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1.
Data supporting relevant Late Cretaceous–Early Eocene sinistral displacement along the Giudicarie fault zone and a minor Neogene dextral displacement along the Periadriatic lineament are discussed. The pre-Adamello structural belt is present only in the internal Lombardy zone, located W of the Adamello massif. This belt is unknown in the Dolomites and surrounding areas located to the E of the Giudicarie lineament. Upper Cretaceous–Early Eocene thick syntectonic Flysch deposits of Lombardy and Giudicarie are well preserved along the southern and eastern border of the pre-Adamello belt (S-vergent Alpine orogen). Towards the E, in the Dolomites and in the Carnic Alps and external Dinarides, only incomplete remnants of Flysch deposits, Aptian–Albian and Turonian–Maastrichtian in age, are present. They can be considered as equivalent to those of Lombardy and Giudicarie formerly in connection to each other along the N-Giudicarie corridor. To the S, the syntectonic Flysch deposits are laterally replaced by the calcareous red pelagites of the Scaglia Rossa and by the carbonate shelf deposits of the Friuli (to the E) and Bagnolo (to the S) carbonate platforms. The different location in the southern structural accretion of the eastern and western opposite blocks (the Dolomites versus the pre-Adamello belt) can be related to the Cretaceous–Eocene convergence. In this frame, the N-Giudicarie fault has been considered as part of a former transfer zone, which produced the sinistral lateral displacement of the Southern Alps front for an amount of some 50 km. During the Late Eocene to Early Oligocene the transfer zone was mostly sealed by the Paleogene Adamello batholith. Oligocene to Neogene compressional evolution inverted the N-Giudicarie fault into a backthrust of the Austroalpine units over the South-Alpine chain. 相似文献
2.
The Neogene kinematics of the Giudicarie fault (part of Periadriatic lineament, NE Italy) have been re-examined using apatite fission-track analysis. Twenty samples were collected along two geological sections; the first one crossing the Tertiary Corno Alto pluton (Adamello batholith) and the Variscan basement (Southalpine domain) adjacent to the South Giudicarie fault, the second one close to the North Giudicarie fault, in the Variscan basement of the Tonale nappe (Austroalpine system). Samples from the southern section show short tracks and ages between 14.7±1.2 Myr and 22.5±2.2 Myr along 1570 m of the profile; samples from the northern profile present long tracks and ages between 11.3±1.3 Myr and 14.7±3.4 Myr along 1225 m of the vertical profile. In the former, the presence of short tracks might indicate either a long permanence of the rocks in the apatite partial annealing zone, or a more complex thermal history; in the latter case we are dealing with rocks which experienced more rapid cooling.
The two differing segments of the Giudicarie fault can be explained either as two completely independent tectonic features or, more likely, by hypothesizing a single fault active in its southern and northern parts at different times. Fission track data support a first exhumation of this single fault c. 15 Ma along the North Giudicarie, with a final exhumation towards the south, in the Adamello area, at c. 8–10 Ma (Mid Tortonian). This age fits with the so-called 'Giudicarie' phase, during which σ1 in the stress field was orientated N280–290°. 相似文献
The two differing segments of the Giudicarie fault can be explained either as two completely independent tectonic features or, more likely, by hypothesizing a single fault active in its southern and northern parts at different times. Fission track data support a first exhumation of this single fault c. 15 Ma along the North Giudicarie, with a final exhumation towards the south, in the Adamello area, at c. 8–10 Ma (Mid Tortonian). This age fits with the so-called 'Giudicarie' phase, during which σ
3.
Wei‐Qiang Ji Marco G. Malus Massimo Tiepolo Antonio Langone Liang Zhao Fu‐Yuan Wu 《地学学报》2019,31(2):120-128
Periadriatic Alpine magmatism has long been attributed to slab breakoff after Adria–Europe continental collision, but this interpretation is challenged by geophysical data suggesting the existence of a continuous slab. Here, we shed light on this issue based on a comprehensive dataset of zircon U–Pb ages and Hf isotopic compositions from the main western Periadriatic intrusives (from Traversella to Adamello). Our zircon U–Pb data provide the first evidence of Eocene magmatism in the Western Alps (42–41 Ma in Traversella), and demonstrate that magmatism started synchronously in different segments of the Alpine belt, when subduction was still active. Zircon U–Pb ages define younging trends perpendicular to the strike of the European slab, suggesting a progressive Eocene–Oligocene slab steepening. We propose that slab steepening enhanced the corner flow. This process was more effective near the torn edge of the European slab, and triggered Periadriatic magmatism in the absence of slab breakoff. 相似文献
4.
The Novate intrusion is a Late Alpine leucogranite that intruded the structures related to dextral back‐thrusting along the Periadriatic Fault System in the Eastern Central Alps. The Novate granite was heterogeneously deformed from amphibolite to greenschist facies conditions during cooling of the intrusion. The deformation inside the granite is characterized by strongly localized and anastomosed ductile shear zones surrounding lenses of weakly deformed granite and by late faults formed at the brittle–ductile transition. The fault kinematic analysis of conjugated shear zones suggests that the Novate leucogranite was emplaced at 25 Ma in an extensional regime along the southern tip of the Forcola Fault. A model of extensional jog opening by vertical shearing along the Forcola Fault provided the space for magma accommodation. The Novate granite is the first evidence for orogen‐parallel syn‐extensional leucogranite emplacement during the Oligocene collision in the Alps. 相似文献
5.
Wolfgang Müller Giacomo Prosser Neil S. Mancktelow Igor M. Villa Simon P. Kelley Giulio Viola Felix Oberli 《International Journal of Earth Sciences》2001,90(3):623-653
Fault rocks from various segments of the Periadriatic fault system (PAF; Alps) have been directly dated using texturally controlled Rb-Sr microsampling dating applied to mylonites, and both stepwise-heating and laser-ablation 40Ar/39Ar dating applied to pseudotachylytes. The new fault ages place better constraints on tectonic models proposed for the PAF, particularly in its central sector. Along the North Giudicarie fault, Oligocene (E)SE-directed thrusting (29-32 Ma) is currently best explained as accommodation across a cogenetic restraining bend within the Oligocene dextral Tonale-Pustertal fault system. In this case, the limited jump in metamorphic grade observed across the North Giudicarie fault restricts the dextral displacement along the kinematically linked Tonale fault to ~30 km. Dextral displacement between the Tonale and Pustertal faults cannot be transferred via the Peio fault because of both Late Cretaceous fault ages (74-67 Ma) and sinistral transtensive fault kinematics. In combination with other pseudotachylyte ages (62-58 Ma), widespread Late Cretaceous-Paleocene extension is established within the Austroalpine unit, coeval with sedimentation of Gosau Group sediments. Early Miocene pseudotachylyte ages (22-16 Ma) from the Tonale, Pustertal, Jaufen and Passeier faults argue for a period of enhanced fault activity contemporaneous with lateral extrusion of the Eastern Alps. This event coincides with exhumation of the Penninic units and contemporaneous sedimentation within fault-bound basins. 相似文献
6.
《Journal of Structural Geology》1999,21(8-9):1103-1108
Resolution of the `Paleomagnetic dilemma', the discrepancy between large paleomagnetically determined dextral displacement of outboard portions of the northern Cordillera, and much smaller offsets implied by mapping and stratigraphic correlations, is fundamental to understanding the tectonic evolution of the Cordillera. This paper presents structural orientation data from the middle Cretaceous Dawson Range batholith of west central Yukon and its wallrocks, and suggests that some of the `missing' displacement may be found in intrusions. The elongate northwest-trending batholith has a margin-parallel foliation, a sub-horizontal stretching lineation, and records syn-intrusive dextral shearing. In country rocks adjacent to the batholith, north-trending lineations are deflected clockwise into near parallelism with the batholith's margins; lineations from wallrock screens within the batholith are all aligned parallel with the batholith's long axis. The Big Creek strike-slip fault forms the north-margin of the batholith and accommodated a minimum of 20 km of dextral slip. These observations imply that the batholith invaded an active dextral shear zone, accommodated shearing while crystallizing, and focused post-crystallization fault development. The batholith is conservatively estimated to have accommodated 45 km of syn-intrusive shearing. Collectively, middle Cretaceous intrusions of the northern Cordillera may account for >400 km of previously unrecognized dextral displacement. 相似文献
7.
ZHANG Jin YUN Long ZHANG Beihang QU Junfeng ZHAO Heng HUI Jie WANG Yannan ZHANG Yiping 《《地质学报》英文版》2020,94(4):988-1006
How the Altyn Tagh fault(ATF) extends eastwards is one of the key questions in the study of the growth of the Qinghai–Tibetan Plateau. Detailed fieldwork at the easternmost part of the ATF shows that the ATF extends eastward and bypasses the Kuantan Mountain; it does not stop at the Kuantan Mountain, but connects with the northern Heishan fault in the east. The ATF does not enter the Alxa Block but extends eastward along the southern Alxa Block to the Jintanan Mountain. The Heishan fault is not a thrust fault but a sinistral strike-slip fault with a component of thrusting and is a part of the ATF. Further to the east, the Heishan fault may connect with the Jintananshan fault. A typical strike-slip duplex develops in the easternmost part of the ATF. The cut and deformed Quaternary sediments and displaced present gullies along the easternmost ATF indicate that it is an active fault. The local highest Mountain(i.e., the Kuantan Mountain) in the region forms in a restraining bend of the ATF due to the thrusting and uplifting. The northward growth of the Qinghai–Tibetan Plateau and the active deformation in South Mongolia are realized by sinistral strike-slipping on a series of NE–SW-trending faults and thrusting in restraining bends along the strike-slip faults with the northeastward motion of blocks between these faults. 相似文献
8.
9.
Brittle–ductile–brittle deformation during cooling of tonalite (Adamello, Southern Italian Alps) 总被引：1，自引：0，他引：1
Late- to post-magmatic deformation in slightly diachronous contiguous intrusions of the north-western Adamello batholith (Southern Alps, Italy) is recorded as, from oldest to youngest: (i) joints, (ii) solid-state ductile shear zones, (iii) faults associated with epidote-K-feldspar veins and (iv) zeolite veins and faults. Structures (ii) to (iv) are localized on the pervasive precursory network of joints (i), which developed during the earliest stages of pluton cooling. High temperature ( 500 °C), ductile overprinting of joints produced lineations, defined by aligned biotite and hornblende, on the joint surfaces and highly localized mylonites. The main phase of faulting, producing cataclasites and pseudotachylytes, occurred at 250 °C and was associated with extensive fluid infiltration. Cataclasites and pseudotachylytes are clustered along different E–W-striking dextral strike-slip fault zones correlated with the activity of the Tonale fault, a major tectonic structure that bounds the Adamello batholith to the north. Ductile deformation and cataclastic/veining episodes occurred at P = 0.25–0.3 GPa during rapid cooling of the batholith to the ambient temperatures ( 250 °C) that preceded the exhumation of the batholith. Timing of the sequence of deformation can be constrained by 39Ar–40Ar ages of 30 Ma on pseudotachylytes and various existing mineral ages. In the whole composite Adamello batholith, multiple magma pulses were intruded over the time span 42–30 Ma and each intrusive body shows the same ductile-to-brittle structural sequence localized on the early joint sets. This deformation sequence of the Adamello might be typical of intrusions undergoing cooling at depths close to the brittle–ductile transition. 相似文献
10.
We present in this paper some new evidence for the change during the Quaternary in kinematics of faults cutting the eastern margin of the Tibetan Plateau. It shows that significant shortening deformation occurred during the Early Pleistocene, evidenced by eastward thrusting of Mesozoic carbonates on the Pliocene lacustrine deposits along the Minjiang upstream fault zone and by development of the transpressional ridges of basement rocks along the Anninghe river valley. The Middle Pleistocene seems to be a relaxant stage with local development of the intra-mountain basins particularly prominent along the Minjiang Upstream and along the southern segment of the Anninghe River Valley. This relaxation may have been duo to a local collapse of the thickened crust attained during the late Neogene to early Pleistocene across this marginal zone. Fault kinematics has been changed since the late Pleistocene, and was predominated by reverse sinistral strike-slip along the Minshan Uplift, reverse dextral strike-slip on the Longmenshan fault zone and pure sinistral strike-slip on the Anninghe fault. This change in fault kinematics during the Quaternary allows a better understanding of the mechanism by which the marginal ranges of the plateau has been built through episodic activities. 相似文献
11.
Neil S. Mancktelow Daniel F. Stöckli Balz Grollimund Wolfgang Müller Bernhard Fügenschuh Giulio Viola Diane Seward Igor M. Villa 《International Journal of Earth Sciences》2001,90(3):593-622
Alpine deformation of Austroalpine units south of the Tauern window is dominated by two kinematic regimes. Prior to intrusion of the main Periadriatic plutons at ~30 Ma, the shear sense was sinistral in the current orientation, with a minor north-side-up component. Sinistral shearing locally overprints contact metamorphic porphyroblasts and early Periadriatic dykes. Direct Rb-Sr dating of microsampled synkinematic muscovite gave ages in the range 33-30 Ma, whereas pseudotachylyte locally crosscutting the mylonitic foliation gave an interpreted 40Ar-39Ar age of ~46 Ma. The transition from sinistral to dextral (transpressive) kinematics related to the Periadriatic fault occurred rapidly, between solidification of the earlier dykes and of the main plutons. Subsequent brittle-ductile to brittle faults are compatible with N-S to NNW-SSE shortening and orogen-parallel extension. Antithetic Riedel shears are distinguished from the previous sinistral fabric by their fine-grained quartz microstructures, with local pseudotachylyte formation. One such pseudotachylyte from Speikboden gave a 40Ar-39Ar age of 20 Ma, consistent with pseudotachylyte ages related to the Periadriatic fault. The magnitude of dextral offset on the Periadriatic fault cannot be directly estimated. However, the jump in zircon and apatite fission-track ages establishes that the relative vertical displacement was ~4-5 km since 24 Ma, and that movement continued until at least 13 Ma. 相似文献
12.
渤海湾盆地是一个在早白垩世被动裂陷盆地基础上发育起来的新生代主动裂陷盆地, 走滑作用贯穿始终, 特别是在兰聊-盐山断层以东, 使这个裂陷盆地具有鲜明的走滑特征。伸展和走滑作用此消彼长, 伸展构造和走滑构造相互叠加、转换, 垂向上相互叠置、交切, 并由此导致变换带的产生。晚中生代以来太平洋板块向欧亚板块俯冲的方向和速度变化、后撤以及板片窗效应、中始新世印欧板块碰撞导致的地幔上涌是控制盆地形成的深部背景, 郯庐断裂带早白垩世强烈的左行走滑、古新世-早始新世弱的左行走滑以及中始新世后的右行走滑活动也深刻地控制和影响着盆地的发育, 盆地内晚中生代-新生代的伸展和走滑构造的演化则是其浅部响应, 并由此控制着岩浆活动以及油气生成、运聚和分布的时空迁移。 相似文献
13.
14.
《International Geology Review》2012,54(3):302-312
Porphyry Cu (Mo–Au) deposits in the Himalayan–Tibetan orogen formed during the Late Triassic, Early Cretaceous, Eocene, Oligocene, and Miocene and can be classified into different metallogenic belts according to their petrologic features, mineralization ages, and tectonic settings. A close spatial relationship to regional strike–slip faults is evident in all five belts. Porphyry Cu (Mo–Au) deposits exist in a wide range of tectonic environments, including island arc, syn-collision, post-collisional convergence, and continental-transform plate boundaries. Porphyry Cu deposits cluster in the southernmost part of the Yidun–Zhongdian Belt, along the N–S-trending Gaze River dextral strike–slip fault. Porphyry Cu deposits in the Lijiang–Jinping Belt lie along the Ailaoshan–Red River continental–transform shear zone and the associated strike–slip faults. The Yulong–Malasongduo porphyry belt is controlled by the Cesuo Fault, a NNW-trending regional dextral transcurrent fault that is associated with Palaeogene westward continental oblique subduction along the Jinsha suture. In the Gangdis Belt, Miocene porphyry Cu deposits are localized along N–S-trending normal faults, which were produced by transpression within the regional NW–SE-trending Karakoram–Jiali fault zone (KJFZ). A close spatial relationship between porphyry Cu deposits and strike–slip faults also exists for the Bangong–Nujiang Belt. 相似文献
15.
在甘肃北山一个东西向展布、椭圆状的晚古生代花岗岩体内主要发育着3期岩墙群,其中中期基性岩墙群最密集,呈现出弧形展布的特征,在该侵入体北部呈北北东向趋势,向南逐渐偏转为北北西向。关于中期岩墙群弧形展布的原因有两种可能的解释,即:纵弯褶皱和应力场扰动。野外观察不支持第一种解释,因为在岩墙或围岩内都没有观察到与褶皱有关的变形构造。本文利用Poly3D软件模拟了近东西向隐伏断层活动对上覆应力场的扰动。计算结果表明,当北北西—南南东向的区域性拉张叠加上沿着隐伏断层发生不协调的右行走滑时,水平大主压应力迹线在隐伏断层上方出现类似的弧形展布。这意味着稍早的花岗岩侵入体冷凝冷却并没有完全焊接地壳内一些大尺度断层,地壳断块的相对独立活动可以造成沿着这些断层发生与区域变形场不协调的右行走向滑动,进而形成岩墙群弧形展布所需要的地应力场。 相似文献
16.
《International Geology Review》2012,54(1):43-65
Porphyry copper deposits sometimes form during the solidification of stocks of relatively oxidized magma of intermediate composition. Most workers have assumed ore-forming systems have special chemical attributes, but none has been found that is useful to guide exploration efforts. Stocks can form where strike–slip movements generate pull-apart pathways into which intrusions can rise from batholithic magma chambers. Upwelling of buoyant, bubble-bearing magma along the sides of a stock brings magmatic fluid to shallow depths where large bubbles can separate and pool under the cupola separating solidified igneous rock from mobile magma. Where rapid seismogenic movement on the bounding strike–slip fault ruptures the solidified, but hot and ductile carapace, downward propagating extension fractures can drain an accumulation of magmatic fluid. Decompression and cooling of fluid that jets upward into extension fractures causes mineral precipitation. Where strike–slip movements cause pull-aparts to dilate with sufficient recurrences – from decades to perhaps a century or so, throttling of the fluid accumulation acts as a safety valve that prevents explosive detonation of the system. Concurrently, the upward infiltration of magmatic fluid from the cupola is strongly focused into the pull-apart and generates the characteristic concentric alteration zones that guide exploration drilling. We conclude that porphyry copper ore deposits form where strike–slip movements are concurrent with the early stages of deep-seated bubbling (?6 km) along the walls of a rapidly cooling stock of magma. Supergiant deposits form where the bubbling front extends into the top of a parent batholith. 相似文献
17.
Paolo D’Adda Andrea Zanchi Maria Bergomi Fabrizio Berra Marco G. Malusà Annalisa Tunesi Stefano Zanchetta 《International Journal of Earth Sciences》2011,100(5):1095-1113
The Triassic succession of the central Southern Alps (Italy) is stacked into several units bounded by south-verging low-angle
thrust faults, which are related to two successive steps of crustal shortening. The thrust surfaces are cut by high-angle
extensional and strike-slip faults, which controlled the emplacement of hypabissal magmatic intrusions that post-date thrusts
motions. Intrusion ages based on SHRIMP U–Pb zircon dating span between 42 ± 1 and 39 ± 1 Ma, suggesting close time relationships
with the earliest Adamello intrusion stages and, more in general, with the widespread calc-alkaline magmatism described in
the Southern Alps. Fission-track ages of magmatic apatites are indistinguishable from U–Pb crystallization ages of zircons,
suggesting that the intrusion occurred in country rocks already exhumed above the partial annealing zone of apatite (depth < 2–4 km).
These data indicate that the central Southern Alps were already structured and largely exhumed in the Middle Eocene. Although
we describe minor faults affecting magmatic bodies and local reactivations of older structures, no major internal deformations
have occurred in the area after the Bartonian. Neogene deformations were instead concentrated farther south, along the frontal
part of the belt. 相似文献
18.
19.
THREE-DIMENSIONAL DEFORMATION ALONG THE ALTYN TAGH FAULT ZONE AND UPLIFT OF THE ALTYN MOUNTAIN, NORTHERN TIBET 相似文献
20.
WANG Yu Institute of Geology China Seismological Bureau Beijing China YANG Tiannan Institute of Geology Chinese Academy of Geological Sciences Beijing China 《Continental Dynamics》1999,(1)
１．ＩｎｔｒｏｄｕｃｔｉｏｎＦｉｇ．１． ＴｅｃｔｏｎｉｃｐｏｓｉｔｉｏｎｏｆｔｈｅＤａｂｉｅｏｒｏｇｅｎｉｃｂｅｌｔａｎｄＴａｎＬｕｆａｕｌｔｉｎｅａｓｔｅｒｎＣｈｉｎａ ＴｈｅＤａｂｉｅｏｒｏｇｅｎｉｃｂｅｌｔａｎｄＴａｎＬｕｓｔｒｉｋｅｓｌｉｐｆａｕｌｔａｒｅｓｉｔｕａｔｅｄｉｎｃｅｎｔｒａｌａｎｄｅａｓｔｅｒｎＣｈｉｎａ,ｒｅｓｐｅｃｔｉｖｅｌｙ（Ｆｉｇ．１）．Ｔｈｅｉｒｅｖｏｌｕｔｉｏｎａｒｙｐｒｏｃｅｓｓｅｓ,ｒｅｌａｔｅｄｔｏｔｈｅａｄｊａｃｅｎｔｇｅｏｌｏｇｉｃｂｌｏｃ… 相似文献