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The elusive crustal resistive boundary beneath the Deccan Volcanic Province and the western Dharwar craton, India 印度德干火山省和达瓦尔克拉通西部下方难以捉摸的地壳电阻边界
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2023-03-23 DOI: 10.1344/geologicaacta2023.21.2
Pratap Akkapolu, Pradeep Naick Bukke, K. K, R. Paluri, Naganjaneyulu Kasturi
The electrical properties of the boundary beneath the Deccan Volcanic Province and the western Dharwar craton are imaged by using the magnetotelluric method. The magnetotelluric study was carried out along a 150km long WNW-ESE profile from Belgaum (in the Deccan Volcanic Province) to Haveri (in the western Dharwar craton).Data from 19 magnetotelluric stations spaced 10-15km apart were used. The dominant regional geo-electric strike direction obtained is N20ºE. Two-dimensional (2-D) inversion is done by using the non-linear conjugate gradient scheme for both apparent resistivity and phase. The 2-D resistivity model shows a high electrical resistivity character (>10,000ohm-m) in the western Dharwar craton. Two conductive anomalies are mapped in the crustal region. In the WNW side of the profile, a conductive feature (~200ohm-m) is imaged in the mid-lower crust and, in the central part of the profile another conductive feature is mapped in the lower crust. The conductive features robustness is tested using linear and non-linear sensitivity analyses. The conductor mapped in the WNW part of the profile is considered as a deep seated fault representing a boundary or a rift related feature beneath the Deccan Volcanic Province and the western Dharwar craton. A zone of enhanced conductivity (<50ohm-m) at an approximate depth of 10-30km may represent the presence of the rift in the region. This conducting feature on the Western side of the E-W trending Kaladgi Basin can be interpreted as the extension of the Kaladgi Basin further west. A well-correlated geological cross-section is also derived to interpret the resistive features mapped in this study. The electrical resistivity nature of the crust is compared with other regions of the world.
使用大地电磁法对德干火山省和达尔瓦尔克拉通西部下方边界的电学性质进行了成像。大地电磁研究是沿着从Belgaum(位于德干火山省)到Haveri(位于达尔瓦尔克拉通西部)的150公里长的WNW-ESE剖面进行的。使用了间隔10-15km的19个大地电磁站的数据。获得的主导区域地电走向为N20ºE。采用视电阻率和相位的非线性共轭梯度格式进行二维反演。二维电阻率模型显示达尔瓦尔克拉通西部具有高电阻率特征(>10000ohm-m)。在地壳区域绘制了两个导电异常。在剖面的WNW侧,在中下地壳中成像了一个导电特征(~200ohm-m),在剖面的中心部分,在下地壳中映射了另一个导电特性。使用线性和非线性灵敏度分析来测试导电特征的稳健性。剖面WNW部分绘制的导体被认为是代表德干火山省和达瓦尔克拉通西部下方边界或裂谷相关特征的深层断层。在大约10-30km的深度处,导电性增强的区域(<50ohm-m)可能代表该区域存在裂谷。东西走向卡拉德吉盆地西侧的这种传导特征可以解释为卡拉德吉流域进一步向西的延伸。还推导了一个相关良好的地质剖面,以解释本研究中绘制的电阻特征。地壳的电阻率性质与世界其他地区进行了比较。
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引用次数: 2
Tectonic geomorphology of Bozdoğan and Karacasu grabens, western Anatolia 安纳托利亚西部Bozdoğan和Karacasu地堑的构造地貌
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2023-02-27 DOI: 10.1344/geologicaacta2023.21.1
E. Özsayın, K. Dirik, F. Ocakoğlu, Sanem Açıkalın Cartigny, Azad sağlam selcuk
Western Anatolia is one of the most rapidly extending and seismically active regions in the world. The circa N-S extension since the Early Miocene caused the formation of E-W trending major grabens and intervening horsts, having earthquake potentials with magnitude ≥5. The E-W oriented Büyük Menderes graben cross-cuts the broadly N-S oriented Bozdoğan and Karacasu grabens, of which the boundary faults of the latter are the source of seismic activity. Geomorphic indices, including drainage basin asymmetry, mountain front sinuosity, valley-floor width to valley height ratio, stream length-gradient index and normalized channel steepness index, were used to evaluate the boundary fault segments of the Bozdoğan and Karacasu grabens. The results indicate that both grabens are tectonically active and therefore regions of earthquake potential, consistent with the epicenters of earthquakes. Thus, it can be inferred that fault segments of second-order grabens, which are crosscut by the boundary faults of seismically active main depressions, are apparently reactivated by ongoing tectonism and may represent seismic activity. This suggestion applies also for similar basins located in the western Anatolia.
安纳托利亚西部是世界上延伸最快、地震最活跃的地区之一。早中新世以来的南北向伸展导致了东西走向的主要地堑和中间地垒的形成,具有≥5级的地震潜力。东西向的Büyük-Menderes地堑横切了大致南北向的Bozdoğan和Karacasu地堑,后者的边界断层是地震活动的来源。利用流域不对称性、山前弯度、谷底宽谷高比、河流长度梯度指数和归一化河道陡度指数等地貌指标对Bozdoğan和Karacasu地堑的边界断裂段进行了评价。结果表明,这两个地堑都是构造活跃的,因此具有地震潜力的区域,与震中一致。因此,可以推断,被地震活跃的主凹陷的边界断层横切的二阶地堑的断层段显然被正在进行的构造作用重新激活,并且可能代表地震活动。这一建议也适用于位于安纳托利亚西部的类似盆地。
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引用次数: 0
Detrital zircon similarities and dissimilarities between the Iberian Pyrite Belt, Ossa-Morena Zone and Meguma 伊比利亚黄铁矿带、Ossa-Morena带和Meguma的碎屑锆石异同
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-12-13 DOI: 10.1344/geologicaacta2022.20.16
João Lains Amaral, A. R. Solá, T. M. Bento dos Santos, M. Chichorro
Despite the so-called exotic nature of the South Portuguese Zone relatively to the other major domains of the Iberian Massif of peri-Gondwanan affinity, Devonian detrital rocks of the oldest strata in the Iberian Pyrite Belt have a remarkable resemblance with the Ossa-Morena Zone’s Neoproterozoic-Cambrian rocks and the West Meguma’s Cambrian-Ordovician rocks, presenting the so-called “West African signature”.
尽管相对于冈瓦纳大陆周围的伊比利亚地块的其他主要区域,南葡萄牙带具有所谓的奇异性质,但伊比利亚黄铁矿带最古老地层的泥盆纪碎屑岩与奥萨-莫雷纳带的新元古代寒武纪岩石和西梅古马的寒武纪-奥陶纪岩石有着显著的相似性,提出所谓的“西非签名”。
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引用次数: 3
Cadomian metabasites of the Eastern Pyrenees revisited 东比利牛斯山脉卡多米亚变质岩重访
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-11-25 DOI: 10.1344/geologicaacta2022.20.17
N. Pujol-Solà, J. Casas, J. Proenza, I. Blanco-Quintero, E. Druguet, M. Liesa, M. J. Román-Alpiste, J. Álvaro
This study presents a new geochemical, petrological, and geochronological U–Pb dataset from Ediacaran metabasites of the Canigó and Cap de Creus massifs, Eastern Pyrenees. The rocks are composed of calcic amphibole + plagioclase + chlorite + epidote ± quartz plus titanite + apatite + ilmenite ± biotite ± rutile as accessory phases and show relict igneous textures. Peak pressure-temperature determinations share common conditions, ranging 452–482ºC and 5.2–7.7kbar. These intermediate P-T conditions suggest Barrovian-type metamorphism, most likely related to a collisional setting. The metabasites correspond to evolved basaltic rocks (Mg#<0.55) with moderate TiO2 content (up to 2.08wt.%) and relatively low Cr (43–416ppm). The rocks are moderately enriched in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) (average (La/Lu)n of 2.7) and the N-MORB normalized multi-element patterns show negative slopes, with prominent negative Nb anomalies ((Nb/La)NMORB=0.33–0.78). These variations are akin to island arc tholeiites generated in back-arc basins and to other metabasites described in the Eastern Pyrenees with a putative Ediacaran age, and they differ from the Ordovician tholeiitic metabasites from the Canigó massif, which derived from a contaminated E-MORB source. The positive ƐNd(T) values (0.82–3.05) of the studied metabasites preclude a notable contribution from an older continental crust. U-Pb dating (LA-ICP-MS) of one chlorite-rich schist sample in contact with the metabasites from the Canigó massif yielded a main peak at ca. 632Ma. We argue that the Cadomian metabasites from the Pyrenees formed during back-arc extension in the continental margin of Gondwana and were later affected by (probably early Variscan) medium-P metamorphism before the HT-LP metamorphism classically described in the Pyrenees.
本文介绍了东比利牛斯山脉Canigó和Cap de Creus地块埃迪卡拉纪变质岩中新的地球化学、岩石学和年代学U-Pb数据集。岩石由钙质角闪洞+斜长石+绿泥石+绿帘石+石英+钛矿+磷灰石+钛铁矿+黑云母±金红石为副相组成,呈残余火成岩结构。峰值压力-温度测定具有共同的条件,范围为452-482ºC和5.2-7.7kbar。这些中间的P-T条件表明巴罗维亚型变质作用,很可能与碰撞环境有关。变质岩为演化玄武岩(Mg#<0.55), TiO2含量适中(2.08wt.%), Cr含量较低(43 ~ 416ppm)。岩石轻稀土元素(LREE)相对重稀土元素(HREE)中等富集(平均(La/Lu)n为2.7),n - morb归一化多元素模式呈负斜率,负Nb异常显著((Nb/La)NMORB=0.33 ~ 0.78)。这些变化类似于弧后盆地中的岛弧拉斑岩和东比利牛斯山脉中描述的其他假定埃迪卡拉纪时代的变质岩,而不同于Canigó地块中来自受污染的E-MORB源的奥陶系拉斑岩变质岩。研究的变质岩的正ƐNd(T)值(0.82-3.05)排除了较老大陆地壳的显著贡献。对一个与Canigó地块中变质岩接触的富绿泥石片岩样品进行了LA-ICP-MS定年,得到了一个约632Ma的主峰。我们认为,来自比利牛斯山脉的卡多米尼亚变质岩形成于冈瓦纳大陆边缘弧后伸展时期,并在比利牛斯山脉经典描述的高温-低温变质作用之前受到(可能是早Variscan)中磷变质作用的影响。
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引用次数: 0
Cadomian/Pan-African consolidation of the Iberian Massif assessed by its detrital and inherited zircon populations: is the ~610Ma age peak a persistent Cadomian magmatic inheritance or the key to unravel its Pan-African basement? 通过碎屑和继承的锆石种群评估伊比利亚地块的卡多米亚/泛非固结:~610Ma时代的峰值是持续的卡多米亚岩浆继承,还是解开其泛非基底的关键?
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-11-23 DOI: 10.1344/geologicaacta2022.20.15
M. Chichorro, A. R. Solá, T. M. Bento dos Santos, João Lains Amaral, Lourenço Crispim
This work assessed the age distribution of Cadomian/Pan-African orogenic events (550-590 and 605-790Ma, respectively) in several zones of Iberian Massif by means of detrital and inherited zircon analysis compilation.
通过碎屑和继承锆石分析汇编,评价了伊比利亚地块若干带卡多米亚/泛非造山事件的年龄分布(分别为550 ~ 590 ma和605 ~ 790ma)。
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引用次数: 2
Shifts in the Ediacaran to Lower Ordovician sedimentary zircon provenances of Northwest Gondwana: the Pyrenean files 冈瓦纳大陆西北部埃迪卡拉纪-下奥陶世沉积锆石来源的变化:比利牛斯纪文件
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-10-21 DOI: 10.1344/geologicaacta2022.20.14
M. Padel, S. Clausen, M. Poujol, Jose Javier Alvaro Blasco
Detrital zircon grains from Cambrian–Lower Ordovician sandstones and quartzites sampled in the Pyrenees were dated by LA-ICPMS in order to assess their provenance sources. Resulting age distributions are compared to other available datasets from neighbouring margins, such as Morocco, the Iberian Peninsula, southern France and Sardinia. Kolmogorov-Smirnov (K-S) test and Crystallization Age-Depositional Age (CA-DA) diagrams were used to compare zircon populations estimating their possible correlation with the arc/rift/drift geodynamic evolution of the northwestern Gondwana margin. During Terreneuvian times, zircon populations allowed the distinction of i) a southwesternmost edge (Anti-Atlas-Ossa-Morena Rift) mostly influenced by Panafrican and Anti-Atlasian sources (ca. 0.63–0.54), ii) a northeasternmost edge (Sardinia) recording the influence of the Saharan Metacraton and the Arabian Nubian Shield, with an distinct Stenian–Tonian shift (ca. 1.25–0.85Ga) and iii) an intermediate palaeogeographic transect, where lies the Central-Iberian, West Asturian-Leonese and Cantabrian Zones, the Montagne Noire and the Pyrenees sharing similar populations and a chronologically progressive influence from Anti-Atlasian/Panafrican to Saharan Metacraton/Arabian Nubian Shield sources. This gradual modification in zircon percentage populations supports similar trends based on climatically sensitive indicators, biogeographic patterns of Cambrian Epoch 2 archaeocyathan and microfossil assemblages, and laterally correlatable episodes of carbonate production, all of them pointing to a Cambrian setting for the Pyrenean Basin between the Montagne Noire (Occitan Domain) and the Sardinian margins of NW Gondwana. The Terreneuvian zircon patterns recorded in the Pyrenees gradually evolved from Cambrian Epoch 2 to Early Ordovician times, reflecting the geodynamic evolution from Panafrican and Cadomian arc-related to rift-dominant conditions. During Furongian and Ordovician times, the relative percentage of zircon populations led to a more spread age curve, characteristic of extensional settings and pointing to rift (passive margin) conditions.
通过LA-ICPMS对比利牛斯山寒武系-下奥陶统砂岩和石英岩中的碎屑锆石颗粒进行了年代测定,以评估其物源。将由此产生的年龄分布与邻近边缘的其他可用数据集进行比较,如摩洛哥、伊比利亚半岛、法国南部和撒丁岛。Kolmogorov-Smirnov(K-S)检验和结晶年龄-沉积年龄(CA-DA)图用于比较锆石种群,估计它们与冈瓦纳大陆西北边缘弧/裂谷/漂移地球动力学演化的可能相关性。在Terreneuvian时代,锆石种群允许区分i)最西南边缘(Anti-Atlas Ossa Morena裂谷),主要受泛非洲和反大西洋来源的影响(约0.63–0.54),ii)记录撒哈拉元克拉通和阿拉伯-努比亚地盾影响的最东北边缘(撒丁岛),具有明显的斯堪的纳维亚-托尼亚期偏移(约1.25–0.85Ga)和iii)一个中间古地理样带,其中位于中伊比利亚、西阿斯图里亚莱昂和坎塔布里亚带、黑山和比利牛斯山,具有相似的人口和从反大西洋/泛非大陆到撒哈拉元克拉通/阿拉伯-努比亚地盾来源的时间上的渐进影响。锆石百分比种群的这种逐渐变化支持了基于气候敏感指标、寒武纪2古脊椎动物和微体化石组合的生物地理模式以及碳酸盐生产的横向相关事件的类似趋势,所有这些都指向了比利牛斯盆地的寒武纪背景,该盆地位于诺伊山(欧西坦地区)和冈瓦纳大陆西北部的撒丁岛边缘之间。比利牛斯山脉记录的Terreneuvian锆石模式从寒武纪2世到早奥陶世逐渐演化,反映了与裂谷主导条件有关的Panafrican弧和Cadomian弧的地球动力学演化。在芙蓉期和奥陶纪,锆石种群的相对百分比导致了更为广泛的年龄曲线,具有伸展环境的特征,并指向裂谷(被动边缘)条件。
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引用次数: 0
The chronology and rotational kinematics in the South-Eastern Jaca Basin (Southern Pyrenees): Las Bellostas section Jaca盆地东南部(比利牛斯山脉南部)的年表和旋转运动学:Las Bellostas剖面
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-09-23 DOI: 10.1344/geologicaacta2022.20.12
Emilio L. Pueyo, A. Rodríguez-Pintó, J. Serra-Kiel, A. Barnolas
Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm. can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm. (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the W-E and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The important difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from ≈70º clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Picodel Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational activity seems to follow a linear and continuous pattern (velocity 9-11º/Ma, R: 0.83-0.96) in contrast to closer structures that show two distinct rotational velocities (i.e. Boltaña). These new data still let open the debate on the rotational kinematics along the South Pyrenean basal thrust.
尽管在南比利牛斯盆地进行了大量的磁地层学研究,旨在校准盆地年代地层学和生物地层学规模,但从这个角度来看,东南部的贾卡盆地仍未被勘探,其与安萨盆地的关系也未被完全了解。在这项工作中,我们提供了950米厚的Las Bellostas剖面的新磁地层学数据,该剖面位于Balzes背斜的北部铰链。周围环境中的大量原始数据支持的经过充分验证的原始信号(正折叠测试和两个伪反平行极性)使我们能够构建八个磁带(从R1到N4)的可靠局部极性序列。此外,该剖面下部(海洋环境)的七个新的生物地层样本(Nummulites和Assilina)使该剖面能够缩小到地磁极性时间尺度(GPTS),并提出了雅卡盆地东南部的精细年龄模型。该剖面始于Cuisian时代的Boltaña组(浅海底带,SBZ11),随后是从C22n到C20n的沉积间隙,如生物地层学数据所示(SBZ11位于裂孔下方,SBZ16位于顶部)。三角洲Sobrarbe组可以追踪到C19n(晚卢泰期)。从这一点(200米)到剖面顶部(950米),至少可以在相当于西部到前三角洲Arguis泥灰岩组的molassic Campodarbe组(C18n.2n-C18n.1r和C18n.1n)(Bartonian)内识别整个C18n时间段,巴尔茨背斜铰链处的构造位置增强了这一点。这些新的年代地层约束有助于完善Jaca盆地东部和Ainsa盆地的W-E和N-S地层关系。本节还使我们能够准确地完善外部Sierras东部旋转活动的运动学。沿剖面的磁偏角和Balzes背斜的邻近古地磁数据的重要差异(从地层剖面底部的顺时针≈70º到顶部的不显著),以及东部Jaca盆地的新年龄模型,有助于表征Balzes逆冲片的旋转活动。旋转发生在C20r(中卢泰阶;45Ma)和C17(下普里亚博阶37-38Ma)之间,与附近的构造(Boltaña、Picodel-Aguila背斜)一致,但与西部构造(圣多明各背斜)明显具有历时性。此外,旋转活动似乎遵循线性和连续的模式(速度9-11º/Ma,R:0.83-0.96),而较近的结构显示出两种不同的旋转速度(即Boltaña)。这些新数据仍然开启了关于南比利牛斯基底逆冲断层旋转运动学的争论。
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引用次数: 1
Geochemistry of Khandadharpahar-Thakuranipahar metabasites from the western Singhbhum Craton, eastern India: implications for subduction-zone tectonics and mantle-wedge metasomatism 印度东部Singhbhum克拉通西部Khandadharpahar Thakuranipahar变质玄武岩的地球化学:对俯冲带构造和地幔楔交代作用的影响
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-09-16 DOI: 10.1344/geologicaacta2022.20.11
R. Rajani
The identification of new rock types in the volcano-sedimentary sequences of the Singhbhum Craton has attractedmuch attention in recent years. The present study deals on newly identified Nb-Enriched Basalts (NEB) from theKhandadharpahar-Kadakala-Thakuranipahar (KKT) section, western Singhbhum Craton, which is comparablein composition to basalts-basaltic andesites and calk-alkaline in character. These metabasites have a porphyritictexture with phenocrysts of pyroxene and plagioclase, as well as a groundmass that has metamorphosed to thegreenschist facies. High Nb contents (7.5-22.8ppm) combined with high (Nb/Th)PM (0.28-0.59), (Nb/La)PM (0.40-0.69) and Nb/U (11.7-34.4) ratios, compared to arc basalts ((Nb/Th)PM= 0.10-1.19; (Nb/La)PMn 0.17-0.99, Nb/U<10), characterized them as NEB. Negative Nb, Zr, Hf and Ti anomalies, and Nb/Th vs La/Nb and Th/Nb vs. La/Sm relationships, collectively indicate typical arc volcanics. The available geochemical parameters suggest a genesisof KKT metabasites through i) slab melt migration from the downgoing oceanic crust, ii) low-degree melting ofthe garnet-bearing peridotite in the mantle wedge metasomatized by the slab melts, iii) slab melt - peridotiteinteraction triggering increasing Nb concentrations and iv) NEB generation in an arc-related environment. Thediscovery of KKT NEB sheds new information on Paleoproterozoic subduction-zone processes and crustal growthin the Singhbhum craton.
近年来,在Singhbhum火山口火山沉积序列中识别新的岩石类型引起了人们的广泛关注。本研究对Singhbhum克拉通西部Khandadharpahar Kadakala Thakuranipahar(KKT)剖面新发现的富铌玄武岩(NEB)进行了研究,其成分与玄武岩、玄武岩、安山岩和钙碱性玄武岩相当。这些变质玄武岩具有含辉石和斜长石斑晶的斑状结构,以及变质为绿片岩相的岩体。高Nb含量(7.5-22.8ppm)与高(Nb/Th)PM(0.28-0.59)、(Nb/La)PM(0.40-0.69)和Nb/U(11.7-34.4)比率相结合,与弧玄武岩((Nb/Th)PM=0.10-1.19)相比;(Nb/La)PMn 0.17-0.99,Nb/U<10),将其表征为NEB。Nb、Zr、Hf和Ti负异常,以及Nb/Th与La/Nb和Th/Nb与La/Sm的关系,共同表明了典型的弧火山岩。可用的地球化学参数表明,KKT变基岩的成因是通过i)来自下行海洋地壳的板状熔体迁移,ii)由板状熔体交代的地幔楔中含石榴石的橄榄岩的低温熔融,iii)板状熔体-橄榄岩的相互作用触发Nb浓度的增加,以及iv)在与电弧相关的环境中产生NEB。KKT NEB的发现为Singhbhum克拉通古元古代俯冲带过程和地壳生长提供了新的信息。
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引用次数: 0
Organic-walled tentaculids of Late Devonian (Frasnian) deposits of the Appalachian and Michigan Basins, Laurussia (NY, MI, OH) Laurussia (NY, MI, OH)阿巴拉契亚和密歇根盆地晚泥盆世(frasian)沉积物的有机壁触手
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-09-15 DOI: 10.1344/geologicaacta2022.20.10
K. C. Meehan, J. Boyle
This is the first report of organic-walled tentaculid remains from Givetian through Frasnian age deposits of the Michigan and Appalachian Basins in western Laurussia. This adds to the geographic scope of similar finds that have been described from the Frasnian through the Famennian in eastern Laurussia. However, those previous specimens were retrieved through palynological preparations and more closely resemble sheath structures rather than the full forms found herein, which were retrieved through complete maceration with ammonium surfactants.
这是第一份关于洛俄罗斯西部密歇根盆地和阿巴拉契亚盆地从吉维期到Frasnian时代沉积物的有机壁帐篷遗迹的报告。这增加了类似发现的地理范围,这些发现已被描述为从劳俄罗斯东部的Franian到Famennian。然而,这些先前的标本是通过孢粉学制备获得的,更接近于鞘结构,而不是本文中发现的完整形式,后者是通过用铵表面活性剂完全浸渍获得的。
{"title":"Organic-walled tentaculids of Late Devonian (Frasnian) deposits of the Appalachian and Michigan Basins, Laurussia (NY, MI, OH)","authors":"K. C. Meehan, J. Boyle","doi":"10.1344/geologicaacta2022.20.10","DOIUrl":"https://doi.org/10.1344/geologicaacta2022.20.10","url":null,"abstract":"This is the first report of organic-walled tentaculid remains from Givetian through Frasnian age deposits of the Michigan and Appalachian Basins in western Laurussia. This adds to the geographic scope of similar finds that have been described from the Frasnian through the Famennian in eastern Laurussia. However, those previous specimens were retrieved through palynological preparations and more closely resemble sheath structures rather than the full forms found herein, which were retrieved through complete maceration with ammonium surfactants.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47046909","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}
引用次数: 0
Characterization of the shallow subsurface structure across the Carrascoy Fault System (SE Iberian Peninsula) using P-wave tomography and Multichannel Analysis of Surface Waves 使用P波层析成像和表面波多通道分析表征Carrascoy断层系统(伊比利亚半岛东南部)的浅层地下结构
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-09-08 DOI: 10.1344/geologicaacta2022.20.9
H. Handoyo, I. DeFelipe, R. Martín-Banda, J. García-Mayordomo, D. Martí, J. J. Martínez-Díaz, J. Insua-Arévalo, Teresa Teixidó, J. Alcalde, I. Palomeras, R. Carbonell
The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world.
伊比利亚半岛东南部的地震活动平行于海岸分布在一个发育良好的走滑断裂系统中,该系统被称为东Betic剪切带(EBSZ)。本工作的重点是EBSZ Carrascoy断层系统内Algezares Casas Nuevas断层浅层地下结构的特征。Carrascoy断层以南与Guadalentín凹陷接壤,这是一个人口稠密、农业活动广泛的地区。因此,该断层系统代表了一种具有重大社会和经济意义的地震灾害。基于地震反射数据的P波层析成像和多通道表面波分析,我们建立了两个速度-深度模型。由此产生的速度模型使我们能够解释最初~250m的深度,并揭示了:i)临界区的厚度;ii)Algezares Casas Nuevas断层的几何形状;iii)Messinian/Tortonian接触的深度,以及iv)Guadalentín凹陷下盲冲断层和破坏带的存在。我们的研究结果还帮助我们估计了自209.1±6.2ka以来Algezares Casas Nuevas断层的表观垂直滑动速率为0.66±0.06m/ky,并可用于改进世界各地构造活动区的地震危险性评估。
{"title":"Characterization of the shallow subsurface structure across the Carrascoy Fault System (SE Iberian Peninsula) using P-wave tomography and Multichannel Analysis of Surface Waves","authors":"H. Handoyo, I. DeFelipe, R. Martín-Banda, J. García-Mayordomo, D. Martí, J. J. Martínez-Díaz, J. Insua-Arévalo, Teresa Teixidó, J. Alcalde, I. Palomeras, R. Carbonell","doi":"10.1344/geologicaacta2022.20.9","DOIUrl":"https://doi.org/10.1344/geologicaacta2022.20.9","url":null,"abstract":"The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44417968","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}
引用次数: 2
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Geologica Acta
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