Levent Kuş, Davut Laçin, Tunahan Aykut, I. Tonguç Uysal
The western Black Sea region is a key area for the study of the Neo‐Tethys orogenic belt, as it contains records of the evolutionary history of the entire Alpine orogeny from subduction to oceanic closure and collision. The Izmir‐Ankara and the Intra‐Pontide suture zones represent the final closure of the Neo‐Tethys oceans. However, when the final closure took place is still disputed. In this study, we investigate syn‐collisional faulting events in the western Black Sea region near Istanbul. We performed kinematic analyses of faulting and U–Pb dating of syntectonic calcite precipitates on the fault planes to constrain the timing of Neo‐Tethys Ocean closure and post‐collisional contractional tectonics. Syntectonic calcite precipitates associated with regional N‐S compressional tectonics provide precise U–Pb ages between 48 and 57 Ma, constraining the early Eocene age of reverse faulting and associated closure of the Intra‐Pontide Ocean.
{"title":"Constraining the Timing of the Closure of the Intra‐Pontide Ocean by U–Pb Dating of Syntectonic Calcite","authors":"Levent Kuş, Davut Laçin, Tunahan Aykut, I. Tonguç Uysal","doi":"10.1111/ter.12743","DOIUrl":"https://doi.org/10.1111/ter.12743","url":null,"abstract":"The western Black Sea region is a key area for the study of the Neo‐Tethys orogenic belt, as it contains records of the evolutionary history of the entire Alpine orogeny from subduction to oceanic closure and collision. The Izmir‐Ankara and the Intra‐Pontide suture zones represent the final closure of the Neo‐Tethys oceans. However, when the final closure took place is still disputed. In this study, we investigate syn‐collisional faulting events in the western Black Sea region near Istanbul. We performed kinematic analyses of faulting and U–Pb dating of syntectonic calcite precipitates on the fault planes to constrain the timing of Neo‐Tethys Ocean closure and post‐collisional contractional tectonics. Syntectonic calcite precipitates associated with regional N‐S compressional tectonics provide precise U–Pb ages between 48 and 57 Ma, constraining the early Eocene age of reverse faulting and associated closure of the Intra‐Pontide Ocean.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"54 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laurentia (ancestral North America) records nearly 4 billion years of crustal evolution. Here, a newly compiled continental‐scale Pb isotopic database is used to evaluate the Precambrian crustal evolution of Laurentia. Pb model ages yield a 2.7 Ga peak, a 2.5–1.8 Ga minimum and 1.8–0.9 Ga continuum. Pb model ages yield thermochronometric data and track crustal growth via arc‐related magmatism and accretionary orogenesis. Model 232Th/204Pb and 238U/204Pb broadly correlate with mapped crustal domains. More homogeneous and less radiogenic 238U/204Pb and 232Th/238U after 2.7 Ga suggests a shift to more juvenile sources, loss of early isotopic reservoirs and greater crustal reworking. U and Th are fractionated from Pb in Proterozoic orogens with abundant ferroan and anorthosite–mangerite–charnockite–granite(AMCG)‐suite magmatism. This fractionation suggests the removal of Pb‐rich lower crust, supporting petrogenetic models involving lithospheric foundering and magmatic underplating. Lithospheric thinning and associated magmatism may have contributed to high middle Proterozoic geothermal gradients.
劳伦提亚（祖先北美洲）记录了近 40 亿年的地壳演化过程。在此，我们利用新编制的大陆尺度铅同位素数据库来评估劳伦提亚前寒武纪的地壳演化。铅模型年龄产生了 2.7 Ga 的峰值、2.5-1.8 Ga 的最小值和 1.8-0.9 Ga 的连续值。铅模型年龄产生了热时数据，并通过与弧有关的岩浆作用和吸积造山作用追踪地壳的生长。模型 232Th/204Pb 和 238U/204Pb 与绘制的地壳域大致相关。2.7Ga之后，238U/204Pb和232Th/238U的同质性更强，辐射性更低，这表明向更年轻的来源转变、早期同位素储层的消失和地壳再加工的增加。在具有丰富的铁闪长岩和正长岩-芒硝-石榴石-花岗岩（AMCG）岩浆岩的新生代造山运动中，铀和钍从铅中分馏出来。这种分馏表明富含铅的下地壳被移除，支持岩石圈创始和岩浆下溢的成岩模式。岩石圈减薄和相关的岩浆活动可能是造成中新生代高地热梯度的原因。
{"title":"Lead Isotopes Constrain Precambrian Crustal Architecture, Thermal History and Lithospheric Foundering in Laurentia","authors":"Ian W. Hillenbrand","doi":"10.1111/ter.12748","DOIUrl":"https://doi.org/10.1111/ter.12748","url":null,"abstract":"Laurentia (ancestral North America) records nearly 4 billion years of crustal evolution. Here, a newly compiled continental‐scale Pb isotopic database is used to evaluate the Precambrian crustal evolution of Laurentia. Pb model ages yield a 2.7 Ga peak, a 2.5–1.8 Ga minimum and 1.8–0.9 Ga continuum. Pb model ages yield thermochronometric data and track crustal growth via arc‐related magmatism and accretionary orogenesis. Model <jats:sup>232</jats:sup>Th/<jats:sup>204</jats:sup>Pb and <jats:sup>238</jats:sup>U/<jats:sup>204</jats:sup>Pb broadly correlate with mapped crustal domains. More homogeneous and less radiogenic <jats:sup>238</jats:sup>U/<jats:sup>204</jats:sup>Pb and <jats:sup>232</jats:sup>Th/<jats:sup>238</jats:sup>U after 2.7 Ga suggests a shift to more juvenile sources, loss of early isotopic reservoirs and greater crustal reworking. U and Th are fractionated from Pb in Proterozoic orogens with abundant ferroan and anorthosite–mangerite–charnockite–granite(AMCG)‐suite magmatism. This fractionation suggests the removal of Pb‐rich lower crust, supporting petrogenetic models involving lithospheric foundering and magmatic underplating. Lithospheric thinning and associated magmatism may have contributed to high middle Proterozoic geothermal gradients.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"25 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joint swarms can be important components of fractured reservoirs. They are often explained as damage around faults or related to mechanical differences between layers, although this does not explain the close spacing of the joints. Joint swarms around Bergen (Norway) are described, which are not related to exposed faults and are not influenced by layering or foliation in the Lower Palaeozoic gneisses. We suggest an evolution whereby: (1) a zone of microcracks develops; (2) one microcrack propagates and becomes connected to a source of mineralising fluid; (3) the fracture becomes a microvein, with a higher tensile strength than the microcracked host rock; (4) another microcrack propagates and the cycle is repeated, producing a zone of microveins; (5) the veins are partly weathered out, producing an apparent joint swarm, or the microveins crack at or near the ground‐surface. Joint swarms in exposed analogues may therefore not occur at reservoir depths.
{"title":"Apparent Joint Swarms Formed by the Crack‐Jump Process","authors":"D. C. P. Peacock, B. Leiss, M. W. Anderson","doi":"10.1111/ter.12747","DOIUrl":"https://doi.org/10.1111/ter.12747","url":null,"abstract":"Joint swarms can be important components of fractured reservoirs. They are often explained as damage around faults or related to mechanical differences between layers, although this does not explain the close spacing of the joints. Joint swarms around Bergen (Norway) are described, which are not related to exposed faults and are not influenced by layering or foliation in the Lower Palaeozoic gneisses. We suggest an evolution whereby: (1) a zone of microcracks develops; (2) one microcrack propagates and becomes connected to a source of mineralising fluid; (3) the fracture becomes a microvein, with a higher tensile strength than the microcracked host rock; (4) another microcrack propagates and the cycle is repeated, producing a zone of microveins; (5) the veins are partly weathered out, producing an apparent joint swarm, or the microveins crack at or near the ground‐surface. Joint swarms in exposed analogues may therefore not occur at reservoir depths.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"32 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gabriele Carnevale, Antonio Caracausi, Massimo Coltorti, Barbara Faccini, Giulia Marras, Michele Paternoster, Silvio G. Rotolo, Vincenzo Stagno, Vittorio Zanon, Filippo Zummo
This study provides new mineral chemistry data together with micro‐thermometric measurements on fluid inclusions hosted in ultramafic xenoliths (lherzolite, wehrlite, and dunite) brought to the surface by the last Mt. Vulture volcano activity (140 ka; southern Italy), and fed by melilitite‐carbonatite magmas. Petrographic evidence and mineralogical compositions of Mt. Vulture xenoliths are consistent with an origin in the upper mantle. Fluid inclusions in rock‐forming minerals of lherzolite and wehrlite xenoliths are CO2‐dominated. The equilibrium temperature calculated by geothermometric estimates ranges from 1039 C (±36°C) to 1142°C (±15°C), and entrapment pressures of fluid inclusions with post‐trapping re‐equilibration correspond to the local crust–mantle boundary (32 km depth), and to a shallow reservoir located at 12–14 km depth. These results contribute to constrain the origin of these xenoliths and the depth of storage of magmas erupted from Mt. Vulture, where carbonatite‐like metasomatism and mantle‐derived CO2 degassing occur.
{"title":"CO2‐Rich Xenoliths at Mt. Vulture Volcano (Southern Italy): New Constraints on the Volcano Plumbing System","authors":"Gabriele Carnevale, Antonio Caracausi, Massimo Coltorti, Barbara Faccini, Giulia Marras, Michele Paternoster, Silvio G. Rotolo, Vincenzo Stagno, Vittorio Zanon, Filippo Zummo","doi":"10.1111/ter.12745","DOIUrl":"https://doi.org/10.1111/ter.12745","url":null,"abstract":"This study provides new mineral chemistry data together with micro‐thermometric measurements on fluid inclusions hosted in ultramafic xenoliths (lherzolite, wehrlite, and dunite) brought to the surface by the last Mt. Vulture volcano activity (140 ka; southern Italy), and fed by melilitite‐carbonatite magmas. Petrographic evidence and mineralogical compositions of Mt. Vulture xenoliths are consistent with an origin in the upper mantle. Fluid inclusions in rock‐forming minerals of lherzolite and wehrlite xenoliths are CO<jats:sub>2</jats:sub>‐dominated. The equilibrium temperature calculated by geothermometric estimates ranges from 1039 C (±36°C) to 1142°C (±15°C), and entrapment pressures of fluid inclusions with post‐trapping re‐equilibration correspond to the local crust–mantle boundary (32 km depth), and to a shallow reservoir located at 12–14 km depth. These results contribute to constrain the origin of these xenoliths and the depth of storage of magmas erupted from Mt. Vulture, where carbonatite‐like metasomatism and mantle‐derived CO<jats:sub>2</jats:sub> degassing occur.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"64 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The warm Miocene (23.0–5.3 Ma) is considered a model case for the global climate of the near future. In view of the current coral reef crisis, studies on Miocene reefs can contribute to predictions regarding the stress resilience of today's reefs against global warming. A Late Miocene (6.2–5.5 Ma) reef coral fauna from Hispaniola Island (Caribbean) characterised by ecologically tolerant taxa was originally interpreted to reflect cool‐eutrophic waters. However, the associated planktonic foraminifer assemblage and new TEX86H–based temperature reconstructions document an oligotrophic shallow‐water environment harbouring 30–31°C. Thus, in conjunction with unusually low vertical growth rates and erratic trace element signatures of massive reef corals, the coral fauna documents critically high temperatures and a response to heat stress rather than cool upwelling. The findings demonstrate the relevance of understanding shallow‐water ecosystems from past warm periods for developing scenarios of a future, warmer world.
{"title":"Elevated Tropical Sea Surface Temperatures During the Globally Warm Miocene Caused Heat Stress for Caribbean Coral Reefs","authors":"Thomas C. Brachert, Lorenz Schwark","doi":"10.1111/ter.12744","DOIUrl":"https://doi.org/10.1111/ter.12744","url":null,"abstract":"The warm Miocene (23.0–5.3 Ma) is considered a model case for the global climate of the near future. In view of the current coral reef crisis, studies on Miocene reefs can contribute to predictions regarding the stress resilience of today's reefs against global warming. A Late Miocene (6.2–5.5 Ma) reef coral fauna from Hispaniola Island (Caribbean) characterised by ecologically tolerant taxa was originally interpreted to reflect cool‐eutrophic waters. However, the associated planktonic foraminifer assemblage and new TEX<jats:sub>86</jats:sub><jats:sup>H</jats:sup>–based temperature reconstructions document an oligotrophic shallow‐water environment harbouring 30–31°C. Thus, in conjunction with unusually low vertical growth rates and erratic trace element signatures of massive reef corals, the coral fauna documents critically high temperatures and a response to heat stress rather than cool upwelling. The findings demonstrate the relevance of understanding shallow‐water ecosystems from past warm periods for developing scenarios of a future, warmer world.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"96 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Benjamin L. Howard, Glenn R. Sharman, James L. Crowley, Ellen Reat Wersan
U–Pb dating of zircon via laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) has become a primary method for determining the age of crystalline rocks and the provenance and maximum depositional age of (meta)sedimentary rocks. Although chemical abrasion has become a standard approach for mitigating Pb loss in zircon dated via high‐resolution thermal ionization mass spectrometry (CA‐TIMS), laser ablation dating is rarely accompanied by chemical abrasion. We evaluate the accuracy of U–Pb dates acquired via LA‐ICP‐MS relative to CA‐TIMS through analysis of a large database of paired analyses from the same zircon crystals. We show that laser ablation 206Pb/238U dates are systematically younger than their CA‐TIMS counterparts, with a greater shift in detrital zircon (−2.0%) versus igneous or metamorphic zircon (−0.9%). Although systematic biases related to “matrix effects” may be a contributing factor, our analysis suggests that unmitigated cryptic Pb loss is likely widespread in laser ablation U–Pb datasets.
{"title":"The leaky chronometer: Evidence for systematic cryptic Pb loss in laser ablation U‐Pb dating of zircon relative to CA‐TIMS","authors":"Benjamin L. Howard, Glenn R. Sharman, James L. Crowley, Ellen Reat Wersan","doi":"10.1111/ter.12742","DOIUrl":"https://doi.org/10.1111/ter.12742","url":null,"abstract":"U–Pb dating of zircon via laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) has become a primary method for determining the age of crystalline rocks and the provenance and maximum depositional age of (meta)sedimentary rocks. Although chemical abrasion has become a standard approach for mitigating Pb loss in zircon dated via high‐resolution thermal ionization mass spectrometry (CA‐TIMS), laser ablation dating is rarely accompanied by chemical abrasion. We evaluate the accuracy of U–Pb dates acquired via LA‐ICP‐MS relative to CA‐TIMS through analysis of a large database of paired analyses from the same zircon crystals. We show that laser ablation <jats:sup>206</jats:sup>Pb/<jats:sup>238</jats:sup>U dates are systematically younger than their CA‐TIMS counterparts, with a greater shift in detrital zircon (−2.0%) versus igneous or metamorphic zircon (−0.9%). Although systematic biases related to “matrix effects” may be a contributing factor, our analysis suggests that unmitigated cryptic Pb loss is likely widespread in laser ablation U–Pb datasets.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"74 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David W. Valentino, Jeffrey R. Chiarenzelli, Teresa E. Jordan, Robert D. Jacobi, Alexander E. Gates
Besides a few isolated rift basins along the Neoproterozoic eastern Laurentian margin, the Appalachian Palaeozoic strata rest unconformably on Mesoproterozoic crystalline basement, reflecting a ca. 550+ Ma hiatus. However, a nearly 3 km deep experimental geothermal borehole through the Appalachian basin at Cornell University, New York, unexpectedly encountered deformed Neoproterozoic greenschist facies phyllites and metavolcanics (Cayuta Formation) beneath the Cambrian non‐conformity. Magnetic modelling shows they are in the 5000 km2 fault‐bounded Ithaca basin, proposed to be associated with Iapetan rifting. The volcanism and metamorphism appear linked to ca. 600–650 Ma thermal events related or unrelated to extension, but requiring uplift and denudation of 5–10 km of rock prior to deposition of the Cambrian Potsdam Group. The Ithaca basin is >350 km inboard of the Laurentian Iapetus margin, indicating a broad Neoproterozoic rift zone for at least the NY and PA portion of eastern Laurentia.
除了沿新新生代东劳伦伦大陆边缘的几个孤立的裂谷盆地外，阿巴拉契亚古生代地层不稳定地稳定在中新生代结晶基底上，反映了约 550+ Ma 的间断。然而，在纽约康奈尔大学穿过阿巴拉契亚盆地的一个近 3 千米深的实验性地热钻孔中，却意外地在寒武纪不整合地层下发现了变形的新元古代绿泥石面辉绿岩和变质火山岩（卡尤塔地层）。磁力模型显示，它们位于面积达 5000 平方公里、以断层为界的伊萨卡盆地，该盆地被认为与伊阿佩坦断裂有关。火山作用和变质作用似乎与约 600-650 Ma 的热事件有关，或与延伸无关，但在寒武纪波茨坦群沉积之前需要 5-10 km 岩石的隆起和剥蚀。伊萨卡盆地位于劳伦提斯Iapetus边缘内侧350千米处，这表明至少在纽约州和宾夕法尼亚州的劳伦提斯东部有一个宽广的新近纪断裂带。
{"title":"Deep borehole discoveries beneath the Appalachian Basin: Broad Rodinian rift and Neoproterozoic tectonothermal event","authors":"David W. Valentino, Jeffrey R. Chiarenzelli, Teresa E. Jordan, Robert D. Jacobi, Alexander E. Gates","doi":"10.1111/ter.12741","DOIUrl":"https://doi.org/10.1111/ter.12741","url":null,"abstract":"Besides a few isolated rift basins along the Neoproterozoic eastern Laurentian margin, the Appalachian Palaeozoic strata rest unconformably on Mesoproterozoic crystalline basement, reflecting a ca. 550+ Ma hiatus. However, a nearly 3 km deep experimental geothermal borehole through the Appalachian basin at Cornell University, New York, unexpectedly encountered deformed Neoproterozoic greenschist facies phyllites and metavolcanics (Cayuta Formation) beneath the Cambrian non‐conformity. Magnetic modelling shows they are in the 5000 km<jats:sup>2</jats:sup> fault‐bounded Ithaca basin, proposed to be associated with Iapetan rifting. The volcanism and metamorphism appear linked to ca. 600–650 Ma thermal events related or unrelated to extension, but requiring uplift and denudation of 5–10 km of rock prior to deposition of the Cambrian Potsdam Group. The Ithaca basin is >350 km inboard of the Laurentian Iapetus margin, indicating a broad Neoproterozoic rift zone for at least the NY and PA portion of eastern Laurentia.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"34 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shiliang Liu, Ao Wang, Weiguo Li, Yusheng Zheng, Shanlin Wang
Current research on rock damage in mining floors primarily focuses on the seepage‐stress coupling effect, overlooking the fact that rock masses in coal measure strata are predominantly layered. To address this gap, cyclic loading and unloading triaxial tests were conducted. Additionally, theoretical analysis, mathematical statistics, and other methods were used to investigate the damage evolution law of layered rock masses in coal measures. This investigation was carried out under the coupled effects of a specific stress path, characterized by ‘stress concentration‐stress unloading‐stress recovery’, and a high confined water seepage field. The results show that the compression modulus increases with the increase in confining pressure and osmotic pressure, but its increasing trend gradually slows down. Within a certain range, increasing the confining pressure and osmotic pressure helps to close rock fractures and increase stiffness.
{"title":"Damage evolution in layered rock masses of a mining floor under the influence of fluid–structure coupling","authors":"Shiliang Liu, Ao Wang, Weiguo Li, Yusheng Zheng, Shanlin Wang","doi":"10.1111/ter.12737","DOIUrl":"https://doi.org/10.1111/ter.12737","url":null,"abstract":"Current research on rock damage in mining floors primarily focuses on the seepage‐stress coupling effect, overlooking the fact that rock masses in coal measure strata are predominantly layered. To address this gap, cyclic loading and unloading triaxial tests were conducted. Additionally, theoretical analysis, mathematical statistics, and other methods were used to investigate the damage evolution law of layered rock masses in coal measures. This investigation was carried out under the coupled effects of a specific stress path, characterized by ‘stress concentration‐stress unloading‐stress recovery’, and a high confined water seepage field. The results show that the compression modulus increases with the increase in confining pressure and osmotic pressure, but its increasing trend gradually slows down. Within a certain range, increasing the confining pressure and osmotic pressure helps to close rock fractures and increase stiffness.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"52 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohammad Mir, Babak Haghighi, Rohollah Taghavi Mendi, Iman Motie
Earthquakes occur when tectonic stresses develop deep within the Earth. In the earthquake zone, the rocks are igneous, including gabbro. Gabbro rocks produce electron–hole pairs under tectonic stresses. These holes flow in the volume of gabbro rock under tectonic pressures and cause changes in electric charge and as a result, produce variable electric and magnetic fields that lead to a signal of electromagnetic waves at the place of pressure. This electromagnetic signal is received on the surface of the Earth after passing through different layers of the Earth. In this work, by applying uniaxial hydraulic pressure on the gabbro rock, a new physical model similar to an earthquake is presented, which by receiving and monitoring electromagnetic signals, can help to investigate the tectonic changes in the Earth. By utilizing the electrical and optical parameters, the intensity of the electromagnetic signal of the earthquake created on the Earth's surface is calculated.
{"title":"Physical modelling of earthquake precursor by the electro‐optical parameters of gabbro rock under compressive stress","authors":"Mohammad Mir, Babak Haghighi, Rohollah Taghavi Mendi, Iman Motie","doi":"10.1111/ter.12740","DOIUrl":"https://doi.org/10.1111/ter.12740","url":null,"abstract":"Earthquakes occur when tectonic stresses develop deep within the Earth. In the earthquake zone, the rocks are igneous, including gabbro. Gabbro rocks produce electron–hole pairs under tectonic stresses. These holes flow in the volume of gabbro rock under tectonic pressures and cause changes in electric charge and as a result, produce variable electric and magnetic fields that lead to a signal of electromagnetic waves at the place of pressure. This electromagnetic signal is received on the surface of the Earth after passing through different layers of the Earth. In this work, by applying uniaxial hydraulic pressure on the gabbro rock, a new physical model similar to an earthquake is presented, which by receiving and monitoring electromagnetic signals, can help to investigate the tectonic changes in the Earth. By utilizing the electrical and optical parameters, the intensity of the electromagnetic signal of the earthquake created on the Earth's surface is calculated.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"253 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141739810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a finite‐differences 3D numerical model that simulates the gravity and thermal structure of the Corsica‐Sardinia Block (CSB), an apparently stable lithospheric domain characterized by cryptic tectonic activity. In the experiments, we change the density and heat production rate of the model crust within a range of geologically realistic values to fit the measured Bouguer gravity anomaly and surface heat flow pattern. The discrepancy between the observed geophysical structure and the outcomes of numerical modelling are discussed in relation to the composition of the CSB crust and finally recast in the geodynamic framework of the western Mediterranean region.
{"title":"Gravity field and geothermal structure of the Corsica‐Sardinia Block","authors":"F. Cocco, L. Casini, A. Funedda","doi":"10.1111/ter.12738","DOIUrl":"https://doi.org/10.1111/ter.12738","url":null,"abstract":"This paper presents a finite‐differences 3D numerical model that simulates the gravity and thermal structure of the Corsica‐Sardinia Block (CSB), an apparently stable lithospheric domain characterized by cryptic tectonic activity. In the experiments, we change the density and heat production rate of the model crust within a range of geologically realistic values to fit the measured Bouguer gravity anomaly and surface heat flow pattern. The discrepancy between the observed geophysical structure and the outcomes of numerical modelling are discussed in relation to the composition of the CSB crust and finally recast in the geodynamic framework of the western Mediterranean region.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"15 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141614010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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