Бидний тухай
Багш ажилтан
Inthisstudy,weemphasizetheNomgongoldgroupoccurrencewhichislocatedintheSantoremineralizationareaof theZaamarorenode, toassesstheprospectsofgoldoccurrencebymineralexplorationgeochemicalmethods(coefficientof ZonalizationandIntensification).TheNomgongoldgroupoccurrencecomprisesofTaliinUlaan, IkhZoolon,Nomgonandthoseoccurrenceswereassociatedatypeofgoldmineralizationwithsecondaryquartzitesrichinironandmanganeseoxidesthat developedalongthesedimentarythickening.ThevaluesoftheIntensificationcoefficient(Ki)andZonalizationcoefficient(Kz)indicesofthistypeofgoldoresweredeterminedandthecorrespondingimageswerecompiled.Formulatingtheseimages, inorderto avoidtheinfluenceofelementswithahighClarkvalue,theratio(thevalueoftheanomalyindex(Ka)oftheinitialvaluetothebackgroundvalue(Bv)wasused.Zonalizationcoefficientmapisthehighest(Kz=20-220)intheNomgonarea,moderate(Kz=20-100) intheareaoftheIkhZoolonandthelowest(Kz=20-40)intheTaliinulaanarea.TheinterpretationofIntensificationcoefficient(Ki)andZonalizationcoefficient(Kz)allowsclassificationofpotentialgoldmineralizationprospectsintothesurfacenearandsurface deepandprecisedefinitionaboutmineralizationzone,situationanditsdevelopmentpattern
The Nariinsukhait deposit is the largest Jurassic coal deposit in southern Mongolia. A total of 90 core samples were obtained from a 493.1 m deep borehole in the central part of the deposit and tested for proximate analysis and caking properties, while 29 composite samples were analyzed for maceral composition and random vitrinite reflectance. The thick seam V stands out for its better quality compared to the upper seams, with an average ash content of 12.4% (ad), total sulfur of 0.5% (ad), volatile matter of 36.7% (daf), inherent moisture of 0.6% (ad), calorific value of 6,600 kcal/kg (ar), and a G index of 84 (ad). Seam V is characterized by higher inertinite content (32.2 vol.%), and lower vitrinite (58.0 vol.%) and mineral matter contents (6.7 vol.%) relative to the upper seams. Additionally, this seam has a higher rank, with random vitrinite reflectance (Rrand) of 0.77%, compared to 0.65-0.70% for the upper seams. According to MNS 6457:2023 standards, seam V is classified as “1/3 coking coal”, while the upper seams are classified as “high volatile gas coal”. Based on TPI, GI and A/I indices, seam V was deposited in oxic, ombrotrophic mire, whereas the upper seams were formed in mesotrophic and rheotrophic mires with high water tables and less oxic conditions. Due to these depositional environments, seam V exhibits higher inertinite, lower ash, and lower sulfur contents than the upper seams. The rank of the Nariinsukhait coals is comparable to that of Jurassic coals in central Mongolia, while the maceral composition and coal quality of the upper seams align with those of Jurassic coals. Seam V is distinct in its high inertinite and low total sulfur contents. The Nariinsukhait coal is primarily semi-soft coking coal (2/3 of total coal resources) and is also suitable as high-quality PCI coal. Further detailed studies are recommended to evaluate its potential for liquefaction and as a coking coal blend. Keywords: coal petrology, peat mires, ombrotrophic, 1/3 coking coal
Coal resources in Southgobi Coal-bearing Region are hosted in Middle Permian and Middle Jurassic sedimentary units. Nariinsukhait coal deposit, located in the western part of the Southgobi Region, is the largest Middle Jurassic coal deposit, with 1.3 billion tons of bituminous coal resources. In 2020, 9 million tons of coals were mined and exported to China from this deposit (Batgerel et al., 2021). Nariinsukhait deposit contains 12 coal seams, numbered from Seam I to XII, which are hosted in the 1370 m thick Middle Jurassic Orgilokhbuleg Formation. The lower seams, Seam I to VI, are found in the Lower Member of the Orgilokhbulag Formation, while Seams VII to XIIa are hosted in the Upper Member of the formation (Baatarkhuyag et al., 2020). Seam I to IV are not economically viable. A total of 90 coal samples from the economically viable seams were collected from a borehole. Proximate analysis was completed for all samples, and subsequently, 29 samples were selected for maceral analysis. The results of coal petrography and proximate analysis reveal distinct characteristics between the seams in the Lower and Upper members. The average vitrinite and inertinite concentrations of Seams V and VI are higher (64.0 vol.% Vt and 31.8 vol.% I.), compared to those of Seams VII to XIIa (75.4 vol.% Vt. and 20.2 vol.% I.). The liptinite content remains relatively constant, averaging 4.2 vol.%. Seams V and VI have lower contents of ash (13.0%, ad), total sulfur (0.6%, ad), and volatile matter (36.9%, daf), along with higher G index (80). In contrast, Seams VII to XIIa exhibit 17.1% ash (ad), 1.3% total sulfur (ad), 40.8% volatile matter (daf), and a lower G index (69).
The Nariinsukhait deposit, which has 1.2 billion tons of coal reserves, is situated in southern Mongolia. In 2020, more than 9 Mt coal was produced from the deposit. Middle and Upper Jurassic 34 sandstone core samples from exploration borehole were studied herein. Petrographically, the sandstones are classified as fieldspatic litharenite and litharenite reflecting relatively weak weathering intensity in source area, probably due to arid or semiarid climate conditions. Provenance analysis indicates that the sandstones are sourced from transitional recycled orogen. Geochemistry of samples indicates that sandstones were derived from acidic and intermediate rocks and mixed with recycled older sedimentary rocks. Possible sources are volcanosedimentary rocks of Mississippian Tost Formation, granite and granodiorite of Early-Late Carboniferous Tavan-Uul complex and sedimentary rocks of Middle-Upper Triassic Noyon Formation. Paleoclimate indices (C-value, Rb/Sr, Sr/Ba, 1000xRb/K2O and CIA) reflect that coal seams were accumulated in warmer and more humid climate, when paleo-weathering was intense, whereas sandstones were deposited in relatively cold and arid climate. In Late Jurassic, it is more likely that paleoclimate became more arid and cold compared with Middle Jurassic, indicated by quite low CIA and Rb/Sr. Moreover, various discrimination diagrams suggested that Middle Jurassic coal-bearing sedimentary rocks were accumulated in foreland basin. It is consistent with previous interpretations of regional tectonic during Triassic and Jurassic time. Keyword sandstone, sedimentary rock, middle jurassic, Noyon Formation, foreland basin
The Bargilt iron deposit is located in the Bor-Undur ore district in the South Kherlen-Buyant metallogenic belt of the Central-Eastern Mongolia metallogenic province. The host rocks of the deposit are schist, biotite gneiss, biotite-amphibolite gneiss, limestone and quartzite. Some of their ages has been on the assumption as the Neoproterozoic unclassified metamorphic complex and acidic volcanic rocks of the Lower-Middle Permian Burent -sogt formation, Quaternary sediments the Paleozoic unnamed intrusive complex, the Middle Permian Burentsogt intrusive complex and the Late Triassic-Early Jurassic Bor-Undur intrusive complex. However, there has been few reports on the constraints of the absolute age of them including U-Pb geochronology. Here we report the description of whole rocks petrography and zircon U-Pb age results of the deposit. Based on petrographical observation, the major host rocks distributed in the open pit of the Bargilt deposit were classified into quartzdiorite gneiss, fine-medium grained hornblende-biotite plagiogranite gneiss, subalkaline granite gneiss, irregular grained leucocratic granosyenite, fine to medium-grained biotite bearing granite and rhyolite. Zircon grains from seven samples were separated from the Bargilt iron deposit and the U–Pb isotopic analyses were conducted using a SHRIMP IIe at KBSI, South Korea. In this deposit, there are different ages rocks distributed such as Neoproterozoic, Cambrian, Devonian, Permian (Guadalupian and Lopingian). These various age range of the rocks in the Bargilt deposit indicate the occurrence of the complex and multiple intrusion events in the study area.
Дэлгэрхаан уулын археологийн олдворуудын чулуулгийн зэвсгийн найрлага, тархалтыг
Төрийн тахилгат Их Богд уул: Газарзүй, Геологийн хөгжлийн түүх, ашигт малтмал
Нарийнсухайтын ордын нүүрсний петрографийн судалгаа, хүлэр хуримтлалын орчинг тодорхойлсон
The objective of the research was to summarize and analyze the existing and emerging methods of sustainability assessment for the territories of Ulaanbaatar City. The principle of target use of territories assumes determination of its possibilities for performance of social and economic functions on the basis of a preliminary assessment of its natural resources, value of natural objects, etc. It is important that the mandatory damage was minimal, and the planned benefits significantly exceeded them. A principle of safety assumes that any anthropogenic impact on the geological environment should not create environmentally harmful and dangerous to the habitat of the present generation and have long-term environmentally harmful consequences for future generations. Generalization and systematization of information about the state and stability of the geological environment should be consistent with the scale of the problems and the level of decision-making (global, regional, local). The results of assessments of the stability of territories can be presented in various forms, as well as the leading natural and man-made factors that affect their stability. They include quantitative, semi-quantitative and qualitative assessments. The cost criteria for evaluating the stability of territories are being widely developed at present in two main directions. The first is assessment of the risk of the impact of dangerous natural and natural-technogenic processes. The second is due to the assessment of the costs required for the construction and normal operation of natural-technical systems or objects, including their engineering protection.
Middle and Upper Jurassic 18 sandstone core samples from exploration borehole, drilled in Nariinsukhait coal deposit, was studied. Geochemistry of samples indicates that sandstones were derived from acidic and intermediate rocks and mixed with recycled older sedimentary rocks. Possible sources are volcano-sedimentary rocks of Mississippian Tost Formation, granite and granodiorite of Early-Late Carboniferous Tavan-Uul complex and sedimentary rocks of Middle-Upper Triassic Noyon Formation. Paleoclimate indices (C-value, Rb/Sr, Sr/Ba, 1000xRb/K2O and CIA) reflect that coal seams were accumulated in warmer and more humid climate, when paleo-weathering was intense, whereas sandstones were deposited in relatively cold and arid climate. In Late Jurassic, it is more likely that paleoclimate became more arid and cold compared with Middle Jurassic, indicated by quite low CIA and Rb/Sr. Redox condition (Th/U, Ni/Co and V/Cr) was variable, probably controlled by paleoclimate. Moreover, various discrimination diagrams suggested that Middle Jurassic coal-bearing sedimentary rocks were accumulated in foreland basin. It is consistent with previous interpretations of regional tectonic during Triassic and Jurassic time. Түлхүүр үг: элсэн чулуу, тектоник, дунд юра, нүүрс, өмнөд Mонгол, форланд
Алаг-Өндөрийн антрацитийн орд нь Улаанбаатар хотоос 370 км, Дорноговь аймаг Сайншанд хотоос 90км Айраг сумаас 80 км-ийн зайнд орших ба Эс Жи Групп ХХК-ын 2009 онд явуулсан хайгуулын ажлын үр дүнд шинээр нээгдсэн. Алаг-Өндөрийн ордын хувьд нүүрсний давхраас дагасан тектоник хөдөлгөөний улмаас 3 салаалсан хагарал үүсч нүүрсний давхраасуудыг 75-150 м шилжүүлэн 3 давхарласан болох нь хайгуулын ажлын үр дүнд тогтоогдсон юм. Эдгээр хагарлууд нүүрсний давхраасны адилаар зүүн хойшоо 60-650 чиглэлтэй сунаж, баруун хойшоо 40-700 шургана. Тектоник хөдөлгөөний улмаас нүүрсний давхраасууд нунтаглагдан зарим хэсэгтээ завсрын чулуулгуудтайгаа холилдон (брекчлэгдсэн) нягтарсны улмаас түүний үнслэгийг өндөрсгөсөн байж болохыг петрографийн судалгаа харуулж байна. Алаг-Өндөрийн ордыг “Ашигт малтмалын нөөц, баялагийн түр заавар”-ыг үндэслэн геологийн тогтоц тектоникийн бүтцийн хувьд нийлмэл буюу III бүлэгт хамааруулж байна. Антрацитийг нүүрсний бусад төрлүүдтэй харьцуулахад шатах хэсгийн дэгдэмхий бодисын гарц бага (<8,0 %), шатах хэсгийн нүүрстөрөгчийн агуулга өндөр (>92,0 %) болон цахилгаан сайн дамжуулдаг онцлогт тулгуурлан янз бүрийн салбарт ашиглаж байна. Тус судалгааны ажлын үндсэн зорилго нь “Алаг-Өндөр” нүүрсний ордын структур-геологийн тогтоц, нүүрсжилтийн онцлог
Тавантолгойн чулуу нvvрсний орд нь Өмнөговь аймгийн Цогтцэций сумын нутагт, сумын төвөөс баруун урагш 18км-т оршдог. Улаанбаатар хотоос 560км-т буюу газар зvйн уртрагийн 105025I-105032I хойд өргөрөгийн 43035I-43039I солбилцолд далайн төвшнөөс дээш 1500-1830 м-ийн өндөрлөгт Их шанхайн массивийн төв Улааннуурын хөндийд байрладаг. Элсэн чулууны петрографи, геохимийн судалгаагаар тухайн чулуулгийн гарал үүсэл, геодинамикийн нөхцөл болон тэжээгч мужийн уур амьсгал, өгөршлийн эрчим зэрэг хурдас хуримтлалын эртний орчныг тодорхойлж болно. Тавантолгой нүүрсний орд орчим тархсан 3300 метр зузаантай пермийн хурдас нь Өмнөд Монголын пермийн хурдсын бүтэн зүсэлт гэж тооцогддог. Нөгөө талаас пермийн цаг үеийн Өмнөд Монголын геологийн хөгжлийн түүхийг сэргээн босгох нь палеозойн цаг үеийн Төв Азийн геодинамикийн түүхийг сэргээн босгоход тодорхой хувь нэмэр болох юм. Энэ судалгаагаар дунд пермийн нүүрс агуулсан Тавантолгой формацийн элсэн чулууны геохимийн судалгаа хийж, нүүрс агуулсан тунамал хурдас хуримтлагдсан орчин, тектоникийн нөхцлийг сэргээн босгохыг зорилоо.
hujirt is a syncline that hosts Jurassic coal deposit in Northern Mongolia. Nine coal samples collected from exploration borehole were selected for analyses of major oxide and trace elements of coal ash. The average value of CAI for the samples is 82.8, reflecting intensive weathering in the source area. The plotted data on A-CN-K diagram displays that rocks in coal were sourced mainly from Early Permian andesite and basalt and Early Paleozoic granodiorite, which borders Khujirt syncline. It is also supported by Al2O3/TiO2 (avg. 18.4) and Ti/Zr (avg. 37.1) ratios. To infer tectonic setting, two multi-dimensional discrimination diagrams were used. The results suggest that the tectonic setting of Khujirt was foreland basin that was probably formed by closure of Mongol-Okhotsk Ocean. Low Rb/Sr (0.02-0.04) and high Sr/Cu (13.8-30.6) ratios of the studied samples indicate that arid climate condition was dominant during the deposition of Khujirt peat accumulation. This conclusion is supported by C-values. Due to arid condition, salinity was high, reflected by substantially high Sr/Ba ratio varying from 1.7 to 2.7.
Middle and Upper Jurassic 18 sandstone core samples from exploration borehole, drilled in Nariinsukhait coal deposit, was studied. Geochemistry of samples indicates that sandstones were derived from acidic and intermediate rocks and mixed with recycled older sedimentary rocks. Possible sources are volcanosedimentary rocks of Mississippian Tost Formation, granite and granodiorite of Early-Late Carboniferous Tavan-Uul complex and sedimentary rocks of MiddleUpper Triassic Noyon Formation. Paleoclimate indices (C-value, Rb/Sr, Sr/Ba, 1000xRb/K2O and CIA) reflect that coal seams were accumulated in warmer and more humid climate, when paleo-weathering was intense, whereas sandstones were deposited in relatively cold and arid climate. In Late Jurassic, it is more likely that paleoclimate became more arid and cold compared with Middle Jurassic, indicated by quite low CIA and Rb/Sr. Redox condition (Th/U, Ni/Co and V/Cr) was variable, probably controlled by paleoclimate. Moreover, various discrimination diagrams suggested that Middle Jurassic coal-bearing sedimentary rocks were accumulated in foreland basin. It is consistent with previous interpretations of regional tectonic during Triassic and Jurassic time.
Based on the geochemistry of coal samples, collected from East and West mines of Nariinsukhait deposit, provenance, tectonic settings and source areapaleoweathering and paleoclimate was reconstructed. Sediments accumulated in peat swamp were mainly from acidic rocks mixed with smaller amount of intermediate rocks, indicated by Al2O3/TiO2 and A-K-CN diagrams. Seam 5 was deposited under realtively hot climate compared with upper seams (Seam 8, 9 and 10). Seam 5 is characterized by high Sr/Cu (avg. 7.4), Sr/Ba (avg. 2.5) and inertinite content (up to 35%). For upper seams, Sr/Cu (4.8), Sr/Ba (1.5) and inertinite content (~14%) are low, indicating more humid climate and fresher water body. CIA, Ni/Co and V/Cr support the findings. In addition, сoal was deposited in foreland basin. Collision tectonic setting was dominant during Triassic and Jurassic period in southern Mongolia.
Нарийсухайтын хотгор нь баруунаас зүүн тийш 300 км сунаж тогтсон бөгөөд Нарийнсухайт хотгор гэсэн нэгжийг Баатархуяг нар 2016 онд анх ялгасан болно
Нарийнсухайтын нүүрсний орд нь Өмнөговийн нүүрсний савд хамаарагдах (Д.Бат-Эрдэнэ нар, 1985) ба Өмнөговь аймгийн Гурвантэс сумын нутагт оршдог. Орд нь Нарийнсухайтын хотгорт орших ба ордын хэмжээнд дунд Юрын Оргилохбулаг (J2ob), дээд Юрын Шархотгор (J3sh), Доод Цэрдийн Өндөр-Ухаа формац (К1uu) формацууд тархсан
The Tavantolgoi deposit, which has more than six billion tons of coal reserves, is situated in southern Mongolia. In 2018, more than 22Mt coal was produced from the deposit. During the exploration program completed in 2017, eighteen sandstone and two andesite samples for petrographical and geochemical analysis were collected from the upper part of coal-bearing Middle Permian Tavantolgoi Formation, which was intersected completely by 960 m deep bore hole. Petrographically, the sandstones are classified as litharenite reflecting relatively weak weathering intensity in source area, probably due to arid or semiarid climate conditions. Provenance analysis indicates that the sandstones are sourced from transitional arc and undissected arc that were probably formed during the closure of Paleoasian ocean between southern Mongolia and North China block. Geochemistry of major oxide and trace element result are summarized as below. CAI values from major oxides of the studied samples vary between 66.7 and 81.5 with an average of 77.0, reflecting weak to moderate intensity of weathering in source area. The plotted data on A-CN-K diagram displays that sandstones were sourced mainly from early Permian andesite and dacite, which are widely distributed around Tavantolgoi. It is also supported by Al2O3/TiO2 (avg. 19.6), TiO2/Zr (avg. 57.7) and petrographical study. C-value, indicator of paleoclimate, in the sandstone ranges from 0.15 to 1.3 with an average of 0.50, suggesting semiarid and semiarid to semimoist condition. However, some samples accumulated during the short period of arid and moist conditions. Rb/Sr and Sr/Cu of the studied samples are consistent with those of C-value. In addition, Sr/Ba (avg. 0.56), Th/U (avg. 2.8) and Ni/Co (avg. 2.0) of the samples suggest that the sandstones were deposited in paleoenvironment with fresh and oxic water.
The Nariin Sukhait mine is located in the southwest of Umnugobi province 50 kilometers from Mongolia's border with China at Shivee Khuren within the Nariin Sukhait deposit, which has relatively complex geological features. The most prominent feature relating to the Nariin Sukhait coal deposit is the arcuate, east-west trending Nariin Sukhait fault. The coal-bearing section, interpreted to be middle Jurassic in age, is exposed primarily in a window adjacent to this fault. The chemical composition of whole indicates (variable composition, values of the ratio Th/U > 3.8-4.2, values Th/Sc 0.3-0.8, values LaN/YbN > 5 and values Eu/Eu* 0.6-0.9) indicates components derived from the active continental margin type. The low CIA values (50–60) indicate the absence or poor chemical weathering in the source area. SEM-CL-imaging of sandstone quartz from Nariin sukhait show three types of quartz: early Q1 cementation has gray to slightly grey luminescences, postdated compaction, and reduced intergranular porosity associated with illite formed during eogenesis. Q2 is characterized by dark luminescence overgrowths and is more voluminous in the thinly bedded sandstones than in the thickly bedded sandstones filling most of the remaining pore space during mesogenesis. Q3 was formed during the early telogenesis stage fully cementing the sandstones and the fractures were filled by hydrothermal chlorite and sulfides. Significant amounts of trace elements Al, Ti, Ca, K and Fe has been detected in quartz overgrowths. Al varies consistently between each cement with averages of 1324, 1523, and 1352 ppm for the Q1, Q2, and Q3 generations, respectively. The geochemical, SEM-CL imaging and EPMA data results suggest a relatively igneous source, whit felsic composition. The sedimentary environment of the sandstone and argillite of these sedimentary rocks was the poor chemical weathering in the source area.
Middle Permian Tavantolgoi coal deposit lies in southern Mongolia and has more than 6 billion tons of coal including significant tonnage of coking coal. In 2017, exploration bore holes were drilled at Borteeg, the largest syncline of the deposit. Eighteen sandstone and two andesite samples for petrographical and geochemical analysis were collected from coal-bearing sequences that were intersected by 960 m deep bore hole. The sandstones are classified as litharenite suggesting that weathering intensity in source area was weak, probably due to short transport distance coupled with relatively arid to semiarid climate conditions. Provenance analysis (Q-F-L, Qm-F-Lt, and Qp-Lvm-Lsm diagrams) suggests that the sandstones are recycled sediments derived from transitional arc and undissected arc that were formed during the closure of Paleoasian ocean between southern Mongolia and North China block. The average value of CIA for the samples is 74.1, reflecting relatively weak intensity of weathering in source area, which is consistent with the results of petrography. The plotted data on A-CN-K diagram displays that sandstones were sourced mainly from Early Permian andesite and dacite, which are widely distributed around Tavantolgoi. It is also supported by Al2O3/TiO2 (avg. 19.6) and petrographical study. To infer tectonic setting, two multi-dimensional discrimination diagrams were used. The results suggest that the tectonic setting of Tavantolgoi syncline, in which the studied sandstone was deposited, was rift.
Seven sandstone samples were collected from Middle Jurassic Orgilokhbulag Formation distributed at Nariinsukhait coal deposit and petrographical study has been completed. According to the results of study, the sandstones are classified into subarkose, sublitharenite and feldspathic litharenite. The sandstone provenance analysis suggests that the sandstones were deposited during the late stage of development of Noyon syncline, which is a foreland basin formed due to early Mesozoic crustal shortening. In addition, MIA suggests that during middle Jurassic time, weathering intensity in the source area of Nariinsukhait sandstone was relatively high, probably due to warm and humid climate.
Ovoot tolgoi lies Noyon syncline of Gurvantes region, Southgobi coal-bearing basin. petrographical studies of coal and coal-hosting sedimentary rocks of ovoot tolgoi have been completed. The studies reveal that Ovoot tolgoi coal has mixed microtithotypes consisting of duroclarite and clarodurite and contains 45.9-73.4% vitrinite, 12.2-35.3% inertinite, 1.7-5.8% liptinite and 2.0-36.1%minerals. coal hosting sandstone can be classified as feldspathic litharenite and litharenite as well as lithic arkose. The results of modal composition data of sandsthones in ovoot tolgoi suggests that the source tectonic settings were mixed and rcycled orogen
Seven sandstone samples were collected from Middle Jurassic Orgilokhbulag Formation distributed at Nariinsukhait coal deposit and petrographical study has been completed. According to the results of study, the sandstones are classified into subarkose, sublitharenite and feldspathic litharenite. The sandstone provenance analysis suggests that the sandstones were deposited during the late stage of development of Noyon syncline, which is a foreland basin formed due to early Mesozoic crustal shortening. In addition, MIA suggests that during middle Jurassic time, weathering intensity in the source area of Nariinsukhait sandstone was relatively high, probably due to warm and humid climate.
Middle Permian Tavantolgoi coal deposit lies in southern Mongolia and has more than 6 billion tons of coal including significant tonnage of coking coal. In 2017, exploration bore holes were drilled at Borteeg, the largest syncline of the deposit. Eighteen sandstone and two andesite samples for petrographical and geochemical analysis were collected from coal-bearing sequences that were intersected by 960 m deep bore hole. The sandstones are classified as litharenite suggesting that weathering intensity in source area was weak, probably due to short transport distance coupled with relatively arid to semiarid climate conditions. Provenance analysis (Q-F-L, Qm-F-Lt, and Qp-Lvm-Lsm diagrams) suggests that the sandstones are recycled sediments derived from transitional arc and undissected arc that were formed during the closure of Paleoasian ocean between southern Mongolia and North China block. The average value of CIA for the samples is 74.1, reflecting relatively weak intensity of weathering in source area, which is consistent with the results of petrography. The plotted data on A-CN-K diagram displays that sandstones were sourced mainly from Early Permian andesite and dacite, which are widely distributed around Tavantolgoi. It is also supported by Al2O3/TiO2 (avg. 19.6) and petrographical study. To infer tectonic setting, two multi-dimensional discrimination diagrams were used. The results suggest that the tectonic setting of Tavantolgoi syncline, in which the studied sandstone was deposited, was rift.
