硅化木保护保育方法探讨与实践 ——以四川射洪硅化木国家地质公园为例

四川射洪硅化木地质公园有我国南方地区规模最大、保存最完好的硅化木化石群。本文主要通过在射洪硅化木国家地质公园王家沟硅化木遗址馆内的硅化木进行保护保育试验,对比了保护保育前后的效果,重点对射洪硅化木形成的地质背景和使用的保护保育方法进行了介绍。     

北京延庆硅化木的矿物学特征分析

通过X射线荧光、红外光谱和X射线衍射等检测方法分析了延庆硅化木的矿物学特征.结果表明:2个不同植物种属但在同一埋藏地形成硅化木标本成因相似,其颜色与所含元素种类及含量密切相关.X射线衍射分析表明,不同颜色和植物种属的硅化木主要组成物相一致,为SiO2,其他矿物极其微量.2个硅化木标本的红外吸收谱带基本一致,均显示典型的...     

延庆千家店地区硅化木赋存层位及形成时代分析

北京延庆千家店土城子组中的硅化木自发现以来,得到了众多学者的关注,但关于硅化木的赋存层位和形成时代一直未有定论,目前主流观点认为硅化木广泛发育于土城子组一段和二段的下部,关于其形成时代则自侏罗纪早期至白垩纪早期的论述均有,这种争论显然不利于木化石的保护、科普和进一步深化认识。在千家店土城子组进行的考察结果展现出与前人观点不同的线索。实地考察、剖面测量和年龄测试结果显示:原位埋藏硅化木形成时代应为晚侏罗世早期,赋存层位为土城子组一段下部,而土城子组二段下部的沉积特征反应出当时水位频繁升降,水体能量剧烈变化,火山活动暂时陷入沉寂的沉积环境,较难满足形成木化石的基本要求。     

神奇的硅化木

硅化木,是古代树木经石化以后形成的一类化石,因其主要成分是二氧化硅而得名。自古以来,人们就视硅化木为收藏珍品,陈列于庙宇、园林、博物馆以及收藏家的案头。     

西天山伊犁地块北缘早石炭世硅化木的发现 及其意义

在西天山伊犁地块北缘琼阿希河谷中首次发现硅化木,对硅化木的基本特征进行了描述。根据地层中腕足、珊瑚化石的鉴定结果,将地层的时代定为早石炭世维宪期,因此该硅化木的产出层位为下石炭统阿克沙克组。硅化木产于阿克沙克组底部黑色薄层状泥岩、粉砂岩中,这套岩性组合形成于扇三角洲前缘水下分流间湾。伊犁地块北缘阿克沙克组底部扇三角洲沉积环境的确定和硅化木化石的发现说明:研究区早石炭世维宪期不是一套连续的海相沉积,而是陆相—海陆过渡相沉积,研究区所处的地理位置距离古陆地不远。这一发现对于重新认识伊犁地块早石炭世古地理和古构造格局具有重要意义。     

西天山伊犁地块北缘早石炭世硅化木的发现及其意义

在西天山伊犁地块北缘琼阿希河谷中首次发现硅化木,对硅化木的基本特征进行了描述。根据地层中腕足、珊瑚化石的鉴定结果,将地层的时代定为早石炭世维宪期,因此该硅化木的产出层位为下石炭统阿克沙克组。硅化木产于阿克沙克组底部黑色薄层状泥岩、粉砂岩中,这套岩性组合形成于扇三角洲前缘水下分流间湾。伊犁地块北缘阿克沙克组底部扇三角洲沉积环境的确定和硅化木化石的发现说明：研究区早石炭世维宪期不是一套连续的海相沉积,而是陆相—海陆过渡相沉积,研究区所处的地理位置距离古陆地不远。这一发现对于重新认识伊犁地块早石炭世古地理和古构造格局具有重要意义。     

义马地区石千峰组发现大量硅化木

长期以来,石千峰组很少发现化石。笔者1987年在河南义马地区石千峰组中段发现了大量的硅化木,其数量之多,保存之好,实乃罕见。      

四川省宜宾市江安硅化木群地质遗迹资源特征及保护策略建议

宜宾市江安县的怡乐镇的硅化木群主要赋存于体罗系上统蓬莱镇组下段的灰黄色钙质长石砂岩中,根据初步显微观察,硅化木为保存次生木质部的一种松柏类植物。江安硅化木群在研究长江流域古气候、古地理、古生态演化和地壳变动等具有重要的价值,当前保护现状令人担忧。本文分析了该地质遗迹资源的特征,研究分析了其保护意义,提出了相应的保护策略建议。     

缅甸硅化木(“树化玉”)的成因

近年,中国宝玉石和观赏石市场上出现了一种十分受人青睐的玉石品种——缅甸“树化玉”(硅化木),媒体广告对其宣传有加,给人们带来无限商机。但对其成因环境之说却十分离谱。现试图避开商业炒作的市场环境,拟从地质科学的角度,以地质事实为依据,揭示缅甸树化玉(硅化木)形成的奥秘。     

藏北南羌塘坳陷盆地中侏罗世硅化木的发现与意义

首次在藏北南羌塘坳陷地区中侏罗世晚期地层中发现硅化木,本文对硅化木的基本特征进行了描述,据同一层位中采集的大量孢粉及双壳类化石证明,该硅化木属中晚侏罗世。结合区域地质及含硅化木地层的沉积学特征分析表明,南羌塘坳陷地区中侏罗世晚期属干热-潮温气候,从而深化了对青藏高原中侏罗世晚期气候环境的认识。     

Electrodialytic remediation of CCA-treated waste wood in pilot scale

When chromated copper arsenate (CCA)-treated wood is removed from service and turns into waste, the contents of Cu, Cr and As remain high due to the strong fixation of CCA in the wood. This high content of toxic compounds presents a disposal challenge. Incineration of CCA-treated waste wood is not allowed in Denmark; instead, the wood is to be land-filled until new methods for handling the wood are available. Since the amounts of CCA-treated wood being removed from service is expected to increase in the years to come, the need for finding alternative handling methods is very relevant. In this study, the usefulness of Electrodialytic Remediation was demonstrated for handling of CCA-treated waste wood in pilot scale. The electrodialytic remediation method, which uses a low-level direct current (DC) as the cleaning agent, combines electrokinetic movement of ions in the wood matrix with the principles of electrodialysis. It has previously been shown that it is possible to remove Cu, Cr and As from CCA-treated wood using electrodialytic remediation in laboratory scale, but until now, the method had not been studied in large scale. The pilot-scale plant used in this study was designed to contain up to 2 m³ wood chips. Six remediation experiments were carried out. In these experiments, the process was up-scaled stepwise by increasing the distance between the electrodes from initially 60 cm to finally 150 cm. The remediation time was varied between 11 and 21 days, and phosphoric acid and/or oxalic acid was used to facilitate the desorption of CCA from the wood. In the most successful of the experiments carried out, the concentration of CCA in the wood was reduced by up to 82% for Cr, 88% for Cu and at least 96% for As.     

Large wood transport as significant influence on flood risk in a mountain village

An important issue that is not considered in most flood risk assessments in mountain villages in Spain is the transport of solids associated with the flood flow, in this case, large wood transport. The transport and deposition of this wood in urban areas may be a potentially worse hazard than the flood flow itself. Despite its importance, large wood is a key ecological element in rivers, so removing it could be an unsuccessful approach. Therefore, efforts are needed in the better understanding of wood transport and deposition in streams. To analyse this process, scenario-based 2D hydrodynamic flood modelling was carried out. Since flood risk assessment has considerable intrinsic uncertainty, probabilistic thinking was complemented by possibilistic thinking, considering worst-case scenarios. This procedure obtained a probabilistic flood map for a 500-year return period. Then, a series of scenarios was built based on wood budget to simulate wood transport and deposition. Results allowed us to identify the main infrastructures sensitive to the passing of large wood and simulate the consequences of their blockage due to wood. The potential damage was estimated as well as the preliminary social vulnerability for all scenarios (with and without wood transport). This work shows that wood transport and deposition during flooding may increase potential damage at critical stream configurations (bridges) by up to 50 % and the number of potentially exposed people nearby these areas by up to 35 %.     

“硅化”不是“树化”“化石”不能称“化玉”对“树化玉”名词的商榷

硅化木,又称树化石、木化石,无论它的内在品质多么优良,依然是“化石”身份,不能把优质硅化木称为“树化玉”。因为按照所谓“化”的含义,“树化玉”就只能解释为“玉”变成了“树”,或解释为“玉”具有了“树”的一些性质和特征,这显然是不对的。再如,古生物化石也不能称为“古生物化玉”。所以将硅化木称“树化玉”是欠妥的。     

The chemical composition of medieval wood ash glass from Central Europe

Medieval wood ash glass classified as 6 early medieval wood ash glasses, 17 wood ash glasses, 5 early wood ash lime glasses, 7 wood ash lime glasses and 9 mixed alkali glasses has been analyzed by microprobe and ICP-mass spectrometry on 61 elements. Their calcium oxide to potassium oxide ratio (CaO/K₂O) increases from early to late medieval glasses according to an increase of the proportion of twigs in the bulk amount of wood (logs plus twigs). Twigs because of their relatively large proportion of bark contain more calcium than wood logs. The ratio CaO/K₂O of the glasses from not yet evaluated excavations can be used for dating. The observation that the 25 minor elements Be, Sc, V, Cr, Ge, Y, Nb, REE (La to Lu), Ta, W and Bi occur in almost equal concentrations in the five subtypes of wood ash glass makes it highly probable that these elements were introduced into the starting mixtures of the glasses by means of quartz from quartz-rich sand with heavy minerals. The majorities of the wood ash glasses contain so-called europium anomalies within the group of rare-earth elements (REE). Their Eu concentrations normalized to those of the Continental Earth's Crust are lower than the normalized samarium and gadolinium concentrations. These Eu anomalies are apparently inherited from the granitic source of quartz in the upper Continental Earth's Crust. Soda ash and soda lime glass as the other major types in the history of glass contain no Eu anomaly. Therefore a different source of quartz has caused this important element constellation for these glass types. The elements K, Cu, Rb and S are physiologically separated from Ca, P, Mn, Sr and B during the growth of the wood and bark, respectively, in the trees. Different sources of the metals Cu and Co were used for colouring the glasses of our report.     

The effects of using wood treated with chromated copper arsenate in shallow-water environments: A review

Studies published over the past several years have documented that copper, chromium, and arsenic leach from pressure-treated wood placed in estuaries, and that these toxic metals accumulate in nearby sediments and biota. We have found bioaccumulation and deleterious effects in the epibiotic (“fouling”) community, particularly in poorly flushed areas and on new wood. The epibiota showed reduced species richness, diversity, and biomass. Barnacles and encrusting bryozoa that settled on new treated wood grew more slowly than those that settled on untreated wood or plastic substrate. In laboratory studies, trophic transfer of the contaminants from epibiota to their consumers has also been demonstrated. We have also found accumulation of the treatment metals in the fine-grained fraction of nearby sediments and in the benthic infauna. Infauna also had reduced species richness and diversity in sediments adjacent to treated-wood structures. While standard toxicity tests with amphipods did not demonstrate acute toxicity of these sandy sediments, sublethal effects on development were seen in juvenile mysids. Overall, the extent and severity of effects of pressure-treated wood in an estuary depends on the amount and age of the wood and the degree of dilution by water movements.     

Mineralogy of granulated wood ash from a heating plant in Kalmar, Sweden

The central heating plant of Kalmar, Sweden produces 200-300 tons wood ash every year. A stabilised material for nutrient recycling is produced by adding water and dolomite to the wood ash and granulating the mixture. Combined mineralogy and chemistry can be used to interpret the transformation processes that occur during hardening and weathering of the granules, thus leading to a possibility to refine the production process and final characteristics of the granules. Mineralogy was separately studied in the wood ash, dolomite, self-hardened wood ash and granules by X-ray diffraction. Magnesium- and calcium-containing minerals are most common in the ash materials in the present study. The amounts of portlandite and calcite present in self-hardened and granulated ash samples are clearly higher than those in the untreated ash, showing that these minerals are formed during the treatments. Additionally, one potassium-containing secondary mineral, syngenite, is formed during the self-hardening of wood ash. Quartz, dolomite and the Fe-K-Mg-silicate in the granules originate from dolomite. The secondary minerals gypsum and calcium silicate hydrate are present in the granules. Portlandite occurs only in control granules in the field study. This suggests that hardening of granules continues in the field and portlandite is transformed into calcite. After up to 3 years on forest soil, the crystalline compounds dolomite, calcite, quartz, ankerite, albite and alumohydrocalcite are present in granules, of which alumohydrocalcite is formed as a secondary mineral in the field. These results suggest that the dissolution of granulated wood ash is strongly delayed compared with untreated wood ash and self-hardened wood ash because of the formation of less soluble compounds during the granulation process.     

Bottom ash of trees from Cameroon as fertilizer

Utilization of wood bottom ash as fertilizer additive contributes to the return of valuable nutrients to agricultural soils, especially when no artificial mineral fertilizer is being used. In general, wood combustion ash is enriched in calcium and potash, and may also contain elevated amounts of zinc, but the concentrations of these elements depend on tree species, part of the tree, harvest season and local soil type. In this study, bottom ash samples from eight different agricultural wood species from Cameroon, Africa were investigated by using X-ray diffraction and atomic absorption spectroscopy to determine the refractory components and the concentrations of selected heavy metals and arsenic. Results show calcite, potassium salts, periclase and quartz as major components. These phase contents were used to calculate major element concentrations, which were subsequently validated by X-ray-fluorescence analysis. The chemical compositions varied within the range of common compositions of wood ashes. Six of the ashes reached sufficient concentrations of calcium to be defined as a “calcium fertilizer”. Pb contents are most variable, ranging from 0.03 to 21.1 mg/kg. Concentrations of Ni, Cu, Zn, Cd, Pb, and As are all lower than the strictest limit concentrations required for wood ash fertilizers and therefore, the studied wood ashes can be used without environmental concern.     

How jet is formed: An organic geochemical approach using pyrolysis gas chromatography–mass spectrometry

Six samples, including wood and jet-like material from the same mummified wood specimens, together with two ‘true’ jet samples, were studied using pyrolysis gas chromatography–mass spectrometry (Py-GC/MS) to obtain detailed insight into the process leading to the formation of jet. Based on morphological and chemical data obtained, the process of “jetification” is characterised by a rapid change when mummified wood is re-exposed to sunlight and aerobic conditions. The transformation from mummified wood to jet is probably caused by relatively small chemical changes, leading to extra linkages between the phenolic compounds and causing the structure to become much more rigid, which is reflected in increased inertness of the material at the macroscopic level.