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51.
Abstract

The Jurassic–Cretaceous Great Artesian Basin is the most extensive, and largest volume, sedimentary feature of continental Australia. The source of its mud-dominated Cretaceous infill is attributed largely to contemporary magmatism along the continental margin to the east, but the source of its Jurassic infill, dominated by quartz sandstone, remains unconstrained. This paper investigates the question of a Jurassic sediment source for the northern part of the basin. Jurassic uplift and exhumation of the continental margin crustal sector to the east provided the primary Jurassic sediment source. (U–Th)/He data are presented for zircon and apatite from Pennsylvanian to mid Permian granitoids of the Kennedy Igneous Association distributed within the northern Tasmanides between the Townsville and Cairns regions and for coeval granites of the Urannha batholith from the Mount Carlton district (N Bowen Basin), also within the northern Tasmanides. The data from zircon indicate widespread Jurassic exhumation of a crustal tract located to the east of the northern Great Artesian Basin and largely occupied by rocks of the Tasmanides. Detrital zircon age spectra for samples of the Jurassic Hutton and Blantyre sandstones from the northeastern margin of the Great Artesian Basin show their derivation to be largely from rocks of the northern Tasmanides. In combination, the detrital age spectra and (U–Th)/He data from zircon indicate exhumation owing to uplift generating appreciable physiographic relief along the north Queensland continental margin during the Jurassic, shedding sediment westward into the Great Artesian Basin during its early development. A portion of (U–Th)/He data for zircon are consistent with late Permian–mid Triassic exhumation within the Tasmanides, attributable to the influence of the Hunter--Bowen Orogeny. Evidence of Cretaceous and Paleocene exhumation episodes is also indicated for some samples, mainly by apatite (U–Th)/He analysis, consistent with data previously published from fission track studies. Overall, new data from the present study reveal that the exhumation related to Jurassic regional uplift and the subsequent erosional reworking of the northeast Australian continental margin is critical for the evolution and development of the northern side of the Great Artesian Basin in eastern Australia. Apart from this, another two previously suggested Permian–Triassic and Cretaceous exhumation and uplift episodes along the northeast Australian continental margin are also confirmed by the dataset of this study.
  1. KEY POINTS
  2. U–Pb detrital zircon ages of sandstone samples from the northeastern Eromanga Basin reveal Paleozoic (480–280 Ma) and Proterozoic (1800–1400 Ma) age clusters.

  3. (U–Th)/He zircon and apatite dating results of granitoids samples from Cairns, Townsville and the Mount Carlton districts are dominated by Jurassic (198–164 Ma) and Permian–Triassic (272–238 Ma) age clusters.

  4. Combination of above two datasets proves the regional uplift-driving Jurassic exhumation episode in the northeast Australian continental is vital for the development of the northern Great Artesian Basin.

  相似文献   
52.
李小明  谭凯旋 《地球学报》2005,26(Z1):248-251
本文简单介绍地质热年代学的含义、应用和进展,并重点介绍了裂变径迹与40Ar/39Ar热年代学  相似文献   
53.
Zircon and apatite fission track (FT) thermochronology was applied to investigate the history of cooling and denudation of the Southern Andes between 41° and 42°15′S in relation to the late Cenozoic activity of the Liquiñe-Ofqui fault zone (LOFZ) and the northward migration of the Chile Triple Junction (CTJ). Fifty-six zircon and 51 apatite FT ages, plus 37 apatite confined track-length distributions were obtained mainly from plutonic rocks of the North Patagonian Batholith (NPB) in the main Andean Cordillera. Apatite FT ages and track lengths indicate a stage of rapid cooling at ∼5--3 Ma along both sides of the LOFZ, whereas older Miocene ages with monotonous cooling histories were obtained further away from the fault. Zircon FT ages range from Cretaceous to Pliocene, with marked differences observed along and across the LOFZ. Three different types of temperature-time histories characterise the post-magmatic cooling of the NPB in the region: deep intrusions with moderate and steady cooling rates, intrusions in the upper crust with very slow cooling rates following a stage of initial rapid cooling, and rapidly cooled and exhumed shallow intrusions, the latter with younger ages towards the fault zone. The most prominent denudation episode along the LOFZ is late Miocene to Pliocene, coeval with plate tectonic reconstructions for the arrival and subduction of the Chile Rise beneath the Taitao Peninsula.  相似文献   
54.
New40Ar-39Ar thermochronological results from the Ladakh region in the India-Asia collision zone provide a tectono-thermal evolutionary scenario. The characteristic granodiorite of the Ladakh batholith near Leh yielded a plateau age of 46.3 ± 0.6 Ma (2σ). Biotite from the same rock yielded a plateau age of 44.6 ± 0.3 Ma (2σ). The youngest phase of the Ladakh batholith, the leucogranite near Himya, yielded a cooling pattern with a plateau-like age of ∼ 36 Ma. The plateau age of muscovite from the same rock is 29.8 ±0.2 Ma (2σ). These ages indicate post-collision tectono-thermal activity, which may have been responsible for partial melting within the Ladakh batholith. Two basalt samples from Sumdo Nala have also recorded the post-collision tectono-thermal event, which lasted at least for 8 MY in the suture zone since the collision, whereas in the western part of the Indus Suture, pillow lava of Chiktan showed no effect of this event and yielded an age of emplacement of 128.2 ±2.6 Ma (2σ). The available data indicate that post-collision deformation led to the crustal thickening causing an increase in temperature, which may have caused partial melting at the base of the thickened crust. The high thermal regime propagated away from the suture with time.  相似文献   
55.
Apatite fission track (AFT) thermochronology has been applied to a composite depth profile of Precambrian basement rocks underlying the Phanerozoic Canadian Williston Basin. Thermal histories derived from the AFT data record cycles of heating and cooling which follow the pattern of regional burial history, but which also indicate major temporal and geographic variations in the timing and degree of maximum Phanerozoic temperatures. These variations in the thermal history were not previously recognised from organic maturity indicators and subsidence models. Specifically, our study suggests a late Paleozoic heat flow anomaly with a geographic extent closer to that of Middle Devonian–Carboniferous Kaskaskia subsidence patterns than to that of the Williston Basin proper. This thermal anomaly has both economic and geodynamic significance. The recognition that potential Upper Cambrian–Lower Ordovician petroleum source rocks became fully mature during the late Paleozoic distinguishes that petroleum system from others that entered the main hydrocarbon generation stage in latest Cretaceous and Paleogene time. The late Paleozoic heat flow anomaly suggested from the AFT data implies a geodynamic coupling between inelastic Kaskaskia subsidence and previously inferred late Paleozoic lithospheric weakening. While the temporally varying heat flow model is preferred, the lack of independent constraints on the maximum thickness of upper Paleozoic strata precludes the outright rejection of the previous constant heat flow model. The AFT data provide important new constraints on the evolution of the epicratonic Williston Basin and its geodynamic models.  相似文献   
56.
Knowledge of the time-scales of emplacement and thermal history during assembly of composite felsic plutons in the shallow crust are critical to deciphering the processes of crustal growth and magma chamber development. Detailed petrological and chemical study of the mid-Cretaceous, composite Emerald Lake pluton, from the northern Canadian Cordillera, Yukon Territory, coupled with U–Pb and 40Ar/39Ar geochronology, indicates that this pluton was intruded as a series of magmatic pulses. Intrusion of these pulses produced a strong petrological zonation from augite syenite, hornblende quartz syenite and monzonite, to biotite granite. Our data further indicate that multiple phases were emplaced and cooled to below the mineral closure temperatures over a time-scale on the order of the resolution of the 40Ar/39Ar technique (1 Myr), and that emplacement occurred at 94.3 Ma. Simple thermal modelling and heat conduction calculations were used to further constrain the temporal relationships within the intrusion. These calculations are consistent with the geochronology and show that emplacement and cooling were complete in less than 100 kyr and probably 70±5 kyr. These results demonstrate that production, transport and emplacement of the different phases of the Emerald Lake pluton occurred essentially simultaneously, and that these processes must also have been closely related in time and space. By analogy, these results provide insights into the assembly and petrogenesis of other complex intrusions and ultimately lead to an understanding of the processes involved in crustal development.  相似文献   
57.
利用磷灰石裂变径迹研究鄂尔多斯盆地西缘热历史   总被引:28,自引:2,他引:26  
磷灰石裂变径迹在地质时期对60~150℃范围内温度变化的热敏感性 ,不仅使其成为研究盆地构造热演化史和区域构造运动的重要手段 ,而且对指导油气勘探有很大的实践意义。本文根据AFTA① 的有关原理 ,退火特性 ,对鄂尔多斯盆地西缘奥陶、二叠、三叠、侏罗、白垩、第三纪等不同时代地层样品开展了较为系统的AFT测试 ,获得了一批可靠的AFTA数据 ,论述了鄂尔多斯盆地西缘的主要构造热事件的次数 ,及该区中生代以来的构造热演化史。研究表明 :自中生代以来 ,该盆地西缘至少经历了四次构造热事件(峰值年龄分别为170Ma±、130Ma±、和75Ma±和17Ma±)。  相似文献   
58.
在西南极和横贯南极山脉地区,新生代裂谷和剥露作用非常普遍。但是,文献中很少记录东南极地区的新生代剥露作用。文中根据东南极普里兹湾拉斯曼丘陵地质样品的磷灰石裂变径迹年龄和热历史的模拟,认为在东南极海岸边缘存在新生代的隆升和伸展作用,其年龄为始于(49.8±12)Ma。该年龄略晚于西南极裂谷系的启动年龄(约60~50Ma)。由于差异隆升作用,在拉斯曼丘陵地区发育了更新的正断层作用--拉斯曼丘陵拆离断层的新活动,其年龄为约5.4Ma。东南极周缘新生代裂谷和伸展作用的普遍存在,是冈瓦纳裂解以来大陆分离和印度洋形成的结果。  相似文献   
59.
氦素定年技术、氦热年代学及其在地质中的应用   总被引:1,自引:0,他引:1  
本文介绍了氦同位素定年技术和氦热年代学,说明了该方法的理论基础和技术要求,以及其在较小幅度剥露作用研究、古地貌研究和年轻地质体定年等方面的应用情况和前景.   相似文献   
60.
We combine structural observations, petrological data and 40Ar–39Ar ages for a stack of amphibolite facies metasedimentary units that rims high‐P (HP) granulite facies felsic bodies exposed in the southern Bohemian Massif. The partly migmatitic Varied and Monotonous units, and the underlying Kaplice unit, show a continuity of structures that are also observed in the adjacent Blanský les HP granulite body. They all exhibit an earlier NE?SW striking and steeply NW‐dipping foliation (S3), which is transposed into a moderately NW‐dipping foliation (S4). In both the Varied and Monotonous units, the S3 and S4 foliations are characterized by a Sil–Bt–Pl–Kfs–Qtz–Ilm±Grt assemblage, with occurrences of post‐D4 andalusite, cordierite and muscovite. In the Monotonous unit, minute inclusions of garnet, kyanite, sillimanite and biotite are additionally found in plagioclase from a probable leucosome parallel to S3. The Kaplice unit shows rare staurolite and kyanite relicts, a Sil–Ms–Bt–Pl–Qtz±Grt assemblage associated with S3, retrogressed garnet?staurolite aggregates during the development of S4, and post‐D4 andalusite, cordierite and secondary muscovite. Mineral equilibria modelling for representative samples indicates that the Varied unit records conditions higher than ~7 kbar at 725 °C during the transition from S3 to S4, followed by a P?T decrease from ~5.5 kbar/750 °C to ~4.5 kbar/700 °C. The Monotonous unit shows evidence of partial melting in the S3 fabric at P?T above ~8 kbar at 740–830 °C and a subsequent P?T decrease to 4.5–5 kbar/700 °C. The Kaplice unit preserves an initial medium‐P prograde path associated with the development of S3 reaching peak P?T of ~6.5 kbar/640 °C. The subsequent retrograde path records 4.5 kbar/660 °C during the development of S4. 40Ar–39Ar geochronology shows that amphibole and biotite ages cluster at c. 340 Ma close to the HP granulite, whereas adjacent metasedimentary rocks preserve c. 340 Ma amphibole ages, but biotite and muscovite ages range between c. 318 and c. 300 Ma. The P?T conditions associated with S3 imply an overturned section of the orogenic middle crust. The shared structural evolution indicates that all mid‐crustal units are involved in the large‐scale folding cored by HP granulites. The retrograde PT paths associated with S4 are interpreted as a result of a ductile thinning of the orogenic crust at a mid‐crustal level. The 40Ar–39Ar ages overlap with U–Pb zircon ages in and around the HP granulite bodies, suggesting a short duration for the ductile thinning event. The post‐ductile thinning late‐orogenic emplacement of the South Bohemian plutonic complex is responsible for a re‐heating of the stacked units, reopening of argon system in mica and a tilting of the S4 foliation to its present‐day orientation.  相似文献   
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