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1.
A paleomagnetic and potassium-argon dating investigation has been carried out on a 530-km-long dike system which transects the western Iberian Peninsula in a northeasterly direction. The K-Ar age determinations were made on mineral separates exclusively. They range between 160 and 200 Ma and the authors suppose that this reflects the actual time interval of the intrusion, in accord with previous results. The paleomagnetic pole derived from 12 sites regularly distributed along the dike (71°N, 236°E) coincides well with other Mesozoic paleomagnetic poles from the western Africa. A contemporaneous pole from stable Europe is tentatively deduced from African and North American Late Triassic/Early Jurassic poles using different reconstruction models around the North Atlantic Ocean. The divergence between this pole and the Iberian pole corresponds to the result obtained for Permian poles.  相似文献   

2.
鄂尔多斯地块构造演化的古地磁学研究   总被引:15,自引:0,他引:15       下载免费PDF全文
鄂尔多斯地块与中朝地台其它地区相同时代地层的古地磁结果基本一致表明:晚二叠世以来,中朝地台经历了从低纬度(19°左右)向中纬度的北移过程,并伴有50°左右的逆时针旋转;晚二叠世—中三叠世地台北移10°(1000km)左右,而方位基本未变;中三叠世—中侏罗世主要发生50°左右的逆时针旋转,而北向位移不明显,这一旋转可能与杨子地台和中朝地台碰撞拼合有关,或者说是印支运动在该地区的反应,中侏罗世—早白垩世地块已基本和现代位置一致  相似文献   

3.
Of 16 sites collected in the Taru grits (Permian) and Maji ya Chumvi beds (Permo-Triassic) of East Africa only 6 sites from the Maji ya Chumvi sediments gave meaningful palaeomagnetic results. After thermal cleaning the 6 sites (32 samples) give an Early Triassic pole at 67°N, 269°E with A95 = 17° in excellent agreement with other African Mesozoic poles. There are now 26 Mesozoic palaeomagnetic poles for Africa from widely diverse localities ranging in present latitude from 35°N to 30°S. The poles subdivide into Triassic (17 poles) and Cretaceous (9 poles) groups whose means are not significantly different. The palaeomagnetic pole for Africa thus remained in much the same position for 170 m.y. from Early Triassic to Late Cretaceous. The data form an especially good set for estimating the palaeoradius using Ward's method. Values of 1.08 ± 0.15 and 1.03 ± 0.19 times the present radius are deduced for the Triassic and Cretaceous respectively with a mean value of 1.08 ± 0.13 for all the Mesozoic data combined. The analysis demonstrates that hypotheses of earth expansion are very unattractive.  相似文献   

4.
The South American palaeomagnetic poles published after the Upper Mantle Conference on Solid Earth Problems held at Buenos Aires in 1970, are summarized.The Late Palaeozoic-Cretaceous section of the South American polar wandering curve is now defined on the basis of twenty palaeomagnetic poles; these poles define five “age groups” at Late Carboniferous, Permo-Carboniferous, Middle Permian, Triassic and Cretaceous times.The comparison of the Late Palaeozoic-Mesozoic sections of the polar wandering curves of South America, Australia and Africa suggests that the former fragmentation of the Gondwana occurred in Late Carboniferous or Permo-Carboniferous times and that the origin of the South Atlantic Ocean took place after the Middle Jurassic (160 m.y.) but before the Early Cretaceous (120 m.y.).  相似文献   

5.
The Mesozoic McCoy Mountains Formation is a 7.3-km-thick deformed clastic sequence exposed in six mountain ranges in southeastern California and southwestern Arizona. Interbedded with Jurassic volcanic rocks at its base, the McCoy Mountains Formation had been assigned a Cretaceous age based upon fossil angiosperm wood found in the upper third of the section. Characteristic natural remanent magnetism (NRM) from 145 oriented samples from 18 sites within the sedimentary terrane yield an in situ mean direction:I = 20.6°, D = 335.1°, α95 = 7.7° (uncorrected for structural tilting). Opaque mineralogy and a failed fold test indicate that the NRM is a chemical remanence acquired post-folding. The paleomagnetic pole position calculated from the in situ mean direction falls adjacent to poles from the Summerville Formation and Canelo Hills Volcanics. We interpret these data to indicate that deformation, mild metamorphism, and resultant magnetization of the McCoy Mountains Formation occurred during Jurassic time. It is suggested that the McCoy Mountains Formation and underlying Jurassic volcanics were deposited adjacent to, and then deformed between, the North American craton and an outlying allochthonous terrane during Jurassic time.  相似文献   

6.
Yanbin  Zhang  Fuyuan  Wu  Simon A.  Wilde  Mingguo  Zhai  Xiaoping  Lu  Deyou  Sun 《Island Arc》2004,13(4):484-505
Abstract   The Yanbian area is located in the eastern part of the Central Asian Orogenic Belt (CAOB) of China and is characterized by widespread Phanerozoic granitic intrusions. It was previously thought that the Yanbian granitoids were mainly emplaced in the Early Paleozoic (so-called 'Caledonian' granitoids), extending east–west along the northern margin of the North China craton. However, few of them have been precisely dated; therefore, five typical 'Caledonian' granitic intrusions (the Huangniling, Dakai, Mengshan, Gaoling and Bailiping batholiths) were selected for U–Pb zircon isotopic study. New-age data show that emplacement of these granitoids extended from the Late Paleozoic to Late Mesozoic (285–116 Ma). This indicates that no 'Caledonian' granitic belt exists along the northern margin of the North China craton. The granitoids can be subdivided into four episodes based on our new data: Early Permian (285 ± 9 Ma), Early Triassic (249–245 Ma), Jurassic (192–168 Ma) and Cretaceous (119–116 Ma). The 285 ± 9 Ma tonalite was most likely related to subduction of the Paleo-Asian Oceanic Plate beneath the North China craton, followed by Triassic (249–245 Ma) syn-collisional monzogranites, representing the collision of the CAOB orogenic collage with the North China craton and final closure of the Paleo-Asian Ocean. The Jurassic granitoids resulted from subduction of the Paleo-Pacific plate and subsequent collision of the Jiamusi–Khanka Massif with the existing continent, assembled in the Triassic. The Early Cretaceous granitoids formed in an extensional setting along the eastern Asian continental margin.  相似文献   

7.
A magnetization which passes the fold test has been observed in 73 limestone samples (10 sites) from the Middle Jurassic Twin Creek Formation. The pole calculated from the site mean poles is located at 68.4°N, 145.0°E (K = 31.8,A95 = 8.7°). This pole lies in a segment of the North American apparent polar wander (APW) path for which there are only a few reliable poles in the literature. The results corroborate earlier studies which conclude that the Jurassic segment of the APW path does not include the present north pole. However, the position of the Twin Creek pole suggests that significantly more APW took place prior to the late Jurassic than previous studies indicated.  相似文献   

8.
From Middle-Upper Jurassic volcanics at the western margin of the Maranha?o Basin (6.4°S, 47.4°W) 15 sites (121 samples) have a mean magnetization directionD = 3.9°,I = ?17.9° withα95 = 9.3°,k = 17.9 after AF cleaning (all sites have normal polarity). This yields a pole (named SAJ2) at 85.3°N, 82.5°E (A95 = 6.9°) which is near to the other known Middle Jurassic South American pole. For 21 sites (190 samples) from Lower Cretaceous basalt intrusions from the eastern part of the Maranha?o Basin (6.5°S, 42°W) the mean direction isD = 174.7°,I = +6.0° withα95 = 2.8°,k = 122 (all sites have reversed polarity) yielding a pole (SAK9) at 83.6°N, 261°E (A95 = 1.9°) in agreement with other Lower Cretaceous pole positions for South America. Comparing Mesozoic pole positions for South America and Africa in the pre-drift configuration after Bullard et al. [13] one finds a significant difference (with more than 95% probability) for the Lower Cretaceous and Middle Jurassic poles and also a probable difference for the mean Triassic poles indicating a small but probably stationary separation of the two continents from the predrift position in the Mesozoic until Lower Cretaceous time which may be due to an early rifting event.  相似文献   

9.
We report paleomagnetic results from oriented drill core samples collected at 10 sites (80 samples) from the Covey Hill and 19 sites (96 samples) from the overlying, fossiliferous Cha?teauguay Formations of the gently dipping Late Cambrian Potsdam Group sandstones exposed in the St. Lawrence Lowlands of Quebec. Stepwise thermal demagnetization analyses ave revealed the presence of two predominant groups of coherent magnetizations C-1 and C-2, after simple correction for bedding tilt. The C-1 group magnetization is a stable direction (D=332°, I=+18°) with unblocking temperatures (TUB) between 550 and 650°C, present in the older Covey Hill Formation; this direction is probably a chemical remanence acquired during the Covey Hill diagenesis and carried predominantly by hematite. The C-2 group magnetization (D=322°, I=+9°) is present at 13 sites of the younger Cha?teauguay Formation; this is probably carried by magnetite and represents a penecontemporaneous, depositional DRM, characterized by TUB spectra 400–550°C. We believe that C-2 is relatively younger than C-1 based on a combination of arguments such as the presence of opposite polarities, internal consistency, similarity and common occurrence of C-1 and C-2 respectively in the Covey Hill and Cha?teauguay members. The corresponding paleomagnetic poles C-1 (46°N, 149°E; dp, dm=3°, 5°) and C-2 (37°N, 156°E; dp, dm=2°, 5°) are not significantly different from most of the other Late Cambrian (Dresbachian-Franconian) poles derived from sediments exposed in the southern region (Texas) of the North American craton which are also believed to have been deposited during Croixian Sauk sea transgression similar to the Potsdam sandstones. Although adequate faunal control is lacking (in particular for the Covey Hill Formation), this comparison with the Cratonic poles suggests a Late Cambrian age to the Potsdam poles. The agreement between the results also gives the evidence for internal consistency of cratonic poles at least for Late Cambrian.The incoherent C-3 group remanence (D=250°, I=?15°) is commonly present at 7 sites in both the formations; this may not correspond to a reliable paleomagnetic signal. The other remanence C-4 (D=180°, I=+10°) is found only at 3 sites located in the uppermost stratigraphic levels of the Cha?teauguay Formation; the corresponding paleomagnetic pole (40°N, 107°E) does not differ significantly from the Ordovician and some Late Cambrian poles. The present data are insufficient to resolve a problem in apparent polar wander for Middle and Late Cambrian time posed by the existence of high-latitude poles for some strata of Middle Cambrian age and low-latitude poles for some strata of Late Cambrian age.  相似文献   

10.
Paleomagnetic analyses of samples collected from a 500 m thick Jurassic section in the Pontides reveal the presence of two components of remanent magnetization: an unstable, low-temperature component which is removed during thermal demagnetization through 220°C and a dominant component which displays consistent directions through 650°. Curie point and IRM studies indicate that goethite is responsible for the low-temperature component whereas both magnetite and hematite contribute to the more stable component. The pole position determined from the stable magnetization is located at 18.8°N, 91.8°E (α95=7.7°, N=134) indicating that the section has undergone more than 90° clockwise rotation since the Late Jurassic. Ancillary geologic evidence, particularly the orientation of Jurassic facies belts is also consistent with a 90° clockwise rotation in this region of northwest Anatolia. The pole suggests that the section may also have migrated slightly northward. Although the age of these movements is currently unknow, it is proposed that they are principally related to the closure of the Neo-Tethys during the Late Cretaceous/Early Tertiary. Some of the rotation may be related to the right lateral movement along the North Anatolian Transform Fault which was initiated in the Miocene.  相似文献   

11.
We present a detailed rock-magnetic and paleomagnetic survey from Autlan volcanic succession in western Mexico. The principal aim of this study is to extend paleomagnetic data from Autlan lavas in order to confirm vertical-axis rotation observed in reconnaissance study and to evaluate long-term variation of the geomagnetic field strength based on existing and global data. The mean inclination (44.7°) is in agreement with the expected inclination for 60 and 70 Ma, as derived from available reference poles for the North American craton. The declination (333.6°), however, is significantly different from those expected, which suggests a statistically significant counterclockwise tectonic rotation ranging between 10° ± 6° and 14° ± 7°. As a measure of paleosecular variation (PSV), we obtained a geomagnetic field dispersion of 9.6° (upper and lower limits: 7.2°–11.9°) in perfect agreement with the previously published PSV compilation of selected Cretaceous data from lavas. The mean virtual dipole moments available for Autlan lavas are about 65% of the present geomagnetic axial dipole but are in reasonably good agreement with other comparable quality determinations between 5 and 90 Ma. This reinforces the hypothesis that low geomagnetic field strengths persisted for the entire Jurassic extending into the Upper Cretaceous.  相似文献   

12.
塔里木地块侏罗、白垩纪的古地磁   总被引:5,自引:0,他引:5       下载免费PDF全文
本文对塔里木地块西北缘库车、拜城一带中新生代剖面进行了古地磁研究。库车与拜城两剖面具有不同方向产状,经产状校正之后,均为同一方向,表明磁性是在第三系褶皱之前获得的。热退磁结果表明500℃之前为现代地磁场方向,解阻温度为675℃,说明磁性载体为赤铁矿。 古地磁结果表明,塔里木地块在晚侏罗—晚白垩世之间没有经历大规模的构造运动。有可能自晚白垩世之后相对西伯利亚地块向北东方向移动过  相似文献   

13.
The palaeomagnetism of Middle Triassic (224 ± 5 m.y.) igneous rocks from the Ischigualasto-Ischichuca Basin (67°40′W, 30°20′S) was investigated through 86 oriented hand samples from 11 sites. At least one reversal of the geomagnetic field has been found in these rocks. Nine sites yield a palaeomagnetic pole at 239°E, 79°S (α95 = 15°, k = 13).The K-Ar age determinations of five igneous units of the Puesto Viejo Formation give a mean age of 232 ± 4 m.y. (Early Triassic). The palaeomagnetism of six igneous units of the Puesto Viejo Formation (68°W, 35°S) was investigated through 60 oriented samples. These units, two reversed relative to the present magnetic field of the Earth and four normal, yield a pole at 236°E, 76°S (α95 = 18°, k = 14).Data from the Puesto Viejo Formation indicate, for the first time on the basis of palaeomagnetic and radiometric data, that the Illawarra Zone, which defines the end of the Kiaman Magnetic Interval, extends at least down to 232 ± 4 m.y. within the Early Triassic. The palaeomagnetic poles for the igneous rocks of the Ischigualasto-Ischichuca Basin and Puesto Viejo Formation form an “age group” with the South American Triassic palaeomagnetic poles (mean pole position: 239°E, 77°S; α95 = 6.6°, k = 190). The Middle and Upper Permian, Triassic and Middle Jurassic palaeomagnetic poles for South America would define a “time group” reflecting a quasi-static interval (mean pole position: 232°E, 81°S; α95 = 4°, k = 131).  相似文献   

14.
Paleomagnetic samples were collected from 190 m of the Late Carboniferous/Early Permian Casper Formation in southeastern Wyoming. A total of 549 samples was drilled near the vicinity of Horse Creek Station at an average stratigraphic interval of 33 cm. All samples were reversely magnetized. Rock magnetic analyses indicate that the primary carrier of remanence in the formation is hematite. A selection criterion applied to the partial demagnetized data restricted the sample population to 233, resulting in a paleomagnetic North Pole located at 47.4°N, 127.4°E (δp=0.7;δm=1.4). The Casper pole agrees well with other Late Carboniferous/Early Permian poles for cratonic North America. The tight clustering of these paleomagnetic poles suggests that little apparent polar motion with respect to North America occurred during this time. Comparing the stable North American poles with paleomagnetic poles from Late Carboniferous/Early Permian strata of the New England-Canadian Maritime region (Acadia) indicates that this region did not reach its present position relative to North America until at least the Early Permian.  相似文献   

15.
Tethyan ophiolites and Pangea break-up   总被引:6,自引:0,他引:6  
Abstract The break‐up of Pangea began during the Triassic and was preceded by a generalized Permo‐Triassic formation of continental rifts along the future margins between Africa and Europe, between Africa and North America, and between North and South America. During the Middle–Late Triassic, an ocean basin cutting the eastern equatorial portion of the Pangea opened as a prograding branch of the Paleotethys or as a new ocean (the Eastern Tethys); westwards, continental rift basins developed. The Western Tethys and Central Atlantic began to open only during the Middle Jurassic. The timing of the break‐up can be hypothesized from data from the oceanic remnants of the peri‐Mediterranean and peri‐Caribbean regions (the Mesozoic ophiolites) and from the Atlantic ocean crust. In the Eastern Tethys, Middle–Late Triassic mid‐oceanic ridge basalt (MORB) ophiolites, Middle–Upper Jurassic MORB, island arc tholeiite (IAT) supra‐subduction ophiolites and Middle–Upper Jurassic metamorphic soles occur, suggesting that the ocean drifting was active from the Triassic to the Middle Jurassic. The compressive phases, as early as during the Middle Jurassic, were when the drifting was still active and caused the ocean closure at the Jurassic–Cretaceous boundary and, successively, the formation of the orogenic belts. The present scattering of the ophiolites is a consequence of the orogenesis: once the tectonic disturbances are removed, the Eastern Tethys ophiolites constitute a single alignment. In the Western Tethys only Middle–Upper Jurassic MORB ophiolites are present – this was the drifting time. The closure began during the Late Cretaceous and was completed during the Eocene. Along the area linking the Western Tethys to the Central Atlantic, the break‐up was realized through left lateral wrench movements. In the Central Atlantic – the link between the Western Tethys and the Caribbean Tethys – the drifting began at the same time and is still continuing. The Caribbean Tethys opened probably during the Late Jurassic–Early Cretaceous. The general picture rising from the previous data suggest a Pangea break‐up rejuvenating from east to west, from the Middle–Late Triassic to the Late Jurassic–Early Cretaceous.  相似文献   

16.
The craton is a long-lived stable geologic unit on the Earth's surface. However, since the Mesozoic, the North China Craton(NCC) experienced large-scale lithospheric removal, the fundamental change of physical and chemical characteristics of the lithospheric mantle, widely distributed crustal deformation, and extensive magmatism. This complex evolution contrary to other cratons is called the NCC destruction. Widespread magmatism in the eastern NCC is an important response to the lithospheric removal at depth and crustal deformation on the surface. The plutons emplace under a tectonic context and therefore record the information of the tectonics; especially, the anisotropy magnetic susceptibility(AMS) pattern of the pluton was acquired with the influence of regional stress. In the past fifteen years, about 22 plutons intruding during the different periods from the Late Triassic to the late stage of the Early Cretaceous have been studied with AMS. The emplacement mechanisms of plutons and the contemporary tectonic setting were discussed to constrain their relationship with the NCC destruction in different stages of magmatism. As a result, the Late Triassic, Early Jurassic, and Late Jurassic plutons exhibit consistent N(E)-S(W)trending magnetic lineations. The early stage of Early Cretaceous plutons display NW-SE trending magnetic lineations, while the late stage of Early Cretaceous plutons show magnetic lineations with various orientations. Combined with previous studies, it is concluded that the emplacements of the plutons intruding in these three stages were controlled by weak N(E)-S(W) trending extension, regional NW-SE trending extension, and weak extension in the shallow crustal level, respectively. The transformation of regional extension from the N(E)-S(W) to the NW-SE direction was accompanied by a strain-increasing tendency. The extensional tectonics in the eastern NCC was interpreted to represent the interaction between Mongol-Okhotsk belt, PaleoPacific plate, and eastern Eurasian continent.  相似文献   

17.
The paleomagnetism of the Late Cretaceous Poços de Caldas alkaline complex (46.6°W, 21.9°S) was investigated through 42 oriented cores from seven sites. Six sites, reversed relative to the present magnetic field of the Earth, yield a pole at 127°W, 82°S (dp = 8°,dm = 13°). This pole is located close to other Late Cretaceous poles for South America obtained by Creer [1] from untreated paleomagnetic samples. The results are significantly different from those for the nearby Early Cretaceous Serra Geral basalt but close to the Triassic pole for South America. The polar wandering path for South America for the Mesozoic seems to be more complicated than anticipated. The available paleomagnetic information may not yet be precise enough to determine the time of opening of the Atlantic.  相似文献   

18.
The Dabie-Sulu orogenic belt was formed by the Triassic continental collision between the South China Block and the North China Block. There is a large area of Mesozoic magmatic rocks along this orogenic belt, with emplacement ages mainly at Late Triassic, Late Jurassic and Early Cretaceous. The Late Triassic alkaline rocks and the Late Jurassic granitoids only crop out in the eastern part of the Sulu orogen, whereas the Early Cretaceous magmatic rocks occur as massive granitoids, sporadic intermedi- ate-ma...  相似文献   

19.
Abstract Geological mapping using detailed tectonic and complex radiolarian analysis revealed significant northward displacement of a number of Russian Far and Northeast Asia terranes. It was recorded that some terranes possibly crossed the equator. Terranes of north-east Russia were composed of different allochthonous formations, ranging in age from Middle Triassic to Maestrichtian-Paleocene and accumulated from the margin to oceanic basins. The Middle to Upper Triassic interval included two formations: (i) volcanogenic, consisting of typical volcanic rocks of the island arcs (up to 800 m thick); and (ii) a chert-limestone-terrigenous one composed of marginal sandstone, siltstone, limestone and tuffic chert (about 400 m). Lower Jurassic allochthonous formations are represented by chert-terrigenous (about 300 m) and jasper-alkaline-basaltic (WPB-type) seamount deposits (about 100 m). Middle Jurassic to Hauterivian allochthonous terranes from the northern part of the Koryak-Kamchatka region include five formations: jasper (bedding jaspers with condensed limestone lenses with Buchias, 80 m), jasper-basalt (with MORB, 100-150 m), ferrotitanic basalt (WPB with lenses of jasper mainly composed of genus Parvicingula, about 75%, 150 m), terrigenous-volcanic (with MORB, IAT, CA basalts and olistostrome, 600 m), tuffic-jasper-basalt (MORB and deposits of arc-trench system, about 500 m) with the same age according to radiolarian data. Aptian? Albian-Maestrichtian ones are predominantly terrigenous-tuffaceous-siliceous. Moreover, the Early and Middle Jurassic faunas of the northwest Pacific margin contain many boreal elements similar to those of New Zealand (Southern Hemisphere), Japan, ODP Site 801. The Late Jurassic faunas of the Koryak and Kamchatka region are mainly North Tethyan and seldom Central Tethyan and are very closely related to those of the Americas. The Tithonian to Early Cretaceous radiolarian are predominantly Central Tethyan and Equatorial in contrast to Boreal Late Cretaceous. The combining in the same region at 60°N Pacific margin of the formations accumulated in different tectonic paleoenvironments and paleoclimatic provinces, is good evidence for the possible significant northward displacement of some terranes in the northwestern Pacific.  相似文献   

20.
Widespread Mesozoic magmatism occurs in the Korean Peninsula (KP). The status quo is poles apart between the northern and southern parts in characterizing its distribution and nature, with the nearly absence of any related information in North Korea. We have the opportunity to have conducted geological investigations in North Korea and South Korea during the past ten years through international cooperation programs. This led to the revelation of a number of granitoids and related volcanic rocks and thus facilitates the comparison with those in East China and Japan. Mesozoic granitoids in the KP can be divisible into three age groups: the Triassic group with a peak age of ~220 Ma, the Jurassic one of ~190–170 Ma and the late Early Cretaceous one of ~110 Ma. The Triassic intrusions include syenite, calc-alkaline to alkaline granite and minor kimberlite in the Pyeongnam Basin of North Korea. They have been considered to form in post-orogenic settings related to the Central Asian Orogenic Belt (CAOB) or the Dabie-Sulu Orogenic Belt (DSOB). The Jurassic granitoids constitute extensive occurrence in the KP and are termed as the Daebo-period magmatism. They correlate well with coeval counterparts in NE China encompassing the northeastern part of the North China Craton (NCC) and the eastern segment of the CAOB. They commonly consist of biotite or two-mica granites and granodiorites, with some containing small dark diorite enclaves. On one hand, Early Jurassic to early Middle Jurassic magmatic rocks are rare in most areas of the NCC, whilst Middle-Late Jurassic ones are not developed in the KP. On the other hand, both NCC and KP host abundant Cretaceous granites. However, the present data revealed contrasting age peaks, with ~130–125 Ma in the NCC and ~110–105 Ma in the KP. Cretaceous granites in the KP comprise the dominant biotite granites and a few amphibole granites. The former exhibit mildly fractionated REE patterns and zircon ε Hf(t) values from -15 to -25, whereas the latter feature strongly fractionated REE patterns and zircon ε Hf(t) values from -10 to -1. Both granites contain inherited zircons of ~1.8–1.9 or ~2.5 Ga. These geochemical characters testify to their derivation from re-melting distinct protoliths in ancient basement. Another Cretaceous magmatic sub-event has been entitled as the Gyeongsang volcanism, which is composed of bimodal calc-alkaline volcanic rocks of 94–55 Ma and granitic-hypabyssal granitic bodies of 72–70 Ma. Synthesizing the Mesozoic magmatic rocks across the KP, NCC and Japan can lead to the following highlights: (1) All Triassic granites in the NCC, KP and Japan have similar characteristics in petrology, chronology and geochemistry. Therefore, the NCC, KP and Japan tend to share the same tectonic setting during the Triassic, seemingly within the context of Indosinian orogensis. (2) Jurassic to earliest Cretaceous magmatic rocks in the NCC seem to define two episodes: episode A from 175 to 157 Ma and episode B from 157 to 135 Ma. Jurassic magmatic rocks in the KP span in age mainly from 190 to 170 Ma, whereas 160–135 Ma ones are rare. With the exception of ~197 Ma Funatsu granite, Jurassic magmatic rocks are absent in Japan. (3) Cretaceous granites in the KP have a peak age of ~110, ~20 Ma younger than those in the NCC, while Japan is exempt from ~130–100 Ma granites. (4) The spatial-temporal distribution and migratory characteristics of the Jurassic-Cretaceous magmatic rocks in Japan, KP, and NE China-North China indicate that the subduction of the Paleo-Pacific plate might not be operative before Late Cretaceous (~130–120 Ma). (5) Late Cretaceous magmatic rocks (~90–60 Ma) occur in the southwestern corner of the KP and also in Japan, coinciding with the metamorphic age of ~90–70 Ma in the Sanbagawa metamorphic belt of Japan. The magmatic-metamorphic rock associations and their spatial distribution demonstrate the affinities of sequentially subduction zone, island arc and back-arc basin from Japan to Korea, arguing for the Pacific plate subduction during Late Cretaceous. (6) This study raises another possibility that the Mesozoic cratonic destruction in the NCC, which mainly occurred during ~150–120 Ma, might not only be due to the subduction of the Paleo-Pacific Plate, but also owe much to the intraplate geodynamic forces triggered by other adjacent continental plates like the Eurasian and Indian plates.  相似文献   

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