Provenance Interpretation Research Articles

Neogene–Quaternary Channel Evolution and Provenance Shift of the Middle Yellow River

AbstractThe formation age of the middle Yellow River and the existence of a northward‐flowing river have been fiercely debated. The age distribution of detrital zircon varied spatiotemporally and produced contradictory provenance interpretations. The Jinshaan Gorge, the main part of the middle Yellow River and key to studying fluvial evolution and clarifying disputes, developed its topography during the late Cenozoic. In this study, we systematically review the Cenozoic tectonic evolution of the North China Craton, perform detrital zircon U–Pb dating in the Neogene−Quaternary sediments and investigate the topography along the Jinshaan Gorge, and the sedimentology and chronological framework of these sediments. We propose that the Gorge of the middle Yellow River could have developed since the Neogene, controlled by the tectono‐geomorphologic evolution of the North China Craton in a dominantly extensional environment. No evidence supports a northward‐flowing river during the Early Pleistocene or even earlier in the Jinshaan Gorge. We attribute the provenance variations of the Cenozoic sediments to detrital mixing of diverse geological units, local and distant, and especially highlight the systematic provenance shift between the Neogene and Quaternary sediments caused by bedrock downcutting and recycling aeolian sediments. The increased 1.5−0.33 Ga component of the lower Yellow River during the Early Pleistocene was likely caused by enhanced loess accumulation and should not be individually used as a proxy for the Yellow River formation. We emphasize the significance of a comprehensive study of river evolution.

Characterization and Making Techniques of Calcareous Construction Materials for Phaya Thon Zu Temple in Bagan Historical Area, Myanmar.

The calcareous materials used in constructing the Phaya Thon Zu temple at the Bagan historical sites in Myanmar are mortars, plasters, and stuccos. Among them, the mortars and plasters are a mixture of original and new materials used for recent conservation treatments. In this study, the making techniques were examined through analysis of calcareous materials by production period. All calcareous materials have a mineral composition similar to soil, except calcite. Stuccos have the most refined aggregates, homogeneous particle size, and the highest lime and organic contents. They were designed to improve ease of carving and weathering resistance, considering the unique characteristics of the stuccos. Because all calcareous materials were mixed with soil, the origin of the clay materials was analyzed. It was concluded that the mortars were produced by mixing clay and sandy soil, and the original mortars showed characteristics similar to soil. It is highly possible that sandy soil from around the Htillominlo temple was used to produce new plasters, and it is estimated that a mixture of clay soil was used for the original plasters and stuccos. A clear provenance interpretation of the original and raw materials used for each construction and the mixing ratio of clay materials need to be discussed through experiments, along with the estimated provenance area of the raw calcareous materials.

Detrital muscovite 40Ar/39Ar geochronology and provenance of Cenozoic deposits in the Qaidam basin, northern Tibetan Plateau and comparison with detrital zircon and apatite records

The single-grain detrital multi-mineral dating techniques are powerful tools for tracing sediment provenance. However, natural biases in sediment source-to-sink systems may lead to heterogeneous sink signals based on detrital single-grain ages. Differing provenance interpretations may arise from detrital multi-mineral geochronologic data because of the potentially diverse origins and transport behaviors of the analyzed detrital minerals. To test this hypothesis, we present new single-grain detrital muscovite 40Ar/39Ar dating results from the Cenozoic Qaidam basin and compile published detrital muscovite 40Ar/39Ar, detrital zircon U-Pb, and detrital apatite fission track age data to interpret muscovite provenance and to explore the potential inconsistencies among multi-dating results and related controlling mechanisms. Our results indicate that detrital muscovite grains from most Cenozoic deposits have a similar, dominated 300–400 Ma age range, with subordinate 200–300 Ma and 400–500 Ma. The new and compiled 40Ar/39Ar age data demonstrate that detrital muscovite records from the Cenozoic Qaidam basin are stratigraphically variable. Samples from middle fine-grained deposits-dominated strata, representing the paleo-megalake period, exhibit a relatively wider age range compared to those from lower and upper coarse-grained deposits-dominated strata, indicating a probable control of sedimentary environments. Comparisons of detrital muscovite, zircon, and apatite records indicate that the detrital zircon age spectra have the oldest ages, the widest age ranges, and the largest number of age groups. Detrital zircon and apatite age spectra exhibit higher spatial variations than detrital muscovite records, likely due to the distinct source-to-sink behaviors of these minerals. The magmatic, metamorphic, and uplift history of source terranes, along with system closure temperatures, originally determine detrital mineral age records, i.e., high-temperature systems yield older ages, and vice versa. Parent-rock types, mineral fertility, and weathering resistance control the numbers and probabilities of the detrital age clusters. Differences in mineral shape, density, and transport and depositional processes (i.e., different transport loads of light, platy minerals vs. heavy, granular minerals) may cause variations in age spectra. These differences in detrital mineral behaviors warrant more attention in multi-mineral dating-based sediment provenance studies. Additionally, 40Ar/39Ar age data compilation based on global Cenozoic sedimentary basins and modern rivers indicates that detrital muscovite records have potentials to determine tectonic settings, but climate-induced exhumation signals need to be distinguished before interpretation.

Grain textural bias in detrital single-mineral provenance studies

Detrital single-mineral geochemistry and geochronology are strong tools in provenance studies and indicate great potentials in addressing issues in earth sciences. Various biases (both natural and artificial) exist objectively and may mislead provenance interpretations. Both the sedimentary sorting process and hand-picking in-laboratory processing may lead to analyzed grain textural (e.g., size and shape) variability and thus may introduce biases in single-mineral provenance analysis. Here, we take the Mesozoic–Cenozoic Qaidam basin, northeastern Tibet, as an example to investigate the relationship between single-mineral grain texture and detrital zircon geochronological and detrital tourmaline, rutile and garnet geochemical data and to explain how grain texture affects detrital single-mineral provenance interpretations. Results indicate that Precambrian zircons take less proportions in coarse (>125 μm), subrounded and high aspect ratio (>2) fractions than Phanerozoic zircons. Parent rock lithology discrimination results of detrital tourmaline and garnet in different grain size fractions show significant differences. Zr-temperature values of detrital rutile have an increasing trend with increasing grain size. The geochemistry of detrital tourmaline, rutile and garnet shows no dependence with grain aspect ratio and roundness. We suggest that inheritance of grain texture features from parent rocks is the major reason. Detrital zircons from recycled (meta)sedimentary rocks tend to be smaller and more rounded than those from igneous rocks. Detrital tourmaline, rutile and garnet grains from different parent rock types vary in size. Grain textural bias may cause the underestimated contributions of the Qilian Shan to the Cenozoic Qaidam basin if small detrital zircons were not involved in the analysis. Quantitative description of the source-to-sink system of the Cenozoic Qaidam is also influenced by grain textural bias. This study highlights the underestimated grain textural bias in single-mineral provenance studies. We suggest that a comprehensive understanding of potential sedimentary sources, depositional processes, sample petrographic features and laboratory analysis procedures is important to reliable provenance interpretations and to related implications in earth sciences.

Multi-isotope approach allows tracking the circulation of ceramics across the Andes (Argentina and Chile)

The circulation of material culture across space is a central topic in Andean archaeology and has witnessed significant growth during the last decades. Ceramics have been a part of this trend through the analysis of the abundance of chemical elements. Aiming at expanding ceramic sourcing and the study of large-scale conveyance of artefacts, we present the first multi-isotopic approach combining strontium, neodymium, and lead isotopes in South America. We explore the utility of an isoscape of bioavailable strontium for the interpretation of ceramic provenance. These first results show that this approach confidently discriminates large areas of provenance. Broadly, the sherds from styles assigned to the western Andean slope (Llolleo, El Molle, local Inka) show low strontium and lead isotope ratios with high neodymium, consistent with the young ages of underlying rocks, including samples recovered across the Andes and confirming their large-scale conveyance. Conversely, sherds assigned to eastern styles (Agrelo) display high strontium and lead ratios and low neodymium ratios. By exploring the potential of this approach to track ceramic production and conveyance, this research contributes to archaeological debates in the Andes and beyond.

Navigating the complexity of detrital rutile provenance: methodological insights from the Neotethys Orogen in Anatolia

Abstract. Sedimentary provenance is a powerful tool for reconstructing convergent margin evolution. However, single mineral approaches, like detrital zircon, have struggled to track sediment input from mafic and metamorphic sources. Detrital rutile complements detrital zircon datasets by offering a path forward in sedimentary provenance reconstructions where metamorphic terranes are potential source regions. However, U–Pb geochronology in rutile can be difficult due to low uranium concentrations and incorporation of common Pb, and multiple workflows are currently in use. Here, we investigate U–Pb and trace element data reduction, processing, and common Pb correction workflows using new detrital rutile U–Pb geochronology and trace element geochemistry results from the Late Cretaceous to Eocene Central Sakarya and Sarıcakaya basins in Anatolia. A significant number of analyses were rejected (54 %) due to signal intensity limitations, namely low U, low Pb, anomalous signal, and inclusions. We identify this as a universal limitation of large-n detrital rutile studies and recommend the systematic reporting of the amount of discarded analysis and the processes for rejection in all studies using detrital rutile U–Pb geochronology. Additionally, we show that (1) the 208Pb and 207Pb common Pb reduction schemes produce similar age distributions and can be used interchangeably, while (2) the Stacey–Kramers distance is a suitable metric for quantifying U–Pb discordance, but a discordance filter is not recommended. (3) Instead, filtering U–Pb data by a power law function based on the corrected date uncertainty is appropriate. (4) The exclusion of low uranium concentration rutile biases date distributions and favors pelitic-derived, higher Zr-in-rutile temperature, and higher U–Pb concordance grains. (5) Paired U–Pb and trace elements can be used to evaluate potential bias in U–Pb data rejection, which reveals that data rejection does not bias the provenance interpretations. Finally, (6) The signature of sediment recycling can be identified through U–Pb dates and Zr-in-rutile temperatures. To better navigate the complexity of detrital rutile datasets and to facilitate the standardization of data reporting approaches, we provide open-access code as Jupyter notebooks for data processing and analysis steps, including common Pb corrections, uncertainty filters, discordance calculations, and trace element analysis.

Discrimination of tectonic provinces using zircon U-Pb ages from bedrock and detrital samples in the northern Andes

Abstract The northern Andes of southern Colombia contain a rich geologic history recorded by Proterozoic to Cenozoic metamorphic, igneous, and sedimentary rocks. The region plays a pivotal role in understanding the evolution of topography in northwestern South America and the development of large river systems, such as the Amazon, Orinoco, and Magdalena rivers. However, understanding of the basement framework has been hindered by challenging access, security concerns, tropical climate, and outcrop scarcity. Further, an insufficient geochronologic characterization of Andean basement complicates provenance interpretations of adjacent basins and restricts understanding of the paleogeographic evolution of southern Colombia. To address these issues, this paper presents a zircon U-Pb geochronological dataset derived for 24 bedrock samples and 19 modern river samples. The zircon U-Pb results reveal that the Eastern Cordillera of southern Colombia is underlain by basement rocks that originated in various tectonic events since ca. 1.5 Ga, including the accretion of discrete terranes. The oldest rocks, found in the Garzon Massif, are high-grade metamorphic rocks with contrasting Proterozoic protolith crystallization ages. Whereas the SW part of the massif formed during the Putumayo Orogeny (ca. 1.2–0.9 Ga), we report orthogneisses for the NE segment with protoliths formed at ca. 1.5 Ga, representing the NW continuation of the Rio Negro Jurena province of the Amazonian Craton. In contrast, crystalline rocks of the Central Cordillera primarily consist of Permian–Triassic (ca. 270–250 Ma) and Jurassic–Cretaceous (ca. 180–130 Ma) igneous rocks formed in a magmatic arc. In southernmost Colombia, the Putumayo Mountains mainly consist of Jurassic–Cretaceous (180–130 Ma) plutonic and volcanic rocks. Furthermore, we analyzed the heavy mineral abundances in modern river sands in southern Colombia (spanning 1°N–5°N) and found that key minerals such as garnet and epidote can be utilized to trace high-grade metamorphic and igneous lithologies, respectively, in the river catchments. The differentiation of basement ages for separate tectonic provinces, combined with heavy mineral abundances in modern sands, can serve as unique fingerprints in provenance analyses to trace the topographic and exhumational evolution of different Andean regions through time.

Petrographic characterization of Late Jurassic to Early Cretaceous sandstones in the offshore Bredasdorp Sub-basin, South Africa: An example of a dynamic recycled provenance interpretation

The Mesozoic syn-rift sediments of the Bredasdorp Sub-basin were deposited during the structural inversion of the orogenic Cape Fold Belt (CFB), a crucial time during the break-up of Gondwana. The Late Jurassic to Early Cretaceous non-marine to marine sediments of the Bredasdorp Sub-basin were studied to infer their composition, parent-rock lithologies, tectonic settings and their dynamic response to tectonic perturbations. The knowledge on the provenance terrains in the Bredasdorp Sub-basin is poorly understood and therefore this research shed light on these provenance terrains. Petrographic quantitative analysis revealed that the mineralogical composition of the sediments comprises mainly of litho-quartzose and feldspatho-litho-quartzose sediments. Modal petrographic data indicates a recycled orogen provenance on QFL plots suggesting the occurrence of a collisional provenance terrain. This setting can be interpreted as the reactivation of the CFB structures eroding the Bokkeveld Group (and younger Karoo Supergroup) and the Table Mountain Group metasediments (and Pre-Cape sediments). The shedding of these sediments in the Bredasdorp Sub-basin were coeval with the deposition of the D-V, V-BUSM and BUSM-1AT1 ‘informal’ sequences. Furthermore, an evolving recycled provenance from sedimentaclastic (un-dissected) to basementaclastic (dissected) sediments are proposed and could be a defining characteristic to the enigmatic offshore Jurassic-Cretaceous stratigraphic nomenclature.During the deposition of the D-V Sequence, a spatial variation in provenance due to intrabasinal uplifted fault blocks (possibly reactivated shear zones) occurred between the erosion of the Bokkeveld Group (and Karoo Supergroup) and the Table Mountain Group (TMG) metasediments. The deposition of the V-BUSM Sequence showed a similar compositional trend within their provenance terrain but showed a stronger correlation to an increased quartz and feldspar content. This is possibly due to the erosion of the dominant TMG, which was further supported by the occurrence of distinct type 3 polycrystalline quartz. The deposition of the BUSM-1AT1 sequence saw an increase in plutonic lithic fragments and feldspar content, indicative of an igneous source, which was attributed to the erosion of the proximal Cape Granite Suite. This distinction is crucial in creating a unifying stratigraphic nomenclature for the Jurassic-Cretaceous sequences of South Africa. A dynamic recycled orogen is envisaged for the Bredasdorp Sub-basin and therefore the use of these type of dynamic models should be incorporated in provenance models especially if there is a well-documented geological setting.

The effects of weathering and sediment source mixing on whole-rock geochemical provenance studies, Cook Inlet forearc basin, south-central Alaska, USA

The provenance of most basin systems today is interpreted based on radiogenic ages or the geochemical composition of detrital minerals, which has all but replaced the use of whole-rock geochemical approaches that can effectively complement provenance information inferred from detrital approaches. Here, we further investigate previous provenance models developed using detrital zircon U-Pb geochronology by applying whole-rock major and trace element geochemistry of fine-grained clastic rocks from the late Oligocene−middle Miocene Tyonek Formation, late Miocene Beluga Formation, and Pliocene Sterling Formation in the Cook Inlet Basin, Alaska, USA. When taken alone, our new geochemical data suggest solely intermediate igneous sediment sources to the basin. When paired with existing detrital zircon U-Pb data, however, significant mixing of felsic and mafic sediment sources is evident, which indicates that thorough mixing of geochemically distinct source terranes can mask the input from individual sources in whole-rock geochemical studies. Furthermore, we demonstrate that both weathering and provenance influence the major element chemistry of sediment source terranes as well as the resultant basinal strata. Our conclusions indicate that the combination of whole-rock geochemistry with other detrital approaches provides a robust interpretation of sedimentary basin provenance.

Provenance Interpretation and Depositional Environment of Sandstones of the Ajali Formation, South of Ifon, Western Flank of Anambra Basin, Southwestern Nigeria

Provenance Interpretation and Depositional Environment of Sandstones of the Ajali Formation, South of Ifon, Western Flank of Anambra Basin, Southwestern Nigeria

Exoscopy of Detrital Zircons from Niamey Neoproterozoic Sandstones (Eastern Edge of the West African Craton, Southwestern Niger): Interpretation of Detrital Sediments Provenance

Exoscopy of Detrital Zircons from Niamey Neoproterozoic Sandstones (Eastern Edge of the West African Craton, Southwestern Niger): Interpretation of Detrital Sediments Provenance

Provenance of the Oligocene Barail Sandstones Exposed In and Around Longsa Village, Wokha District, Nagaland: Reflections from Petrography and Heavy Minerals

Petrographic and heavy mineral compositions of the Oligocene Barail sandstones exposed in and around Longsa village of Wokha District, Nagaland, have been utilized for provenance interpretation. Grey and yellow coloured sandstones of the study area are comprised of angular to sub-rounded monocrystalline, non-undulatory quartz and the various lithic fragments. The overall composition of sandstones (Q-90.10%, F-1.70 %, RF-8.18%) matches with those of sublith-arenites category. The heavy mineral assemblage of the studied Barail sandstones is represented by euhedral/rounded to sub-rounded grains of zircon, tourmaline, rutile, kyanite, sillimanite, andalusite, titanite, staurolite and iron oxide. The studied sandstone composition suggests that the Barail sediments were derived from mixed provenance. Heavy mineral analysis also corroborates the above. Keywords: Petrography, Heavy Minerals, Provenance, Barail Group, Nagaland

Detrital zircons of the vast Triassic Snadd and De Geerdalen formations, Barents Shelf, reveal temporal changes in sediment source

Studies of detrital-zircon age distributions from Triassic sedimentary rock successions on the Arctic Barents Shelf have resulted in different provenance interpretations. Here, we provide new U–Pb/Hf detrital-zircon data from eleven samples of the Snadd and De Geerdalen formations, covering the Barents Shelf in a north–south transect, that help refine the provenance of these sedimentary rocks and show how stratigraphic variations reflect changing source regions. The sample locations cover different stratigraphic levels and geographic locations within the formations. The detrital-zircon age spectra in the lower part (lowest Ladinian and lower Carnian) are dominated by two age peaks at 300 and 540 Ma, whereas the zircon distributions in the stratigraphically younger deposits (latest Carnian and early Norian) are dominated by a 235 Ma age peak and two minor peaks at 300 and 425 Ma. The apparent relative contribution of detritus of different ages changes gradually from lower to higher stratigraphic levels, marked by an increase in both the 235 and 425 Ma age peaks, a decrease in the 300 Ma component and a progressive loss of the 540 Ma age peak. The zircon Hf-isotopic compositions display predominantly juvenile zircon populations, except for a mixed juvenile and evolved signature in the youngest Permo-Triassic grains. A regional comparison of detrital-zircon age spectra in latest Carnian/early Norian deposits extends the depositional system into the Sverdrup Basin, supporting a much larger depositional system than hitherto known. The gradual change in detrital-zircon age spectra likely represents a gradual shift in zircon provenance. We interpret these variations to reflect an early source region in the north Urals, gradually changing to a dominant source region in the Taimyr Peninsula region.

Detrital zircon geochronology and provenance of Cenozoic deposits in the Qaidam basin, northern Tibetan plateau: An overview with new data, implications and perspectives

An increasing number of detrital zircon U–Pb geochronological data have been reported to trace sediment provenance for the Cenozoic Qaidam basin, which is crucial to understanding crustal deformation, paleoclimate change and basin development in northern Tibetan Plateau and to assessing geodynamic models of plateau growth. However, the existing provenance interpretations are highly diverse and how the northern Tibet has evolved remains controversial. This contribution presents new detrital zircon dating results from Cenozoic outcrop and borehole samples and compiles published data from the whole Qaidam basin, adjacent small Cenozoic basins and the surrounding mountains. Our new synthesis indicates that, Paleoproterozoic signals (1800–2000 Ma and 2350–2500 Ma), rather than the Permian–Triassic ages, can be applied effectively to distinguish the Qilian, Altun and Eastern Kunlun-sourced detrital zircons. The Cenozoic Qaidam basin exhibits spatiotemporally variable detrital zircon age populations. Most sandstones from the western and southern basin are characterized by Phanerozoic bimodal age spectra (i.e., 400–480 Ma and 220–280 Ma) with minor Precambrian signals, indicating major contributions from the neighboring Altun and Eastern Kunlun ranges. By contrast, almost all the northern and eastern basin sandstones display prominent early Paleozoic detrital zircon ages; but Paleoproterozoic, Neoproterozoic (750–950 Ma) and Permian–Triassic signals only appear as dominant age clusters in some samples. Different temporal variation trends are observed from the investigated sections in this region, revealing variable zircon supply from different micro-terranes in the Qilian Mountains. This implies that using detrital zircon provenance data from a single section or from a local area of the Qaidam basin to address regional tectonic and climatic issues of the northern Tibetan Plateau unlikely provide useful results. We propose that the Cenozoic Qaidam basin deposits were derived from localized, adjacent source regions, rather than cross-basinal, distant mountains. Our conclusions support models with synchronous deformation throughout most of northern Tibet in the Cenozoic. The observed spatiotemporal variations in detrital zircon populations are not only attributed to tectonic deformation-induced source changes, but can also be due to heterogeneity of the source terranes (e.g., durability and zircon fertility) and variable factors (e.g., hydrodynamic sorting, recycling and sedimentary microenvironment) in transport-deposition processes. This study also highlights the importance of involving detrital zircon textural and sedimentological parameters to zircon provenance interpretations. An integrated provenance analysis combining other detritus components is helpful to comprehensively characterize source-to-sink systems for sedimentary basins.

Eocene to present evolution of the Pearl River, China: A quantitative provenance interpretation on large detrital zircon U–Pb geochronological data

AbstractDrainage evolution of the Pearl River, one of the major rivers in the eastern margin of the Asian continent, has important implications for the tectonomorphic evolution of the northern margin of the South China Sea and the southeastern Tibetan Plateau. Previous reconstructions using different methods suggested discrepant timings for the formation of river, ranging from Early Oligocene to Middle Miocene. Here, we address this heavily debated topic using quantitative unmixing modelling of detrital zircon data from the Pearl River Mouth Basin in the northern margin of the South China Sea. In this study, we develop a novel approach for estimating the relative contributions of detrital zircon sources to their shared sink, and propose to use the correlation coefficients among zircon contribution models to evaluate the trade‐off among sources with similar age spectra, to avoid the potential overinterpretation of individual contributions. Our new method is applied to new (997) and published detrital zircon U–Pb data from offshore boreholes and modern Pearl River samples to quantitatively interpret and reconstruct the sediment provenance of the Pearl River Mouth Basin and the development of the Pearl River. Our findings reveal that the provenance change of the Pearl River Mouth Basin can be divided into three main stages. Eocene sediments were mainly sourced in the intra‐basinal highlands and the eastern coastal tributaries, indicating a local drainage system. Early Oligocene provenances extended westward, as shown by the increase in sediment contribution from the central and western parts of the Pearl River (28% in total). Since the Late Oligocene, the eastern, central and western parts of the modern Pearl River have contributed equal amounts of zircons to the Pearl River Mouth Basin, indicating the establishment and long‐term stability of the modern‐like drainage system, as highlighted by our new data acquired from the borehole Miocene strata. The Late Oligocene westward expansion of the Pearl River is consistent with the timing of the coeval breakup and spreading of the South China Sea and the intensified Asian monsoon precipitation, highlighting the importance of base level fall and climate in controlling the drainage evolution.

“Disrespect des Fonds”

The Trinity College Archives has recently accessioned papers from one of its notable alumni, Michael Ignatieff. His international career as a writer, professor, and politician means that his papers exist in multiple archives around the world and will likely never be reunited. In the face of this reality, this paper proposes that Ignatieff’s materials at the Trinity College Archives should not be organized into a fonds. New interpretations of fonds, provenance, and original order justify the creation of two distinct collections: one for Ignatieff’s professional materials, and one for his personal papers. A system of metadata tags should be used to identify the relationships between items in these two collections and would allow the Archives to integrate the materials with othersin their collection.

Provenance Interpretation and Petrological Characteristics of the Four Lion Three-story Stone Pagoda and Stone Lantern in Hwaeomsa Temple, Korea

In this study, the lithological characteristics of the Four Lion Three-story Stone Pagoda and Stone Lantern in Hwaeomsa temple were analyzed, and the origin was interpreted. The stone properties composing the stone pagoda and the lantern are dark gray medium to coarse grained granodiorite with small to large mafic microgranular enclaves (MME), and show a fairly heterogeneous lithology. The stone properties constituting the main stone cultural heritages in the precincts of the temple use the same granodiorite as the stone pagoda and lantern. Magnetic susceptibilities of the stones ranged from 2.03 to 19.40 (mean 11.59)×10-3 SI unit, and the stones showed an almost identical distribution. The same granodiorites as the stone properties are exposed as a small intrusive rocks in the valley of Hwaeomsa temple, Toji-myeon and Gwangui-myeon area. As a result of comparing the lithological characteristics, magnetic susceptibility and geochemical behavior, it was confirmed that the rocks are identical to very similar rocks used in the stone cultural heritages of the temple. Also, many ancient quarrying traces are found in the outcrops of granodiorite, indicating that this was a place where stone quarried. Therefore, the grandiorite can be used as a substitution stones that may be needed in the repa ir process of the stone pa goda a nd stone la ntern.

One size does not fit all: Refining zircon provenance interpretations via integrated grain shape, geochronology, and Hf isotope analysis

Sediment provenance studies commonly utilize isotopic signatures to resolve detrital mineral sources and routing. However, non-unique ages and geochemical characteristics across geographically distinct crystalline source regions can lead to significant ambiguities in mineral provenance interpretations. Such ambiguity is apparent in southern Australia’s Cenozoic Eucla Basin, which hosts world-class heavy mineral sand resources. Here, new Hf isotope data are provided from four heavy mineral prospects (N = 8, n = 844 [N = samples, n = grains]). Zircon grain shape data are also presented for a suite of detrital Eucla Basin samples (N = 22, n = 35,604) and the basin’s underlying basement, the Coompana Province (N = 13, n = 824). The data are integrated with published detrital and non-detrital primary zircon data to investigate the efficacy of grain shape analysis to better resolve the basin’s mineral provenance. Zircon Hf isotope compositions indicate a primary Mesoproterozoic juvenile source for zircon melts (∼1250–1000 Ma, −2.5 <ɛHf > ∼+5) with additional contributions from a range of juvenile to evolved late Archean to Phanerozoic-aged zircon bearing magmas (−28.0 <ɛHf > +11). U–Pb geochronology and Hf isotopes are incapable of differentiating Mesoproterozoic-aged source rocks bounding the region for the majority of heavy mineral deposits analyzed as potential sources express overlapping crystallization ages and similarities in Hf-isotope characteristics. However, distinct zircon grain shapes (i.e., perimeter, major axis and circularity) facilitate improved differentiation across these Mesoproterozoic sources. Filtering of U–Pb age, Hf isotope and shape data implicate the underlying Madura and Coompana provinces as dominant sediment sources for Eucla Basin detritus aged ∼1400–1000 Ma. The lack of direct sediment pathways between the underlying basement provinces and placer sediments analyzed demonstrates the significance of zircon reworking from intermediate sedimentary basins in the formation of the economically significant Eucla Basin beach placers. Zircon grain shape represents a cheaply acquired and readily incorporated grain characteristic that can enhance provenance investigations.

Identifying sources of non-unique detrital age distributions through integrated provenance analysis: An example from the Paleozoic Central Colorado Trough

AbstractTo address the longstanding issue of provenance interpretation of non-unique detrital zircon age populations, we integrated zircon U-Pb, rare earth element (REE), and εHf(t) data from upper Paleozoic strata in the northern Central Colorado Trough and Cambrian intrusions with petrography, paleocurrent data, and structural and stratigraphic observations. This data set indicates that Cambrian sediment was shed by multiple local sources instead of distant sources hundreds of kilometers away, and it reveals a detailed history of tectonic drainage reorganization in the northern Central Colorado Trough during Ancestral Rocky Mountain deformation. During the Early–Middle Pennsylvanian, Cambrian detrital zircons were a minor constituent of northern Central Colorado Trough sediment. However, during the Late Pennsylvanian–early Permian, westward advancement of the adjacent Apishapa Uplift deformation front precipitated drainage reorganization, which resulted in an episode of dominant Cambrian detrital zircon sourcing. Paleocurrent and petrographic data indicate that the source of Cambrian detritus was shed by an igneous rock body that was ≤15 km northeast of the depocenter, which has since been eroded away or mantled by Tertiary volcanic rocks. The addition of zircon petrochronology to the data set applied here was critical in confirming this hidden source of detritus and elucidating the compositional characteristics of that igneous rock. Zircon εHf(t) provided a regional provenance indicator of a western Laurentian affinity, and REE composition aided in discriminating possible local sources of Cambrian zircon. Furthermore, this work serves as a case study of a dominant Cambrian detrital zircon signature sourced from outside of the wellknown Amarillo-Wichita Uplift, and it has implications for the interpretation of such detrital spectra in the context of a direct-from-basement source or the recycling of Cambrian zircon-dominated rocks. In summary, we demonstrate the utility of this multi-provenance proxy approach in interpreting a complex structural history of a dynamic hinterland and concomitant drainage reorganization through an in-depth investigation into the basin record.

A geochemical and mineral chemical assessment of sediment provenance and post-depositional alteration of auriferous conglomerates in the Singhbhum Craton

The Mesoarchean Dhosrapahar Group and the Phuljhari Formation in the Singhbhum Craton host so far subeconomic gold occurrences in metaconglomerate beds, similar to the world-famous conglomerate-hosted gold deposits of the Mesoarchean Witwatersrand Basin in South Africa. In the studied metaconglomerates from India, gold occurs as invisible inclusions in pyrite and as native gold grains associated with detrital chromite, quartz, zircon and metamorphic chlorite. Unlike most Archean paleoplacer deposits, the inferred detrital gold here appears unrelated to detrital pyrite, thereby highlighting the decoupling of the sources for the various placer components. To this end, we attempt to delineate the possible source rocks and assess the extent of post-depositional alteration to better understand the controls on gold accumulation in these conglomerates. Elevated Ni, Co and As, to a lesser extent V, Cu, and Se contents in Au-bearing inclusion-rich detrital pyrite are suggested to be derived from Paleoarchean banded cherts in the Gorumahisani Greenstone Belt. Relatively immobile trace element ratios, as recorded by the conglomerate matrix, reflect a predominantly felsic source with minor sediment input from mafic/ultramafic sources. Fractionated chondrite-normalized light rare earth and flat heavy rare earth element patterns, along with a distinct negative Eu-anomaly, obtained for the samples from the Phuljhari Formation point to a differentiated felsic source, most likely the c. 3.05 Ga K-rich Mayurbhanj Granite. In contrast, depleted heavy rare earth element patterns and a weak negative Eu-anomaly in the conglomerates from the Dhosrapahar Group indicate derivation from a felsic source that had experienced garnet fractionation, the obvious candidate being the underlying c. 3.37 Ga Rairangpur tonalite-trondhjemite-granodiorite (TTG) suite. Detrital rutile is rich in Cr and V, and Zr-in-rutile geothermometry yielded crystallization temperatures between ~800 and 1000 °C. The most likely source of this rutile are 3047±17 Ma gabbro-anorthosite bodies in the basement. Post-depositional modification of the conglomerates is dominantly manifested as greenschist-facies metamorphic overprint, and is reflected also by detrital chromite texture and chemistry, and the occurrence of secondary rutile, euhedral pyrite, and secondary gold with metamorphic chlorite. Our provenance interpretations do not indicate any likely point-source of detrital gold, suggestive of the entire Archean hinterland, irrespective of composition, as a potential source, as already indicated for the Mesoarchean auriferous conglomerates of the Witwatersrand Basin. This contention is further substantiated by the evidence presented here for moderate-to deep chemical weathering of the Archean hinterland of the Singhbhum Craton.