Journal of Geodynamics最新文献

{"title":"A black hole particle swarm optimization method for the source parameters inversion: application to the 2015 Calbuco eruption, Chile","authors":"Leyang Wang ,&nbsp;Xibo Jin ,&nbsp;Wenbin Xu ,&nbsp;Guangyu Xu","doi":"10.1016/j.jog.2021.101849","DOIUrl":"10.1016/j.jog.2021.101849","url":null,"abstract":"<div><p><span>The traditional genetic algorithm and simulated annealing methods have been widely used in geophysical modeling. However, these nonlinear inversion methods require a lot of calculations, many control parameters and are unstable. In this paper, a particle swarm optimization algorithm combined with black hole strategy (BH-PSO) is proposed to solve these problems. The comprehensive experiments show that the BH-PSO method consumes less time than the simulated annealing (SA) method and has a higher accuracy than the genetic algorithm (GA). It is more applicable to the inversion of parameters of volcanic magma chamber, and easier to be generalized to other kinematic source parameters inversion. Based on BH-PSO method, Sentinel-1 data, composite dislocation model (CDM), Yang model and Mogi model, the magma chamber parameters of Calbuco eruption in 2015 were retrieved. The results show that the RMSE of CDM model is 1.1 cm, which can better fit the surface deformation than the Mogi model and Yang model. The final results show that the magma chamber is located about 0.8 km northeast of the crater, about 9 km below the surface, and the total volume of the erupted volcanic material obtained with the CDM Model is of 0.209 km</span>³, without considering dense rock equivalent.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101849","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43522358","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}

{"title":"Stress changes associated with the significant first subevent of the 2008 Wenchuan earthquake and implications for the rupture behavior transition","authors":"Yujiang Li ,&nbsp;Lianwang Chen ,&nbsp;Hong Li ,&nbsp;Yuanzhong Lu","doi":"10.1016/j.jog.2021.101859","DOIUrl":"10.1016/j.jog.2021.101859","url":null,"abstract":"<div><p>The rupture process of the Wenchuan earthquake demonstrated a transition from thrust-dominated slip to northeastward strike-slip motion along the Longmen Shan Fault Zone. The initial stress has been reported as playing a critical role in this process; however, the stress changes, especially those caused by the significant first subevent of the Wenchuan earthquake are not well understood. Here, we employ a three-dimensional finite element model of the Sichuan-Yunnan region to analyze the stress change caused by the significant first subevent and explore the possible influence on the following ruptures. The results indicate that the auxiliary maximum principal compressive stress (S_H) associated with the significant first subevent was horizontal and that the auxiliary stress regime was S_H&gt;S_h&gt;S_v, supporting the ongoing regional thrust motion near the southwestern segment of the rupture plane. However, in the northeastern segment, the auxiliary stress regime transitioned to S_H&gt;S_v&gt;S_h, demonstrating that the stress changes promoted the transition of the rupture behavior from predominantly thrust motion in the southwest to right-lateral strike-slip motion in the northeastern segment, which was also supported by the dominant shear stress change and the subtle normal stress change along the fault plane in the northeastern segment. In addition, our modeled results also indicate that the orientation of the maximum principal compressive stress changed from SEE to northeastward NEE along the strike of Longmen Shan Fault Zone. This anticlockwise rotation hastened the rupture behavior transition, suggesting that both the initial stress and the stress changes associated with the first subevent jointly controlled the following northeastward rupture of the Mw7.9 Wenchuan earthquake.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101859","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42232309","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}

{"title":"A simple picture of mantle wedge flow patterns and temperature variation","authors":"Ikuko Wada","doi":"10.1016/j.jog.2021.101848","DOIUrl":"10.1016/j.jog.2021.101848","url":null,"abstract":"<div><p>The solid-state mantle flow is an important factor that controls the mass and heat transfer in the solid Earth. This study aims to provide a simple picture of three-dimensional (3-D) mantle flow patterns in the sub-arc region of subduction zones<span> based on the results of 3-D steady-state numerical models with varying subduction parameters. Here, the mantle wedge flow pattern is evaluated based on the azimuthal directions of the mantle inflow from the back-arc and the down-dip outflow. The outflow direction generally parallels the subduction direction, but the inflow direction relative to the outflow direction depends on the local subduction obliquity – the angle between the subduction direction and the strike-normal axis of the subducting slab. A change in the strike of the slab leads to a change in the obliquity and thus the inflow direction. Such change is common along curved margins as the strike of the slab tends to follow that of the margin, or vice versa. Along convex-arc-ward margins, the mantle inflow is deflected towards the region of lowest obliquity but with reduced vigor due to lower dynamic pressure gradients that partly drive the flow, resulting in a cooler mantle wedge. Along concave-arc-ward margins, the mantle inflow is deflected away from the region of lowest obliquity but with increased vigor, resulting in a hotter mantle wedge. These effects increase with decreasing radius of curvature. Along-margin change in the dip of the subducting slab also affects the inflow direction through its impact on the strike of the slab, but its effect is relatively small. We express the azimuthal inner angle between the inflow and outflow directions as a function of obliquity and apply the function to predict sub-arc mantle inflow directions in the circum-Pacific and neighboring regions. Within and among these margins, the inner angle varies over its full range of 0–180°. Most of the margins that are 1000s of kilometers in length are either straight or curved concave-arc-ward with large radii of curvature, for which small or gradual along-margin changes in the mantle inflow direction and the mantle wedge temperature are predicted. A large drop in the mantle wedge temperature by up to a couple of hundred degrees is predicted at short convex-arc-ward segments, such as at the Kuril-Japan and Bonin-Mariana junctions. The fringes of flat slab segments are curved with small radii of curvature, likely resulting in sharp lateral changes in the inflow direction and the mantle wedge temperature.</span></p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101848","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44272939","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}

{"title":"Effects of multi-seamount subduction on accretionary wedge deformation: Insights from analogue modelling","authors":"Chunyang Wang ,&nbsp;Weiwei Ding ,&nbsp;Wouter P. Schellart ,&nbsp;Jiabiao Li ,&nbsp;Chongzhi Dong ,&nbsp;Yinxia Fang ,&nbsp;Tianyao Hao ,&nbsp;Zhengyi Tong","doi":"10.1016/j.jog.2021.101842","DOIUrl":"10.1016/j.jog.2021.101842","url":null,"abstract":"<div><p>Deformation patterns caused by the subduction of a single seamount or aseismic ridge have been well studied in analogue and numerical models. However, the effects of sequential multi-seamount subduction on accretionary wedge deformation have rarely been investigated in details. We performed a series of analogue modelling experiments of sequential subduction involving two seamounts of variable shape, spacing and rheological properties of strata to better understand the deformation mechanisms of an accretionary wedge with multi-seamount subduction. The results demonstrate that a seamount significantly hinders the seaward propagation of the accretionary wedge and facilitates lateral propagation. Two structural quiet zones form at the leading and trailing edges of the subducted seamount in the early stage of collision. As the seamount deeply penetrates into the wedge, the structural quiet zone in the leading edge is remoulded by a duplex structure, which may help the upward transport of deep subducted sediments back into the shallow area. Comparatively, the structural quiet zone in the trailing edge remains undeformed because it is situated in the stress shadow of the seamount. Deformation of the strata between two subducting seamounts may occur by thrusts laterally propagating into the seamount gap, which is facilitated by the décollement layer. The modelling results provide insights into the complex deformation mechanisms related to seamounts collision observed in the accretionary wedge offshore from the Costa Rica margin.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101842","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46097490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The magmatic evolution of the Neotethyan rift: Geochronologic, isotopic, and geochemical evidence from A-type felsic magmatism, NW Iran","authors":"Ghasem Nabatian ,&nbsp;Xian-Hua Li ,&nbsp;Maryam Honarmand ,&nbsp;Rasoul Esmaeili","doi":"10.1016/j.jog.2021.101829","DOIUrl":"10.1016/j.jog.2021.101829","url":null,"abstract":"<div><p>The Ajabshir rhyolitic magma in the northwest (NW) of Iran is an Early Carboniferous (332.5 ± 2.2 Ma), approximately 50m-thick succession, consisting of quartz, alkali feldspar, and biotite phenocryst with a porphyritic texture. This magmatic unit occurred as lava flows and sills intruded into the early Cambrian Lalun Formation. The Ajabshir magma has a calc-alkaline to high potassic calc-alkaline affinity and peraluminous character and displays many of the classic features of A-type magmas, enrichment in HFSEs (Zr + Nb + Ce + Y = 664–808 ppm), Nb (120−218 ppm), Zr (298−362 ppm), Ga (34−38 ppm), Ce (100−132 ppm), high Ga/Al and FeO*/(FeO*+MgO), zircon saturation temperature, and low contents of CaO, Sr, and Eu. The LREE enrichment, non-depletion in HREE, and negative Eu anomalies in the chondrite normalized diagrams exhibit similarities to the REE patterns of “hot-dry-reduced rhyolites”, further pointing to the evolution of Ajabshir rhyolitic magma from an OIB-type parental melt via a fractional crystallization process. The zircon yield εHf_(t) values of +1.4 to +5.5 correspond to two-stage zircon Hf model ages of 0.9–1.2 Ga. The δ¹⁸O values of the zircon range from +5.8‰ to +7.37‰. The zircon isotopic data together with whole-rock geochemical signatures suggest that the mantle-derived magma was modified by crustal components during its ascent to the surface. The Ajabshir A-type rhyolitic magma provides more evidence for an extensional tectonic setting during the Early Carboniferous in NW Iran, contemporaneous with the rifting of the Neotethyan Ocean at the northern margin of Gondwana.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101829","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48465356","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}

{"title":"Crustal deformation in Volcanic covered area as inferred from magnetotelluric studies: An example from India","authors":"K.S. Ajithabh ,&nbsp;Prasanta K. Patro","doi":"10.1016/j.jog.2021.101840","DOIUrl":"10.1016/j.jog.2021.101840","url":null,"abstract":"<div><p>We present 2D and 3D inversion results using data from 22 broadband magnetotelluric sites in Saurashtra peninsula, India. The configuration of the Deccan basalt and sub-basaltic Mesozoic sediments is imaged using 2D inversion by implementing the appropriate regularization operator and the model is analogous to the 3D model. The regional fault systems are imaged within the highly resistive granitic crustal segment. The trend of these deep extending faults, seismicity and dyke patterns have similarities with those in Narmada – Son Lineament (NSL) region and it hints the possible extension of NSL to Saurashtra, in which both regions are now separated by Gulf of Cambay. Imaged fault systems have played a vital role in the magmatic transport to the surface during the Deccan volcanic event, and it has resulted in the modification of the crustal segments.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101840","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48638569","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}

{"title":"Investigation of ionospheric and atmospheric anomalies associated with three Mw >6.5 EQs in New Zealand","authors":"Muhammad Arqim Adil ,&nbsp;Ayesha Abbas ,&nbsp;Muhsan Ehsan ,&nbsp;Munawar Shah ,&nbsp;Najam Abbas Naqvi ,&nbsp;Amjad Alie","doi":"10.1016/j.jog.2021.101841","DOIUrl":"https://doi.org/10.1016/j.jog.2021.101841","url":null,"abstract":"<div><p><span><span>The dual-frequency Global Positioning System (GPS) provides insights to detect the </span>ionospheric<span> perturbations with Total Electron Content (TEC) variations induced by the Earthquakes (EQs) or geomagnetic storm effects. In this paper, we investigate abnormal ionospheric signatures before three large magnitudes (M</span></span><em>_w</em><span><span> &gt; 6.5) and shallow hypocentral depth &lt; 20 km EQs in New Zealand from daily GPS TEC time series retrieved from International GNSS Services (IGS) stations around the </span>epicenter. Furthermore, geomagnetic activities are completely quiet within 5–15 days before two EQs (M</span><em>_w</em> 7.8 and M<em>_w</em> 6.8) and one EQ of M<em>_w</em> 6.6 occurred in active storm days (hereafter, geomagnetic storm-EQ event). The anomalies are detected on the basis of a statistical analysis of running median and Inter Quartile Range (IQR) to signify the abnormality in daily TEC time series for 30 days before and 10 days after each EQ. We observe less intensity TEC anomalies of &lt; 2 TECU during UT = 15–24 h (for New Zealand, UT = LT + 13) within 5–15 days before two EQs of M<em>_w</em> 7.8 and M<em>_w</em> 6.8. Whereas, a chain of positive and negative anomalies is generated by geomagnetic storm-EQ event (M<em>_w</em> 6.6) far beyond 5–15 days before and after the main shock due to active storm conditions (Kp&gt; 3; Dst &lt; −50 nT). Furthermore, geomagnetic storm anomalies are dominant on M<em>_w</em> 6.6 EQ day to active storm conditions. To validate the ionospheric anomalies as possible seismic precursors, the atmospheric anomalies in relative humidity and OLR (outgoing longwave radiations) are also examined to exhibit the evolution of ionospheric anomalies from the lithosphere to ionosphere via the atmosphere. Moreover, EQ induced regular and collocated atmospheric anomalies over the epicenters of M<em>_w</em> 7.8 and M<em>_w</em> 6.8 and irregular atmospheric anomalies exist over the seismogenic zone of M<em>_w</em> 6.6 due to geomagnetic storm-EQ nature. The observed EQ anomalies will aid in the improvement of lithosphere atmosphere ionosphere coupling hypothesis during the seismic preparation phase over the epicenter of future EQ.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101841","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72103775","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}

{"title":"Central volcanoes and caldera collapses in the late Miocene – Late Pleistocene Tibesti Volcanic Province, northwest Chad","authors":"Abdelsalam Elshaafi ,&nbsp;Agust Gudmundsson","doi":"10.1016/j.jog.2021.101846","DOIUrl":"10.1016/j.jog.2021.101846","url":null,"abstract":"<div><p>The Tibesti Volcanic Province (TVP) in northwest Chad represents the second largest of the five Gharyan–Tibesti volcanic provinces and covers an area around 29,000 km². The other four provinces are in Libya, but all five provinces are from late Miocene to Quaternary and may have a common mantle source. The TVP, however, differs from the other four as regards volcano-tectonic processes, eruption style, and production of volcanic materials. The volcanic products of the TVP were erupted from the end of Miocene to late Pleistocene, range from basaltic to acidic, and suggest a double magma source – a shallow chamber fed by a deeper and larger reservoir. More specifically, field observations and numerical modelling results suggest that the basaltic magmas forming scoria cones, primarily at the periphery of the TVP, came from a deeper magma reservoir in the lower crust while the rhyolite and ignimbrites were fed by a shallow crustal magma chamber. By contrast, the volcanic products of the four volcanic provinces in Libya are primarily basalts and fed directly from single deep reservoirs. In the period from 8 Ma to 7−5 Ma, the evolution of the TVP was characterised by the formation of central volcanoes. Subsequently, in the period from 7−5 Ma to 0.43 Ma, the TVP was subject to caldera collapses that produced large-volume ignimbrites (&gt;100 km³). Here we present numerical models with plausible loading conditions to understand better the volcano-tectonic evolution of the TVP and the spatial and temporal distribution of its major volcanic units. Our results suggest that the normal local stress field encouraged the formation of a central-volcano edifice (a volcanic cone) fed by radial dykes and inclined sheets and mostly erupting small volumes. By contrast, stress fields generated as a result of small crustal uplift or doming, due to the accumulation of magma in a deep-seated reservoir, triggered the formation of a ring-fault and the injection of a ring-dyke above the lateral margins of a shallow crustal magma chamber. Subsequently, the piston-like caldera subsidence helped to squeeze magma out of the shallow chamber resulting in large eruptions.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101846","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43191268","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}

{"title":"Lateral flow of thick continental lithospheric mantle during tectonic quiescence","authors":"Claudio Alejandro Salazar-Mora ,&nbsp;Victor Sacek","doi":"10.1016/j.jog.2021.101830","DOIUrl":"10.1016/j.jog.2021.101830","url":null,"abstract":"<div><p>The amalgamation of continental blocks naturally results in a lithosphere with lateral variations in thickness due to the juxtaposition of thicker cratonic and thinner orogenic lithospheres, which in turn evolve together through time. After the amalgamation, this mosaic of continental blocks can experience longstanding periods of relative tectonic quiescence until the next tectonic event, for instance continental rifting. Using geodynamic numerical models, we explored the internal deformation of the continental lithosphere during periods of tectonic quiescence taking into account lateral variations of lithospheric thickness. We observed that the orientation of lateral flow of the thick cratonic lithosphere depends primarily on the compositional density contrasts (Δρ) between the asthenosphere and continental lithospheric mantle and on the width of the juxtaposed mobile belt lithosphere. In the case of mobile belts wider than 300 km, the margin of the thick craton flows towards (or underplates) the base of the thin lithosphere when Δρ ≥ 32−48 kg/m³, whereas for smaller Δρ values, the thick cratonic margin flows away from mobile belt, preserving a sharp thickness variation. For mobile belts narrower than 300 km, the Δρ threshold between underplate or outward behavior decreases with the mobile belt width. Underplating of cratonic lithosphere beneath the thin lithosphere is efficient in mobile belts narrower than 300 km and for higher Δρ, which allows them to cool, thicken and stiffen. Lateral flow of cratonic lithosphere is not efficient to underplate wide mobile belts thoroughly, so the latter are influenced by asthenospheric heat for prolonged periods and thus remain less rigid. Therefore, we propose that protracted tectonic quiescence of supercontinents can develop lithospheric rheological inheritances that may or may not facilitate post-quiescence continental lithospheric rifting.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101830","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42351057","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}

{"title":"Eocene dike swarm and felsic stock in Central Iran: Roles of metasomatized mantle wedge and Neo-Tethyan slab","authors":"Ahmad Jamshidzaei ,&nbsp;Ghodrat Torabi ,&nbsp;Tomoaki Morishita ,&nbsp;Akihiro Tamura","doi":"10.1016/j.jog.2021.101844","DOIUrl":"10.1016/j.jog.2021.101844","url":null,"abstract":"<div><p>The Eocene felsic stock and dike swarm with intermediate composition from Central Iran (southwest of Jandaq) are studied to understand geodynamic evolution of the Central-East Iranian Microcontinent (CEIM). Field relationships show that the dikes, composed of trachyandesite and basaltic trachyandesite, cross-cut the felsic stock. Whole rock geochemical data reveal the calc-alkaline nature of stock and high-K calc-alkaline to shoshonitic nature of dikes. The felsic stock and intermediate dikes show LREE and LILE enrichment and HFSE (Ta, Nb and Ti) depletion, suggesting that they probably formed in a subduction zone and are similar to the volcanic arc rocks. The rock samples of felsic stock have geochemical characteristics of the high silica adakites (HSA) produced by melting of a subducted oceanic crust. On the other hand, the dikes have characteristics of low silica adakites (LSA) produced by partial melting of a lithospheric mantle peridotite previously metasomatized by slab-derived melts. The Eocene felsic stock and dikes probably formed by subduction of the CEIM-confining oceanic crusts beneath the CEIM. The field and geochemical studies indicate that the magma originated from melting of basic section (amphibolite) of the subducted slab (HSA) will arrive to the Earth surface before the magma formed by melting of mantle wedge peridotites (LSA).</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jog.2021.101844","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42719042","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}