Sedimentary provenance

The petrographic and geochemical composition of the Dharla River sediments has been examined to infer their sediment type, degree of weathering, provenance, and tectonic settings. Petrographically the sediments are characterized by the high quartz content (64.97 to 74.24 wt%), followed by feldspar (7.04 to 15.20 wt%), mica (5.38 to 19.92 wt%), lithic fragment (3.46 to 8.14 wt%), and heavy minerals (1.98 to 6.94 wt%). Geochemical composition shows marked enrichment of SiO 2 (mean ~ 74.16%) and a strong negative correlation with the other major oxides because of quartz dilution. The Chemical index of alteration (CIA, 45.52 to 63.51); Plagioclase index of alteration (PIA, 43.13 to 66.55); W index (20.15 to 32.86) and Rb/Sr ratios (0.35 to 0.98) suggest low to moderate intensity of chemical weathering in the source area. Geochemical classifications of the studied samples show mostly litharenitic immature type of sediments also reflects high index of compositional variability (ICV, 0.96 to 1.72). The ternary diagrams of Al 2 O 3-(CaO + Na 2 O)-K 2 O (or A-CN-K) and of mafic rocks, felsic rocks and degree of weathering of the source rocks (or MFW) and several immobile trace element ratios (e.g. light rare earth element/heavy rare earth element or LREE

Detrital sand grains from three beaches (Tecolutla,
Nautla, and Veracruz) along the western Gulf of Mexico were
studied by a scanning electron microscope, to investigate the
depositional environment and paleoclimate. Totally, 24
microtextures are identified; among them, 13 are grouped as
mechanical origin, 5 as mechanical and/or chemical origin, and
6 as chemical origin. These microtextures are nonuniformly
distributed among the three beach areas. Concoidal fractures,
straight and arcuate steps at Tecolutla and Veracruz beaches
indicate that the sand grains were derived from the crystalline
rocks. The abundance of angular outline grains at the Nautla
beach supports for short transportation probably close to the
source area. The domination of rounded sand grains in the
Veracruz beach reveals that the sediments were derived by
the aeolian mechanism. Chattermark trials at the Veracruz
beach sands are indicating a wet tropical climate. Chemical
features like silica globules, silica pellicle, and trapped diatoms
in the Tecolutla and Veracruz beach sands suggest a silica
saturated environment. Similarly, chemical etching and solution
pits are common in the Veracruz beach sands, which are
probably linked to the contaminated sea water. Desiccation
crack at Veracruz beach sands is an indicator of temperature
changes in the beach environment. Broken benthonic foraminifera Elphidium discoidale sp. present in the Veracruz beach indicates a high-energy littoral environment.

The intramontane Middle Magdalena Valley Basin (MMV) has a multistoried evolution. At the beginning it was a foreland basin associated to the Central Cordillera uplift since the end of the Cretaceous to Paleocene. Now, it is a broken foreland basing associated to the Oriental Cordillera uplift since at least the late Eocene time. In this way, the MMV holds the sedimentary record and the geologic uplift story of both ranges.
With the aim to constrain the timing of uplift of the Oriental Cordillera in this part of the basin, it was carried out paleocurrent measurements, conglomerate and sandstone petrography, facies and provenance modeling of the sedimentary record outcropping in the Nuevo Mundo Sincline to the east of the MMV.
It was identified a change in paleocurrent direction from E – NE to W – NW in the upper part of the Esmeraldas Formation (late Eocene) which remains in the overlying Mugrosa, Colorado and Real formations. In the same way, the petrography study and provenance modeling indicate that there was at least two area sources of sediments, one for the La Paz and Esmeraldas units, other for Mugrosa, Colorado units and both contributed with sediment to the upper Real Formation. Facies distribution shows proximal facies to the S-SW in the La Paz Fm, W in Esmeraldas Fm, E in the Mugrosa Fm and E-NE in the Colorado and Real formations. The above direct information collected from the outcrops let us document the first Oriental Cordillera uplift in this part of the basin as late Eocene. This is a very important finding to the exploration of oil in the western foothills of the Oriental Cordillera of Colombia.

We examined an International Ocean Discovery Program (IODP) drilling core from Site U1501, located on the distal margin of the northern South China Sea (SCS) basin to unravel the sediment provenance evolution in the Paleogene and the evolution of river catchments during basin opening. We attempt to understand the major factors driving river development in a rift basin by utilizing provenance tools to constrain sediment transport pathways and compare these with the regional tectonics during the Paleogene in order to resolve competing models for drainage evolution and test their relationships with the evolving topography of SW China and the SE Tibetan Plateau. For this purpose, ten samples were collected from a 200-m-thick, syn-rift Eocene/pre-Eocene interval. Detrital zircon U-Pb data were collected by LA-ICP-MS to identify the sediment provenance and differentiate fluvial sources. Bulk rock geochemistry data was utilized to shed light on chemical weathering conditions and compositional maturity to further decipher sediment transportation patterns. We compare our data with adjacent IODP Site U1435 and several industrial boreholes located in the Pearl River Mouth Basin (PRMB). We applied multiple statistical tests, including K-S, Monte Carlo mixing and multidimensional scaling testing, to evaluate U-Pb age spectra similarities and to estimate endmember contributions from a variety of source areas. Our results from Site U1501 show that sediments deposited as fluvial sands during the rifting stage, were predominantly derived from the East Cathaysia block, probably from local sources. A progressive increase in older detrital zircon U-Pb ages peaks (>200 Ma) was observed at Site U1435 and in PRMB strata, signaling a spatial shift in sediment provenance from east to west occurring between the late Eocene and the early Oligocene. This trend reflects a transition in sediment delivery from local small-catchment streams to a more regional drainage eroding the east and north of the South China Block. Westward drainage expansion is likely impacted by the uplift of the Tibetan Plateau.

The deposits of large Asian rivers with unique drainage geometries have attracted considerable attention due to their explanatory power concerning tectonism, surface uplift and upstream drainage evolution. This study presents the first petrographic, heavy mineral, Nd and Sr isotope geochemistry, and detrital zircon geochronology results from the Holocene Irrawaddy megadelta alongside modern and ancient sedimentary provenance datasets to assess the late Neogene evolution of the Irrawaddy River. Contrary to models advocating a steady post-middle Miocene river, we reveal an evolution of the Irrawaddy River more compatible with regional evidence for kinematic reorganization in Myanmar during late-stage India-Asia collision. Quaternary sediments are remarkably consistent in terms of provenance but highlight significant decoupling amongst fine and coarse fraction 87 Sr/ 86 Sr and ε Nd due to hydraulic sorting. Only well after the late Miocene do petrographic, heavy mineral, isotope geochemistry, and detrital zircon U-Pb results from the trunk Irrawaddy and its tributaries achieve modern-day signatures. The primary driver giving rise to the geometry and provenance signature of the modern Irrawaddy River was regional late Miocene (≤10 Ma) basin inversion coupled with uplift and cumulative displacement along the Sagaing Fault. Middle to late Miocene provenance signatures cannot be reconciled with modern river geometries, and thus require significant loss of headwaters feeding the Chindwin subbasin after ∼14 Ma and the northern Shwebo subbasin after ∼11 Ma. Large-scale reworking after ∼7 Ma is evidenced by modern Irrawaddy River provenance, by entrenchment of the nascent drainage through Plio-Pleistocene inversion structures, and in the transfer of significant sediment volumes to the Andaman Sea.

Compositional and geochemical analyses of sands collected from the Chachalacas (CHA) and Veracruz (VER) beach areas along the western Gulf of Mexico were studied to determine the provenance and tectonic setting of the source region. The modal composition showed that the proportion of quartz (Q) is
lower in CHA than in VER sands. The average quartz-feldspar-lithic fragment (QFL) ratios for the CHA and VER sands are Q75F8L17 and Q86F4L10, respectively. The X-ray diffractometer (XRD) and Scanning Electron
Microscope equipped with EDAX spectrometer (SEM-EDS) data revealed that the CHA sands were abundant in heavy minerals like magnetite, ilmenite, and zircon. The rare earth element concentration (REE) is higher in CHA than in VER sands, which is due to the concentration of heavy minerals in CHA
sands. The weathering indices such as chemical index of alteration (CIA), plagioclase index of alteration,
and AeCNeK (A ¼ Al2O3, CN¼CaO* þ Na2O, K ¼ K2O) plot suggested that the intensity of weathering in
the source area was low to moderate. The index of chemical variability (ICV) for the CHA (~1.9e3.0) and
VER (~0.82e1.33) sands indicated that the compositional maturity was higher for the VER sands. The concentrations of Co, Cr, Ni, and V are lower in VER sands than in CHA sands, indicating that the CHA sands were derived from the intermediate source rocks. Provenance modelling revealed that the CHA sands were associated with the mixture of basalt, andesite, dacite, and trachyandesite in the ratio of
5:20:25:50. The VER sands were best matched with a mixture having 75e90% dacite and 25e10% andesite compositions. The provenance difference between the two beach areas suggested that longshore current play a less significant role in mixing and homogenization of sands. The multidimensional tectonic discrimination diagrams revealed rift and collision settings for the VER and CHA beach areas, respectively, which is consistent with the general geology of the study areas.

Combined petrographic and geochemical methods are utilized to investigate the provenance, tectonic setting, palaeo-weathering and climatic conditions of the Cambrian Araba clastic sediments of NE Egypt. The  60 m thick Araba Formation consists predominantly of sandstone and mudstone
interbeddedwith conglomerate. Petrographically the Araba sandstones are mostly sub-mature and classified as subarkoses with an average framework composition of Q80F14L6. The framework components are dominated by monocrystalline quartzwith subordinate K-feldspar, togetherwith volcanic and granitic rock fragments. XRD analysis demonstrated that clay minerals comprise mixed-layer illite/smectite (I/S), illite and smectite, with minor kaolinite. Diagenetic features of the sandstone include mechanical
infiltration of clay, mechanical and chemical compaction, cementation, dissolution and replacement
of feldspars by carbonate cements and clays. The modal composition and geochemical parameters (e.g. Cr/V, Y/Ni, Th/Co and Cr/Th ratios) of the sandstones and mudstones indicate that they were derived from felsic source rocks, probably from the crystalline basement of the northern fringe of the Arabian–Nubian Shield. The study reveals a collisional tectonic setting for the sediments of the Araba
Formation. Palaeo-weathering indices such as the chemical index of alteration (CIA), chemical index
of weathering (CIW) and plagioclase index of alteration (PIA) of the clastic sediments suggest that the source area was moderately chemically weathered. On the northern margin of Gondwana, early Palaeozoic weathering occurred under fluctuating climatic conditions.

Приводятся результаты детального геологического и минералого-геохимческого исследования ме- таморфических пород, получивших развитие в подошве офиолитового комплекса п-ова Камчат- ский Мыс, Восточная Камчатка. Выявлены несколько минеральных типов метабазитов (от наибо- лее высокометаморфизованных клинопироксен-гранат-амфиболовых пород до альбит-эпидотовых амфиболитов), фиксирующих регрессивный этап изменения исходного относительно высокобари- ческого парагенезиса. Петрогеохимические характеристики исследованных пород позволяют отно- сить их к метаморфизованным производным плутонических пород N-MORB типа (предположитель- но габброидов с толеитовой спецификой). Образование метаморфитов связывается с субдукцией в позднемеловое-палеоценовое время океанической плиты, с формированием инвертированного термального градиента в верхней части субдуцируемой плиты и метаморфизмом базитов в условиях фации гранатовых амфиболитов, последующим их аплифтом и эксгумацией при обдукции надсуб- дукционных офиолитов в эоцене-миоцене.

During the Early Cretaceous important changes occurred in South-western Gondwana related to its fragmentation, and South Atlantic Ocean opening. Then, two basins developed in southernmost Patagonia: the AustralMagallanes Basin and the Rocas Verdes-Magallanes Basin. The Río Mayer Formation corresponds to the initial sedimentary stages of the Austral Basin including black shales, marls and fine-grained  sandstones deposited in an outer shelf environment. We studied and sampled three detailed sedimentary logs at Río Guanaco Locality (S 49°
57′ 11"; W 72° 04′ 56″), dividing this unit into three informal sections (lower, middle and upper). Whole rock geochemical analyses were carried out over the three sections with the focus on trace elements, in particular, rare earth elements (REE). While, the lower section of the unit shows an affinity to acid volcanic source areas, the middle and upper sections show an affinity to intermediate source areas. These changes through the Río Mayer Formation can be correlated with the initial magmatic activity hosted in the Southern Patagonian Batholith during the Neocomian. Considering the REE patterns, the lower section of the Río Mayer Formation shows an affinity to the felsic compositions of the Tobífera Formation, while the upper section would be related to the erosion of the Punta Barrosa/Cerro Toro formations of the Rocas Verdes-Magallanes Basin. The clear distinction between the REE patterns of the Río Mayer and Zapata formations is considered evidence of the compartmentalization of these basins during the Early Cretaceous. Finally, the absence of correlation between the geochemistry of the studied unit and the Jurassic volcanic rocks of the Deseado Massif indicates that the north-eastern sector of the basin was not a source area for the Austral Basin, at least during the deposition of the Río Mayer Formation in the study area.

ABSTRACT:
There is a known bias in C/N, d13C and d15N values of organic matter (OM) due to pre-analysis acid treatment methods. We report here, for the first time, the results of a pre-analysis acid treatment method comparison of measured C/N, d13C and d15N values in bulk OM from a sedimentary sequence of samples to illustrate this bias. Here we show that acid treatment significantly reduces the accuracy (between method biases) and precision (within method bias) of C/N, d13C and d15N values of OM, suggesting a differential response of sample OM between methods and sample horizons, and in some cases inefficient removal of inorganic carbon. We show that different methods can significantly influence environmental interpretation in some of our sample horizons (i.e. interpretation of aquatic vs. terrestrial OM source; C3 vs. C4 vegetation). Specifically, there are unpredictable and non-linear differences between methods for C/N values in the range of ~ 1 – 100; d13C values in the range of 0.2 – 6.8 ‰ and; d15Nvalues in the range of 0.3 – 0.7 ‰. Importantly, these ranges are mostly much greater than the instrument precision (defined as the standard deviation of replicate analysis of standard reference materials; for this study, ± 0.5 for C/N values, ± 0.1 ‰ for d13C values and; ± 0.1 ‰ for d15N). The accuracy and precision of measured C/N, d13C and d15N values of bulk OM is not just dependent upon environmental variability, but on acid pre-treatment, residual inorganic carbon and organic matter state and composition. Collectively, this makes the correlation between samples prepared in different ways, including those from down core reconstructions, highly questionable.

Keywords: C/N ratios, δ13C, δ15N, organic matter; pre-analysis acid treatment methods, environmental interpretation, palaeoclimate.

The Khao Khwang fold-and-thrust belt,
central Thailand, developed within a basin
that formed on the southwestern margin of
the Indochina block. Because of limited geo-
chronological and provenance constraints,
the time of deposition, sediment source loca-
tion, and tectonic significance of the basin
have been uncertain. Here, we present 837
U-Pb detrital zircon ages and 271 Hf isotope
in situ analyses from Permian–Triassic clas-
tic units within the Khao Khwang fold-and-
thrust belt in order to constrain the prov-
enance, maximum depositional ages, and
depositional environment of the southwestern
margin of the Indochina terrane through
the late Paleozoic to early Mesozoic. The key
lithological units, the Sap Bon, Pang Asok,
and Nong Pong Formations, are part of the
Saraburi Group and have detrital age spectra
spanning from Late Triassic to Paleoarchean.
The entire data set has a common age peak
at ca. 450 Ma, and all samples contain grains
with ages of 0.2–0.3, 0.4–0.6, 1.0–1.3, 1.7–1.8,
and 2.2–2.7 Ga. A few grains predate 3.0 Ga.
Multidimensional scaling analysis of detrital
zircon ages from throughout SE Asia demon-
strates that the age spectra of the siliciclastic
units of the Saraburi Group resemble those
of Permian–Triassic detritus found elsewhere
in the Khorat Plateau and throughout Viet-
nam and southeast China, implying that these
areas shared similar sources. These sources
may have been the, now largely covered,
Indochina basement, and/or contiguous con-
tinental crust in terranes already amalga-
mated to Indochina at that time. Detrital zir-
cons as young as 205 ± 6 Ma show that some
formations of the Saraburi Group, previously
considered to be of Middle–Late Permian
age, are no older than Late Triassic. We pro-
pose a depositional model for the region of a
Permian rift or passive-margin setting that
evolved into piggyback and foredeep basins
during an extended period of folding and
thrusting in the Triassic.

Banganapalle Formation (Kurnool Group) comprises intercalated arenaceous and argillaceous lithofacies with a basal conglomerate unit. Geochemically, basal conglomerate unit shows wide variation in major oxide contents due to the presence of polymictic clasts of diverse composition, viz.  quartzite, shale, granite and vein quartz. Quartz arenites are highly mature (CMI: >10) as indicated by negative correlation between SiO2 and Al2O3, MgO, K2O and Na2O. The argillaceous lithofacies (shale) contains significant amount of sulphide minerals and carbonaceous matter and higher concentration of trace elements viz., Cr, Ni, Ba, Zr and Nb as compared to arenites. Major element distribution pattern, CIA values and discriminant function plots of these lithounits suggest that Banganapalle sediments were mainly derived from two different sources i.e., basement granitoids and quartzose Cuddapah sediments in passive margin setup. Uranium mineralisation in the area is fracture controlled and has no direct bearing with the geochemistry of sediments. Porous and permeable quartz arenites and the basal conglomerates with reductants in the form of sulphides and carbonaceous matter are best suited loci for uranium mineralisation.

Keywords: Palnad Sub-basin, Banganapalle Formation, geochemistry, Chemical Index of Alteration (CIA), provenance, paleo-weathering, uranium mineralization.

Late Archaean metasedimentary basins in the Eastern Goldfields Province are spatially
and  temporally  associated  with  regional  shear  zones  and  strike-slip  faults  related  to
terrane  accretion  and  mineralisation.    Sedimentary  rocks  are  preserved  in  narrow
unconformity-  and  fault-bound  basins  associated  with  regularly  spaced  and  parallel
structural sites across the Eastern Goldfields Province.  Basins are widely separated and
have  diverse  provenance,  yet  facies  relationships  and  geochronological  constraints
suggest they are genetically and temporally connected.
In  the  Kalgoorlie  Terrane,  basins  are  characterised  by  a  progression  of  increasing
provenance complexity from the Black Flag Beds, through the Merougil Formation, to
the  Kurrawang  Formation.    Upward-deepening  facies  and  an  apparent  westerly
migration  of  source  terranes  suggest  a  transpressional  to  transtensional  strike-slip
setting.  A depositional age of ~2650 Ma for the Merougil Formation suggests a close
relationship  between  structural  controls  on  basin  development  and  widespread  gold
mineralisation.
In  the  Southern  Gindalbie  Terrane,  proximally  sourced  basaltic  conglomerates  and
immature  volcaniclastics  in  the  Penny  Dam  Formation  contrast  with  arkosic  deep
marine  (flysch)  turbidites  of  the  Mount  Belches  Formation,  and  are  interpreted  to
represent  the  longitudinal  transition  between  a  remnant  ocean  basin  and  an  exposed
oceanic crustal terrane in the hinge of an oblique convergent margin.  These units record
an  oblique  ~E-W  accretionary  collision  between  oceanic  terranes  in  the  east  and
volcanic  arc  terranes  in  the  west,  and  are  consistent  with  a  regional  convergent
transpressional strike-slip setting.
The Yilgangi Conglomerate in the Kurnalpi Terrane was deposited after ~2664 Ma, and
is interpreted as derived from proximal intermediate volcanic arc terranes.  Sediments
are preserved in a tilted wedge-shaped body adjacent to a regional terrane margin, and
are interpreted to have developed in a transpressional setting in response to convergence
along a curved strike-slip fault trace.  A similar setting is inferred for the Jones Creek
and Yandal units, with mostly proximal felsic igneous sources deposited in subaerial to
fluvial environments.
The Wallaby and Lancefield Conglomerates near Laverton were deposited after ~2666
Ma by high-energy mass-flows in a submarine canyon, and contain voluminous basalt
clasts derived from proximal sources.  However, detrital zircons with ages of ~2800 Ma and ~2900 Ma indicate longitudinal sedimentary provenance with components similar
in  age  to  the  Duketon  and  Burtville  greenstone  terranes  to  the  north,  and  ~3000  Ma
zircons  represent  unknown  or  enigmatic  sources.  A  spatial  association  between
conglomerates  and  inferred  canyon-bounding  faults  suggests  a  transtensional  dip-slip
geometry and a close correlation between interpreted zones of dip-slip faulting and the
location of known mineralisation.
At the regional scale, sedimentary basins developed in zones of accommodation along
strike-slip faults at the margins of accreted terranes in response to heterogeneous flexure
associated with oblique terrane collision.  Uranium-lead detrital zircon geochronology
constrains the maximum depositional age of most basins to ~2665 Ma, although this age
may reflect the most widespread magmatic event, and tectonostratigraphic relationships
suggest actual depositional ages may be closer to the ~2650 Ma maximum determined
for  the  Merougil  Formation.    Syn-depositional  deformation  is  recorded  and  suggests
regional  transpression,  with  provenance  relationships  indicating  the  preservation  of
terranes in approximately the present-day geometry following sedimentary quiescence.
Amalgamated  tectonic  terranes  in  the  Eastern  Goldfields  Province  are  interpreted  to
include an oceanic island arc in the east, a continental arc in the central region, and a
continental margin to the west.
The temporal and spatial association of basin-controlling faults with gold mineralisation
suggests  that  an  understanding  of  the  Late  Archaean  tectonic  evolution  may  provide
improved models for mineral exploration in the Eastern Goldfields Province.  Further,
regional models based on large-scale structures and genetic associations, such as those
presented  here,  suggest  it  may  be  possible  to  target  prospective  structural  or
stratigraphic repetitions.  With much of the Eastern Goldfields Province under surficial
cover and relatively unexplored, these techniques may offer great rewards for those who
seek the next generation of giant ore deposits in the Eastern Goldfields Province.

The aim of this work is to constrain the provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico (~ 1089 –1785 m water depth). To achieve this, 10 piston sediment cores (~ 5–5.5 m long) were studied for mineralogy, major, trace and rare earth element geochemistry. Samples were analyzed at three core sections, i.e. upper (0–1 cm), middle (30–31cm) and lower (~ 300–391cm). The textural study reveals that the core sediments are characterized by silt and clay fractions. Radiocarbon dating of sediments for the cores at different levels indicated a maximum of 28,000 year BP. The enrichment factor (EF) results indicated that the Cd and Zn contents of the upper section sediments were influenced by an anthropogenic source. The trace element ratios and authigenic U content of the core sediments indicated the existence of anoxic depositional environment.

Loess sediments in Austria deposited ca. 30–20 ka ago yield different zircon age signatures for samples collected around Krems (SE Bohemian Massif; samples K23 and S1) and Wels (halfway between the Bohemian Massif and the Eastern Alps; sample A16). Cathodoluminescence (CL) imaging reveals both old, multistage zircons with complex growth histories and inherited cores, and young, first-cycle magmatic zircons. Paleoproterozoic ages between 2,200 and 1,800 Ma (K23 and S1), an age gap of 1,800–1,000 Ma for S1 and abundant Cadomian grains, indicate NW African/North Gondwanan derivation of these zircons. Also, A16 yields ages between 630 and 600 Ma that can be attributed to “Pan-African” orogenic processes. Significant differences are seen for the <500 Ma part of the age spectra with major age peaks at 493–494 and 344–335 Ma (K23 and S1), and 477 and 287 Ma (A16). All three samples show negative initial ɛHf signatures (−25 to −10, except one grain with +9.4) implying zircon crystallization from magmas derived by recycling of older continental crust. Hf isotopic compositions of 330- to 320-Ma-old zircons from S1 and K23 preclude a derivation from Bavarian Forest granites and intermediate granitoids. Rather, all the data suggest strong contributions of eroded local rocks (South Bohemian pluton, Gföhl unit) to loess material at the SE edge of the Bohemian Massif (K23 and S1) and sourcing of zircons from sediment donor regions in the Eastern Alps for loess at Wels (A16). We tentatively infer primary fluvial transport and secondary eolian reworking and re-deposition of detritus from western/southwestern directions. Finally, our data highlight that loess zircon ages are fundamentally influenced by fluvial transport, its directions, the interplay of sediment donor regions through the mixing of detritus and zircon fertility of rocks, rather than Paleowind directions.

The current meeting marks authors decade-long collaboration with the Geological Society of America (GSA) in proposing and conducting topical sessions highlighting the importance of undergraduate research involving basic geology and ‘now-a-days’ hot environmental topics since 2004. Topical sessions conducted from 2004-Present, were primarily aimed at opening the door to K12-16 students to sharing their basic geology-and-environmental research as part of experiential learning, comprehension and acquiring critical thinking skills. Through these sessions, well-over 275 students have had the opportunity to present their research at the GSA meetings in the past. Many of the presenters, mostly K9-12 students, either graduated or are now graduating from college have expressed their deep appreciation for having this opportunity made available to them. The current topical session is aligned with GSA’s central thrust of providing training and preparing the next generation's much needed STEM and geoscience workforce in order to meet future challenges of natural resource exploration, management and sustainable environmental planning. It is well-known that undergraduate research experience is vital to geology students and an early involvement in geological research really allows students to measure their strengths and their academic preparation compared to their peers at other institutions at an international convention of such magnitude. From the standpoint of recruitment and retention of geoscience students, such an early experience is also known to work as a catalyst and bring success to many academic institutions. The majority of graduates chose to major in the geosciences at some point during their undergraduate education and this also highlights the importance of undergraduate geoscience courses, particularly stimulating entry level courses, outdoor field and faculty-supported research experience to the recruitment of majors and future graduates. Students who did research and presented at the GSA annual meetings since 2004 reported that such academic experience was deemed to be very useful by their employer since their current job responsibilities require critical thinking skills and in-depth field analyses of geologic data on a regular basis.

Sedimentological and mineralogical studies from two sandstone formations of pre-Santonian (Awi Formation) and post-Santonian (Lokoja Formation) ages were carried out aiming to characterize their provenance and depositional environments. Detailed field studies, textural and mineralogical analyses involving lithologic descriptions, grain size analysis, thin section, heavy mineral, and X-ray diffraction analyses were carried out. Both sandstones exhibit fining upwards succession and unconformably overlie the basement complex. Other sedimentary structures include grain imbrications, mud drapes, cross stratifications, flaser beds, and ripple marks. Textural studies show that the sandstones have medium to coarse grains and are moderate to poorly sorted, positively skewed, and platykurtic. These characteristics suggest that high-energy conditions prevailed during the deposition of that sandstones. Bivariate analysis of skewness versus sorting showed that the sandstones were deposited in a fluvial environment. Petrographic analysis revealed angular to sub-angular grains with the dominance of quartz and feldspars in the arkosic and sub-arkosic arenites with variable, but low lithic and heavy mineral constituents. The result of the heavy mineral analysis shows dominance of non-opaque minerals (64%) compared with opaque minerals (35.08%). While the heavy mineral assemblage suggests derivation from igneous and metamorphic rocks, the presence of garnet and sillimanite point to nearness to the source. Analysis of clay-sized fraction revealed a dominance of kaolinite with illite and montmorillonite making the subordinate group within the clay minerals present. Clay species ration (high kaolinite: illite ratio) together with results from petrography suggests the possibility of warm and humid paleoclimatic conditions prevalent during deposition. From the integration of textural analysis (multivariate analysis) and observed sedimentary structures (cross-stratification, floodplain deposits, clay drapes), an agitated, fluvio-deltaic to nearshore environment of deposition is indicated by the overall sandstone geometry. This confirms the continental source for the sediments. The modal analysis further suggests a continental block provenance within a tectonic setting dominated by cratonic to recycled orogen. Such a setting is analogous to the Oban Massif for the Awi Formation and the North and Central basement complex and sediments in their second cycle of sedimentation sourced from the post-Santonian deformational episode for the Lokoja Formation.

A multidisciplinary mineralogical, geochemical and biomarker study of Indus Fan sediments cored during International Ocean Discovery Program (IODP) Expedition 355 to the Laxmi Basin was carried out to define the different compositional signatures of sand, silt and clay. Upper Pliocene-lower Pleistocene turbidites from sites U1456 and U1457 were selected as the best candidates for this study. The integrated dataset presented here was obtained by coupling traditional and innovative bulk-sediment and single-mineral techniques on the same samples. Turbiditic deposits mostly consist of medium to fine silt, including rich and diverse heavy-mineral assemblages. Such a fine grain size forced us to push the limits of high-resolution quantitative heavy-mineral analysis down to as low as 5 μm. Heavy-mineral analysis allowed us to establish a Himalayan origin of the detritus in the studied turbidites. Heavy-mineral concentrations are higher in channel-fill than in overbank deposits. Mineralogical and geochemical data concur in revealing that fast-settling ultradense minerals such as zircon are preferentially concentrated in channel-fill deposits, whereas the top of overbank deposits are notably enriched with slow-settling platy phyllosilicates. Biomarker analysis represents a most suitable complementary technique that is able to investigate the provenance signature of the finer sediment fraction, largely consisting of clay. This technique allowed us to identify a largely terrigenous origin of organic matter at Site U1456 and an open marine origin at Site U1457. The latter site lies closer to the Laxmi Ridge, where thermal maturity increases with depth to reach the early oil window (127°C at c. 320 m below the seafloor).

The Chablais Prealps (Haute-Savoie, France) represent a well-preserved accretionary wedge of the Western Alpine Tethys. They comprise a stack of sedimentary nappes related to palaeogeographic realms ranging from
the Ultrahelvetic to the Southern Penninic. The provenance analysis is based on the Gazzi-Dickinson method and on QEMSCAN ® for heavy-minerals. The Quartzose petrofacies is the most important of the two sources, and supplied three of the four formations of the Voirons Flysch. It is similar to the sources that fed the other flyschs from the Gurnigel nappe. It is characterised by a mature, quartz-rich assemblage and a heavy-mineral population dominated by apatite and the zircon–tourmaline–rutile mineral group. These observations suggest a Clastic wedge provenance. The Feldspathic petrofacies is derived from a feldspar-rich source associated with metamorphic clasts and a heavymineral population dominated by garnet. This provenance characterises only one formation of the Voirons Flysch, and is related to the axial belt provenance. This provenance analysis shows that the Middle Eocene to Early Oligocene Voirons Flysch was fed by two sources, in contrast to the other flyschs of the Gurnigel nappe, and further suggests that this flysch was not deposited in the Piemont Ocean but in the Valais domain. Based on the results and comparative
provenance analysis with the other flyschs of the Gurnigel nappe, we propose a generic feeding model which involves the Sesia–Dent Blanche nappe, the sedimentary nappes incorporated in the accretionary prism, and probably the Briançonnais basement.