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1.
新疆觉洛塔格地层分区东部石炭系 总被引：2，自引：0，他引：2
觉洛塔格地层分区广泛发育早石炭世及晚石炭世早期的火山－沉积建造。以雅满苏大断裂为界，分为南部的雅满苏地层小区和北部的苦水地层小区，为两个不同的沉积构造环境：南部为岛弧火山岩沉积相区；北部为弧间盆地沉积相区。雅满苏小区划分出小热泉子组、雅满苏组、白鱼山组和底坎尔组４个岩石地层单位。苦水小区划分出雅北组、梧桐窝子组、干墩组、白鱼山组和苦水组５个岩石地层单位。分别叙述了两个地层小区岩石地层单位的分布、剖面层序及确定地层时代的化石依据。 相似文献
2.
R. J. Korsch 《Australian Journal of Earth Sciences》2013,60(3-4):261-269
The Coffs Harbour Association, New England Orogen, consists of thick, monotonous units of Late Palaeozoic greywacke, laminated siltstone and mudstone, and massive argillite. The rocks of the association have a common provenance, being derived predominantly from a volcanic arc source consisting of mainly dacite, with minor andesite and rhyolite. The Coramba beds in the Coffs Harbour Block are divided into four petrofacies based on QFL data and the occurrence of detrital hornblende. Upwards, the petrofacies are: A—volcanolithic, B—feldspathic, C—horn‐blende‐feldspathic, D—hornblende‐volcanolithic. The petrofacies and vertical variation in non‐volcanic detritus indicate minor erosion and exposure of a non‐volcanic source, followed first by recommencement of volcanism, penecontemporaneously with sedimentation, then further erosion of the non‐volcanic source area. There was little temporal change in the character of volcanic detritus shed from the source area. Equivalents of the four petrofacies are recognised in other blocks of the association, although because of structural complexity, a complete A‐D sequence has not been found. The Coffs Harbour sandstones are similar to sands in modern ocean basins derived from an arc system of either continental margin or island arc type. The sandstones are not similar to recycled orogenic provenances, such as found in accretionary prisms or trench‐slope basins; the compositions suggest that the sandstones were deposited in either a forearc or backarc setting. 相似文献
3.
4.
S. J. Craven 《Australian Journal of Earth Sciences》2017,64(3):401-418
Detrital zircon from the Carboniferous Girrakool Beds in the central Tablelands Complex of the southern New England Orogen, Australia, is dominated by ca 350–320 Ma grains with a peak at ca 330 Ma; there are very few Proterozoic or Archean grains. A maximum deposition age for the Girrakool Beds of ca 309 Ma is identified. These data overlap the age of the Carboniferous Keepit arc, a continental volcanic arc along the western margin of the Tamworth Belt. Zircon trace-element and isotopic compositions support petrographic evidence of a volcanic arc provenance for sedimentary and metasedimentary rocks of the central Tablelands Complex. Zircon Hf isotope data for ca 350–320 Ma detrital grains become less radiogenic over the 30 million-year record. This pattern is observed with maturation of continental volcanic arcs but is opposite to the longer-term pattern documented in extensional accretionary orogens, such as the New England Orogen. Volcanic activity in the Keepit arc is inferred to decrease rapidly at ca 320 Ma, based on a major change in the detrital zircon age distribution. Although subduction continues, this decrease is inferred to coincide with the onset of trench retreat, slab rollback and the eastward migration of the magmatic arc that led to the Late Carboniferous to early Permian period of extension, S-type granite production and intrusion into the forearc basin, high-temperature–low-pressure metamorphism, and development of rift basins such as the Sydney–Gunnedah–Bowen system. 相似文献
5.
辽宁义县—北票地区义县组地层层序——义县阶标准地层剖面建立和研究之一 总被引：30，自引：1，他引：30
义县地区广义的义县组可解体为王家屯组 (暂命名 )和义县组 ;分属王家屯和义县火山旋回 ,前者为偏酸、偏碱性 ,后者主体为中基性、末期为中酸性火山岩系 ,并广泛发育潜火山岩相的玄武玢岩、安山玢岩和火山集块角砾熔岩筒。该区有七个主要沉积层 ,自下而上分别为王家屯组马神庙层、义县组老公沟层、业南沟层、砖城子层、大康堡层、朱家沟层和金刚山层 ;产有较丰富的无脊椎动物、脊椎动物和植物化石。以砖城子层、大康堡层和金刚山层为界 ,义县火山旋回可划分为 4个亚旋回 ,分别代表火山活动的初始期、主期、晚期和末期。北票四合屯地区的义县组相当义县地区义县组的第一和第二亚旋回 ,含鸟类化石的主沉积层 (尖山沟层和上园层 )可与砖城子层对比 相似文献
6.
论河北承德上谷早侏罗世南大岭组 总被引：2，自引：0，他引：2
利用最新资料描述了承德上谷南大岭组四个实测剖面的地层层序,岩性岩石组合,沉积构造等特征,厘定了南大岭组含义为一套中基性火山岩系,其间的沉积岩系作为非正式填图单位,证实了火山岩系与沉积系在空间上呈指状交互关系,根据植物化石确定南大岭组中时代为早侏罗世,论述火山岩岩石学,岩石化学特征。 相似文献
7.
Kodjopa Attoh 《Precambrian Research》1982,18(3):275-290
The structure of an early Proterozoic volcanic—sedimentary belt in northeastern Ghana is inferred from the distribution of lithologic units and interpretation of Bouguer gravity anomaly associated with the belt. It is shown from gravity modelling that the vertical thickness (depth) of the volcanic—sedimentary succession is ca. 3 km and that the structure of the western part of the belt is an overturned anticline, an interpretation consistent with facing data. This structure provides the basis from which the stratigraphic order of the mapped lithic units is deduced: (1) fine-grained epiclastic sediments interbedded with minor felsic tuffs, followed by (2) tholeiitic basaltic lavas, which are overlain by (3) calc-alkaline andesitic and dacitic lavas and tuffs; the youngest volcanic unit belonging to the sequence is a calc-alkaline mafic tuff (4). A manganese-rich chemical sediment is preserved at the boundary between the tholeiitic mafic lava and calc-alkaline intermediate volcanic rock units. The early Proterozoic sequence, which is unconformably overlain by coarse fluviatile sediments, is estimated to be ca. 8500 m thick. The stratigraphic sequence in the study area contrasts strongly with the conceptual stratigraphic schemes which are currently held to be valid for similar lithologic associations of early Proterozoic age (Birimian) in the West African shield. 相似文献
8.
Numerical analysis of the hydrogeologic controls in a layered coastal aquifer system, Oahu, Hawaii, USA 总被引：3，自引：1，他引：2
Delwyn S. Oki William R. Souza Edward L. Bolke Glenn R. Bauer 《Hydrogeology Journal》1998,6(2):243-263
The coastal aquifer system of southern Oahu, Hawaii, USA, consists of highly permeable volcanic aquifers overlain by weathered
volcanic rocks and interbedded marine and terrestrial sediments of both high and low permeability. The weathered volcanic
rocks and sediments are collectively known as caprock, because they impede the free discharge of groundwater from the underlying
volcanic aquifers. A cross-sectional groundwater flow and transport model was used to evaluate the hydrogeologic controls
on the regional flow system in southwestern Oahu. Controls considered were: (a) overall caprock hydraulic conductivity; and
(b) stratigraphic variations of hydraulic conductivity in the caprock. Within the caprock, variations in hydraulic conductivity,
caused by stratigraphy or discontinuities of the stratigraphic units, are a major control on the direction of groundwater
flow and the distribution of water levels and salinity. Results of cross-sectional modeling confirm the general groundwater
flow pattern that would be expected in a layered coastal system. Groundwater flow is: (a) predominantly upward in the low-permeability
sedimentary units; and (b) predominantly horizontal in the high-permeability sedimentary units.
Received, October 1996 Revised, August 1997 Accepted, September 1997 相似文献
9.
《International Geology Review》2012,54(15):1914-1939
ABSTRACTGlobal-scale Palaeozoic plate tectonic reconstructions have suggested that Laurentia was obliquely approaching against the northwestern margin of Gondwana until the final agglutination of Pangea. In this contribution integrated petrographic analysis, heavy mineral analysis, and tourmaline geochemistry were done, and U–Pb detrital zircon geochronology was obtained, in late Palaeozoic sedimentary and meta-sedimentary units from the Floresta and Santander Massifs in the Eastern Colombian Andes in order to constrain their provenance and related it with the magmatic, sedimentary, and deformational record of the Gondwana–Laurentia convergence until the late Carboniferous to Permian formation of Pangea. Late Devonian to early Carboniferous sandstones from the Floresta Massif changed from sublithoarenites to lithoarenites, tracking the progressive uplift and unroofing of sedimentary and metamorphic rocks, with associated volcanic activity. The U–Pb detrital zircon geochronology from the sedimentary and metasedimentary of Floresta and Santander documents Mesoproterozoic and Palaeoproterozoic sources, and younger Ordovician to Silurian age populations, that can be related to the early to middle Palaeozoic plutonic rocks and the Amazon Craton. The limited Silurian to Early Devonian detrital ages that contrast with the more significant Middle to Late Devonian zircons that document the erosion of contemporaneous magmatic sources formed after a late Silurian to Early Devonian reduction on the magmatic activity along the proto-Andean margin. These rocks were apparently deformed and metamorphosed between the late Carboniferous and the early Permian. It is suggested that the filling and deformation record of these rocks documented the changes in plate convergence obliquity at the western margin of Gondwana associated with the migration of Laurentia until its final position in Pangea. Between the late Carboniferous and the early Permian, peri-Gondwanan continental terranes also collided with the continental margin. Over-imposed Mesozoic tectonics have contributed to the final redistribution of these terranes to their current position.Abbreviations:LA: laser ablation inductively couple mass spectrometer; CL: cathodoluminiscence 相似文献
10.
A. V. Zernack S. J. Cronin V. E. Neall J. N. Procter 《International Journal of Earth Sciences》2011,100(8):1937-1966
The >25 ka volcaniclastic ring-plain succession in south-west Taranaki has been remapped to establish a much more detailed
understanding of the older stratigraphic record of Mt. Taranaki. Coastal cliff exposures show a range of volcaniclastic lithofacies,
including debris-avalanche and lahar deposits, and allow a detailed chronological reconstruction of past volcanic and sedimentary
events. Five new debris-avalanche deposits were identified, and their distribution in coastal cross-sections mapped. In addition,
four previously described units were renamed and their stratigraphic position and lateral extent redefined. Chronostratigraphic
control of the younger (<50 ka) sequence was obtained by radiocarbon dating of wood found within, or peat interbedded with,
the deposits. Emplacement ages of the older units were estimated from their stratigraphic position and underlying marine wave-cut
surfaces. Overall, at least 14 widespread debris-avalanche deposits occur within the <200 ka ring-plain record of Mt. Taranaki,
suggesting one major edifice failure on average every 14,000 years, with an increase in frequency since 40 ka. The stratigraphic
reconstruction of the ring-plain succession showed that the same pattern of deposition was repeatedly produced throughout
the existence of Mt. Taranaki. Depending on their sedimentological characteristics, the different volcanic and sedimentary
lithofacies can be related to phases of edifice-construction or collapse events. Based on the identified cyclic sedimentation
pattern, we present a new episodic stratigraphy that integrates existing and new lithostratigraphic units into a coherent
chronostratigraphic framework that can be applied to the entire volcanic and volcaniclastic succession at Mt. Taranaki. This
model takes into account the complex geological processes that have taken place on the volcano and provides a more uniform
stratigraphic terminology that could be applied to repeatedly collapsing stratovolcanoes elsewhere. 相似文献
11.
A. M. Mazukabzov A. M. Stanevich D. P. Gladkochub T. V. Donskaya V. B. Khubanov Z. L. Motova T. A. Kornilova 《Doklady Earth Sciences》2018,478(2):171-174
The geological position, composition, and age of detrital zircons of sedimentary deposits of the Nugan Formation of the Western Baikal region underlying the Golousta Formation of the Baikal series of Ediacaran age have been studied. The formation of both stratigraphic units due to the same sources of detrital material, located within the southern flank of the Siberian Craton, has been proved. The deposits of the Nugan Formation have been demonstrated to mark the rifting stage of the formation of the passive margin of the Paleo-Asiatic Ocean: their accumulation occurred in the Late Cryogenian during the interval 720–640 Ma. 相似文献
12.
Monika Agnieszka Kusiak Artur K&#x;dzior Mariusz Paszkowski Kazuhiro Suzuki Ignacio Gonzlez-lvarez Boles&#x;aw Wajsprych Marek Doktor 《Lithos》2006,88(1-4):56-71
This paper reports the results of CHIME (chemical Th–U–Pb isochron method) dating of detrital monazites from Carboniferous sandstones in the Upper Silesia Coal Basin (USCB). A total of 4739 spots on 863 monazite grains were analyzed from samples of sandstone derived from six stratigraphic units in the sedimentary sequence. Age distributions were identified in detrital monazites from the USCB sequence and correlated with specific dated domains in potential source areas. Most monazites in all samples yielded ca. 300–320 Ma (Variscan) ages; however, eo-Variscan, Caledonian and Cadomian ages were also obtained. The predominant ages are comparable to reported ages of certain tectonostratigraphic domains in the polyorogenic Bohemian Massif (BM), which suggests that various crystalline lithologies in the BM were the dominant sources of USCB sediments. 相似文献
13.
Norberto J. Uriz Carlos A. Cingolani Farid Chemale Jr Moacir B. Macambira Richard Armstrong 《International Journal of Earth Sciences》2011,100(2-3):571-589
The Silurian?CDevonian siliciclastic sedimentary units known as Sierra Grande Formation and the upper part of the Ventana Group crop out in the eastern area of the North Patagonian Massif and in the Ventania system, toward the Atlantic border of Argentina. Both sequences show similar stratigraphical characteristics and were deposited in a shallow marine platform paleoenvironment. Previous contributions have provided evidence of an allochthonous Patagonia terrane that amalgamate to Gondwana during the Permian?CTriassic. However, other lines of research support a crustal continuity southward, where the Pampean and Famatinian events extend into the northern Patagonia. In either case, the detrital input to the Eo?CMesopaleozoic basins generated along the passive margin tectonic setting should reflect the sedimentary sources. In this contribution, new age data on the sedimentary provenance of these units is provided by U?CPb and Lu?CHf isotopic studies on detrital zircons, using LA-ICP-MS and SHRIMP methodologies. The main sedimentary sources of detrital zircons for both regions are of Cambrian?COrdovician and Neoproterozoic age, while a secondary mode is Mesoproterozoic. Zircons from older cratonic sources (Mesoarchean?CPaleoproterozoic ages) are scarcely recorded. The sample from the upper section of the Devonian Lolén Formation (Ventana Group) shows an important change in the sedimentary provenance, with a main mode of Mesoproterozoic detrital zircons. Detrital source areas considering the orogenic cycles known for southwest South America (Famatinian, Pampean?CBrasiliano, Mesoproterozoic?C??Grenvillian?? and Paleoproterozoic?C??Transamazonian??) are proposed. 相似文献
14.
Andr Weissheimer de Borba Ana Maria Pimentel Mizusaki Anderson Jos Maraschin Diogo Rodrigues Andrade da Silva 《Journal of South American Earth Sciences》2008,26(4):485-497
Integrated petrographic and Sm–Nd isotopic data were applied in order to constrain the provenance of the Early Paleozoic Santa Bárbara Formation, Sul-rio-grandense Shield, southern Brazil. This unit comprises continental sandstones, conglomerates and siltstones deposited under semi-arid climate in a rift or pull-apart basin. Samples were collected within a stratigraphic framework composed of three sequences, in which the two basal ones present northeastwards paleoflow, and the third one marks the inversion of basin filling. Samples from sequence I show, in the south, a strong influence of intermediate volcanic (Hilário Formation) sources, and a significant increase in quartz and metamorphic fragments upsection. In the northern deposits, there is a possible influence of juvenile units (Cambaí/Vacacaí), and a more significant input of Paleoproterozoic-sourced sedimentary rocks (e.g. Maricá Formation) upsection. Samples collected from the topmost deposits of sequence II present a clear increase in the amount of volcanic fragments (mostly acidic), reflecting denudation of the “Caçapava high”. Data obtained in sequence III (Pedra do Segredo) show a progressive decrease in quartz content and a significant increase in feldspathic, plutonic fragments. A more evolved phase of denudation of the “Caçapava high”, exposing leucogranitoids of the Caçapava do Sul complex, is proposed for this interval. 相似文献
15.
新疆吐哈盆地南缘大草滩一带出露一古生代基岩“天窗”,主要为一套火山岩—火山沉积岩,前人将其归为泥盆纪大南湖组。在该区新发现的大草滩蛇绿岩两侧识别出了两套厚度较大、时代为早—中泥盆世的复理石沉积,缺乏火山熔岩和碳酸盐岩夹层,与大南湖组层型剖面存在一定的差别。北侧复理石沉积可划分为三段,南侧受构造改造,仅发育上下两段。两侧砂岩样品的粒度参数呈现典型浊积岩特征,且自下而上水动力存在增强的趋势。通过岩性组合、沉积构造、粒度特征对该浊积岩进行沉积相分析,共识别出9种浊积岩相,进而识别出浊积扇中的3种沉积环境,其中在内扇和中扇环境中各识别出3种沉积亚环境。沉积相在垂向上的分布规律显示南北两侧的复理石分别为外扇—中扇和外扇—中扇—内扇的两套进积序列,结合碎屑颗粒组分和区域大地构造背景,推断该浊积岩形成于大南湖岛弧的弧前盆地。 相似文献
16.
AbstractDetrital zircon populations from Carboniferous to Permian sandstones from the Lozar Section of Spiti, northern India, were analyzed with the typology method in order to obtain complementary information on the source areas of the sediments. Zircon grains were subdivided into several groups and subgroups, according to degree of abrasion and morphological features.First appearance of detrital zircons with distinct typologic signature within successive stratigraphic intervals provided useful data about the tectono-magmatic evolution of the northern Indian margin during Late Paleozoic rifting of Gondwana and initial opening of Neotethys. The base of the studied sequence (Lower Carboniferous Thabo Fm.) is characterized by a largely cratonic provenance, seemingly from the Indian Shield to the South. In the Upper Carboniferous Chichong Fm., first occurrence of typical zircons from anatectic granites and increasing abundance of granitoid detritus suggest rapid uplift and unroofing of anatectic rocks of probable Cambro-Ordovician age. In the lowermost Permian (Asselian) glaciomarine Ganmachidam Diamictite, euhedral detrital zircons with peculiar features, associated with Cr-rich chromian spinels and mafic to felsic volcanic rock fragments, hint at emplacement of bimodal alkaline magmatic suites. The same sources, possibly including subvolcanic bodies, continued to be eroded until final break-up, documented by the Permian Kuling Group. 相似文献
17.
18.
M. I. Valladares P. Barba J. M. Ugidos J. R. Colmenero I. Armenteros 《International Journal of Earth Sciences》2000,89(1):2-20
2 O3, TiO2, Zr, and Nb abundances in shales from all the units, strongly suggest a gradual compositional change within this sedimentary
succession. Together with the petrological data, the chemical results do not reveal any obvious coeval volcanic contribution
to the sediments. On the basis of the chemical data, a comparison is made with other European zones containing detrital sediments
composed of reworked crustal components.
Received: 4 January 1999 / Accepted: 1 December 1999 相似文献
19.
《China Geology》2019,2(2):169-178
A comparative comparative study on the detrital mineral composition of stream sediments of the Yangtze River (Changjiang) and Yellow River (Huanghe) shows that, light minerals of the Yangtze River basin were mainly quartz, feldspar, and detritus, the compositional characteristics of light minerals differed among tributaries, the main stream had a generally higher maturity index than tributaries; heavy mineral content tended to decrease progressively from the upper stream to lower stream of the Yangtze River, the primary assemblage was magnetite-hornblende-augite-garnet-epidote, and diagnostic minerals of different river basins were capable of indicating the nature and distribution of the source rock. Detrital mineral assemblages in sediments of tributaries and the main stream of the Yellow River were basically similar, Primary heavy mineral assemblage was opaque mineral-garnet-epidote-carbonate mineral and alteration mineral. Variations in the contents of garnet, opaque mineral, and hornblende mainly reflected the degree of sedimentary differentiation in suspended sediment and the hydrodynamic intensity of a drainage system. The heavy mineral differentiation index F revealed sedimentary differentiation of diagnostic detrital mineral composition due to changes in regional hydrodynamic intensity and can serve as an indicator for studying the dynamic sedimentary environment of a single-provenance river and the degree of sedimentary differentiation of its detrital minerals. Changes in detrital mineral content of the Yellow River was not completely controlled by provenance but reflected gravity sorting of the detrital mineral due to variations in the ephemeral river hydrodynamic intensity and sedimentary environment, however the index changing of Yangtze River were mainly influenced by the complex sediment sources. Therefore caution must be exercised in using the detrital mineral composition of marginal sea to determine the contribution of the Yangtze River and Yellow River.© 2019 China Geology Editorial Office. 相似文献
20.
Kryza Ryszard Turniak Krzysztof Muszyński Andrzej Zalasiewicz Jan A. 《International Journal of Earth Sciences》1994,83(1):5-19
The Gackowa Formation of inferred Cambrian —Ordovician age is part of the metamorphosed pre-Variscan basement of the southern Kaczawa Mountains of the Sudetes region, south-west Poland. Previously variously interpreted as lavas, tuffs and sandstones, it is shown to consist of about 200 m of originally well-sorted siliclastic sedimentary rocks within a sequence of predominantly mafic volcanic rocks. Four facies have been distinguished based on relict sedimentary structures and textures and these suggest that deposition took place on a storm-dominated shelf, mostly above the wave base. The petrography, detrital zircon morphologies and geochemistry suggest affinity with, and derivation in large part from, acid volcanic rocks at a comparable stratigraphic position in a separate tectonostratigraphic unit to the south. The Gackowa Formation and its acid volcanic source rocks have a clear continental geochemical signature, in contrast with the mantle-derived basic/bimodal volcanic rocks below and above; it is suggested that the parent acid magma originated by crustal melting during the ascent of these mantle-derived magmas. A continental crust setting is inferred for the deposition of the Gackowa Formation sandstones, thus suggesting a continental setting for the associated within-plate basalts. The entire volcanic/sedimentary succession resembles elements of the Lower Palaeozoic of Germany, and all may have formed in an initial rift setting during Late Precambrian to Ordovician times. 相似文献