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1.
Verzhbitsky E. V. Lobkovsky L. I. Kononov M. V. Byakov A. F. 《Izvestiya Physics of the Solid Earth》2012,48(11):785-797
An insufficient number of dated native samples and indistinct magnetic anomalies in the Amerasian Basin prevent geophysicists from identifying the exact age of most of its structural elements. Due to this, it is impossible to gain an insight into the evolution of this vast region, which is highly promising in terms of its hydrocarbon potential. Therefore, the geological time of the formation of the structural elements composing the Amerasian Basin is determined either hypothetically or very loosely (for example, Late Cretaceous-Cenozoic). In order to more precisely estimate the time of formation of the structural elements within the Amerasian Basin, we applied the geothermal method, which is highly informative in terms of the age of the lithosphere, its thickness, and the evolution of the basin structures. Besides, this method provides far narrower time constraints for the formation of the structures compared to the geological data. Based on the thermal flow data, we have numerically calculated the age of the structural elements composing the Amerasian Basin: Podvodnikov Basin (97–79 Ma), Makarov Basin (75–61 Ma), Alpha-Mendeleev Ridge (97–79 Ma), and Lomonosov Ridge (69–57 Ma). The age of these structures derived from the geothermal data agrees with the estimates determined from the geological, geomagnetic, seismic, and radiometric data. Based on the age of the structures estimated from the thermal flow data and the analysis of the geological and geophysical evidence, conclusions are made concerning the genesis and character of formation of the Podvodnikov and Makarov basins and the Alpha-Mendeleev and Lomonosov ridges within the Amerasian Basin.
相似文献2.
Multiparameter geophysical measurements and geological samples from CESAR suggest that close to Canada the Alpha Ridge is oceanic in nature and was built in part by volcanic activity. It is unclear whether this part of the ridge formed in an intraplate or a plate margin environment. Estimates from paleontological, heat flow and magnetic data place the construction of a volcanic ridge within the Cretaceous period between about 120 and 80 Ma ago, the interval in which the Canada Basin seafloor formed but clearly before the creation of the Lomonosov Ridge. The place of the Makarov Basin in this chronology remains unclear. 相似文献
3.
E. V. Verzhbitskii M. V. Kononov V. D. Kotelkin 《Journal of Volcanology and Seismology》2007,1(6):357-371
The distribution of heat flow in the North Pacific Ocean has been examined, and a map of geothermal and geomagnetic fields for the Bering Sea as it is known today has been made. Reliable data are lacking regarding the time of origin for features of oceanic and continental genesis in the Bering Sea, which is an obstacle to the study of geodynamic processes in the North Pacific. Heat flow data were used to yield numerical estimates for the age of seafloor features in the Bering Sea: the Kamchatka Basin (21 Ma), Shirshov Ridge (95 Ma for the northern part and 33 Ma for the southern), the Aleutian Basin (70 Ma), Vitus Rise (44 Ma), Bowers Ridge (30 Ma), and Bowers Basin (40 Ma). These age estimates are corroborated by combined geological, geophysical, and plate kinematic data. A thermochemical model of global mantle convection has been developed in order to perform a numerical simulation of the thermal process involved in the generation of extended regional features in the North Pacific (the Emperor Fracture Zone, Chinook Trough, etc.). The modeling suggests a plume-tectonic origin for these features, yielding the optimal model for the tectonic evolution of the North Pacific. An integrated geological and geothermal analysis leads to the conclusion that the northern and southern parts of the Shirshov Ridge are different, not only in geologic age, but also in tectonic structure. The northern part is of imbricated-thrust terrane origin, while the southern part is of ensimatic island-arc origin, similar to that of Bowers Ridge. The seafloor of the Aleutian Basin is an outlier of the Upper Cretaceous Kula plate where, in the Vitus Rise area, backarc spreading processes originated during Eocene time. The terminating phase of activity in the Bering Sea began about 21 Ma by spreading in the older seafloor of the Kamchatka Basin. We developed plate-tectonic reconstructions of evolution for the North Pacific for the times 21, 33, 40, and 70 Ma in the hotspot system based on age estimates for the seafloor features derived from heat flow data and modeling of the thermal generation of regional faults, as well as on an analysis of geomagnetic, tectonic, and geological data. 相似文献
4.
The tectonic structure and anomalous distributions of geophysical fields of the Sea of Okhotsk region are considered; the lack of reliable data on the age of the lithosphere beneath basins of various origins in the Sea of Okhotsk is noted. Model calculations based on geological and geophysical data yielded an age of 65 Ma (the Cretaceous-Paleocene boundary) for the Central Okhotsk rise underlain by the continental lithosphere. This estimate agrees with the age (the end of the Cretaceous) derived from seismostratigraphic data. A comparative analysis of theoretical and measured heat fluxes in the Akademii Nauk Rise, underlain by a thinned continental crust, is performed. The analysis points to a higher (by 20%) value of the measured thermal background of the rise, which is consistent with a high negative gradient of gravity anomalies in this area. Calculations yielded an age of 36 Ma (the Early Oligocene) and a lithosphere thickness of 50 km for the South Okhotsk depression, whose seafloor was formed by processes of backarc spreading. The estimated age of the depression is supported by kinematic data on the region; the calculated thickness of the lithosphere coincides with the value estimated from data of magnetotelluric sounding here. This indicates that the formation time (36 Ma) of the South Okhotsk depression was estimated correctly. Numerical modeling performed for the determination of the basement age of rifting basins in the Sea of Okhotsk gave the following estimates: 18 Ma (the Early Miocene) for the Deryugin basin, 12 Ma (the Middle Miocene) for the TINRO basin, and 23 Ma (the Late Oligocene) for the West Kamchatka trough. These estimates agree with the formation time (Oligocene-Quaternary) of the sedimentary cover in rifting basins of the Sea of Okhotsk derived from geological and geophysical data. Model temperature estimates are obtained for lithologic and stratigraphic boundaries of the sedimentary cover in the Deryugin and TINRO basins and the West Kamchatka trough; the temperature analysis indicates that the latter two structures are promising for oil and hydrocarbon gas generation; the West Kamchatka trough possesses better reservoir properties compared to the TINRO and Deryugin basins. The latter is promising for the generation of hydrocarbon gas. Paleogeodynamic reconstructions of the Sea of Okhotsk region evolution are obtained for times of 90, 66, and 36 Ma on the basis of kinematic, geomagnetic, structural, tectonic, geothermal, and other geological and geophysical data. 相似文献
5.
L. I. Lobkovsky E. V. Shipilov M. V. Kononov 《Izvestiya Physics of the Solid Earth》2013,49(6):767-785
By interpretation of the complex geological and geophysical data and paleotectonic reconstructions based on the results of deep seismic tomography, a new deep geodynamic mechanism is developed to describe the formation and evolution of Amerasian and Eurasian basins, together with their adjacent geological structures of the Arctic region. The Mesozoic and Cenozoic transformations of the lithosphere in a number of regions of the Arctic Ocean are considered. The role and place of the upper-mantle convection is explored, and the chronology of the key structure-forming events is analyzed. 相似文献
6.
本文从四个方面讨论了东南沿海地区地温场的形成及其分布规律:1.区域地质构造条件,其中着重讨论了岩浆岩的分布及其与地质构造的关系;2.测温资料的分析和处理;3.地温分布的主要特征;4.控制地温场的主要因素。本文除对深部地壳结构及区域地质构造等主要控制因素进行了讨论外,还就岩浆岩中特别是燕山期花岗岩中放射性元素的含量及其蜕变产生热对地温场可能产生的影响进行了探讨。 从而认为东南沿海地区的地温场形成模式主要有传导型的地温场和传导附加以对流型的地温场两种类型 相似文献
7.
V. Klevenz D. Vance D.N. Schmidt K. Mezger 《Earth and Planetary Science Letters》2008,265(3-4):571-587
Records of the past neodymium (Nd) isotope composition of the deep ocean can resolve ambiguities in the interpretation of other tracers. We present the first Nd isotope data for sedimentary benthic foraminifera. Comparison of the ?Nd of core-top foraminifera from a depth transect on the Cape Basin side of the Walvis Ridge to published seawater data, and to the modern dissolved SiO2–?Nd trend of the deep Atlantic, suggests that benthic foraminifera represent a reliable archive of the deep water Nd isotope composition. Neodymium isotope values of benthic foraminifera from ODP Site 1264A (Angola Basin side of the Walvis Ridge) from the last 8 Ma agree with Fe–Mn oxide coatings from the same samples and are also broadly consistent with existing fish teeth data for the deep South Atlantic, yielding confidence in the preservation of the marine Nd isotope signal in all these archives. The marine origin of the Nd in the coatings is confirmed by their marine Sr isotope values. These important results allow application of the technique to down-core samples.The new ?Nd datasets, along with ancillary Cd/Ca and Nd/Ca ratios from the same foraminiferal samples, are interpreted in the context of debates on the Neogene history of North Atlantic Deep Water (NADW) export to the South Atlantic. In general, the ?Nd and δ13C records are closely correlated over the past 4.5 Ma. The Nd isotope data suggest strong NADW export from 8 to 5 Ma, consistent with one interpretation of published δ13C gradients. Where the ?Nd record differs from the nutrient-based records, changes in the pre-formed δ13C or Cd/Ca of southern-derived deep water might account for the difference. Maximum NADW-export for the entire record is suggested by all proxies at 3.5–4 Ma. Chemical conditions from 3 to 1 Ma are totally different, showing, on average, the lowest NADW export of the record. Modern-day values again imply NADW export that is about as strong as at any stage over the past 8 Ma. 相似文献
8.
Yu Higuchi Yutaka Yanagimoto Kazuyoshi Hoshi Sadao Unou Fumio Akiba Kunishige Tonoike Keita Koda 《Island Arc》2007,16(3):374-393
Abstract To clarify the regional distribution and characteristics of the sedimentary deposits in the northern part of the Philippine Sea, multichannel seismic reflection surveys of 26 864 km in total length were performed. The seismic reflection data were interpreted and correlated with available Deep Sea Drilling Project/Ocean Drilling Program (DSDP/ODP) data and a general stratigraphic framework of the area was established. The sedimentary deposits in this area were divided into five layers; Units I, II, III, IV and V in ascending order. Their approximate geological ages are the Early Eocene, Middle to Late Eocene, Oligocene, Miocene and Pliocene‐Pleistocene, respectively. Seismic records were classified into three seismic facies, Facies A, B and C, on the basis of their characteristics. They were judged to represent pelagic and hemipelagic sediments of non‐volcanic origin, fine pyroclastic sediments and coarse pyroclastic or volcanic sediments, respectively, by comparing them with lithological data in the DSDP/ODP holes. From the thickness and facies distributions of these sediments, a sedimentary history in the area was reconstructed as follows. The oldest sediments in the study area, Unit I, interfinger with some parts of the Daito Ridge (acoustic basement) in the Minami Daito Basin. The geological age of the unit is estimated by microfossils in the sediment and supports the idea that this part of the Daito Ridge is composed of the Early Eocene oceanic basalt. Later, a fair amount of sediments were deposited in the Minami Daito Basin in the Middle to Late Eocene age. A large volume of volcanic materials was supplied from the Paleo‐Kyushu‐Palau Ridge in the Kita Daito Basin in the Eocene and Oligocene ages. The eastern part of the Shikoku and Parece Vela basins is characterized by volcanic sediments supplied from the Nishi Shichito and West Mariana Ridges in the Miocene age. However, pelagic and hemipelagic sediments prevail in the northern part of the Shikoku Basin in the Miocene or later. In short, the area of principal sedimentation has generally shifted from west to east through geological time, reflecting the evolution of the island arc systems with the same trend in the northern Philippine Sea. 相似文献
9.
10.
利用合肥盆地内６个磷灰石裂变径迹样品资料，反演模拟了该盆地自侏罗纪晚期以来各时代地层古地温变化，估算了沉降率与剥蚀率．模拟结果与其他地质资料推论一致，它揭示出该盆地南北两地存在不同的构造变化和受热史，反映了大别山构造发展对盆地南北两地区影响的差异．盆地南部靠近大别山地区的晚侏罗世地层在白垩纪早期埋藏温度曾大于１２０℃；早白垩世后期的构造抬升（剥蚀率约１３０ｍ／Ｍａ）使温度降至３０-４０℃；自白垩纪后期始，该地区一直处于动荡的但总体为持续抬升的构造环境中．盆地北部地区晚侏罗世与早白垩世早期地层在白垩纪期间埋藏温度曾达到和超过１００℃，但随后的大幅度构造抬升（剥蚀率约１９０ｍ／Ｍａ）使其温度降至３０-６０℃；第三纪早期，局部区域的裂陷（沉降率约６０ｍ／Ｍａ）使温度又升至８０℃左右．指出合肥盆地构造演化大体可分形成、隆升、局部裂陷和再隆升４个阶段． 相似文献
11.
Cenozoic basin-forming processes in northwestern Kyushu were studied on the basis of geological and geophysical data. Gravity anomaly analysis delineated four sedimentary basins in the study area: Goto-nada, Nishisonogi, Amakusa-nada, and Shimabara. Borehole stratigraphy and reflection seismic interpretation suggest that the Goto-nada Basin was subdivided into the Paleogene and Plio-Pleistocene depocenters (Goto-nada 1 and 2). In the Paleogene, Amakusa-nada Basin was rapidly subsiding together with the Shimabara Basin as part of a large graben. Goto-nada 1 and Nishisonogi basins belonged to another depositional area. After stagnant subsidence stage in the early Miocene, the study area became a site of basaltic activity (since 10 Ma) and vigorous subsidence in the Plio-Pleistocene. Goto-nada 2 Basin is accompanied with numerous east–west active faults, and separated from the Amakusa-nada Basin by a northeast– southwest basement high, Nomo Ridge. Plio-Pleistocene subsidence of the Amakusa-nada Basin is related with low-angle normal faulting on the eastern flank of the Nomo Ridge. Shimabara Basin is a composite volcano-tectonic depression which is studded by east–west faults. Focal mechanism on active faults suggests transtensional stress regime in the study area. 相似文献
12.
Initial interpretations of the CESAR geological samples are re-examined in light of new data from the Alpha Ridge and circum-Arctic region. A composite stratigraphy for the CESAR and Fletcher Island (T-3) pre-Neogene cores shows a sequence of Campanian-Maastrichtian organic-rich terrigenous mud overlain by Maastrichtian-Eocene biosiliceous marine deposits with a low organic content, terminating in volcanoclastic mudstone of Late Eocene age. CESAR core 6 contains a transition zone in which biosiliceous sediment is replaced by volcanoclastic and terrigenous sediment of Paleocene-Eocene age. Palynomorphs provide a Late Eocene age for the volcanic outcrop dredged from Northern Alpha Ridge. Textural and geochemical studies of laminated biosiliceous sediments were made with special techniques for quantitative analyses of very small samples (1–10 mg) and particle sizes of less than 5 microns. Results show that the laminated sediments were deposited very slowly in an oxidizing environment. Laminae in CESAR core 6 mainly reflect cyclical variations in the formation and/or accumulation of particulate iron, probably due to periodic hydrothermal venting. Absence of detrital sediment, sparsity of pyroclastic material and lack of diagenetic alteration of the biogenic sediments suggest that the eastern Alpha Ridge was not an area of major tectonic activity during the Eurekan Orogeny, from ca. 80-40 Ma. 相似文献
13.
JIN Zhijun ZHANG Yiwei & CHEN Shuping . Key Laboratory for Hydrocarbon Accumulation Ministry of Education China University of Petroleum Beijing China . Exploration Production Research Institute China Petroleum & Chemical Corporation Beijing China 《中国科学D辑(英文版)》2005,48(11):1949-1959
Wave analysis of basins is not only important to the crustal undation theory but also significant to petro-leum exploration by providing information such as the unconformity formation, migration and interchanges between uplifts and depressions, the migrations of sedimentary facies, and basin evolutionary stages. Early in the last century, Haarmann (1930, cited in Jacobs[1] and Scheidegger[2]) and Bemmelen (1933, cited in Jacobs[1] and Scheidegger[2]) put forward the theory of crustal undatio… 相似文献
14.
低温热年代学数据是一个与热历史过程紧密相关的资料类型,与高温年代学不同,低温热年代学表观年龄本身在很多情况下没有直接的地质意义.当且仅当样品线性持续冷却的情况下,表观年龄才可以被直接解释为样品经过其封闭温度的大致时间.因此,只有结合地质约束通过对低温热年代学数据进行热历史模拟才能更好地揭示其所蕴含的地质信息.对川东北地... 相似文献
15.
依据钻孔系统稳态测温、静井温度资料与实测热导率数据分析了柴达木盆地地温场分布特征,建立了柴达木盆地热导率柱,新增了17个大地热流数据.柴达木盆地现今地温梯度介于17.1~38.6℃·km-1,平均为28.6±4.6℃·km-1,大地热流介于32.9~70.4mW·m-2,平均55.1±7.9mW·m-2.盆地不同构造单元地温场存在差异,昆北逆冲带、一里坪坳陷属于"高温区",祁南逆冲带属于"中温区",三湖坳陷、德令哈坳陷及欧龙布鲁克隆起属于"低温区",盆地现今地温场分布特征受控于地壳深部结构、盆地构造等因素.以现今地温场为基础,采用磷灰石、锆石裂变径迹年龄分布特征定性分析与径迹长度分布数据定量模拟相结合,研究了柴达木盆地晚古生代以来的沉积埋藏、抬升剥蚀和热演化史,并结合区域构造背景,对柴达木盆地构造演化过程进行了探讨,研究表明柴达木盆地晚古生代以来经历了六期(254.0—199 Ma,177—148.6 Ma,87—62 Ma,41.1—33.6 Ma,9.6—7.1 Ma,2.9—1.8 Ma)构造运动,六期构造事件与研究区构造演化的动力学背景相吻合.其中白垩纪末期(87—62 Ma)的构造事件导致了柴达木盆地东部隆升并遭受剥蚀,欧龙布鲁克隆起形成雏形,柴达木盆地北缘在弱挤压环境下形成坳陷盆地;中新世末的两期构造事件(9.6—7.1 Ma和2.9—1.8 Ma)使柴达木盆地遭受强烈挤压,盆地快速隆升,构造变形强烈,基本形成现今的构造面貌. 相似文献
16.
David R Gray Martin Hand Richard A Armstrong Robert T Gregory 《Earth and Planetary Science Letters》2004,222(2):407-422
Poly-deformed and poly-metamorphosed glaucophane-eclogite mega-boudins beneath the Samail Ophiolite, Oman record an early subduction-related high-P metamorphism as well as subsequent overprinting deformation and metamorphism related to exhumation. Previously published Rb/Sr ages of 78 Ma and 40Ar/39Ar ages of 82-79 Ma record the major NE-directed shearing event that partially exhumed the eclogites to a shallower crustal level. New Sm/Nd garnet-garnet leachate-whole rock isochron data from garnet-bearing eclogite assemblages in the As Sifah subwindow in NE Oman are 110±9 Ma (DG02-87D); 5-point isochron) and 109±13 Ma (DG02-86E; 3-point isochron). On the basis of microfabric and field structural relationships these ages are interpreted to reflect the timing of prograde, peak high-P metamorphism in the rocks structurally beneath the Samail Ophiolite. This metamorphism clearly predates the age of formation of the obducted Samail oceanic lithosphere (97-94 Ma) as well as the subsequent obduction onto the margin (80-70 Ma). A U-Pb SHRIMP zircon age from small (<200 μm in length) zircons with herring-bone textured zoning from DG02-87D indicate that rapid zircon growth associated with high-Si phengites occurred at 82±1 Ma. Zircon growth is possibly related to liberation of Zr on garnet breakdown during decompression metamorphism under high-P conditions with exhumation. These data require that crustal stacking models attendant with ophiolite obduction are inappropriate to explain the Oman high-P metamorphism. 相似文献
17.
Barry J. Katz Christopher G.A. Harrison Eugene H. Man 《Earth and Planetary Science Letters》1979,44(2):279-286
The “second region” of the kinetic curve for the racemization (epimerization) of isoleucine in foraminifera is defined from previously published data corrected for the thermal history experienced by the samples. These kinetic parameters are applied to racemization data from Deep Sea Drilling Project Sites 332A and 333 from the Deep Drill Valley, Mid-Atlantic Ridge, and Site 148 from the Aves Ridge, in order to determine whether there are any observable effects due to the geothermal gradient. The data for Site 148 clearly show an increase of temperature with depth. The data for the two sites of the Mid-Atlantic Ridge do not show this clear relationship. When bottom water temperature variations are taken into consideration, the effects of the geothermal gradient become apparent. Since the degree of racemization is dependent upon both age and temperature, a knowledge of the age of a sample places constraints upon its thermal history, and hence on the heat flow at the location since deposition of the sample. The crude heat flow models thus developed are compatible with present geologic and geophysical information. It appears probable that detailed heat flow models may be developed by improving analytical precision. 相似文献
18.
The Dongfang 13-1 is located in the diapiric structure belt of the Yinggehai Basin. The formation pressure of its main gas reservoir in the Miocene Huangliu Formation is up to 54.6 MPa(pressure coefficient=1.91) and the temperature is as high as 143°C(geothermal gradient 4.36°C/100 m), indicating that it is a typical high-temperature and overpressured gas reservoir. The natural gas is interpreted to be coal-type gas derived from the Miocene mature source rocks containing type II2-III kerogens as evidenced by high dryness index of up to 0.98 and heavy carbon isotopes, i.e., the δ13C1 ranging from -30.76‰ to -37.52‰ and δ13C2 ranging from -25.02‰ to -25.62‰. The high temperature and overpressured Miocene petroleum system is related mainly to diapir in the Yinggehai Basin and contains more pore water in the overpressured reservoirs due to undercompaction process. The experimental and calculated results show that the solubility of natural gas in formation water is as high as 10.5 m3/m3 under the temperature and pressure conditions of the Sanya Formation, indicating that at least part of the gas may migrate in the form of water-soluble phase. Meanwhile, the abundant gas source in the Basin makes it possible for the rapid saturation of natural gas in formation water and exsolution of soluble gas. Therefore, the main elements controlling formation of the Dongfang 13-1 gas pool include that(1) the diapir activities and accompanying changes in temperature and pressure accelerate the water-soluble gas exsolution and release a lot of free gas;(2) submarine fan fine sandstone in the Huangliu Formation provides good gas-water segregation and accumulation space; and(3) the overlying overpressured mud rocks act as effective caps. The accumulation mechanism reveals that the high temperatural and high pressure structure belt near the diapir structures has a good potential for large and medium-sized gas field exploration. 相似文献
19.
南海北部深水区是中国重要的油气潜力区.本文在前人对其现今地温场和正演热史研究的基础上,利用磷灰石(U-Th)/He和镜质体反射率(Ro)数据对根据拉张盆地模型正演获得的热历史进行了进一步约束,并在此基础上对南海北部深水区的烃源岩热演化进行了研究.研究结果表明基于盆地构造演化模型的正演热历史可以作为烃源岩热演化计算的热史基础,而盆地内主力烃源岩热演化计算结果显示:南海北部深水区存在4个生烃中心,即珠江口盆地的白云凹陷和琼东南盆地的乐东凹陷、陵水凹陷和松南凹陷,生烃中心烃源岩有机质现今处于过成熟状态,以生气为主;受盆地基底热流显著升高的影响,32~23.3 Ma时段为南海北部深水区烃源岩快速成熟阶段,琼东南盆地烃源岩有机质现今(2.48 Ma后)还存在一期加速成熟过程,而珠江口盆地则不存在此期快速成熟过程. 相似文献
20.
Abstract Apatite and zircon fission track ages from Ryoke Belt basement in northeast Kyushu show late Cretaceous, middle to late Eocene, middle Miocene and Quaternary groupings. The basement cooled through 240 ± 25°C, the closure temperature for fission tracks in zircon, mainly during the interval 74-90 Ma as a result of uplift and denudation, the pattern being uniform across northeast Kyushu. In combination with published K-Ar ages and the Turonian-Santonian age of sedimentation in the Onogawa Basin, active suturing along the Median Tectonic Line from 100-80 Ma, at least, is inferred. Ryoke Belt rocks along the northern margin of Hohi volcanic zone (HVZ) cooled rapidly through ∼100°C to less than 50°C during the middle Eocene to Oligocene, associated with 2.5-3.5 km of denudation. The timing of this cooling follows peak heating in the Eocene-Oligocene part (Murotohanto subbelt) of the Shimanto Belt in Muroto Peninsula (Shikoku) inferred previously, and coincides with the 43 Ma change in convergence direction of the Pacific-Eurasian plate and the demise of the Kula-Pacific spreading centre. Ryoke Belt rocks along the southern margin of HVZ have weighted mean apatite fission track ages of 15.3 ± 3.1 Ma. These reset ages are attributed to an increase in geothermal gradient in the middle Miocene combined with rapid denudation and uplift of at least 1.4 km. These ages indicate that heating of the overriding plate associated with the middle Miocene start of subduction of hot Shikoku Basin lithosphere extended into the Ryoke Belt in northeast Kyushu. Pleistocene apatite fission track ages from Ryoke Belt granites at depth in the centre of HVZ are due to modern annealing in a geothermal environment. 相似文献