Tertiary stratigraphy of Western Australia     

Patrick G. Quilty 《Australian Journal of Earth Sciences》2013,60(3):301-318

This paper is a summary of the present knowledge of the Tertiary stratigraphy of Western Australia. Also included is new information on the Cainozoic of the Carnarvon Basin, a result of petroleum exploration in the area.

Tertiary rocks formed during more than one cycle of deposition in three basins (Eucla, Perth, and Carnarvon), and also as thin units deposited in a single transgression along the south coast. The Tertiary stratigraphy of the Bonaparte Gulf Basin is not well known.

Drilling in the Eucla Basin has encountered up to 400 m of Tertiary in the south central part, with uniform thinning towards the margins. The section begins with a middle‐upper Eocene carbonate unit which represents the dominant event in the Tertiary sedimentation in this basin. More carbonates were deposited in the late Oligocene‐early Miocene and middle Miocene.

Along the south coast, the so‐called Bremer Basin, the Plantagenet Group (up to 100 m) of siltstone, sandstone, spongolite, and minor limestone, was deposited during the late Eocene.

The Perth Basin contains up to 700 m of Tertiary sediment, formed during at least two phases of sedimentation. The upper Paleocene‐lower Eocene Kings Park Formation consists of marine shale, sandstone, and minor limestone, with a thickness of up to 450 m. The Stark Bay Formation (200 m) includes limestone, dolomite, and chert formed during the early and middle Miocene. Events after deposition of the Stark Bay Formation are not well known.

The northern Carnarvon Basin and Northwest Shelf contain by far the most voluminous Tertiary sediment known from Western Australia: 3500 m is known from BOCAL's Scott Reef No. 1. A more usual maximum thickness is 2500 m. Most sediments were laid down in four episodes, separated by unconformities: late Paleocene‐early Eocene; middle‐late Eocene; late Oligocene‐middle Miocene; and late Miocene to Recent.

The Paleocene‐early Eocene cycle consists of about 100–200 m (up to 450 m in the north) of carbonate, shale, and marl of the Cardabia Group containing rich faunas of planktonic foraminifera.

The middle‐late Eocene sediments include diverse rock types. Marine and nonmarine sandstone formed in the Merlinleigh Trough. At the same time, the Giralia Calcarenite (fauna dominated by the large foraminifer Discocyclina) and unnamed, deeper water shale, marl, and carbonate (with rich planktonic foraminiferal faunas) formed in the ocean outside the embayment. Thickness is usually of the order of 100–200 m.

The main cycle of sedimentation is the late Oligocene‐middle Miocene, during which time the Cape Range Group of carbonates formed. This contains dominantly large foraminiferal faunas, of a wide variety of shallow‐water microfacies, but recent oil exploration farther offshore has recovered outer continental shelf facies with abundant planktonic foraminifera. A minor disconformity representing N7 and perhaps parts of N6 and N8 is now thought to be widespread within the Cape Range Group. The last part of this cycle resulted in sedimentation mainly of coarse calcareous marine sandstone (unnamed), and, in the Cape Range area, of the sandstone and calcareous conglomerate of the Pilgramunna Formation. Maximum thickness encountered in WAPET wells is 900 m.

After an unconformity representing almost all the late Miocene, sedimentation began again, forming an upper Miocene‐Recent carbonate unit which includes some excellent planktonic faunas. Thickness is up to 1100 m.

Thin marine sediments of the White Mountain Formation outcrop in the Bonaparte Gulf Basin. They contain some foraminifera and a Miocene age has been suggested.  相似文献   

SHRIMP zircon geochronology and geochemistry of the Orlica-Śnieżnik gneisses (Variscan belt of Central Europe) and their tectonic implications     

Krzysztof Tumiak  Stanislaw Mazur  Richard Wysoczanski 《Geodinamica Acta》2013,26(5):293-312

Abstract

The Orlica-?nie?nik dome comprises large orthogneiss bodies interbedded with amphiblite-grade metasediments and minor metavolcanics. New U-Pb and Pb-Pb SHRIMP zircon ages for two major gneiss units of the dome, the ?nie?nik and Giera?tów gneiss, yielded similar ages of ca. 500 Ma. This is interpreted to reflect the magmatic crystallization age from the same or similar igneous precursors, in agreement with the geochemical characteristics of these rocks. Some zircon cores in both gneisses, interpreted to be inherited xenocrysts, have ages of ca. 530–540 Ma, and, additionally, of ca. 565 Ma and 2.6 Ga in the ?nie?nik gneiss. Igneous grains in both gneiss types have high-U rims, which are dark under cathodoluminescence. They are much better developed in the Giera?tow gneiss and they yield a well-defined weighted mean U-Pb age of 342 ± 6 Ma. These high-U rims are interpreted to have grown close to the peak of HT metamorphism which is responsible for the migmatitic texture of the Giera?tow gneiss. The Visean HT-LP metamorphism in the Orlica-?nie?nik dome is interpreted as a result of rapid uplift and decompression due to overthrusting of high grade rocks over the Moravo-Silesian nappe pile. Our data support geodynamic models that ascribe a predominant influence in the tectonic evolution of the West Sudetes to the Variscan oro- genic events. This is suggested by the inheritance of zircon xenocrysts from the Cadomian basement and by the Late Cambrian- Early Ordovician magmatic event, both typical of the Armorican terrane assemblage, as well as by the Early Carboniferous age of the metamorphism. © 2000 Éditions scientifiques et médicales Elsevier SAS  相似文献   

Neotectonics of Turkey – a synthesis     

Erdin Bozkurt 《Geodinamica Acta》2013,26(1-3):3-30

Abstract

Turkey forms one of the most actively deforming regions in the world and has a long history of devastating earthquakes. The belter understanding of its neotectonic features and active tectonics would provide insight, not only for the country but also for the entire Eastern Mediterranean region. Active tectonics of Turkey is the manifestation of collisional intracontinental convergence- and tectonic escape-related deformation since the Early Pliocene (~5 Ma). Three major structures govern the neotectonics of Turkey; they are dextral North Anatolian Fault Zone (NAFZ), sinistral East Anatolian Fault Zone (EAFZ) and the Aegean–Cyprean Arc. Also, sinistral Dead Sea Fault Zone has an important role. The Anatolian wedge between the NAFZ and EAFZ moves westward away from the eastern Anatolia, the collision zone between the Arabian and the Eurasian plates. Ongoing deformation along, and mutual interaction among them has resulted in four distinct neotectonic provinces, namely the East Anatolian contractional, the North Anatolian, the Central Anatolian ‘Ova’ and the West Anatolian extensional provinces. Each province is characterized by its unique structural elements, and forms an excellent laboratory to study active strike-slip, normal and reverse faulting and the associated basin formation. © 2001 Éditions scientifiques et médicales Elsevier SAS  相似文献   

新疆铁木尔特铅锌铜矿床锆石U-Pb和黑云母⁴⁰Ar/³⁹Ar年代学及其矿床成因意义   总被引：4，自引：4，他引：0  

郑义  张莉  郭正林 《岩石学报》2013,29(1):191-204

新疆铁木尔特铅锌铜矿床位于阿尔泰造山带南缘克兰盆地内,矿体呈脉状产于康布铁堡组火山岩地层中.为准确厘定其成岩成矿时代,作者分别对矿区赋矿火山岩和含矿石英脉中的云母进行了年龄测定,获得2件火山岩样品的锆石LA-ICP-MS U-Pb年龄分别为396±5Ma和405±5Ma,2件黑云母样品的40 Ar/39 Ar坪年龄分别为240±2Ma和235±2Ma,相应的39Ar/36Ar-40Ar/36Ar等时线年龄分别为238±3Ma和233±3Ma,与坪年龄在误差范围内一致.据此,认为矿区内康布铁堡组火山岩形成于396～405 Ma,成矿作用发生于235～240Ma;成岩年龄早于成矿年龄约165Ma.因此,铁木尔特铅锌铜矿为典型的后生矿床,而不可能是同生VMS型矿床.考虑到成矿年龄稍晚于区域大规模变质作用(约250Ma),推测成矿作用与阿尔泰造山带碰撞造山作用有关.结合矿床地质特征和流体包裹体特征,认为铁木尔特铅锌铜矿为典型的陆陆碰撞体制下形成的造山型矿床.  相似文献   

最小二乘直线拟合方法及其在同位素地质年代学中的应用研究   总被引：2，自引：0，他引：2  

范文博  王文龙  陈岳龙  李大鹏 《地质论评》2013,59(5):801-815

最小二乘法(least squares method)是直线拟合常用的方法,在自然科学和社会科学内被广泛应用,尤其在同位素地质年代学领域更是必不可少。仅考虑x或y误差的普通最小二乘法(normal/ordinary least squares)广为人知,但事实上最小二乘法并非如此简单,尤其是在同时考虑x、y误差(乃至误差相关)并采用加权处理时,其数学处理方法会变得十分复杂,而此时普通最小二乘法显得极不合理。本文在前人研究的基础上,结合同位素地质年龄计算的需要,对直线拟合的最小二乘法进行了系统地总结研究,详细介绍了普通最小二乘法、加权普通最小二乘法(normal/ordinary weighting least squares)、标准加权最小二乘法(standard weighting model)、标准独立加权最小二乘法(standard independent weighting model)、独立加权最小二乘法(independent weighting model)及误差相关最小二乘法(error correlated independent weighting model)的数学原理及相关变量的计算过程。在此基础上,进一步阐述了MSWD(mean squared weighted deviation)这个同位素地质年代学中经常使用的参数的数学意义,以及MSWD对计算结果的评判意义。准确理解这些数学方法,对于我们合理选择同位素地质年龄相关参数的计算方法,科学评价直线拟合结果并探讨其地质意义至关重要。我们的研究同时有助于拓展和完善数学领域最小二乘法的基本理论,并可用于其他领域相似的研究之中。  相似文献   

Early Mesoproterozoic metamorphism in the Barossa Complex,South Australia: links with the eastern margin of Proterozoic Australia     

L. J. Morrissey  M. Hand  B. P. Wade  M. Szpunar 《Australian Journal of Earth Sciences》2013,60(8):769-795

LA-ICP-MS U–Pb geochronological data from metamorphic monazite in granulite-facies metapelites in the Barossa Complex, southern Australia, yield ages in the range 1580–1550 Ma. Metapelitic rocks from the Myponga and Houghton Inliers contain early biotite–sillimanite-bearing assemblages that underwent partial melting to produce peak metamorphic garnet–sillimanite-bearing anatectic assemblages. Phase equilibrium modelling suggests a clockwise P–T evolution with peak temperatures between 800 and 870°C and peak pressures of 8–9 kbar, followed by decompression to pressures of ～6 kbar. In combination with existing age data, the monazite U–Pb ages indicate that the early Mesoproterozoic evolution of the Barossa Complex is contemporaneous with other high geothermal gradient metamorphic terranes in eastern Proterozoic Australia. The areal extent of early Mesoproterozoic metamorphism in eastern Australia suggests that any proposed continental reconstructions involving eastern Proterozoic Australia should share a similar tectonothermal history.  相似文献   

Highly retentive core domains in K-feldspar and their implications for 40Ar/39Ar thermochronology illustrated by determining the cooling curve for the Capoas Granite,Palawan, The Philippines     

M. A. Forster  R. Armstrong  B. Kohn  G. S. Lister  M. A. Cottam  S. Suggate 《Australian Journal of Earth Sciences》2013,60(7):883-902

K-feldspar from the late Miocene Capoas Granite on Palawan in The Philippines appears to contain highly retentive diffusion domains that are closed to argon diffusion at near-solidus temperatures during cooling of this ～7 km-diameter pluton. This is an important result, for K-feldspar is commonly considered not retentive in terms of its ability to retain argon. Closure temperatures for argon diffusion in K-feldspars are routinely claimed to be in the range ～150–400°C but the release of ³⁹Ar from irradiated K-feldspar during furnace step-heating experiments in vacuo yields Arrhenius data that imply the existence of highly retentive core domains, with inferred closure temperatures that can exceed ～500–700°C. These high closure temperatures from the Capoas Granite K-feldspar are consistent with the coincidence of ⁴⁰Ar/³⁹Ar ages with U–Pb zircon ages at ca 13.5 ± 0.2 Ma. The cooling rate then accelerated, but the rate of change had considerably slowed by ca 12 Ma. Low-temperature (U–Th)/He thermochronology shows that the cooling rate once again accelerated at ca 11 Ma, perhaps owing to renewed tectonic activity.  相似文献   

SHRIMP U–Pb phosphate dating shows metamorphism was synchronous with magmatism during the Paleoproterozoic Capricorn Orogeny     

A. M. Piechocka  J.-W. Zi  C. J. Gregory  S. Sheppard  B. Rasmussen 《Australian Journal of Earth Sciences》2013,60(7):973-990

Abstract

Unlike many Phanerozoic orogens, where the primary effects of orogenic events can be easily determined, Precambrian orogens are commonly characterised by repeated tectonothermal events making it challenging to decipher the geological history. The Capricorn Orogen is a complex Precambrian intraplate orogen located within the West Australian Craton that has been subjected to four separate reworking tectonic events between 1820 and 900?Ma. Although direct U–Pb ages for metamorphism have been obtained for the younger events, there is only limited geochronological data for the oldest event, the 1820–1770?Ma Capricorn Orogeny. This is primarily because of multiple episodes of deformation and metamorphism overprinting and obscuring the original tectonic fabrics and destroying metamorphic chronometers. In this study, we use in situ U–Pb monazite and xenotime geochronology, from a feldspathic metasandstone, a quartz–muscovite–chlorite–garnet pelitic schist, a quartz–muscovite–tourmaline schist and a garnet–biotite–plagioclase pelitic gneiss, to obtain the first direct age constraints for metamorphism during the Capricorn Orogeny in the northern Gascoyne Province. Metamorphism was synchronous with the 1820–1775?Ma magmatism in the northern part, and possibly in the southern part, of the Gascoyne Province. Furthermore, our results hint at a late stage hydrothermal fluid event at ca 1750–1730?Ma, post-dating the magmatism in the northern Gascoyne Province.  相似文献   

滇中新元古代澄江组层型剖面锆石U-Pb年代学及其地质意义   总被引：1，自引：0，他引：1  

崔晓庄  江新胜  王剑  卓皆文  熊国庆  陆俊泽  邓奇  伍皓  刘建辉 《现代地质》2013,27(3)

澄江组是华南新元古代地层中的重要地层单元之一,其确切沉积时限对于建立和完善华南新元古代区域地层格架具有关键意义。对滇中澄江组层型剖面顶部的凝灰岩夹层进行高精度SHRIMP锆石U-Pb定年研究,获得3组有效的206Pb/238U加权平均年龄值,其分别为(819±14)Ma(MSWD=0.15)、(781±11)Ma(MSWD=0.24)和(725±11)Ma(MSWD=0.65)。其中,最年轻的一组年龄值(725±11)Ma被解释为澄江组顶部凝灰岩夹层的形成时间,可以代表滇中澄江组的顶界年龄,从而进一步确认澄江组的沉积时限为800～725 Ma。结合相关研究资料,证实澄江组与开建桥组、莲沱组的沉积时限基本相当,三者与下冰期长安组不存在对比关系,而应与冰期前板溪群的上部进行对比。此外,推测两组年龄值较老的锆石可能是与新元古代罗迪尼亚(Rodinia)超大陆裂解有关的幕式岩浆活动的记录。  相似文献   

Zircon U-Pb geochronology of ore-bearing plagiogranite porphyry in the Tuanjiegou gold deposit, Heilongjiang Province, NE China     

HU Xinlu  DING Zhenju  HE Mouchun  YAO Shuzhen  ZHU Bopeng  SHEN Jun  CHEN Bin  CUI Yubao 《《地质学报》英文版》2013,87(Z1):699-700

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