Evidence of Mesozoic multiple hydrothermal activity in the basement at Nonnenmattweiher (southern Schwarzwald), Germany

Two botryoidal hematites from the qtz-fl-hem veins at the Nonnenmattweiher cirque (zone of Badenweiler-Lenzkirch, Südschwarzwald) were dated using the (U + Th)-He method. One hematite gives an Early Triassic age (234 ± 5 Ma) and the second straddles the Cretaceous/Jurassic time boundary (126 ± 4 Ma). The ages bracket the ∼entire age spectrum reported to date for Mesozoic vein-type mineralizations in the Schwarzwald. The maximum sedimentary overburden and associated palaeo-temperatures (>130 °C) in the basement of the southern Schwarzwald during the Jurassic did not cause severe age-resetting of the hematites. This implies that both ages probably are formation ages rather than ages of cooling, provided that the ⁴He retentivities of both hematites are similar. The fact that two hematites from the veins at Nonnenmattweiher yield highly discordant Mesozoic ages suggests multiple hydrothermal activity during the Mesozoic. A previously published age of two adularia (∼155 Ma), intermediate between the hematite ages, supports this view. Received: 1 February 1996 / Accepted: 6 September 1996     

Fission track data from the Bathurst Batholith: Evidence for rapid mid‐Cretaceous uplift and erosion within the eastern highlands of Australia

Apatite fission track thermochronology reveals that uplift and erosion occurred during the mid‐Cretaceous within the Bathurst Batholith region of the eastern highlands, New South Wales. Apatite fission track ages from samples from the eastern flank of the highlands range between ca 73 and 139 Ma. The mean lengths of confined fission tracks for these samples are > 13 μm with standard deviations of the track length distributions between 1 and 2 μm. These data suggest that rocks exposed along the eastern flank of the highlands were nearly reset as the result of being subjected to palaeotemperatures in the range of approximately 100–110°C, prior to being cooled relatively quickly through to temperatures < 50°C in the mid‐Cretaceous at ca 90 Ma. In contrast, samples from the western flank of the highlands yield apparent apatite ages as old as 235 Ma and mean track lengths < 12.5 μm, with standard deviations between 1.8 and 3 μm. These old apatite ages and relatively short track lengths suggest that the rocks were exposed to maximum palaeotemperatures between approximately 80° and 100°C prior to the regional cooling episode. This cooling is interpreted to be the result of kilometre‐scale uplift and erosion of the eastern highlands in the mid‐Cretaceous, and the similarity in timing of uplift and erosion within the highlands and initial extension along the eastern Australian passive margin prior to breakup (ca 95 Ma) strongly suggests these two occurrences are related.     

Post‐Variscan exhumation of the Central Anti‐Atlas (Morocco) constrained by zircon and apatite fission‐track thermochronology

The origin of the Anti‐Atlas relief is one of the currently debated issues of Moroccan geology. To constrain the post‐Variscan evolution of the Central Anti‐Atlas, we collected nine samples from the Precambrian basement of the Bou Azzer‐El Graara inlier for zircon and apatite fission‐track thermochronology. Zircon ages cluster between 340 ± 20 and 306 ± 20 Ma, whereas apatite ages range from 171 ± 7 Ma to 133 ± 5 Ma. Zircon ages reflect the thermal effect of the Variscan orogeny (tectonic thickening of the ca. 7 km‐thick Paleozoic series), likely enhanced by fluid advection. Apatite ages record a complex Mesozoic–Cenozoic exhumation history. Track length modelling yields evidence that, (i) the Precambrian basement was still buried at ca. 5 km depth by Permian times, (ii) the Central Anti‐Atlas was subjected to (erosional) exhumation during the Triassic‐Early Cretaceous, then buried beneath ca. 1.5 km‐thick Cretaceous‐Paleogene deposits, (iii) final exhumation took place during the Neogene, contemporaneously with that of the High Atlas.     

Phanerozoic upper crustal tectono-thermal development of basement rocks from central Madagascar: An integrated fission-track and structural study

An integrated study of fission-track (FT) dating and structural geology revealed a complex tectono-thermal history preserved in basement rocks of central Madagascar since the amalgamation of Gondwana at the end of the Cambrian. A detailed study of five domains argues for several cooling steps with associated brittle deformations during the separation of Madagascar.Titanite and apatite FT ages range between 483 Ma and 266 Ma and between 460 Ma and 79 Ma, respectively. The titanite FT data indicate that the final cooling after the latest metamorphic overprint was terminated at c. 500 Ma (FC1). A 150 Myr phase of minor cooling (SC2), possibly related to a phase of tectonic quiescence and isostatic compensation, followed episode FC1. Between the Carboniferous and Early Jurassic, when an intracontinental rift developed between East Africa and Madagascar, complex brittle deformation effected the western margin of Madagascar and led to differential cooling of small basement blocks (FC3–FC5). During this period, ductile structural trends were reactivated at the western basement margin and in the centre of the island.A Late Cretaceous thermal event (T1) affected apatite FT data of samples from western–central and the eastern margin of Madagascar. These ages are related to the Madagascar–India/Seychelles break-up, whereby the thermal penetration along the eastern coast was restricted to the west by the Angavo shear zone (AGSZ). The Cretaceous evolution of the eastern margin was associated with minor erosion and was triggered by vertical displacements along brittle structures.     

Apatite fission-track dating and low-temperature history of the Bavarian Forest (southern Bohemian Massif)

Apatite fission-track (AFT) dating applied to uplifted Variscan basement blocks of the Bavarian Forest is employed to unravel the low-temperature history of this segment of the Bohemian Massif. Twenty samples were dated and confined track lengths of four samples were measured. Most samples define Cretaceous APT ages between 110 and 82 Ma (Albian to Campanian) and three samples give older ~148–140 Ma (Jurassic–Cretaceous boundary) ages. No discernible regional age variations exist between the areas north-east and south-west of the Pfahl shear zone, but >500 m post-Jurassic and post-Cretaceous vertical offsets along this and other faults can be inferred from elevation profile analyses. The AFT ages clearly postdate the Variscan exhumation history of the Bavarian Forest. Thermal modeling reveals that the ages are best explained by a slight reheating of the basement rocks to temperatures within the apatite partial annealing zone during the middle and late Jurassic and/or by late Cretaceous marine transgression causing burial heating, which affected marginal low-lying areas of the Bohemian Massif and the Bavarian Forest. Late Jurassic period was followed by enhanced cooling through the 120–60 °C temperature interval during the subsequent exhumation phase for which denudation rates of ~100 m myr^?1 were calculated. On a regional scale, Jurassic–Cretaceous AFT ages are ubiquitous in marginal structural blocks of the Bohemian Massif and seem to reflect the exhumation of these zones more distinctly compared to central parts.     

Meso–Cenozoic cooling and exhumation history of the Orlica‐Śnieżnik Dome (Sudetes,NE Bohemian Massif,Central Europe): Insights from apatite fission‐track thermochronometry

This study presents the first suite of apatite fission‐track (AFT) ages from the SE part of the Western Sudetes. AFT cooling ages from the Orlica‐?nie?nik Dome and the Upper Nysa K?odzka Graben range from Late Cretaceous (84 Ma) to Early Palaeocene–Middle Eocene (64–45 Ma). The first stage of basin evolution (~100–90 Ma) was marked by the formation of a local extensional depocentre and disruption of the Mesozoic planation surface. Subsequent far‐field convergence of European microplates resulted in Coniacian–Santonian (~89–83 Ma) thrust faulting. AFT data from both metamorphic basement and Mesozoic sedimentary cover indicate homogenous Late Cretaceous burial of the entire Western Sudetes. Thermal history modeling suggests that the onset of cooling could be constrained between 89 and 63 Ma with a climax during the Palaeocene–Middle Eocene basin inversion phase.     

Low-temperature thermochronology of the flanks of the southern Upper Rhine Graben

The Upper Rhine Graben (URG) is the most perceptible part of the European Cenozoic Rift System. Uplifted Variscan basement of the Black Forest and the Vosges forms the flanks of the southern part of the graben. Apatite and zircon fission-track (FT) analyses indicate a complex low-temperature thermal history of the basement that was deciphered by inverse modelling of FT parameters. The models were tested against the observed data and independent geological constraints. The zircon FT ages of 28 outcrop samples taken along an E–W trending transect across the Black Forest and the Vosges range from 136 to 312 Ma, the apatite FT ages from 20 to 83 Ma. The frequency distributions of confined track lengths are broad and often bimodal in shape indicating a complex thermal history. Cooling below 120°C in the Early Cretaceous to Palaeogene was followed by a discrete heating episode during the late Eocene and subsequent cooling to surface temperature. The modelled time–temperature (t–T) paths point to a total denudation of the flanks of URG in the range of 1.0–1.7 km for a paleogeothermal gradient of 60°C/km, and 1.3–2.2 km for a paleogeothermal gradient of 45°C/km since the late Eocene.     

四川攀西红格矿区辉长岩和正长岩的SHRIMP U-Pb和Sm-Nd定年及其地质意义

用SHRIMP U-Pb和Sm-Nd定年技术,对攀西红格矿区含矿层状辉长岩、碱性正长岩进行了年龄测定。获得红格辉长岩中3种不同晶形锆石的U-Pb年龄分别为258.4±4.1Ma、1841±34Ma、2487±12Ma,由辉长岩、辉石和磷灰石所构成的Sm-Nd等时线年龄为253±14Ma;碱性正长岩中锆石的U-Pb年龄为257.2±1.5Ma。结果表明,红格辉长岩中具有典型基性岩锆石特征的锆石U-Pb年龄(258Ma)与同一地质样品的Sm-Nd年龄(全岩+矿物内部等时线年龄),以及同一矿区的正长岩锆石U-Pb年龄在测定误差范围内一致。鉴于层状辉长岩和碱性正长岩在空间上密切共生,在形成时间上一致,可以认为它们都属于晚二叠世末岩浆活动的产物;而1841Ma和2487Ma的锆石,可能是在基性-超基性岩浆的上侵过程中,从基底所捕获的岩浆锆石和继承锆石,其年龄信息,揭示了康滇地轴岩浆岩带的下部或结晶基底存在元古代甚至新太古代末期的岩石或物质。     

Neogene kinematics of the Giudicarie fault (Central-Eastern Alps, Italy): new apatite fission-track data

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°.     

Cretaceous to Cenozoic evolution of the northern Lhasa Terrane and the Early Paleogene development of peneplains at Nam Co,Tibetan Plateau

Highly elevated and well-preserved peneplains are characteristic geomorphic features of the Tibetan plateau in the northern Lhasa Terrane, north–northwest of Nam Co. The peneplains were carved in granitoids and in their metasedimentary host formations. We use multi-method geochronology (zircon U–Pb and [U–Th]/He dating and apatite fission track and [U–Th]/He dating) to constrain the post-emplacement thermal history of the granitoids and the timing and rate of final exhumation of the peneplain areas. LA-ICP-MS U–Pb geochronology of zircons yields two narrow age groups for the intrusions at around 118 Ma and 85 Ma, and a third group records Paleocene volcanic activity (63–58 Ma) in the Nam Co area. The low-temperature thermochronometers indicate common age groups for the entire Nam Co area: zircon (U–Th)/He ages cluster around 75 Ma, apatite fission track ages around 60 Ma and apatite (U–Th)/He ages around 50 Ma. Modelling of the thermochronological data indicates that exhumation of the basement blocks took place in latest Cretaceous to earliest Paleogene time. By Middle Eocene time the relief was already flat, documented by a thin alluvial sediment sequence covering a part of the planated area. The present-day horst and graben structure of the peneplains is a Late Cenozoic feature triggered by E–W extension of the Tibetan Plateau. The new thermochronological data precisely bracket the age of the planation to Early Eocene, i.e. between ca. 55 and 45 Ma. The erosional base level can be deduced from the presence of Early Cretaceous zircon grains in Eocene strata of Bengal Basin. The sediment generated during exhumation of the Nam Co area was transported by an Early Cenozoic river system into the ocean, suggesting that planation occurred at low elevation.     

Mesozoic and Cenozoic thermal history of the Western Reguibat Shield (West African Craton)

Using low‐temperature thermochronology on apatite and zircon crystals, we show that the western Reguibat Shield, located in the northern part of the West African Craton, experienced significant cooling and heating events between Jurassic and present times. The obtained apatite fission track ages range between 49 and 102 Ma with mean track lengths varying between 11.6 and 13.3 μm and Dpar values between 1.69 and 3.08 μm. Zircon fission track analysis yielded two ages of 159 and 118 Ma. Apatite (U–Th)/He uncorrected single‐grain ages range between 76 and 95 Ma. Thermal inverse modelling indicates that the Reguibat Shield was exhumed during the Early Cretaceous, Late Cretaceous, Palaeocene–Eocene and Quaternary. These exhumation events were coeval with regional tectonic and geodynamic events, and were probably driven by a combined effect of plate tectonics and mantle dynamics.     

Cooling age record of domal uplift in the core of the Higher Himalayan Crystallines (HHC), southwest Zanskar, India

The cooling and tectonic history of the Higher Himalayan Crystallines (HHC) in southwest Zanskar (along the Kishtwar-Padam traverse) is constrained by K-Ar biotite and fission-track (FT) apatite and zircon ages. A total of nine biotite samples yields ages in the range of 14–24 Ma, indicating the post-metamorphic cooling of these rocks through ∼ 300°C in the Miocene. Overall, the ages become younger away from the Zanskar Shear Zone (ZSZ), which marks the basement-cover detachment fault between the HHC and the Tethyan sedimentary zone, towards the core of the HHC. The same pattern is also observed for the FT apatite ages, which record the cooling of the rocks through ∼ 120°C. The apatite ages range from 11 Ma in the vicinity of the ZSZ to 4 Ma at the granitic core of the HHC. This pattern of discordant cooling ages across the HHC in southwest Zanskar reveals an inversion of isotherms due to fast uplift-denudation (hence cooling) of the HHC core, which is, in turn, related to domal uplift within the HHC. The Chisoti granite gneiss is the exposed domal structure along the studied traverse. Cooling history of two granite gneisses at the core of the HHC is also quantified with the help of the biotite, zircon and apatite ages; the time-temperatures thus obtained indicate a rapid pulse of cooling at ∼ 6 Ma, related to accelerated uplift-denudation of the HHC core at this time. Long-term denudation rates of 0.5–0.7 mm/yr are estimated for the high-grade rocks of the Higher Himalaya in southwest Zanskar over the past 4.0–5.5 m.yr.     

New age constraints on the cooling and unroofing history of the Trans-Himalayan Ladakh Batholith (Kargil area), N. W. India

Thermotectonic history of the Trans-Himalayan Ladakh Batholith in the Kargil area, N. W. India, is inferred from new age data obtained here in conjunction with previously published ages. Fission-track (FT) ages on apatite fall around 20±2 Ma recording cooling through temperatures of ∼100°C and indicating an unroofing of 4 km of the Ladakh Range since the Early Miocene. Coexisting apatite and zircon FT ages from two samples in Kargil show the rocks to have cooled at an average rate of 5–6°C/Ma in the past 40 Ma. Zircon FT ages together with mica K−Ar cooling ages from the Ladakh Batholith cluster around 40–50 Ma, probably indicating an Eocene phase of uplift and erosion that affected the bulk of the batholith after the continental collision of India with the Ladakh arc at 55 Ma. Components of the granitoids in Upper Eocene-Lower Oligocene sediments of the Indus Molasse in Ladakh supports this idea. Three hornblende K−Ar ages of 90 Ma, 55 Ma, and 35 Ma are also reported; these distinctly different ages probably reflect cooling through 500–550°C of three phases of I-type plutonism in Ladakh also evidenced by other available radiometric data: 102 Ma (mid-Cretaceous), 60 Ma (Palaeocene), and 40 Ma (Late Eocene); the last phase being localised sheet injections. The geodynamic implications of the age data for the India-Asia collision are discussed.     

Evidence for Differential Unroofing in the Adirondack Mountains, New York State, Determined by Apatite Fission-Track Thermochronology

Apatite fission-track ages of 168-83 Ma for 39 samples of Proterozoic crystalline rocks, three samples of Cambrian Potsdam sandstone, and one Cretaceous lamprophyre dike from the Adirondack Mountains in New York State indicate that unroofing in this region occurred from Late Jurassic through Early Cretaceous. Samples from the High Peaks section of the Adirondack massif yielded the oldest apatite fission-track ages (168-135 Ma), indicating that it was exhumed first. Unroofing along the northern, northwestern, and southwestern margins of the Adirondacks began slightly later, as shown by younger apatite fission-track ages (146-114 Ma) determined for these rocks. This delay in exhumation may have resulted from burial of the peripheral regions by sediment shed from the High Peaks. Apatite fission-track ages for samples from the southeastern Adirondacks are distinctly younger (112-83 Ma) than those determined for the rest of the Adirondack region. These younger apatite fission-track ages are from a section of the Adirondacks dissected by shear zones and post-Ordovician north-northeast-trending normal faults. Differential unroofing may have been accommodated by reactivation of the faults in a reverse sense of motion with maximum compressive stress, sigma1, oriented west-northwest. A change in the orientation of the post-Early Cretaceous paleostress field is supported by a change in the trend of Cretaceous lamprophyre dikes from east-west to west-northwest.     

The thermo-tectonic history of the Song-Kul plateau, Kyrgyz Tien Shan: Constraints by apatite and titanite thermochronometry and zircon U/Pb dating

The Song-Kul Basin sits on a plateau at the Northern and Middle Kyrgyz Tien Shan junction. It is a lacustrine basin, occupied by Lake Song-Kul and predominantly developed on igneous basement. This basement was targeted for a multi-method chronological study to identify the different magmatic episodes responsible for basement formation and to constrain the timing of the development of its present-day morphology. Zircon U/Pb dating by LA-ICP-MS revealed four different magmatic episodes: a Late Cambrian (~ 500 Ma) island arc system, a Late Ordovician (~ 450 Ma) subduction related intrusion, an Early Permian (~ 290 Ma) collisional stage, and a Middle to Late Permian (~ 260 Ma) post-collisional magmatic pulse. Middle to Late Triassic (~ 200–230 Ma) titanite fission-track ages and Late Triassic – Early Jurassic (~ 180–210 Ma) apatite fission-track ages and thermal history modeling indicate the Song-Kul basement was already emplaced in the shallow crust at that time. An exhumed fossil apatite fission-track partial annealing zone is recognized in the bordering Song-Kul mountain ranges. The area experienced only minor post-Early Mesozoic denudation. The igneous basement was slowly brought to apatite (U–Th)/He retention temperatures in the Late Cretaceous–Palaeogene. Miocene to present reactivation of the Tien Shan does not manifestly affect this part of the orogen.     

Maturity of central Madagascar's landscape — Low-temperature thermochronological constraints

Low-temperature thermochronological data from two profiles across central Madagascar give apatite fission track and apatite (U–Th)/He ages ranging between 258 Ma and 176 Ma and from 239 Ma to 48 Ma, respectively. Thermal models derived from these data, as well as modelling of basement denudation and the sedimentary record, indicate that first order topography of central Madagascar developed mainly due to flexural uplift during Mesozoic times. This was in response to successive erosion and depositional loading associated with the sedimentation in the Morondava and Majunga basins, both of which are now exposed along the western margin of Madagascar. Our data suggest that the eastern margin of the island had a similar denudation history and was probably at a similar topographic level before the late Cretaceous break-up of Madagascar and the India/Seychelles block. Cretaceous normal faulting, without major amounts of denudation, led to the development of the present east coast topography defined by a tectonically juvenile escarpment. In the centre of the island Cenozoic tectonics and volcanism has had a minor and localised influence on the landscape of central Madagascar.     

Apatite fission‐track analysis of Cretaceous alkaline rocks of Ponta Grossa and Alto Paranaíba Arches,Brazil

This work presents fission‐track ages and thermal history modelling of apatite samples from two Brazilian alkaline formations: Alto Paranaíba and Ponta Grossa Arches. The apatite fission‐track ages obtained for Alto Paranaíba Arch agree with those determined by other radiometric dating methods presenting higher closure temperatures. The ages given by the fission‐track thermochronometer suggest that no strong tectonic event has occurred after Alto Paranaíba Formation during Upper Cretaceous. This event is also supported by thermal history modelling of this arch, which is characterized by fast cooling followed by residence at lower temperatures. On the other hand, apatite fission‐track ages from Ponta Grossa Arch are systematically lower than other radiometric ages, suggesting that at least one tectonic event occurred after Ponta Grossa Formation, around 130 Ma. Copyright © 2015 John Wiley & Sons, Ltd.     

赞比亚东北部班韦乌卢地块泛非期以来构造演化的裂变径迹约束

本文利用锆石和磷灰石裂变径迹方法探讨了班韦乌卢地块泛非期以来的主要构造演化时间。为研究班韦乌卢地块的构造活动,本文从班韦乌卢地块中部卡帕图地区的沉积盖层姆波罗科索群的姆巴拉组、萨马组和卡布韦卢马组中采集多件新鲜的岩石样品,并获得5件锆石和2件磷灰石样品裂变径迹分析结果。5件锆石裂变径迹年龄介于575±35～380±22 Ma之间,其峰值年龄组为600～572 Ma和420～390 Ma。2件磷灰石裂变径迹年龄介于59±6～27±4 Ma之间,其峰值年龄组为99～80 Ma和19～11 Ma。它们的峰值年龄组分别对应的主要时代为新元古代的埃迪卡拉纪、早泥盆世、晚白垩世和中新世。对比区域上已有的年龄数据可知,南部非洲地区新元古代的埃迪卡拉纪、早泥盆世和晚白垩世的构造活动是一个区域性的构造事件,仅中新世(19～11 Ma)的构造活动在区域上的表现尚不明确。综合前人成果资料,自泛非构造运动以来,班韦乌卢地块至少经历600～572 Ma、488～441 Ma、420～390 Ma、375～293 Ma、99～80 Ma及19～11 Ma六个构造事件。班韦乌卢地块泛非期以来的构造演化研究程度很低,...     

新疆东天山红云滩地区构造-热演化探讨:来自Ar-Ar和(U-Th)/He热年代学的约束

红云滩岩体位于东天山觉罗塔格西部,对其进行热演化历史研究对于揭示觉罗塔格地区乃至整个东天山地区的构造-热演化历史具有重要意义。本文对红云滩岩体进行黑云母Ar-Ar、锆石(U-Th)/He和磷灰石(U-Th)/He测年,并结合前人的锆石U-Pb测年结果,精细刻画出该岩体自形成以后经历的热演化过程,并据此识别出东天山红云滩地区发生过多期快速抬升冷却事件。黑云母阶段升温Ar-Ar法同位素定年得到的坪年龄为316.9±1.8Ma,单颗粒锆石和磷灰石(U-Th)/He同位素定年得到的平均年龄分别为213.7±9.6Ma和65.5±1.3Ma。热年代学数据及模拟结果表明东天山红云滩地区自晚古生代以来经历了3个快速冷却阶段,分别为:晚石炭世至早二叠世(ca.330~296Ma)、晚三叠世(222~220Ma)、晚白垩世(91~77Ma)。其中,晚石炭世至早二叠世的快速冷却作用是岩体侵位后与围岩热传导冷却及伴随天山造山隆升冷却综合作用的结果,晚三叠世和晚白垩世的两期快速冷却事件分别与羌塘-欧亚板块、Kohistan-Dras岛弧-拉萨地块碰撞的远程效应造成的东天山地区隆升作用有关。新生代以来,红云滩岩体所在的阿奇山-雅满苏地区构造活动相对较弱,未发生较为明显的隆升作用,与天山西段新生代的构造活动有着明显的差异。