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1.
为揭示东喜马拉雅构造结那木拉断裂带上新世以来强烈活动特征,对采集自那木拉断裂带的三件基岩样品进行黑云母40Ar/39Ar、磷灰石裂变径迹两种热年代学方法测年;并利用"Pecube"软件对测得年龄数据及断裂带两侧已发表年龄数据进行定量模拟计算。测试结果显示黑云母40Ar/39Ar年龄范围为4.44±0.71 Ma~3.45±0.24 Ma,磷灰石裂变径迹年龄范围为3.7±0.4 Ma~1.8±0.2 Ma。年龄数据及其模拟计算结果表明,约3 Ma以前那木拉断裂带南侧地壳隆升最快,隆升速率约2.5 km/Ma,断裂带以正断层运动特征为主;约3 Ma以来那木拉断裂带北侧地壳隆升最快,约为1.3 km/Ma,断裂带以逆断层运动特征为主。那木拉断裂带运动特征变化可能与约8 Ma以来东喜马拉雅构造结快速地壳隆升剥露区域由南向北逐渐迁移有关。 相似文献
2.
准噶尔盆地周缘山脉抬升-剥露过程的FT证据 总被引：6，自引：3，他引：3
本文主要通过磷灰石裂变径迹测年结果结合温度.时间热模拟反演的研究,探讨准噶尔盆地周缘造山带的抬升.剥露作用过程及其差异性特征.研究结果表明,准噶尔周缘造山带自晚三叠世至新近纪至少经历三次大的抬升-剥露事件,结合样品位置分析,推测准噶尔盆地周缘造山带的抬升-剥露作用具有明显不均一特征.始于晚三叠-早侏罗世的山脉抬升作用范围有限,仅局限于准噶尔东北缘;但是,发生在中-晚白垩世(～115～95Ma)的这期构造抬升作用在盆地周缘的所有山系都有记录;古近纪早期(～60～50Ma)在准噶尔盆地北缘有一期隆升事件,但该事件也仅仅局限于盆地北缘;新近纪～25Ma以来发生在巴里坤(博格达山)的局部抬升冷却事件,仅仅局限于天山北缘,而此时准噶尔盆地的东西两侧山脉可能相对稳定.推测该期抬升事件应是印-亚碰撞的远程效应在天山地区的构造表现. 相似文献
3.
裂变径迹年代学测试表明,吉隆地区高喜马拉雅约30km的南北剖面上锆石裂变径迹年龄介于13～2.4Ma之间,磷灰石裂变径迹年龄介于1.9～0.6Ma之间;在空间上,裂变径迹年龄与高程及纬度都具有正相关关系。综合区域热年代学资料,裂变径迹年代学数据揭示出研究区高喜马拉雅经历了3个阶段的冷却剥露过程:①中新世中期至约13Ma,藏南拆离系(STDS)大规模伸展拆离作用引发的高喜马拉雅岩石区域性的构造剥露;②中新世晚期伴随STDS韧性变形的结束,缓慢冷却剥露阶段;③上新世前后,5.8～2.7Ma以来,快速并不断加速的冷却剥露作用。综合对比研究区构造地貌特征及热年代学空间格局,提出上新世以来高喜马拉雅快速并加速的剥露作用,是由流域以河流切蚀为代表的地表作用过程驱动。 相似文献
4.
通过对西昆仑北部山前的碎屑锆石裂变径迹年代学分析,将年龄划分为8个峰值区间:P1—4.7Ma以来;P2—13～9Ma;P3—24～18Ma;P4—47～33Ma;P5—79～57Ma;P6—131～103Ma;P7—185～180Ma;P8—267～235Ma,各峰值分布受阶段性抬升剥露和热事件共同影响。P8与P5主要受热事件控制,P6、P4、P3、P2、P1主要和抬升剥露有关,P7主控因素不明显。裂变径迹年龄峰值与西昆仑及邻区发生的一系列重大构造事件的时限吻合,并伴随强烈的区域性断裂活动,指示裂变径迹年龄峰值记录了西昆仑及邻区构造演化的重大事件;其中,晚白垩世以来喜马拉雅东、西构造结抬升具有相似性,反映了青藏高原自印度板块与欧亚大陆碰撞以来经历了相似的阶段性抬升。柯克亚连续沉积剖面显示西昆仑及邻区4.7Ma以来开始最后一次大规模抬升,并指示上新世以来西昆仑及邻区的径迹年龄储备表现出由多样性向一致性、由无规律向年轻化的发展趋势,暗示4.7Ma以来的抬升具整体抬升性质;3.6Ma为抬升的转折点,表现为抬升剥露速率加快、基底开始大规模出露地表,西昆仑山对南边的水流形成障碍。 相似文献
5.
东昆仑东段哈拉郭勒-哈图一带中生代的岩石隆升剥露--锆石和磷灰石裂变径迹年代学证据 总被引：4，自引：2，他引：4
根据对东昆仑地区东段哈拉郭勒—哈图一带不同高度基岩的系列锆石裂变径迹年龄分析，结合磷灰石裂变径迹年龄分析和中酸性侵入岩角闪石压力计分析揭示了东昆仑东段中生代的岩石隆升剥露冷却历史．巴隆哈图一带中酸性侵入岩角闪石压力计分析结果反映晚海西—印支期以来的总体剥露幅度约8～9km，早二叠世至晚三叠世初剥蚀作用极为缓慢，大约为20～40m／Ma．不同高程样品的锆石裂变径迹年龄分析结果揭示了东昆仑地区东段在中晚侏罗世处于缓慢的岩石隆升剥露阶段，其中中侏罗世相对较快，抬升速率77～88m／Ma，晚侏罗世相对较慢，抬升速率小于37m／Ma，且呈减慢趋势，这种减慢趋势反映了早中侏罗世之交强构造抬升期后的逐渐衰退．锆石裂变径迹—磷灰石裂变径迹年龄分析结果反映了中侏罗世以来的剥蚀速率一般不超过55m／Ma，岩石的剥蚀速率与岩石的抬升速率基本为同一量级，中侏罗世—白垩纪剥蚀作用与岩石抬升作用基本处于平衡状态。 相似文献
6.
宁武盆地及周缘岩体的抬升剥蚀对于山西地块中—新生代构造演化具有重要的指示意义。本文对宁武盆地及周缘岩体进行裂变径迹分析,磷灰石裂变径迹年龄97～47 Ma,锆石裂变径迹年龄161～141 Ma。裂变径迹记录了早白垩世早期(145～125 Ma)、晚白垩世(85～70 Ma)、古新世晚期—始新世早期(59～53 Ma)和渐新世晚期(28 Ma)的4次抬升剥蚀事件。综合分析山西地块的裂变径迹数据,表明隆起区晚古生代以来发生了多期抬升剥蚀事件。山西地块中—新生代构造演化具有时空差异。周缘岩体样品的裂变径迹年龄大于盆地内沉积地层样品的年龄,指示了周缘山体先于盆地抬升剥蚀。晋东北抬升剥蚀时限早于晋西南。山西裂谷系西南端裂开较早。裂谷系发育具有由南向北扩展的特征,这与地层保留记录相一致。山西地块现今地貌格局是在中生代发育一系列雁行状排列的复背斜和复向斜构造基础上发展而成的。 相似文献
7.
对青藏高原东南缘晚新生代抬升扩展的研究是联系青藏高原周缘陆内变形发展特征的重要问题.通过藏东南察隅地区的磷灰石裂变径迹分析揭示,自北向南的德姆拉岩体、阿扎贡拉岩体和察隅岩体受控于断裂构造而表现出的晚新生代差异抬升-剥露是高原向周缘扩展的一种指示.抬升-剥露的时序为15.1～13.7Ma、6.3～4.3Ma、3.5～3.3Ma、1.9～1.7Ma和1.1～1.0Ma.活动性总体上向南扩展和迁移.晚中新世(约6～5Ma)是岩体抬升-剥露速率出现转折的关键时期,在藏东南--滇西北地区具有区域响应,并可能奠定了现今青藏高原东南缘的地势发展格局.从青藏高原东北部到东南部,高原晚新生代陆内变形向周缘的扩展和增生表现出多阶段、准同时和不均衡的发展特性. 相似文献
8.
前人已经对西天山及邻区以及阿尔金断裂带进行了大量中—新生代隆升-剥露的研究工作,但对东天山地区的研究工作很少。天山造山带中—新生代期间的隆升-剥露过程是否具有均一性,目前仍没有确切的认识。为了获得东天山地区中生代以来的隆升-剥露信息,对吐哈盆地东南缘雅满苏地区磷灰石裂变径迹进行了研究。研究表明,在不同构造位置采集的花岗岩、砂岩、火山岩样品年龄集中分布在81~53Ma,样品年龄记录了东天山地区晚白垩世—古新世发生的冷却事件。磷灰石裂变径迹平均长度为13.60~14.36μm,接近于磷灰石初始径迹长度约14.5μm,表明径迹形成后没有发生过明显的退火作用。根据地温梯度计算得到东天山晚白垩世以来的平均隆升速率约为4.31×10-2 mm/a。进一步的热史模拟表明,晚白垩世—古新世(80~50Ma)期间东天山地区经历了一次隆升-剥露事件;始新世以后(50 Ma),东天山地区地壳处于稳定状态,东天山隆起带现在的构造面貌基本继承了中生代的特征。 相似文献
9.
喜马拉雅山脉新生代差异隆升的裂变径迹热年代学证据 总被引：2，自引：1，他引：2
裂变径迹年龄资料记录的雅鲁藏布江以南的喜马拉雅山脉的冷却年龄具有明显的时空差异性。在南北方向上,特提斯喜马拉雅的冷却年龄主要在8 Ma以前,局部为5.0~2.6 Ma,而高喜马拉雅的冷却年龄集中在5 Ma以后,大多数在3 Ma以来;在东西方向上体现在喜马拉雅东西构造结之间的高喜马拉雅带上,东喜马拉雅的不丹东部区域的裂变径迹热年代学数据揭示了8.0~3.0 Ma的冷却剥露的历史;东喜马拉雅的不丹西部区域为7.0~1.4 Ma;中喜马拉雅的尼泊尔地区为5.0~0.2 Ma;西喜马拉雅的印度西北部地区为3.0~1.0 Ma。最年轻的裂变径迹年龄显示出由中间向两侧增大,反映了地质晚近时期东西构造结间的高喜马拉雅山脉的剥露幅度由中间向两边减弱的趋势,揭示了以中喜马拉雅为隆升中心向两边拓展的趋势。综合有关裂变径迹年代学资料表明,喜马拉雅山脉的隆升主要发生在中新世以来,其表现为18~11 Ma、9 Ma以来的两个快速隆升期。喜马拉雅山脉隆升的动力体制可能由早期的挤压隆升—中新世的伸展隆升—上新世以来构造隆升为主,局部气候作用和构造作用耦合的山脉隆升机制。 相似文献
10.
11.
喜马拉雅造山带东构造结拉布拉多期和格林威尔期造山作用的记录 总被引：6，自引：6，他引：0
位于喜马拉雅东构造结西北部的南迦巴瓦复合体,是构造应力最强、隆升和剥蚀最快、新生代变质和深熔作用最强的地区。为厘定该地区早期的变质岩浆作用,本文对南迦巴瓦复合体北部的花岗片麻岩和混合岩进行了岩石学和年代学研究。花岗片麻岩原岩为富钾的偏铝质花岗岩,具有岩浆弧花岗岩的成分特征。花岗片麻岩中的锆石具有岩浆锆石的环带结构,记录了487.9±1.6Ma的一期构造岩浆事件;混合岩的锆石具有明显的核-边结构,核部和边部的不协和线交点年龄分别为1559±13Ma、1154±12Ma。对比印度大陆东部的西隆高原、东高止造山带,发现三者都经历了拉布拉多期、格林威尔期以及泛非期的造山作用。因此,我们认为喜马拉雅东构造结与这两个地区密切相关,可能是他们向北的延伸,这三者可能组成统一的印度大陆东部造山带,一起经历了哥伦比亚超大陆、Rodinia和冈瓦纳超大陆的聚合与裂解过程。 相似文献
12.
GEOTECTONIC OF NAMCHE BARWA SYNTAXIS IN EAST TIBET, CHINA 相似文献
13.
The Eastern Himalayan Syntaxis of Namche Barwa carries critical information for understanding the geodynamies of the Indian-Asian collision. In this syntaxis, the Nyingchi Group is a sequence of medium-high grade metasediments, located on the north side of the Indus-Yarlung Suture Zone. 相似文献
14.
西藏南部南迦巴瓦地区中新世-上新世地壳深熔作用 总被引：1，自引：0，他引：1
位于喜马拉雅东构造结的南迦巴瓦地块经历了复杂的构造变形、强烈的变质和深熔作用,是研究碰撞造山过程中地壳深熔作用的重要对象。完整地厘定新生代晚期岩浆作用期次对于揭示南迦巴瓦地区的构造演化历史和深部过程具有重要意义。南迦巴瓦地块3件淡色花岗岩样品的锆石U-Pb定年结果显示该地块经历了11.30±0.16Ma和2.59±0.04Ma两期地壳深熔作用,可能与南迦巴瓦地块晚新生代快速隆升和剥蚀相关。南迦巴瓦地块保存了大量的~11Ma变质作用和地壳深熔作用记录指示该时间段为构造活动剧烈期。上新世晚期的淡色花岗岩表明,穹窿的隆升和剥蚀所导致的岩浆作用至少持续到了~2.59Ma,代表了南迦巴瓦地区一次年轻的构造岩浆事件。 相似文献
15.
The origin of the Greater Himalayan Sequence in the Himalaya and the paleogeographic position of the Lhasa terrane within Gondwanaland remain controversial. In the Eastern Himalayan syntaxis, the basement complexes of the northeastern Indian plate (Namche Barwa Complex) and the South Lhasa terrane (Nyingchi Complex) can be studied to explore these issues. Detrital zircons from the metasedimentary rocks in the Namche Barwa Complex and Nyingchi Complex yield similar U–Pb age spectra, with major age populations of 1.00–1.20 Ga, 1.30–1.45 Ga, 1.50–1.65 Ga and 1.70–1.80 Ga. The maximum depositional ages for their sedimentary protoliths are ~ 1.0 Ga based on the mean ages of the youngest three detrital zircons. Their minimum depositional ages are ~ 477 Ma for the Namche Barwa Complex and ~ 499 Ma for the Nyingchi Complex. Detrital zircons from the Namche Barwa Complex and Nyingchi Complex also display similar trace-element signatures and Hf isotopic composition, indicating that they were derived from common provenance. The trace-element signatures of 1.30–1.45 Ga detrital zircons indicate that the 1.3–1.5 Ga alkalic and mafic rocks belt in the southeastern India is a potential provenance. Most 1.50–1.65 Ga zircons have positive εHf(t) values (+ 1.2 to + 9.0), and most 1.70–1.80 Ga zircons have negative εHf(t) values (− 7.1 to − 1.9), which are compatible with those of the Paleo- to Mesoproterozoic orthogneisses in the Namche Barwa Complex. Provenance analysis indicates that the southern Indian Shield, South Lhasa terrane and probably Eastern Antarctica were the potential detrital sources. Combined with previous studies, our results suggest that: (1) the Namche Barwa Complex is the northeastern extension of the Greater Himalaya Sequence; (2) the metasedimentary rocks in the Namche Barwa Complex represent distal deposits of the northern Indian margin relative to the Lesser Himalaya; (3) the South Lhasa terrane was tectonically linked to northern India before the Cambrian. 相似文献
16.
Within the Namche Barwa area, SE Tibet, the Indus–Yarlung suture zone separates the Lhasa terrain in the north from the Himalayan unit including the Tethyan (sedimentary and volcanic rocks), Dongjiu (greenschist to lower amphibolite facies), Namche Barwa (granulite facies), Pei (amphibolite facies) and Laiguo (greenschist facies) sequences in the south. Two fault systems were distinguished in the Namche Barwa area. The former includes a top-down-to-the-north normal fault in the north and two top-to-the-south thrust zones in the south named as Upper and Lower Thrusts, respectively. The Namche Barwa and Pei sequences were exhumed southwards from beneath the Dongjiu sequence by these faults. Thus, the fault system is regarded as a southward extrusion structure. Subsequently, the exposed Dongjiu, Namche Barwa, Pei and Laiguo sequences were displaced northwards onto the Lhasa terrain by the top-to-the-north fault system, thus, marking it as northward indentation structure. Monazite TIMS U–Pb dating demonstrates that the normal fault and the Lower Thrust from the southward extrusion system were probably active at ~ 6 Ma and ~ 10 Ma, respectively. Zircon U–Pb SHRIMP and phlogopite K–Ar ages further suggest that the Upper Thrust was active between 6.2 ± 0.2 Ma and 5.5 ± 0.2 Ma. The northward indentation structures within the core portion of the eastern Himalayan syntaxis were perhaps active between 3.0 Ma and 1.5 Ma, as inferred by published zircon U–Pb SHRIMP and hornblende Ar–Ar ages. The monazite from upper portions of the Pei sequence dated by U–Pb TIMS indicates that the precursor sediments of this sequence were derived from Proterozoic source regions. Nd isotopic data further suggest that all the metamorphic rocks within eastern Himalaya (εNd = ? 13 to ? 19) correlate closely with those from the Greater Himalayan Sequences, whereas the western Himalayan syntaxis is mainly comprised of Lesser Himalayan Sequences. The two indented corners of the Himalaya are, thus, different. 相似文献
17.
Zeming Zhang Xin DongM. Santosh Feng LiuWei Wang Fei YiuZhenyu He Kun Shen 《Gondwana Research》2012,21(1):123-137
The Namche Barwa Complex (NBC) in the eastern Himalayan syntaxis, south Tibet, is generally interpreted as the north-eastern extremity of the exposed Greater Himalayan Sequence, comprising Neoproterozoic to early Paleozoic sedimentary strata along the northern margin of the Indian continent. Field and petrological investigations indicate that the NBC consists mainly of orthogneiss, paragneiss, amphibolites and calc-silicate rocks. U-Pb zircon data demonstrate that the protoliths of the orthogneiss formed during late Paleoproterozoic at ca. 1610 Ma and also in early Paleozoic at ca. 490-500 Ma. The amphibolites were derived from mafic magmatic rocks formed during 1645 to 1590 Ma. Zircons in the paragneisses have highly variable inherited zircon ages ranging from the Neoarchean to early Paleozoic, with four major age populations of 2490 Ma, 1640 Ma, 990 Ma and 480 Ma. The calc-silicate rock has zircons with early Paleozoic metamorphic age of 538 Ma. Almost all the rocks of the NBC have been metamorphosed during Cenozoic with the metamorphic zircon U-Pb ages ranging from 8 to 30 Ma and a peak at 23 Ma. These, together with previous results suggest that the NBC was originally derived from an Andean-type orogeny following the Columbia supercontinent assembly, and experienced multiple reworking during the Grenvillian, Pan-African and Himalayan orogenies. We conclude that the NBC in the eastern Himalayan syntaxis was derived from different provenance and tectonic setting as compared to those of the Greater Himalayan Sequence which constitutes the high-grade metamorphic core of the western and central Himalayan orogenic belt. We thus infer that the NBC was originally part of the eastern segment of the Central Indian Tectonic Zone. 相似文献
18.
环东冈瓦纳大陆周缘的古生代造山作用:东喜马拉雅构造结南迦巴瓦岩群的岩石学和年代学证据 总被引：25，自引：15，他引：10
喜马拉雅造山带东端的南迦巴瓦岩群是高喜马拉雅结晶岩系的一部分,主要由麻粒岩相和角闪岩相变质的片麻岩、斜长角闪岩、片岩和钙硅酸盐岩组成.长英质片麻岩主要由斜长石、钾长石、石英、石榴石、黑云母和褐帘石组成.片麻岩中的锆石具有核一边结构,由一个大的继承岩浆核和一个窄的变质生长边组成.锆石岩浆核具同心韵律环带.其REE配分模式以HREE富集和负Eu异常为特征,并具有高的Th/U比值.锆石U-Pb年代分析表明,这种继承岩浆锆石给出的加权平均年龄为490～500Ma.地球化学特征表明,这些片麻岩的原岩是花岗岩和花岗闪长岩,形成在俯冲带的岩浆弧构造环境.钙硅酸盐岩中的锆石具有高级变质岩中变质生长锆石的典型特征,即具有相对较低的REE含量,不明显的负Eu异常和较低的Th/U比值.变质锆石所获得的U-Pb加权平均年龄为505Ma.本文和现有的研究结果表明,喜马拉雅造山带是一个复合造山带,它经历了古生代的原始造山作用,在新生代印度与欧亚板块的碰撞过程中发生了再造山作用.喜马拉的古生代造山带作用是原特提斯洋向冈瓦纳大陆北缘俯冲和亚洲微陆块(包括拉萨和羌塘地块)增生的结果,是在冈瓦纳大陆拼合之后其边缘发生的安底斯型造山作用,因此,它并不属于在冈瓦纳超大陆聚合过程中陆-陆碰撞形成的泛非造山带. 相似文献
19.
Walter Kurz Andreas Wölfler Robert Rabitsch Johann Genser 《Swiss Journal of Geoscience》2011,104(2):323-343
The Lavanttal Fault Zone (LFZ) is generally considered to be related to Miocene orogen-parallel escape tectonics in the Eastern
Alps. By applying thermochronological methods with retention temperatures ranging from ~450 to ~40°C we have investigated
the thermochronological evolution of the LFZ and the adjacent Koralm Complex (Eastern Alps). 40Ar/39Ar dating on white mica and zircon fission track (ZFT) thermochronology were carried out on host rocks (HRs) and fault-related
rocks (cataclasites and fault gouges) directly adjacent to the unfaulted protolith. These data are interpreted together with
recently published apatite fission track (AFT) and apatite (U-Th)/He ages. Sample material was taken from three drill cores
transecting the LFZ. Ar release spectra in cataclastic shear zones partly show strongly rejuvenated incremental ages, indicating
lattice distortion during cataclastic shearing or hydrothermal alteration. Integrated plateau ages from fault rocks (~76 Ma)
are in parts slightly younger than plateau ages from HRs (>80 Ma). Incremental ages from fault rock samples are in part highly
reduced (~43 Ma). ZFT ages within fault gouges (~65 Ma) are slightly reduced compared to the ages from HRs, and fission tracks
show reduced lengths. Combining these results with AFT and apatite (U-Th)/He ages from fault rocks of the same fault zone
allows the recognition of distinct faulting events along the LFZ from Miocene to Pliocene times. Contemporaneous with this
faulting, the Koralm Complex experienced accelerated cooling in Late Miocene times. Late-Cretaceous to Palaeogene movement
on the LFZ cannot be clearly proven. 40Ar/39Ar muscovite and ZFT ages were probably partly thermally affected along the LFZ during Miocene times. 相似文献
20.
The Kohistan Arc Complex is an integral part of the NW Himalayan collision system and is bounded by two major suture zones, the Indus Suture Zone (ISZ) and the Northern Suture in the south and north respectively. Fission‐track analyses on samples collected along the Indus River across the arcuated ISZ in the Besham region are presented here. The footwall yields zircon and apatite fission‐track (FT) ages of ∼23 Ma and ∼3.7 Ma respectively; the hanging wall ages range from 24 to 42 Ma for zircon and ∼10 Ma for apatite. Thus, the change in ISZ kinematics from thrusting to normal faulting was not later than Oligocene and normal faulting on this ISZ segment was still active at least into early Pliocene times. At this time normal faulting had already ended at other ISZ segments, but it was still (or again) active across the ISZ in the Besham region most likely as a local phenomenon caused by the growth of the Indus Syntaxis, a transverse antiform parallel to the Nanga Parbat Syntaxis. 相似文献