritus, indicating either a terminal phase of explosive volcanism or erosion of older felsic volcanic products.

The successions exposed in the Pin and Spiti valleys, a classical area for the Tethyan Triassic, provides an extraordinarily complete sedimentary and paleontologic record and is thus well-suited to check the validity of global eustatic charts and applicability of sequence stratigraphic concepts. New detailed stratigraphic data allowed us to present a revised lithostratigraphic scheme - largely based on previous works by Hayden (1904) and Srikantia (1981) - which can be directly compared with successions exposed all along the Tethys Himalaya from Zanskar to Tibet. The Permian/Triassic boundary represents a major break in sedimentation, with time gaps of up to several Ma testified in the upper Pin valley. In the Induan to Anisian, the Tamba Kurkur Fm. mainly documents global eustatic changes, with transgressive stages characterized by sedimentation of condensed nodular Lmestones on the outemost shelf/uppermost slope (e.g., Griesbachian/Early Dienerian, Spathian) and regressive stages marked by mudrock deposition on the continental shelf (e.g., Late Dienerian/Smithian). A glauconitic condensed horizon occurs at the Anisian/Ladinian boundary, and the top of the formation reaches the Early Ladinian in more complete proximal sections. Greater clay supply characterizes the late Early Ladinian, but accumulation rates remain low in the lower part of the Hanse Group(Kaga and Chomule Fms.), to increase sharply in the late Early to early Late Carnian ("Grey beds"), reaching 100 m/Ma in the latest Carnian (Nimaloksa Fm.). At least nine, third- to fourth-order transgressive,/regressive sequences can be recognized in the Nimaloksa Fm. and Alaror Group, where facies distribution pattems indicate that the Spiti continental margin deepened towards the north. The Nimaloksa Fm. documents progradation of a carbonate ramp in the latest Carnian(Lower Member), followed in the Early Norian by subtidal mixed carbonate/terrigenous sedimentation (Middle Member) and by platform carbonate deposits (Upper Member). Next, the major disconformity at the base of the Alaror Group testifies to an extensional tectonic event, followed by rapid increase in quanzo-feldspathic detritus in the late Early Norian. Siliciclastic supply is reduced only during flooding stages, marked by oolitic ironstone or phosphatic condensed horizons ("Juvavites beds", "Monotis shale'); cleaner waters foster local development of knoll reefs round the Early/Middle Norian boundary ("Coral limestone'). Accumulation rates gradually begin to decrease before the close of the Triassic, when the "Quartzite series" records a sharp regressive event, followed by renewed transgression at the base of the Kioto Group.

After initial opening of Neotethys in the Permian, thermal subsidence and deepening continued in the Triassic. In the Scythian, three pelagic nodular carbonate intervals of Early Griesbachian to Early Dienerian, Early to mid-Smithian and latest Smithian to earliest Aegean age are interbedded with shelfal shales (Tamba Kurkur Formation). Ammonoid-and conodont-rich condensed carbonates were deposited on the outer shelf, with maximum depths around 150+200 m reached during transgressive stages. The Anisian to lowermost Norian shelfal succession mostly consists of marly limestones and marls (Mukut Formation). Thick calcareous siltstones rapidly accumulated in the Carnian, testifying to a new stage of tectonic extension affecting the Tethys Himalayan passive margin. The thick Tarap Formation of largely mid-Norian age points to strong continuing subsidence. Interbedded siltstones and subarkosic sandstones ("lower member") are locally overlain by coral-bearing patch reefs ("middle member"). Chamosite-bearing hybrid arenites deposited at transgressive stages characterize the "upper member". The Triassic succession is capped by subarkoses and quartzarenites, interbedded with dolomitic to bioclastic hybrid sandstones and silty limestones ("Quartzite Series"), in turn overlain by the Kioto Limestone.

Despite decades of study, the factors that controlled the formation and evolution of the upper reaches of the Yellow River, including uplift of the northeastern Tibetan Plateau, Pliocene-Pleistocene climate change, and autogenetic processes are still poorly constrained. The stratigraphic record of such paleogeographic evolution is recorded in the sequence of nine terraces formed during progressive incision of the Yellow River in the last 1.7 Ma. This article investigates in detail for sediment provenance in terraces of the Lanzhou area, based on heavy-mineral and geochemical (REE) signatures. Two main provenance changes are identified, pointing each to a major paleogeographic reorganization coupled with expansion of the upper Yellow River catchment and enhanced sediment fluxes. The first change took place between the deposition of terrace T9 (formed around 1.7 Ma) and terrace T8 (formed around 1.5 Ma), when rapid fluvial incision point to tectonic control and active uplift of northeastern Tibetan Plateau. The second change took place between deposition of terrace T4 (formed around 0.86 Ma) and terrace T3 (formed around 0.14 Ma), during a period of low incision rates and notably enhanced sediment fluxes as a response to enhanced East Asian Summer Monsoon and consequently increased precipitations, pointing instead chiefly to climatic control.

As a Quaternary repository of wind-reworked Indus River sand at the entry point in the Himalayan foreland basin, the Thal Desert in northern Pakistan stores mineralogical information useful to trace erosion patterns across the western Himalayan syntaxis and the adjacent orogenic segments that fed detritus into the Indus delta and huge deep-sea fan throughout the Neogene. Provenance analysis of Thal Desert sand was carried out by applying optical and semi-automated Raman spectroscopy on heavy-mineral suites of four eolian and 11 fluvial sand samples collected in selected tributaries draining one specific tectonic domain each in the upper Indus catchment. In each sample, the different types of amphibole, garnet, epidote and pyroxene grains—the four dominant heavy-mineral species in orogenic sediment worldwide—were characterized by SEM-EDS spectroscopy. The chemical composition of 4249 grains was thus determined. Heavy-mineral concentration, the relative proportion of heavy-mineral species, and their minerochemical fingerprints indicate that the Kohistan arc has played the principal role as a source, especially of pyroxene and epidote. Within the western Himalayan syntaxis undergoing rapid exhumation, the Southern Karakorum belt drained by the Hispar River and the Nanga Parbat massif were revealed as important sources of garnet, amphibole, and possibly epidote. Sediment supply from the Greater Himalaya, Lesser Himalaya, and Subhimalaya is dominant only for Punjab tributaries that join the Indus River downstream and do not contribute sand to the Thal Desert. The detailed compositional fingerprint of Thal Desert sand, if contrasted with that of lower course tributaries exclusively draining the Himalaya, provides a semi-actualistic key to be used, in conjunction with complementary provenance datasets and geological information, to reconstruct changes in paleodrainage and unravel the relationship between climatic and tectonic forces that controlled the erosional evolution of the western Himalayan-Karakorum orogen in space and time.

In the last two centuries, since the dawn of modern geology, heavy minerals have been used to investigate sediment provenance and for many other scientific or practical applications. Not always, however, with the correct approach. Difficulties are diverse, not just technical and related to the identification of tiny grains, but also procedural and conceptual. Even the definition of “heavy minerals” is elusive, and possibly impossible. Sampling is critical. In many environments (e.g., beaches), both absolute and relative heavy mineral abundances invariably increase or decrease locally to different degrees owing to hydraulic-sorting processes, so that samples close to "neutral composition" are hard to obtain. Several widely shared opinions are misleading. Choosing a narrow size-window for analysis leads to increased bias, not to increased accuracy or precision. Only point-counting provides real volume percentages, whereas grain-counting distorts results in favor of smaller minerals. This paper also briefly reviews the heavy mineral associations typically found in diverse plate-tectonic settings. A mineralogical assemblage, however, only reproduces the mineralogy of source rocks, which does not correlate univocally with the geodynamic setting in which those source rocks were formed and assembled. Moreover, it is affected by environmental bias, and by diagenetic bias on top in the case of ancient sandstones. One fruitful way to extract information on both provenance and sedimentological processes is to look for anomalies in mineralogical–textural relationships (e.g., denser minerals bigger than lower-density minerals; harder minerals better rounded than softer minerals; less durable minerals increasing with stratal age and stratigraphic depth). To minimize mistakes, it is necessary to invariably combine heavy mineral investigations with the petrographic analysis of bulk sand. Analysis of thin sections allows us to see also those source rocks that do not shed significant amounts of heavy minerals, such as limestone or granite, and helps us to assess heavy mineral concentration, the “outer” message carrying the key to decipher the “inner message” contained in the heavy mineral suite. The task becomes thorny indeed when dealing with samples with strong diagenetic overprint, which is, unfortunately, the case of most ancient sandstones. Diagenesis is the Moloch that devours all grains that are not chemically resistant, leaving a meager residue difficult or even impossible to interpret when diagenetic effects accumulate through multiple sedimentary cycles. We have conceived this friendly little handbook to help the student facing these problems, hoping that it may serve the purpose.

Nature Communications 6: Article number: 8511 (2015); Published: 9 October 2015; Updated: 18 February 2016. The original version of this Article contained errors in the Supplementary Information files: Zircon U-Pb age results for sample 23, shown in Supplementary Fig. 3, are incorrect, and missing from Supplementary Data 1, while several identification labels relating to Yellow River Lanzhou terraces samples are missing from Supplementary Data 2.

Blocks embedded within the Kopría Mélange of western Rhodos yield well-preserved, abundant microfossils including early Middle Pennsylvanian fusulinacean faunas represented by species belonging to the genera Eoschubertella, Profusulinella, Pseudostaffella and Ozawainella. A less diagnostic fauna mainly composed of the genus Paraachaediscus and an undetermined species of Howchinia has been also recorded and referred to a probable Mississippian age.This tropical to subtropical microfauna with Urals-Paleotethyan paleobiogeographic affinity provides new constraints for the paleogeographic interpretation of the Aegean region during the still poorly understood transition from the Variscan to the Alpine deformational cycle. In one olistolith, fusulinid-bearing strata are underlain by a basal conglomerate horizon whose composition indicates both "recycled orogenic" provenance and significant chemical weathering in a warm, humid climate. Sedimentologic and petrographic data, combined with the age and Urals-Paleotethyan affinity of the microfossil assemblages, are evidence for a major transgression that coincided in time with the end of the Variscan Orogeny. This may suggest original deposition of the mélange on the northern European margin of Paleotethys, although a southern origin be ruled out. Subsequent accretion to the External Hellenides, on the southern, Gondwanan margin of Paleotethys, could have taken place during the Eo-Cimmerian orogeny at the end of the Middle Triassic, shortly before the opening of the Pindos Basin.