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1.
Dr. Zoltan De Cserna 《International Journal of Earth Sciences》1960,50(1):595-605
The evolution of the border region of part or all of a craton, on the basis of geological data gathered from Mexico, may best be described in terms of geotectonic cycles. These consist, in chronological order, of (1) an orthogeosynclinal phase (eu- and miogeosynclines) with or without initial magmatic activity, (2) an anatexitic phase consisting of batholith emplacement with attendant regional metamorphism in the eugeosyncline and deposition of a clastic or flysch wedge over the miogeosyncline, (3) an orogenic phase consisting principally of the folding and thrusting of the sediments of the miogeosyncline together with the clastic or flysch wedge against the foreland, and (4) a taphrogenic or block-faulting phase accompanied by (a) accumulation of post-orogenic debris or molasse, (b) subsequent magmatic activity consisting largely of igneous extrusions with fewer intrusions, and (c) final magmatic activity consisting of igneous extrusions. A region that has gone through the above phases of a geotectonic cycle may be termed a structural belt. In the post-Precambrian geologic history of Mexico, three geotectonic cycles are recognized: one occurred along the Pacific border of Mexico between Cambrian and middle Jurassic (?) time (Jaliscoan geotectonic cycle), the second occurred along the present Gulf of Mexico border of the country at the same time (Huastecan geotectonic cycle), and the third occurred over the entire country from the United States border to the Guatemalan border between Late Jurassic and Pliocene time (Mexican geotectonic cycle). The early Mesozoic clastic rocks in northwestern Mexico may signify a fourth geotectonic cycle in that region. In the three recognized geotectonic cycles, however, the geologic record shows only two orogenic phases, one of which occurred in late Paleozoic time in an arcuate belt along the eastern side of Mexico (Coahuilan orogeny), and the other in early Tertiary time in a belt traversing central Mexico from the United States border to the Guatemalan border (Hidalgoan orogeny). 相似文献
2.
Review: Micro-organic contaminants in groundwater in China 总被引：1，自引：0，他引：1
Weihong Dong Wei Xie Xiaosi Su Chuanlei Wen Zhipeng Cao Yuyu Wan 《Hydrogeology Journal》2018,26(5):1351-1369
Micro-organic contaminants (MOs) in groundwater, which may have adverse effects on human health and ecosystems worldwide, are gaining increased attention in China. A great deal of research has been conducted to investigate their sources, occurrences and behavior in aquifers. This paper reviews the main sources, distribution, concentrations and behavior of a wide range of MOs in groundwater in China. These MOs include well-established persistent organic pollutants—polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), polychlorinated biphenyls (PCBs), endocrine disrupting chemicals (poly brominated diphenyl ethers (PBDEs), phthalic acid esters (PAEs), bisphenol A (BPA)—and some contaminants of emerging concern such as pharmaceutical and personal care products (antibiotics, caffeine, shampoos) and perfluorinated compounds (PFCs). The results reveal that the main MOs in groundwater are PAHs, organochlorine pesticides (OCPs), PBDEs, PAEs, and antibiotics. Moreover, some PFCs such as perfluorobutane sulfonic acid (PFBS), perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) have only recently been observed in groundwater as emerging organic contaminants. Additionally, most MOs are distributed in populated and industrialized areas such as the southeast coast of China. Finally, industrial emissions, wastewater treatment plant effluents and agricultural wastewater are found to be dominant sources of MOs in groundwater. Based on the existing pollution levels, regulation and amelioration of MOs are warranted. 相似文献
3.
《Applied Geochemistry》2000,15(1):13-25
The carboxylate (formate, acetate, propionate and oxalate) and common inorganic anions (F−, Cl− and SO2−4) compositions for aqueous fluid inclusion leachates from 17 mineral samples collected from various deposits have been determined using ion chromatography in conjunction with microthermometric measurements on the fluid inclusions of their host minerals. The minerals, quartz, fluorite, barite, beryl and a few `ore' minerals (wolframite, pyrite and galena), came from hydrothermal vein-type deposits in felsic igneous rocks or Archean metamorphic rocks. The results indicate that short-chain carboxylates are common components in hydrothermal fluids and can be present in considerable amounts. Formic acid (as formate) is the dominant species over other carboxylic acids. The present study raises new questions about the origin and geochemical significance of carboxylates in hydrothermal ore-forming processes. 相似文献
4.
5.
The dislocation substructures in olivine from coarse-grained peridotite xenoliths in kimberlites from the Lesotho region have been determined. The [100] dislocations may be located in simple (100) tilt boundaries while the density of free or individual [100] dislocations is 106/cm2 or less. The [001] dislocations form (010) twist arrays or more complex (100) subboundaries with the [100] dislocations; the density of free [001] dislocations increases to 8 × 108/cm2 in those grains in which tangles are observed. The simple (100) subboundaries are considered to result from a high temperature, slow strain-rate deformation (creep-like process) while the more complex subboundaries composed of [100] and [001] dislocations, as well as the high density of [001] dislocations, indicate faster strain rates and/or lower deformation temperatures than the creep deformation. These two broad phases of deformation have been interpreted as an early stage of mantle-type flow followed by deformation during or subsequent to the emplacement of the kimberlite. 相似文献
6.
In the present study, roadside-deposited sediment samples collected from Kuwait city district, in Kuwait, were analyzed for specific heavy metals (As, Cr, Cu, Mn, Ni, Pb, and Zn). Contamination assessment status of heavy metals in roadside sediments was made using mathematical models in terms of enrichment factor (EF), geoaccumulation index (I geo), and contamination factor (CF). The sediments showed remarkably high levels of all the metals, except Ni, above background concentrations in the following order (As, Cu, Pb, Zn, Mn, and Cr). CF and I geo revealed overall moderately uncontaminated and moderate contamination, respectively, but the EFs for all metals ranged between moderate and significant enrichment. 相似文献
7.
Nodules of various compositions, including ferromanganese nodules, have been found in bottom sediments of an artificial reservoir
in the central Altai Territory. The nodules were formed in the alkaline environment against the background of a high carbonate
content and saturation with oxygen. The rate of nodule growth is no less than 1.7–1.8 mm/yr and the pH value of water varies
from 8.0 to 9.7. Fe and Mn contents in soil and loam of the drainage area are lower than the global clarke value, whereas
Ca, K, and Na contents are much higher. The main mass of bottom sediments in the reservoir is markedly enriched in Cd, Mg,
Mn, Sr, Ni, Cr, Sb, V, and Pb, but they are depleted in Cu, Mo, Zn, and Li, relative to the soil and loam. Elements in ferromanganese
nodules are arranged in the following way in terms of the decreasing concentration coefficient: Mn (27) > Ba (13.4) > Co (10.7)
> Mo (9.2) > Cd (5.35) > Ni (3.88) > V (3.52) > Cu (3.3) > Fe (3.2) > Sb (2.17) > Sr (2.04) > Pb (1.5) > Zn (1.43) > Cr (1.1)
> Li (0.78) > Mg (0.75) > Na (0.69) > K (0.67) > Ca (0.51). The microelemental composition of nodules in the reservoir qualitatively
fits the composition of ferromanganese nodules in seas and oceans. However, the contents of major ore elements (Ni, Cu, Co,
Zn, Pb, Mo, and V) in ferromanganese nodules from the World Ocean are much higher than in nodules from the examined reservoir. 相似文献
8.
地球史中的构造活动论和发展阶段论 总被引：1，自引：0，他引：1
从全球构造的活动论和地壳演化的发展阶段论出发,简要地讨论如下科学问题:(1)岩石圈形成;(2)中国大陆形成和演化;(3)造山过程;(4)裂谷作用过程中的某些问题。研究认为:(1)岩石圈不是地球形成时就已存在了,亦不是一次形成的,而是对流地幔(或软流圈)多次(或多阶段)分异形成的;基于岩浆作用、沉积作用、变质作用和成矿作用等在地球发展历史中长远阶段性的变化的可能指示,提出岩石圈-软流圈系统的不可逆的长远期阶段性变化特征,并可划分为若干阶段。(2)基于对中国大陆形成与演化的大阶段的研究,认为显生宙以来,中国大陆是由塔里木、扬子、中朝、华夏、蒙古和印度等陆块经过多个阶段的造山运动,镶嵌组装在一起的一个复合大陆,其拼合组装的各个阶段的洋陆分布的格局是不一样的,这种构造重组一定伴随岩石圈-软流圈动力系统的重组和构造体制的重大转换。(3)燕山带燕山期可识别出5个造山幕,每个造山幕的岩浆作用、沉积建造、变质作用、变形方式均有差异,造山过程的幕式阶段性标志明显;并认为华北地区现今面积的大小,并不能代表侏罗纪-白垩纪时的状态,燕山带的面积在侏罗纪—白垩纪时期远比现在的小。(4)提出华北大陆裂谷作用在古近纪与新近纪—第四纪的伸展作用是两次幕式事件,而不是前人认为的一次事件的两个相,同时,认为古近纪的断陷性质盆地发育对应纯剪切机制,而新近纪—第四纪拗陷性质盆地发育对应于分布剪切机制。(5)认为燕山期和喜山期华北地区岩石圈减薄作用的机制、过程不同,分属两个不同的阶段的动力学系统,而不是一个连续的渐变过程。 相似文献
9.
Brian McGowran 《中国地质大学学报(英文版)》2005,16(3):200-218
INTRODUCTION Microfossilsaregenerallythemostversatileand “useful”offossilsforbothcorrelationandagedeter minationandpaleoenvironmentalanalysis.Among microfossilstheforaminiferaarepre eminent(Fig. 1).Wefindinthesamesample—beitoutcropor subsurface,onshor… 相似文献
10.
Studies of the deformation styles, formation types and isotopic age data indicate that the Altaides has successively experienced 5 stages of orogeny: (1) the Kanas orogeny forming the angular unconformity between the Baihaba Formation (O_3) and the Habahe Group (Z-O_2); (2) the Daqiao orogeny (S_3-D_(1-2) giving rise to the early Hercynian quasi-aulacogen extensional continental crust of the area; (3) the Altay orogeny (middle-late Hercynian) leading to the oblique intracontinentai collision and the formation of large shear arc-shaped thrust system and representing a strong orogeny stage; (4) the pan-Altay orogeny (latest Hercynian-Indosinian) resulting in the uplifting and erosion of the mountains as a whole; (5) the Himalayan movement causing the rejuvenation of fault systems and block uplift of the Aitaides since the Cenozoic. 相似文献
11.
R.S. Bhathal 《Earth》1971
In any rock six kinds of magnetic anisotropy can be distinguished, viz.: (1) shape alignment of grains; (2) alignment of crystals with magneto-crystalline anisotropy; (3) alignment of magnetic domains; (4) the stringing-together of magnetic grains, which is a special case of (1); (5) stress-induced anisotropy; and (6) exchange anisotropy. Each of these anisotropies, together with the method of measurement and practical uses in the fields of geology and geophysics, is discussed. 相似文献
12.
13.
Andrea Zerboni 《Geoarchaeology》2011,26(3):365-391
In the Khartoum region of central Sudan, Mesolithic sites were established on sandy ridges distributed along the Nile. Most of the excavations carried out in recent decades have revealed limited preserved archaeological structures or layers corresponding to subsequent phases of human presence due to the disturbance of the deposits. Post‐depositional processes affecting Mesolithic sites include (1) the excavation of Neolithic to Post‐Meroitic cemeteries at the same sites, (2) surface erosion, and (3) pedoturbation leading to the mixing of the stratigraphy. During a recent field operation along the western bank of the White Nile, archaeological contexts that were only partially disturbed were identified. Employing a geoarchaeological approach and the micromorphological study of sediments (supported by 14C dating), settlements were placed in their paleoenvironmental contexts and differences between in situ Mesolithic layers and those disturbed by later processes were identified. Furthermore, it was possible to interpret the functional aspects of three categories of pits containing Mesolithic pottery (fireplace pits, fireplace pits with shell accumulations, and waste pits) and to discuss their significance within the wider framework of North African archaeology. Finally, this project has demonstrated the importance of integrating the geosciences (especially micromorphology) and archaeology in the study of processes leading to the formation and preservation of open‐air prehistoric sites in arid landscapes. © 2011 Wiley Periodicals, Inc. 相似文献
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15.
辽东古元古宙成矿带中的变质蒸发岩及其意义 总被引：2，自引：0，他引：2
辽宁东部－吉林南部的古元古宙变质岩系中存在一些成分特殊的岩石。这些岩石的出现与蒸发岩有关，其突出特征是富含K、Na、B、Mg等组分。蒸发岩是特殊环境下（干旱气候）的沉积产物，其物质组成以Na、K、Ca的盐类矿物为主，还可含硼酸盐等组分。识别蒸发岩，尤其是变质蒸发岩的标志可以归纳为以下几点：（1）岩相及岩性组合；（2）特殊的岩石产状和组构；（3）高盐度的流体包裹体溶液和（4）硼、磷等同位素数据。辽东古元古宙大型硼矿床中电气石岩与硼酸盐之间的密切 成因关系提供了认识SEDEX型金属矿床中广泛分布的电气石岩和成矿流体成因的钥匙。 相似文献
16.
Anil Kumar Haritash Ramanathan Baskar Nirmal Sharma Sumit Paliwal 《Environmental Geology》2007,51(8):1439-1445
Slate quarrying in Mahendragarh district of Haryana state has resulted in changes in soil properties. Most of the mining area
is devoid of vegetation. The soil in and around the mining area (0–1 km) is alkaline (pH 11.2–11.7) but non-saline (electrical
conductivity < 4). The alkaline nature of the soil was attributed to the high concentrations of hydroxyl (OH−), carbonate (CO32−) and bicarbonate (HCO3
−) present in minerals of mined materials. Biotite, limonite, kaolinite, gibbsite, muscovite, geothite, dolomite and so on
were the chief minerals added to soil through mining. The physical properties of soil, i.e. porosity, water-holding capacity
(WHC), bulk density and particle density represented poor soil health in mining area (34.4, 29.8%, 1.636, 2.496 g/cc, respectively)
and they improved with distance away from it (46.4, 38.3%, 1.070, 2.180 g/cc, respectively, at a distance of 1 km). Porosity
and WHC were found to be a function of increased organic matter away from the mining area. CO32−, HCO3−, phosphate (PO43−), lead (Pb) and iron (Fe) were more in mining area and decreased with distance. On the other hand, sodium (Na+), potassium (K+), chloride (Cl−), sulphate (SO42−), organic carbon, total Kjeldahl’s nitrogen, cation exchange capacity, chromium (Cr) and cadmium (Cd) increased with distance
from mining area. High concentration of heavy metals in mining area was a cause of concern (0.93 μg/g Cd, 22.35 μg/g Cr, 26.25 μg/g
Pb, 1,383.75 μg/g Fe). The change in physico-chemical properties could be because of the addition of chemical constituents
that are a part of major minerals present in mined material. The soil away from mining area represented comparatively better
properties. 相似文献
17.
Selenium speciation in Lower Cambrian Se-enriched strata in South China and its geological implications 总被引：3，自引：0，他引：3
To understand the impact of Selenium (Se) into the biogeochemical cycle and implications for palaeo-redox environment, a sequential extraction method was utilized for samples including black shales, cherts, a Ni-Mo-Se sulfide layer, K-bentonite and phosphorite from Lower Cambrian Se-enriched strata in southern China. Seven species (water-soluble, phosphate exchangeable, base-soluble, acetic acid-soluble, sulfide/selenide associated, residual Se) and different oxidation states (selenate Se(VI), selenite Se(IV), organic Se, Se (0) and mineral Se(-II)) were determinated in this study. We found that the Ni-Mo-Se sulfide layer contained a significantly greater amount of Se(-II) associated with sulfides/selenides than those in host black shales and cherts. Furthermore, a positive correlation between the degree of sulfidation of iron (DOS) and the percentage of the sulfide/selenide-associated Se(-II) was observed for samples, which suggests the proportion of sulfide/selenide-associated Se(-II) could serve as a proxy for palaeo-redox conditions. In addition, the higher percentage of Se(IV) in K-bentonite and phosphorite was found and possibly attributed to the adsorption of Se by clay minerals, iron hydroxide surfaces and organic particles. Based on the negative correlations between the percentage of Se(IV) and that of Se(-II) in samples, we propose that the K-bentonite has been altered under the acid oxic conditions, and the most of black shale (and cherts) and the Ni-Mo-Se sulfide layer formed under the anoxic and euxinic environments, respectively. Concerning Se accumulation in the Ni-Mo-Se sulfide layer, the major mechanism can be described by (1) biotic and abiotic adsorption and further dissimilatory reduction from oxidized Se(VI) and Se(IV) to Se(-II), through elemental Se, (2) contribution of hydrothermal fluid with mineral Se(-II). 相似文献
18.
Oilfield brines (produced water) are produced as a waste product daily at the gathering centers (GCs) in Kuwait oilfields. The geochemical evolution of the water produced at the GC (fresh brine) to stagnant pit water (evaporate) has been investigated in the northern fields of Kuwait, and a model is presented showing time-dependent variations. Kuwait oilfield brines are globally similar to others in other large sedimentary basins (USA, Canada), but modifications have occurred due to seawater injection practices performed episodically during the oil extraction process. Brine water chemistry changes from generally average brine chemistry (based on cations and anions) to saturated mixture of seawater, oilfield brine, and anthropogenic chemical pollutants. The objective of this study was to harmonize the database of brine waters in terms of regional identity by comparison with oilfield brines elsewhere, identify water–rock interaction, and statistically treat daily recordings from the pits in order to identify injection peaks and troughs. Laboratory analysis of major and minor cations and anions from the Rawdatayn samples gave the following concentration ranges in parts per million (ppm): (Na+, 11,698–203,977), (Ca2+, 2,216–98,514), (Mg2+, 1,602–28,885), (K+, 1,528–16,573), (Sr2+, 70–502), (Ba2+, 0.01–18.04), (Fe2+, 0.01–8.93), (Li+, 0.09–6.48), (Si2+, 0.00–13.18), (B3+, 0.05–37.45), (SO 4 2+ , 330–3100). For the Sabriyah oilfield samples, the major and minor cations and anions concentration ranges in ppm are: (Na+, 9,807–274,947), (Ca2+, 2,555–77,992), (Mg2+, 1,415–28,183), (K+, 764–19,201), (Sr2+, 77.84–641), (Ba2+, 0.15–6.76), (Fe2+, 0.016–38.88), (Li+, 0.05–6.83), (Si2+, 0.0195–16.84), (B3+, 7.17–55.33), (SO 4 2+ , 44,812–135,264). The stable isotopic analysis of five samples indicates normal trends in oxygen and hydrogen isotopes that classify the waters as “connate” which follow an evaporation trend. Carbon isotopic signatures are normal for hydrocarbon fields and average out around GC15, δ18O‰?=?1.4, δD‰?=??10, δ13C‰?=??3.6; while for GC23, δ18O‰?=?2.3, δD‰?=??4, δ13C‰?=??2.5; for GC25, δ18O‰?=??2.0, δD‰?=??14, δ13C‰?=??4.6; for pit1, δ18O‰?=?2.3, δD‰?=??5, δ13C‰?=??18.3; and for pit 2, δ18O‰?=?2.5, δD‰?=??4, δ13C‰?=??17.8. Carbon isotope average values for all brine samples from the GCs is?=??56 which falls within normal hydrocarbon formation water category. Data spikes coincide with injection periods at the following times (A: May–Jun, 2006), (B: Sep–Oct, 2006), (C: Jan–Feb, 2007), (D: Mar, 2007), (E: May–Jun, 2007), (F: Feb, 2006), (G: Mar–Apr, 2006) and, subsequently the decay to “normal” brine occurs over a period of several weeks. The database was large enough to apply a principal component statistical analysis (PCA). PCA and geo-statistical techniques reveal several distinct population groups. The main chemical groups in the data are as follows: plateau, spike groups, and pit evaporation group. The spike periods correlate closely with seawater injection periods (Jan–Feb, Mar–Apr, May–Jun, and Sep–Oct). The pit chemistry reveals exceptionally high evaporation processes coinciding with summer peak temperature. PCA results show distinct groupings centered around the major elements reminiscent of other oilfields, but with the added evaporation trend strongly enhanced. 相似文献
19.
J. Magdalena Santana-Casiano M. González-Dávila A. G. González F. J. Millero 《Aquatic Geochemistry》2010,16(3):467-482
Fe(II)-Fe(III) redox behavior has been studied in the presence of catechol under different pH, ionic media, and organic compound
concentrations. Catechol undergoes oxidation in oxic conditions producing semiquinone and quinone and reduces Fe(III) in natural
solutions including seawater (SW). It is a pH-dependent process. Under darkness, the amount of Fe(II) generated is smaller
and is related to less oxidation of catechol. The Fe(II) regeneration is higher at lower pH values both in SW with log k = 1.86 (M−1 s−1) at pH 7.3 and 0.26 (M−1 s−1) at pH 8.0, and in NaCl solutions with log k of 1.54 (M−1 s−1) at pH 7.3 and 0.57 (M−1 s−1) at pH 8.0. At higher pH values, rate constants are higher in NaCl solutions than in SW. This is due to the complexation
of Mg(II) present in the media with the semiquinone that inhibits the formation of a second Fe(II) through the reaction of
this intermediate with other center Fe(Cat)+. 相似文献
20.
Regularities in the formation and evolution of volcanosedimentary complexes in the Early Precambrian
O. G. Lazur 《Lithology and Mineral Resources》2009,44(6):587-598
The main objective of this work was to define directions and principal features of the evolution of volcanism and sedimentation
in Early Precambrian active volcanic zones. Analysis of reconstructed type sections of intensely metamorphosed and greenstone
(sedimentary-volcanic) complexes revealed a general similarity of their structure and universal presence of two principal
(contrast and differentiated) volcanic associations that replace each other from the bottom to top (Lazur, 2006). Volcanic
complexes are crowned with significantly sedimentary sequences and the manifestation of bimodal (basalt-rhyolite) or acid
(dacite-rhyolite) volcanism (Luchitskii et al., 1982). Our work is based on specific rock complexes, for which the primary
nature of intensely metamorphosed Early Precambrian rocks has been reconstructed by geological, mineralogical, geochemical,
and other methods (Lazur, 1986; Rosen et al., 2005). 相似文献