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1.
Qualitative stylistic evidence from ceramic vessels and limited petrographic analysis suggested that a distinctive group of ceramics with visible inclusions of biotite (Gold Mica Fabric) was produced on the island of Aegina, Greece, during the Middle Helladic and Late Helladic I periods. To quantitatively evaluate this provenance, we sampled all potential source rocks on Aegina, Methana, and Poros. Electron microprobe analysis of amphibole in these samples revealed that each of these volcanic centers has its own unique mineralogical signature. Comparative analyses of amphibole in Zerner's original stylistic “Gold Mica Fabric” type sample with the reference samples reveal that two sherds are Aeginetan. Three additional sherds from this sample may have a non‐Aeginetan provenance, probably from a back‐arc setting outside the Saronic Gulf. These results suggest that the hypothesis of a single source production site for Aeginetan Ware should be reexamined. © 2002 Wiley Periodicals, Inc. 相似文献
2.
In an effort to further characterize the Middle and Late Helladic pottery industry on Aegina, we have analyzed amphibole in 23 sherds imported to the coastal settlement of Asine. The sherds derive from vessels of different classes and shapes and range in age from MH I‐II to LH IIIB‐IIIC Early. All sherds come from vessels that carry manufacturing marks, and their amphiboles have compositions that are incompatible with those of Methana, Poros, and Melos. Twenty of the sherds have amphiboles that are identical in composition and overlap a narrow range of amphibole compositions found in specific lava flows on the northern portion of Aegina. Given that the dacites across Aegina contain amphiboles with a wide range in compositions, we suggest that the narrow range of amphibole compositions in the sherds indicates that they were derived from either a specific clay source on the island, located in a stream system southeast of the prehistoric settlement at Kolonna, or that the potters used a specific temper source along the same stream system. Multiple clay or temper sources would have produced sherds with a broader range of amphibole compositions reflecting the diversity of amphibole compositions found on Aegina. One sherd has amphibole compositions indicative of an additional Aeginetan component that is not found in the other sherds. Two sherds have amphiboles with compositions that do not match any known reference amphiboles for Aegina, Methana, Poros, or Melos. These may have been derived from still unsampled dacites on Aegina or have been manufactured from materials located outside the Saronic Gulf. © 2004 Wiley Periodicals, Inc. 相似文献
3.
Surface sediment samples from near-shore shallow water as well as deeper water locations N and NE of the island of Methana were investigated geochemically. Shallow water samples from Thiafi Bay reveal up to 38-fold enrichment of As, associated with elevated contents of Sb, Fe and Zn. Deeper water samples NE of Methana show moderate Mn enrichment accompanied with elevated trace metal concentrations of As and, in some samples, Cd and Cu. In an area, where small mounds of possible hydrothermal origin were observed on the sea floor, fine-grained Fe-rich sediment was sampled with enrichment of typical hydrothermal trace elements As, P and Sb. Element enrichment in the investigated areas off Methana corresponds in terms of absolute concentrations and element suite to comparable hydrothermally influenced sediments from other locations of the Hellenic volcanic arc. The region between Methana peninsula and Aegina Island is not marked by vigorous hydrothermal activity, but localised enrichments of Fe and/or Mn, As, Sb as well as associated trace elements typically found in hydrothermally influenced sediments were identified. 相似文献
4.
Normally, the use of clays as reference materials in chemical provenance studies of ancient ceramics is complicated due to the original clay paste processing. The primary mixing and/or refining of raw materials during pottery production makes a straightforward comparison of archaeological ceramics with extant geological materials difficult if not impossible in many cases. However, in the case of Pliocene clays from Aegina (Greece), which were examined chemically and mineralogically and compared with Bronze Age pottery produced on the island, a successful exception can be presented. The chemical composition of a large group of Aeginetan pottery resembles the chemical composition of clays from a deposit in close vicinity to the main Bronze Age settlement of the island. Clays from specific outcrops exhibit considerable chemical and mineralogical homogeneity, and the suitability of those clays for pottery production apparently made substantial clay paste processing unnecessary. © 2004 Wiley Periodicals, Inc. 相似文献
5.
David M. Pyle Tjeerd H. van Andel Panayiotis Paschos Paul van den Bogaard 《Quaternary Research》1998,49(3):280-286
A newly recognized 2-m-thick trachytic volcanic ash deposit from northwestern Greece is dated at 374,000 ± 7000 yr and correlated with the Middle Pleistocene volcanic activity of central Italy. The deposit represents ash fallout from one of the largest volcanic eruptions in Europe of the past 400,000 yr and should provide an important stratigraphic marker within the poorly dated Middle Pleistocene deposits of Italy and Greece. 相似文献
6.
A geochemical survey on the thermal fluids released by the volcanic/geothermal system of Methana Peninsula and Loutraki area was undertaken. 相似文献
7.
《Tectonophysics》1999,301(1-2):111-132
As a first deep geophysical survey, thirteen magnetotelluric and magnetovariation soundings in the period range of 0.0085–6000 s have been carried out in the Methana Peninsula and Trizina area (Greece), which form the western part of the active Hellenic Volcanic Arc. Data have been processed using robust techniques and further analysed using decomposition methods in order to find the regional azimuth. By using the smooth inverse of Smith and Booker (J. Geophys. Res. 96, 3905–3922, 1991), the 2-D modelling has resolved a low-resistivity area (<30 Ω m) at depths of 2–3 km beneath the volcanics, whereas elsewhere the resistivity is much higher (>100 Ω m). Parkinson induction arrows also at the range 0.01–0.1 s point towards the centre of the peninsula. The conductivity anomaly is interpreted as being connected with the volcanic history of Methana, as a cooler remnant of former magmatic activity. The contrast with the much higher resistivities suggested at depths >5 km, is discussed in terms of fluid mobility, limitation of the MT method and extensional processes in the southern Aegean. 相似文献
8.
Volcanic centers (volcanoes, fumaroles or solfatara fields), epicenters of strong shallow earthquakes (with focal depths up to 20 km) and epicenters of intermediate depth strong earthquakes (with focal depths between 120 and 160 km) in the southern Aegean volcanic arc can be grouped into five, well defined, linear clusters trending about N60°E. This lineation of shallow earthquakes and volcanic activity is attributed to five corresponding normal faults which are named after the five corresponding volcanic centers (Sousaki, Methana, Milos, Santorini and Nisyros). This is supported by a similar trend of the geomorphological features (grabens and islands) and of geophysical features (Bouguer anomalies), as well as by other seismological data (fault plane solutions and the origins of tsunamis) and geological information on the Santorini caldera. The greater volcanic activity in the eastern volcanic centers (Santorini and Nysiros) compared to the western volcanic centers (Sousaki, Methana and Milos) is attributed to the higher rate of extensional crustal deformation. In the eastern part of the volcanic arc it is 26 mm/yr: in the west it is 2 mm/yr. The delineation of the epicenters of the intermediate depth earthquakes along the same five lines indicates the existence of five corresponding rupture zones in the lower (leading) part of the descending lithospheric slab (at depths of 120–180 km). These deep zones are probably the sources of hot material which is ascending vertically upwards and intrudes into the crust along its fracture zones. The orientation of these zones explains the focusing of the macro-seismic results of these deep shocks at narrow regions of the sedimentary arc (Peloponnesus, Crete, etc). 相似文献
9.
HSU Ta-Wei SHAU Yen-HongDepartment of Marine Resources National Sun Yat-Sen University Kaohsiung China 《《地质学报》英文版》2002,76(1):15-30
The Ordovician volcanic rocks in the Mayaxueshan area have been pervasively altered or metamorphosed and contain abundant secondary minerals such as albite, chlorite, epidote, prehnite, pumpellyite, actinolite, titanite, quartz, and/or calcite. They were denoted as spilites or spilitic rocks in terms of their petrographic features and mineral assemblages. The metamorphic grades of the volcanic rocks are equivalent to that of the intercalated metaclastic rocks. This indicates that both the spilitic volcanic rocks and metaclastic rocks in the Mayaxueshan area have formed as a result of Caledonian regional metamorphism. We suggest that the previously denoted spilitic rocks or altered volcanic rocks should be re-denoted as metabasalts or metabasaltic rocks. The metamorphic grade of the volcanic rocks increases with their age: prehnite-pumpellyite facies for the upper part of the Middle Ordovician volcanic rocks, prehnite-pumpeilyite to lower greenschist facies for the lower part of the Middle Ordovician vol 相似文献
10.
Charles B. Officer 《地学学报》1992,4(3):394-404
Iridium enhancements are associated with the fine particle emanations from present day basaltic and acidic volcanic eruptions but are not associated with impact craters, with one possible exception of Precambrian age. Microscopic dynamic deformation features are associated with structures originating from a meteorite impact, volcanic and internal explosion event(s), and high tectonic strain-rate(s). The Cretaceous/Tertiary (K/T) distributions of inidium and shocked minerals extend over a stratigraphic interval of a few hundred thousand years, in agreement with the known record of intense volcanism at K/T time but not in accord with the signature expected from a single meteorite impact. The recently studied K/T sections in Haiti add further information on the associations of shocked minerals and iridium enhancements. 相似文献
11.
拉拉铜矿床位于康滇地轴西南缘,赋矿围岩是古元古界河口组变质火山岩,矿床为火山喷发沉积-变质层控型铜矿床[1]。笔者通过野外地质调查、室内显微镜鉴定、电子探针成分分析等手段,研究了矿石组构、成分及主要有用伴生元素钼、钴、金、稀土、铂族元素等的赋存状态,有用伴生元素以独立矿物存在为主,类质同象为次。研究中发现了铂族矿物(铋碲镍钯矿、碲钯镍矿),得出矿床综合利用价值巨大的结论,并对进一步综合利用提出了建议。根据矿床野外产出及矿石组构特征,将成矿过程划分为火山喷发沉积成矿期、变质热液成矿期及表生期。 相似文献
12.
A program of ceramic analysis, by which archaeologically excavated pottery can be efficiently and economically grouped by fabric and geographic origin, has been devised. the fabric is segregated by xeroradiography, macroscopic observation, and heavy-mineral analysis before it is identified petrologically. the program has enabled determination of the effects of certain aspects of trade patterns and economics on life in the ancient city of Roman-Period Caesarea Maritima. This program was tested on an 84-sherd corpus of Pompeian Red Ware. Xeroradiography, heavy-mineral analysis, and petrology each segregated the sherds into two fabrics, one of which contained 83 sherds. This latter fabric had not been reported in earlier studies of Pompeian Red Ware which concentrated on samples from England and Europe. However, the similarities between this new fabric and another known fabric suggest that the Caecuban and Falernian regions west of Terracina and east of Capua should be the source of this ware. an astonishing result was that other known fabrics were not found at Caesarea Maritima. A potential chronological hypothesis was formulated to account for this observation. 相似文献
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14.
四川万州中侏罗统上沙溪庙组粘土岩中火山灰的岩矿和地球化学证据 总被引：2，自引：0，他引：2
四川盆地东北缘万州地区中侏罗世上沙溪庙组产出稳定层状浅色粘土岩。利用X射线、X荧光光谱、等离子光谱（ICP）等方法对矿物成分、常量、微量和稀土元素进行了测试分析,粘土岩主要矿物为蒙脱石、伊利石和绿泥石。通过与澳大利亚后太古代平均页岩（PAAS）、北美平均页岩（NASC）、地壳粘土岩背景值以及其它具有代表性岩石的对比发现,本区粘土岩微量元素具有明显的低V,低Ti和低铁族元素的特点,高Al2O3／TiO2比值和低Ti／Th比值特征显著,某些层位具有明显的Eu负异常。推断本区粘土岩沉积物源具有火山灰和陆源碎屑的二元混合成因,各层位成分的差异显示了不同沉积时间内二者的混合比例发生变化。区域对比和地球化学资料显示火山灰可能来自于西部600km远的特提斯洋岛弧火山。 相似文献
15.
CLAUDE FROGET 《Sedimentology》1981,28(6):793-804
The study of clays from sites 338 to 343 enables the main lines of the palaeogeographical evolution of the Vøring plateau, off Norway, to be determined. The following stages are proposed: (1) In early Eocene sediments, clays provide evidence of erosion of the Scandinavian shield; detrital primary minerals (illite, chlorite) derived from crystalline rocks are dominant. This erosion results from tectonic movements coeval with the opening of the Norwegian basin. The rejuvenation of marginal relief hinders pedogenesis, which is only indicated by the presence of minerals coming from the few soils which are developed. (2) From the Middle Eocene, primary minerals decrease while smectite becomes dominant. This trend increases through the late Eocene and at the beginning of the Middle Oligocene, where only smectite is present. During this period the basin margins are stabilized after the initial movements. In essentially pelagic marine sediments, the smectite seems to be derived from volcanic rocks. (3) During the Middle Oligocene and early to Middle Miocene, smectite is always dominant, but primary minerals reappear, with mixed-layers indicating a moderate continental alteration. This composition suggests a modification of the climate, mainly marked by an increase in humidity. (4) In Pliocene and Plio-Pleistocene sediments, primary minerals are dominant, while smectite decreases. The glacial climate is responsible for this mineralogy. Detrital minerals would come from the erosion of Scandinavian moraines and from rafting by icebergs. 相似文献
16.
苏北盆地粘土矿物转化模式与古地温 总被引：16，自引：0，他引：16
以苏北盆地为例,系统研究了火成岩发育区粘土矿物组合特征及其控制因素;建立了粘土矿物转化模式;根据粘土矿物成岩演化特点,进行古地温分析。研究表明,苏北地区粘土矿物的分布主要受埋藏成岩作用、岩浆侵入、母质来源三种因素的影响,发育四种类型的粘土矿物组合和三种粘土矿物转化模式;火山碎屑岩母岩区和基性岩浆侵入区具有特殊的粘土矿物组合和成岩演化模式,前者以富含蒙皂石矿物为特点;后者出现高岭石与伊/蒙有序间层矿物共生组合,并具有不连续的演化序列;苏北盆地短有序I/S矿物出现于镜质组反射率 0.5 %～ 0.5 5 %的深度,伊/蒙间层矿物转变成伊利石在镜质组反射率 0.75 %～ 0.8%,可以用于热成熟度和古地温的估算;而蒙皂石消失的界面则不具有指标意义 相似文献
17.
AbstractThe fabric and the anisotropy of magnetic susceptibility of the Cabo Ortegal eclogite (NW Spain) are studied. These mafic rocks were metamorphosed and deformed under high pressures and temperatures between 390 and 370 Ma in a subduction/collision tectonic setting. Massive eclogite slices and deformed eclogite in shear zones have bulk magnetic susceptibilities of 31 to 82·10?5 S.I. and 28 to 75·10?5 S.I., respectively. The paramagnetic mineral fraction is the principal magnetic susceptibility carrier. This fraction includes notably garnet and clinopyroxene as matrix minerals, and ilmenite and rutile as accessory constituents. Though magnetic anisotropy degree varies between 3.1 % and 6.6 %, variations of this parameter in each rock type are marked. In the deformed eclogite, magnetic lineation (Kmax) and the pole to the magnetic foliation (Kmin) are coaxial and coincident with macroscopic petrofabric elements (foliation and lineation). In the massive eclogite, the magnetic fabric is dispersed along the principal structural planes and inversions are associated with samples with small degrees of anisotropy. The anisotropy of magnetic susceptibility is interpreted as being due to the crystallographic preferred orientation and spatial organisation of the polymineralic aggregate. Relating the evolution of the symmetry of magnetic fabric to the symmetry of petrofabric or deformation is rather precluded since susceptibility has multiple origins and bulk magnetic fabric is due to minerals of different symmetry. © Elsevier, Paris 相似文献
18.
CAI Hou＇an LIANG Handong ZHANG Jun LUO Chunping 《《地质学报》英文版》2006,80(1):46-51
The Meishan section of China has been confirmed as the ＂Global Stratotype Section and Point＂ of the P/T boundary. In the section, the authors found several types of iron grains, including pyrite, pure iron grains and goethite. From the research of macro minerals, it is easy to find that the grains rich in iron appear from the bottom of the event layer of the section. In other words, it is probably residue of the geochemical catastrophe of that time. Therefore, it is important to trace the source of these iron grains and their relationships, which probably provides evidence for volcanic eruption or impact-volcanoes and has directive significance to the crisis during the P/T transitional period. Through the study of the characterization and relationships of these iron grains, the authors make a preliminary discussion on the P/T mass extinction. 相似文献
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20.
The Smartville Complex is a late Jurassic, rifted volcanic arc in the northern Sierra Nevada, California. Near Auburn, California, it consists of a lower volcanic unit, dominated by basaltic flows, and an upper volcanic unit of andesitic volcaniclastic rocks, both of which have been intruded by dykes and irregular bodies of diabase. These rocks contain relict igneous minerals, and the metamorphic minerals albite, chlorite, quartz, pumpellyite, prehnite, epidote, amphibole, titanite, garnet, biotite, K-feldspar, white mica, calcite, and sulphide and oxide minerals.
Prehnite–pumpellyite (PrP), prehnite–actinolite (PrA), and greenschist (GS) zones have been identified. The pumpellyite-out isograd separates the PrP and PrA zones, and the prehnite-out isograd separates the PrA and GS zones. The minerals Ab + Qtz + Mt + Tn are common to most assemblages in all three zones. The MgO/(MgO + FeO) ratio of the effective bulk composition has an important and systematic effect on the observed mineral assemblages in the PrP zone. Prehnite-bearing assemblages contain the additional minerals, Pmp + Amp + Ep + Chl in MgO-rich rocks, and either Pmp + Ep + Chl or Amp + Ep + Chl in less magnesian rocks. Subcalcic to calcic amphibole is common in the PrP zone. The mineral assemblage Prh + Act + Ep + Chl, without Pmp, characterizes the PrA zone, and the mineral assemblage Act + Ep + Chl, without Prh or Pmp, characterizes the GS zone. The disappearance of pumpellyite and prehnite occurred by continuous reactions.
The sequence of mineral assemblages was produced by burial metamorphism at P–T conditions of 300° 50°C at approximately 2.5 ± 0.5 kbar. During metamorphism, the composition of the fluid phase was nearly 100% H2 O and the oxygen fugacity was between the hematite–magnetite and quartz–fayalite–magnetite buffers. 相似文献
Prehnite–pumpellyite (PrP), prehnite–actinolite (PrA), and greenschist (GS) zones have been identified. The pumpellyite-out isograd separates the PrP and PrA zones, and the prehnite-out isograd separates the PrA and GS zones. The minerals Ab + Qtz + Mt + Tn are common to most assemblages in all three zones. The MgO/(MgO + FeO) ratio of the effective bulk composition has an important and systematic effect on the observed mineral assemblages in the PrP zone. Prehnite-bearing assemblages contain the additional minerals, Pmp + Amp + Ep + Chl in MgO-rich rocks, and either Pmp + Ep + Chl or Amp + Ep + Chl in less magnesian rocks. Subcalcic to calcic amphibole is common in the PrP zone. The mineral assemblage Prh + Act + Ep + Chl, without Pmp, characterizes the PrA zone, and the mineral assemblage Act + Ep + Chl, without Prh or Pmp, characterizes the GS zone. The disappearance of pumpellyite and prehnite occurred by continuous reactions.
The sequence of mineral assemblages was produced by burial metamorphism at P–T conditions of 300° 50°C at approximately 2.5 ± 0.5 kbar. During metamorphism, the composition of the fluid phase was nearly 100% H