Lithosphere最新文献

{"title":"Study of Road Performance and Curing Mechanism of Coal Gangue by Curing Agent","authors":"Zhe Ren, Rui Zhang, Jian Zhang, Qiang Gao, Chuanxiao Liu, Yingying Wan, Jianjun Liu, Qingliang Hu, Chengbin Ren","doi":"10.2113/2024/lithosphere_2023_183","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_183","url":null,"abstract":"Coal gangue is a type of rock waste product with dark gray color during coal mining and washing. The curing agent stabilizes soils by improving their physico-mechanical properties, allowing the soils to be reused in engineering as the subgrade fill. This study investigates the impact of SAHP curing agent on road performance parameters of coal gangue. The results showed that the road performance parameters of coal gangue increase with the curing agent content. The compressive resilience modulus of 7 days and California bearing ratio of coal gangue with 0.2% curing agent meet the specifications. The scanning electron microscope reveals the presence of agglomerated gels and hexagonal prism crystals between coal gangue particles. The observed crystals are ettringite, and the gels are silicate gel (nSiO2·mH2O) formed by the reaction of Na2O·nSiO2 with CO2 and H2O, as determined by combined X-ray diffraction and energy spectrum analysis. The improved coal gangue by the curing agent can be utilized as subgrade fill, supporting the reuse of coal gangue in highway engineering.Mine wastes are generated nearly in all mining operations. As the unwanted by-products of mining, they are often placed in large heaps on the mining sites. Inappropriate disposal of the mine wastes (coal gangue, tailings, and other wastes) would release hazardous substances, which exert great impact on the local ecological environment and human health [1, 2]. The oxidation of sulfide minerals is the main source of acid mine drainage (AMD), which results in the surface and groundwater contamination. As the typical sedimentary rock, coal contains a large amount of carbon, sulfur, and hydrogen elements. The oxidation of pyrite is the major source of AMD or coal mine drainage (CMD) in the coal industry [3]. During the complex oxidation process among water, air, and exposed coal rock, the heavy metals leach into the water gradually. A comprehensive evaluation of the quality of the soils, stream, and water bodies near the coal-washing waste dump from the geochemical perspective is necessary for water remediation plan [4]. It is worth noting that, not all CMD are hated, advanced technology makes it possible to reuse the mining wastes, such as recovering rare earth elements [3].Large size of the mining industry determines the deposition of coal gangue, which occupies a large area of land resources [2, 5]. Oxidation and spontaneous combustion exist during the long-term coal gangue accumulation, and harmful gases such as SO2, NOx, and CO can also be released [1]. Coal gangue has been utilized in the preparation of cement [6], powder asphalt mortar [7], and autoclaved aerated concrete [8]. With the rapid development of transportation infrastructure construction, coal gangue was also proposed to be reused in highway engineering as the filling material.Coal gangue can satisfy the basic requirements for road engineering materials after being compacted or stabilized, which offers certain potential ","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140072422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon Isotopic Behavior During Hydrocarbon Expulsion in Semiclosed Hydrous Pyrolysis of Type I and Type II Saline Lacustrine Source Rocks in the Jianghan Basin, Central China","authors":"Shaojie Li, Lunju Zheng, Xiaowen Guo, Yuanjia Han","doi":"10.2113/2024/lithosphere_2023_294","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_294","url":null,"abstract":"Organic carbon isotopic analysis is a significant approach for oil-source correlation, yet organic carbon isotopic behavior during oil expulsion from saline lacustrine source rocks is not well constrained, and this hinders its wide application for fingerprinting oils generated by saline lacustrine source rock. To resolve this puzzle, semiclosed hydrous pyrolysis was conducted on typical saline lacustrine source rocks from the Qianjiang Formation (type I kerogen) and Xingouzui Formation (type II kerogen) sampled in the Jianghan Basin, China, under high-temperature high-pressure conditions (T = 275℃–400℃; P = 65–125 MPa). Experimental results show that there is minor carbon isotopic fractionation (<3‰) between pyrolyzed and nonpyrolyzed retained oil fractions during the main oil generation/expulsion stage of both type I and II source rocks. Carbon isotopic fractionations between expelled and retained oil fractions are also minor (<2‰) during this stage. The δ13C values of retained and expelled oil fractions generated by the type I saline lacustrine source rock correlate positively with the degree of oil expulsion, whereas the influence of oil expulsion on the δ13C values of oil fractions generated by the type II source rock was not consistent. In addition, carbon isotopic analysis also unravels the mixing of oil-associated gases with different maturity levels and/or generated via different processes. Outcomes of this study demonstrate that oil expulsion from type I and II saline lacustrine source rocks cannot be able to result in large-degree carbon isotopic fractionation, indicating that carbon isotopic analysis is a feasible approach for conducting oil-source correlation works in saline lacustrine petroleum systems.Oil is generated through the thermal degradation of kerogen in hydrocarbon source rock and expelled after migrating within the source rock [1-3]. Oil migration within the source rock can be mainly through diffusion in organic matter networks, whole-phase flow, migration of a liquid-saturated gas phase, and so on [4-6]. Only portions of generated oils are expelled [7], and oil retained within source rocks is an important component of the rock. Besides the economic significance of retained oils (i.e., shale oil [8]), retained oil also has the ability to enhance the hydrocarbon-generating potential of source rocks because it has greater gas generation potential than overmature kerogen, especially for C2–C5 gaseous hydrocarbons [9-11].Fractionation of organic compound classes occurs during oil expulsion. In general, organic fractions with higher molecular weight and higher degrees of polarity are more likely to be retained in source rocks rather than being expelled out of rocks [12-14], and molecular fractionations within individual compound classes may not be substantial [15, 16]. Compared with polar compounds and aromatic hydrocarbons, paraffins are more readily to be expelled [14, 16, 17]. Therefore, the degree of oil expulsion has a si","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139462814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochronological and Geochemical Constraints on the Magmatic Evolution of the Dun Mountain Ophiolite Belt, New Zealand","authors":"Daniel Patias, Renjie Zhou, Jonathan C. Aitchison","doi":"10.2113/2024/lithosphere_2023_283","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_283","url":null,"abstract":"New whole-rock major and trace element geochemical, zircon U-Pb geochronological, and Hf isotopic data from gabbroic rocks in New Zealand’s mid-Permian Dun Mountain ophiolite belt (DMO) provide insight into the evolution of subduction systems and early stages of intraoceanic arc development. Fe-oxide-bearing gabbros yielded high εHf(t) values (+10.3 to +13) and zircon U-Pb ages of 271.6 ± 0.6 Ma. In contrast, Fe-Ti-oxide-bearing gabbros of 268.1 ± 0.6 Ma show more enriched geochemical characteristics, including a wide range of εHf(t) values (+15.5 to +6.8). New findings strengthen the evolutionary model for the DMO and place constraints on its youngest known magmatic episode. We infer that late magmatism fingerprinted by these gabbros, including consistent negative Nb-Ta anomalies, reflects early stages of arc development and formation of island arc tholeiites on the DMO. Our model is consistent with other existing regional geochronological and geochemical data, implying that the DMO had an early stage of normal-mid-ocean ridge basalt crustal accretion followed by an influx of slab-derived components and maturity of the subducting system between ca. 271.6 and 268 Ma. These results extend our understanding of the evolution of distinct intraoceanic systems.Ophiolites are fragments of ancient oceanic lithosphere that have been incorporated into continental margins [1, 2]. They can be formed in distinct tectonic settings, including mid-ocean ridge, back-arc, and forearc [3, 4]. However, since the recognition of lava with island arc tholeiites (IAT) and calc-alkaline geochemical signatures in the Troodos ophiolite [5], a growing number of studies have associated these fragments of ancient oceanic lithosphere to intraoceanic convergent plate margins [6]. Such ophiolites, formed during sea-floor spreading above the subducting slab, are referred to as suprasubduction zone (SSZ) ophiolites [7]. They are widely interpreted to form during subduction initiation and early growth of island arcs [2, 7, 8]. As a result, studying their geochemical and geochronological signatures is crucial for understanding plate tectonic processes and intraoceanic systems [3, 9-12].Different geochemical signatures, such as forearc basalt (FAB), boninite, and IAT, can often be found in rocks from the ophiolitic crustal section. These signatures are widely used to identify different stages of the ophiolite and the evolution of the intraoceanic system [13, 14]. However, diverse processes can affect the geochemical characteristics of ophiolitic rocks, for example, the injection of fluids and melts from the slab [15, 16], distinct episodes of melt extraction from the mantle [17], and cumulate processes [18, 19]. Additionally, specific processes, such as colder, denser slabs descending more quickly or a thicker sedimentary cover of the slab, can also contribute to the geochemical heterogeneity of ophiolitic rocks [20-22]. This complexity can make it challenging to determine an ophioli","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139501389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on Shear Slip Characteristics of Sandstone Plane Joints under Normal Dynamic Load Disturbance","authors":"Kangyu Wang, Caiping Lu, Yang Liu, Caijun Shao, Jian Zhou, Zhaowei Zhan","doi":"10.2113/2024/lithosphere_2023_282","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_282","url":null,"abstract":"Rock joints are susceptible to slip instability due to dynamic load disturbances such as blasting, earthquakes, and fracturation. A series of direct shear tests under the dynamic load were conducted on sandstone plane joints using the RDS-200xl. The work investigated the effects of normal static loads and normal dynamic-load frequencies and amplitudes on plane joints. Besides, the following items were proposed, that is, the peak-to-valley response rate, shear velocity vibration dominant frequency, shear-stress reduction coefficient, and discrete element numerical simulation method for plane-joint direct shear tests. The results were as follows: (1) The normal dynamic load frequency played a role in attenuating the shear stress amplitude with a threshold value of 0.5 Hz. (2) The shear velocity of the plane joint was completely controlled by the high normal dynamic load frequency. Their vibrational dominant frequencies were identical. (3) The amplitude of shear stress increased, and the median stress decreased with the increased normal dynamic load amplitude. The reduction-coefficient equation for sandstone plane joints was proposed to evaluate the shear stress under the normal dynamic load disturbance. (4) The shear-stress hysteresis phenomenon existed in the plane joints under the normal dynamic load, which required excessive shear displacements to reach peak shear strength. The peak shear displacement increased with the increased normal static load. Numerical simulations and indoor tests showed that high- and low-shear-velocity regions were the main reason for shear-stress hysteresis. The findings are conducive to revealing the shear destabilization mechanism of rock joints under dynamic load disturbance.Rock is a complex geological body composed of joints and rock masses, and shear damage along the joints is one of the main damage modes of rocks [1]. The shear behavior of rock joints is an important basis for the project design and safety assessment in practical engineering. The force form of rock engineering is a combination of dynamic and static loads due to blasting, explosion, or seismic stimulation. Compared with static-load shear damage, the shear behavior of rocks under the dynamic load is more complicated. Research findings indicate that fault slip exhibits an inherent instability, characterized by a concurrent misalignment and a decline in the stress. When an earthquake occurs, normal and shear stresses change around the fault [2-4]. Therefore, it is of great significance to study the shear behavior of rock joints under the dynamic–static load combination.Tests consider real stresses in rock engineering, and research generally focuses on dynamic loading conditions in rocks’ normal and tangential directions. Guo et al. [5] investigated the fatigue damage and irreversible deformation of salt rocks under the uniaxial cyclic loading. The fatigue life of salt rocks is mainly affected by their structure and normal stress amplitude. Liu et al","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139923763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Oligocene to Early Pliocene Exhumation and Structural Development in the Western Himalaya, Northern Pakistan: Implications for the Cenozoic Metamorphic Overprint","authors":"Irum Irum, Humaad Ghani, Edward R. Sobel, Gerold Zeilinger, Uwe Altenberger","doi":"10.2113/2024/3252550","DOIUrl":"https://doi.org/10.2113/2024/3252550","url":null,"abstract":"New middle Miocene to Pliocene (~14–3 Ma) apatite fission track (AFT) cooling ages combined with published K–Ar/Ar–Ar and zircon fission track (ZFT) ages from the Hazara and Swat regions of Pakistan are used to explain the Oligocene to Pliocene structural evolution in the Western Himalaya. The structural model explains the distribution of K–Ar/Ar–Ar ages in three distinct age groups (Proterozoic, Paleozoic-Mesozoic, and Eocene to Oligocene). The Proterozoic to Mesozoic sequence of northern Hazara and Swat experienced elevated temperature and pressure conditions, evident by reset Eocene to Oligocene K–Ar/Ar–Ar hornblende and Eocene to Miocene muscovite ages, caused by Kohistan overthrusting the Indian margin during and after the India–Asia collision. Samples from the Indus syntaxis with Paleo to Mesoproterozoic K–Ar/Ar–Ar hornblende ages and Eocene to Oligocene Ar–Ar muscovite ages show no signs of Cenozoic metamorphism; these samples were thermally imprinted up to the Ar–Ar muscovite closure temperature. Neoproterozoic to Lower Paleozoic rocks from the southern parts of Hazara and Swat show Mesozoic to Oligocene partially reset Ar–Ar muscovite ages and preservation of Ordovician metamorphism. The combined analysis of published K–Ar/Ar–Ar (muscovite), ZFT, and new AFT ages (~14–12 Ma) suggests that the Main Central thrust/Panjal thrust was active from Oligocene to early Miocene (~30–18 Ma), and the Nathia-Gali and Main Boundary thrusts were active from the middle to late Miocene (~14–9 Ma) in the Hazara area. New and published AFT ages (~6–3 Ma) from the Indus syntaxis suggest that early Pliocene tectonic thickening in the hinterland formed the N–S trending Indus anticline, creating an erosional half window in the Main Mantle thrust, forming the Indus syntaxis, and dividing the Main Central thrust sheet into the Hazara and Swat segments.The Himalaya, one of the most tectonically active mountain ranges in the world, exposes thrust belts that record both in-sequence and, less frequently, out-of-sequence propagation of deformation over million to millennial and decadal time scales (Figure 1). Detailed geochronologic, thermochronologic, geomorphologic, and thermobarometric studies in different parts of the Himalayan Orogen have highlighted differences in the structural style, spatiotemporal development of the structures, and effects of Cenozoic Himalayan metamorphism on the subducting Indian plate (1, and references therein). The Himalaya is tectonostratigraphically subdivided into four zones (Tethys-, Greater-, Lesser-, and Sub-Himalaya), bounded by southward-younging thrusts originating from the sole thrust known as the Main Himalayan thrust (MHT). However, studies in the Northwestern Himalaya have suggested that deformation switched back to the hinterland, resulting in the formation of out-of-sequence thrusts, reactivation of older thrusts, and zones of high seismicity and exhumation driven by tectonic and climatic processes [2-4].The Himalaya can ","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139509447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compressive Fracture Behavior and Acoustic Emission Characteristics of Sandstone under Constant Crack Water Pressure","authors":"Jiancheng Huang, Yong Luo, Chengzhi Pu, Song Luo, Xuefeng Si","doi":"10.2113/2024/lithosphere_2023_314","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_314","url":null,"abstract":"Engineering rock containing flaws or defects under a large water source is frequently subject to the couple influence of constant crack water pressure and geostress. To investigate the fracture behavior of precracked rock under hydromechanical coupling with constant crack water pressure, compression tests were conducted on red sandstone specimens containing a single crack of different angles using a device to realize the constant crack water pressure during loading, and the failure process of rock specimens was monitored by acoustic emission (AE) technique. The results show that the presence of constant crack water pressure has a significant promotion effect on the development of shear wing cracks, and the promotion effect is influenced by the prefabricated crack angle and water pressure. As the constant crack water pressure increases, the failure mode of the 0° precrack specimen changes from “X”- shear failure to the single oblique shear failure along the shear wing crack direction, the main failure crack of the inclined precracked specimens (precrack angles of 15°, 45°, and 60°) changes from a small acute angle with the prefabricated crack to a direction along the shear wing crack, and irregular cracks occur at the chipped prefabricated crack in the 90° precracked specimen. With an increase in the constant crack water pressure, the average energy for a single hit, cumulative AE energy, and cumulative AE hits decrease, and the proportion of the tensile cracks increases and that of the shear cracks decreases.In underground mining, water conservancy and hydropower, geothermal development, and oil exploitation projects, rock structure inevitably contains various flaws and can be damaged and destroyed due to stress variations [1-7]. Therefore, the study of the failure characteristics of rocks with original crack, such as the crack propagation mechanism [8-11], mechanical properties [12-14], and acoustic emission (AE) characteristics [15-17], has been popular in recent years. Water, as a common liquid in the earth crust, is commonly present in rock flaws in underground engineering structures [18]. Due to the low permeability, rocks are often subjected to the influence of crack water pressure. In general, there are two common types of crack water pressure in rocks, as demonstrated by cases I and II in Figure 1. In case I, the crack water is not connected to a large water source, and the crack water pressure is not replenished in time during crack expansion. Therefore, the crack water pressure decreases as the crack expands. In case II, the crack water is connected to a large water source, the crack water pressure is immediately replenished during the crack propagation, so that the water pressure remains almost constant. This type of crack water pressure is termed the constant crack water pressure. With the rapid development of various types of rock engineering, increasing underground projects are being constructed under large water sources (e.g., tunn","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139772995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleogene Sedimentary Basin Development in Southern Nevada, USA","authors":"Jens-Erik Lundstern, Theresa M. Schwartz, Cameron M. Mercer, Joseph P. Colgan, Jeremiah B. Workman, Leah E. Morgan","doi":"10.2113/2024/lithosphere_2023_225","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_225","url":null,"abstract":"The cause of the transition from Mesozoic and early Cenozoic crustal shortening to later extension in the western United States is debated. In many parts of the extant Sevier hinterland, now the Basin and Range Province, the sedimentary sections that provide the most direct record of that transition remain poorly studied and lack meaningful age control. In this paper, we present field characterization supported by U-Pb detrital zircon and 40Ar/39Ar feldspar ages for ten sections across southern Nevada. We describe a newly identified basin, here named the Fallout Hills basin, which preserves >1.0 km of sedimentary deposits as old as middle Eocene, ca. 48 Ma. Deposition occurred during the 20 m.y. (million years) before the 27.60 ± 0.03 Ma Monotony Tuff blanketed much of south-central Nevada, based on 47.6 Ma and younger detrital zircon maximum depositional ages (MDAs) from near the Pintwater and Spotted Ranges. Elsewhere in southern Nevada, prevolcanic Cenozoic strata commonly form thinner (~100 m), isolated exposures that yield detrital zircon MDAs ≤10 m.y. older than (and in some cases essentially the same age as) the ca. 27–28 Ma ignimbrites that cap the sections. A variable but overall upward-fining facies pattern is observed in both the Fallout Hills basin and the thinner sections. These localized patterns imply topographic changes that are unlikely to reflect plate-scale processes and are not consistent with large-magnitude extension. Instead, variable uplift due to magmatism combined with antecedent topographic relief from thrust faulting and subsequent erosion likely provided accommodation for these deposits.Supracrustal rocks often provide some of the only records of topographic evolution and magmatic activity in ancient orogenic systems. They are, therefore, valuable for inferring the geometry, timing, and causal factors of tectonism and for constraining topographic change for use in geodynamic models [1, 2]. There is active debate concerning the fundamental transition that occurred in the western United States (Figure 1) from Mesozoic and early Cenozoic crustal shortening to Neogene basin-and-range extension [3, 4], which has implications for the study of crustal dynamics worldwide, including the stability of compressional orogens and the causes of extension. Sedimentary rocks deposited during this transition are sparse and generally not well studied across Nevada, eastern California, and western Utah, where one model has proposed that Cretaceous shortening thickened the crust sufficiently to support an orogenic highland commonly referred to as the Nevadaplano [5], while another has suggested that elevated topography was achieved only later due to south-migrating middle Cenozoic volcanism [3, 6]. Detailed constraints on the timing and setting of deposition would be valuable for understanding surface dynamics and the associated driving forces during this time and would assist with testing between sharply differing models that have been p","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140323592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Whole-Rock and Apatite Geochemistry of Late Triassic Plutonic Rocks in the Eastern Songpan-Ganzi Orogenic Belt: Petrogenesis and Implications for Tectonic Evolution","authors":"Haoyu Yan, Zhiqin Xu, Guangwei Li, Bihai Zheng, Jianguo Gao, Xiaoping Long","doi":"10.2113/2024/lithosphere_2023_284","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_284","url":null,"abstract":"To constrain the late Triassic tectonic evolution of the Songpan-Ganzi orogenic belt, we present new whole-rock and in situ apatite geochemistry for plutonic rocks in its eastern margin. The Taiyanghe pluton can be classified into two rock types: dioritic and granitic rocks. The former exhibits low SiO2 and MgO contents but high Al2O3, Th, LREE contents, and Th/Yb and Th/Nb ratios, as well as low Ba/La and Ba/Th ratios and enriched Sr-Nd isotopic compositions, which, together with apatite geochemistry and Nd isotopes, indicate that they were derived from low degrees of partial melting of lithospheric mantle metasomatized by sediment-derived melts. The latter is characterized by high Sr and low Y and Yb, with elevated Sr/Y and (La/Yb)N ratios, implying an adakitic affinity. Notably, their similar Sr-Nd isotopic compositions indicate an origin from partial melts of a newly underplated lower crust. The Maoergai granitic rocks, characterized by high Sr and low Y and Yb contents with high Sr/Y and (La/Yb)N ratios, are indicative of adakitic rocks. In combination with the enriched whole-rock Sr-Nd isotopes and the apatite Nd isotopic data, we suggest that they were generated by the partial melting of the ancient thickened mafic lower crust. The Markam and Yanggonghai felsic granitoid rocks are peraluminous and similar to typical S-type granitoids, indicating an origin from remelting of the Triassic metasedimentary rocks. Based on the temporal-spatial relationship of the late Triassic plutonic rocks in the orogenic belt, we suggest that these rocks were formed in association with the roll-back and subsequent break-off of a subducted slab of the Paleo-Tethys Ocean. During the subduction, the formation of the Maoergai adakitic rocks was triggered by slab roll-back, whereas the magmatic “flare up” (ca. 216–200 Ma) was likely caused by slab break-off. This indicates that the final closure of the Paleo-Tethys Ocean happened in the end of the Triassic or Early Jurassic.Orogenic belts are important sites where voluminous magmatic rocks with diverse lithologic and geochemical characteristics are produced [1-3]. However, the diversity of magmatic rocks developed in orogenic belts has been a topic of debate concerning their sources, magmatic processes, and geodynamic settings involved in petrogenesis [1-7]. Particular attention has been usually focused on the geodynamic framework, which can be generally regarded to be grouped into two types according to the temporal relationship to the tectonic evolutionary process of orogenic belts: subduction and postcollision [4, 8]. Magmatic rocks with diverse geochemical characteristics in orogenic belts offer a critical window to understand the tectonic evolution of these stages [1, 3, 4, 7]. Therefore, the tectonic evolution of orogenic belts could be accurately reconstructed by investigating the temporal-spatial variability and geochemical signatures of these diverse magmatic rocks.The Songpan-Ganzi orogenic belt is widel","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139465083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical and Experimental Study on Parameter Optimization of Active Sources in Seismic Tomography","authors":"Xinyuan Tian, Siyuan Gong, Linming Dou, Shun Hu, Bengang Chen, Qiang Lu","doi":"10.2113/2022/1742306","DOIUrl":"https://doi.org/10.2113/2022/1742306","url":null,"abstract":"\u0000 Given the high cost of active seismic tomography and the large influence on mining production, as well as the uncontrollable inversion period and accuracy of the target area during the passive seismic tomography, an optimization algorithm based on adding a certain number of artificial microseism (active sources) was proposed through the distribution characteristic of microseismic events (passive sources). The active source parameter optimization method realizes the combination of active source and passive source and improves the accuracy of inversion at the same time. The method uses a multiobjective optimization genetic algorithm to fuse the accuracy index and stability index that preevaluates the inversion effect and solves the best combination of active sources to improve the inversion effect. At the same time, experimental studies were carried out. After the active source was added, the inversion accuracy of high-stress areas and the ability to resist data errors were greatly improved. The inversion results were more in line with the law of stress transfer and stress distribution, which enhanced the connectivity of the low-velocity area of the fault zone or weakened zone.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139624354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep Subsurface Pseudo-Lithostratigraphic Modeling Based on Three-Dimensional Convolutional Neural Network (3D CNN) Using Inversed Geophysical Properties and Shallow Subsurface Geological Model","authors":"Baoyi Zhang, Zhanghao Xu, Xiuzong Wei, Lei Song, Syed Yasir Ali Shah, Umair Khan, Linze Du, Xuefeng Li","doi":"10.2113/2024/lithosphere_2023_273","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_273","url":null,"abstract":"Lithostratigraphic modeling holds a vital role in mineral resource exploration and geological studies. In this study, we introduce a novel approach for automating pseudo-lithostratigraphic modeling in the deep subsurface, leveraging inversed geophysical properties. We propose a three-dimensional convolutional neural network with adaptive moment estimation (3D Adam-CNN) to achieve this objective. Our model employs 3D geophysical properties as input features for training, concurrently reconstructing a 3D geological model of the shallow subsurface for lithostratigraphic labeling purposes. To enhance the accuracy of pseudo-lithostratigraphic modeling during the model training phase, we redesign the 3D CNN framework, fine-tuning its parameters using the Adam optimizer. The Adam optimizer ensures controlled parameter updates with minimal memory overhead, rendering it particularly well-suited for convolutional learning involving huge 3D datasets with multi-dimensional features. To validate our proposed 3D Adam-CNN model, we compare the performance of our approach with 1D and 2D CNN models in the Qingniandian area of Heilongjiang Province, Northeastern China. By cross-matching the model’s predictions with manually modeled shallow subsurface lithostratigraphic distributions, we substantiate its reliability and accuracy. The 3D Adam-CNN model emerges as a robust and effective solution for lithostratigraphic modeling in the deep subsurface, utilizing geophysical properties.Litho-strata manifest a broad range of rock properties arising from distinct geological processes, for example, weathering, compaction, metamorphism, and deformation. These intricate processes, when combined, yield complex representations of various litho-strata. Furthermore, lithostratigraphy dictates the physical and chemical attributes of the litho-strata, the distribution of which is intimately intertwined with mineral resource distribution. Traditional lithostratigraphic identification methods, for example, borehole drilling and trenching, necessitate manual interpretation of field-collected or borehole core samples. While direct, these methods prove costly, time-consuming, and inadequate for identifying deep subsurface litho-strata in a large area. Additionally, human subjectivity and experience wield considerable influence over these conventional approaches’ outcomes. Hence, there exists a need for more reliable lithostratigraphic identification methods using physical or chemical properties. Three-dimensional geological modeling plays a vital role in portraying subsurface spatial characteristics, for example, litho-strata, fault networks, physical and chemical properties, and quantitative mineralization [1-3]. With the advancements in deep-penetration geophysical and geochemical exploration, the prospect of studying geological bodies’ physical and chemical properties from a 3D perspective becomes feasible [4-6]. These methodologies deepen the comprehension of the lithostratigraphy’","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}