日本地震学者研究断层气体He/Ar和N_2/Ar的变化与地震的关系

近几年来,日本名古屋大学理学部杉崎隆一和志知龙一研究了断层气体中 He/Ar 和N_2/Ar(He-氦,Ar-氩,N-氮)的变化与地震的关系。他们自1976年以来,连续地观测了断层气体的这两个比值。结果表明,在名古屋震级 M≥4的有感地震前,He/Ar 和 N_2/Ar的值都会升高,一般在出现峰值以后就会发生地震。因此,他们认为,断层气体中的 He/Ar和 N_2/Ar 值的变化是地震的一种前兆。他们     

断层气体的释放与地震活动关系的初步研究

北京城北塔院断层土壤气中的He~4/Ne~(20),He~4/Ar~(40),Ar~(40)/Ar~(36),CH_4/CH_4~(16),CO_2/Ar和N_2/Ar比值与1990年7月21日大海坨4.5级地震和1990年9月22日沙河东4.0级地震有很好的对应关系,而且在1991年1月29日山西忻州5.1级地震,2月20日高丽营3.0级地震和3月26日大同5.8级地震前后,He~4/Ar~(40)和Ar~(40)/Ar~(36)的值均有异常变化。并且利用塔院断层土壤气中CO_2/Ar,N_2/Ar,CH_4/CH_4~(16),He~4/Ne~(20),He~4/Ar~(40)和Ar~(40)/Ar~(36)的值,在地震前10天和1天预报了9月22日沙河东4.0级地震。同样,根据He~4/Ar~(40)和Ar~(40)/Ar~(36)的异常变化,于3月9日向地震局值班室汇报了异常情况。研究表明,气体地球化学的这几项指标能确切地反映地壳深处应力变化的信息。     

同位素地球化学方法与地震研究及地震预报

通过在地震活动区对有关地质体的K—Ar、Ar—Ar、FT、TL、~(14)C、ESR、U系等同位素年代学、地下水及其释放气体的D/H、~(13)C/~(12)C、~(18)O/~(16)O等稳定同位素以及He、Ar等稀有气体同位素的研究,可获得有关新构造运动的时间序列、断层运动的时间、地质体热历史以及地下断层流体运动的许多重要信息。因而,同位素地球化学已逐渐在研究地震成因机制以及监测预报地震中发挥重要作用。     

中国大陆科学钻探工程主孔地下流体特征及与地震活动的关系初步研究

收集了中国大陆科学钻探主孔工程(CCSD)主孔中117～2045 m深度地下流体某些组分(He、 Ar、 CO₂、 CH₄)的浓度资料和2001年7月1日至2002年4月30日时间段内钻孔周围500 km范围内震级M_L≥1.0地震目录资料, 对其流体资料进行日均值处理、 差分分析和最大相关系数处理。 由日均值浓度看出地震前后He、 Ar、 CO₂、 CH₄浓度存在明显异常; 最大相关系数分析表明, CH₄和CO₂组分两者相关性好, 最大相关系数平均值为0.95, 均方差为0.08, 说明两者可能具有相同的来源。 CH₄和CO₂浓度日均值最大相关系数在地震前后出现明显的异常波动。 主孔中的地下流体特征及与周围地震活动的对应关系揭示大陆科学钻探主孔中的地下流体异常与区内地震活动可能存在一定关系。     

滇西地区断层气体成因研究

本文讨论了滇西地区由温泉释放的断层气体中各主要组分(He、H_2、Ar、N_2、CO_2、CH_4、Hg)的分布特征及其成因机制。 作者指出,滇西地区断层气体中直接来自地幔的He是微不足道的,较高水平的He释放(>100ppm)可能直接来自地层中的火成岩;H_2的释放与地层岩性无关,而与深大断裂的活动或地震活动有成因联系;洱源地区九台等泉点中CH_4含量达2—3％,同位素测定表明,它是典型的无机成因,是该区深部热动力变质作用的产物;滇西地区断层气体中Hg的分布特征表明,并不是所有的活动性断裂都有高含量的Hg释放。具有较高含量的幔源CO_2和Hg释放是红河断裂的两个最重要的地球化学特征。     

活断层释放的二氧化碳——断层气体的化学特征和断层活动

1.前言最近,与地震发生有关的活动断层越来越引起人们的注意,并从多方面进行了调查和研究。其中,可称作地球化学信息的活断层周围物质的化学特性也是人们的研究对象之一。特别是从活动断层散发出来的气体成分的变化和地震活动的关系更是研究的一项内容。由于断层活动,上层物质和地下深处物质可能交流,地下深部气体就会因震前地壳形变而释放。例如,杉崎在1981年就用地壳形变和 He/Ar 变     

大别山榴辉岩的氦、氩同位素组成及其岩石成因

论述了石榴石和绿辉石的氦、氩同位素地球化学特征,并讨论了大别山榴辉岩的成因。测得3 He/4He 值为(1-19 ～4-63) ×10 - 7 ,40Ar/36Ar 值为1209 ～4416 ,4 He/40Ar 值分布在0-07 ～1-39 范围内,3 He/36 Ar 值的变化范围为(0-59 ～2-85) ×10 - 4 。大别山榴辉岩中保留了原始的稀有气体同位素, 但是退变质作用使氦同位素优先丢失。氦、氩同位素地球化学资料表明,榴辉岩可能形成于亏损的地幔或者是一种亏损型“地幔岩”中     

大西洋中脊TAG热液区硫化物中流体包裹体的He-Ne-Ar同位素组成

对大西洋中脊TAG (Trans-Atlantic Geotraverse)热液区硫化物中流体包裹体的He, Ne和Ar同位素组成进行了测定, 流体包裹体的3He/4He比值为2.2～13.3 Ra, 均值为7.2 Ra, 与该区喷口热液流体(3He/4He=7.5～8.2 Ra)和MORB(3He/4He=6～11 Ra)相比, 其变化范围明显较大. 20Ne/22Ne比值为10.2～11.4, 明显高于大气值(9.8). 而40Ar/36Ar比值的变化范围从287到359, 接近大气值(295.5). 这些结果表明, 热液硫化物中流体包裹体的稀有气体是地幔和海水端员混合的产物, 热液流体捕获的地幔源稀有气体中有部分可能来自下地幔, 且流体包裹体中的He主要来自上地幔, Ne和Ar主要来自海水.     

地震前H2 Hg等断层气的异常变化

观测断层气的变化,可以了解断裂的活动和地震前兆信息,1989年11—12月,在夏垫断裂和怀来后郝窑地热区。建立了两个断层气观测点,观测H_2、Ar、N_2、CO_2、Hg等断层气成分。在几次中强地震前,H_2和Hg出现了较大的异常变化。文中主要阐述和讨论这些断层气与地震活动的关系。     

Helium and argon isotope geochemistry of the Tibetan Qulong porphyry Cu-Mo deposit,China

The Qulong porphyry Cu-Mo deposit,generated in the Miocene post-collisional extension environment of the Gangdese Copper(Molybdenum) Metallogenic Belt,is one of the largest porphyry Cu deposits in China.This study reports the noble gas isotopic compositions of volatiles released from fluid inclusion reserved in pyrite from the Qulong deposit.~3He/~4 He and ~(40)Ar/~(36)Ar ratios range from 0.54 to 1.015 Ra and 300-359,respectively.Concentrations of ~4 He and ~(40)Ar range from 1.77 to 2.62 × 10~(-8) cm~3 STP and 1.7-34 × 10~(-8) cm~3 STP,respectively.The isotopic composition of noble gases indicates that the ore-forming fluids of the Qulong Cu-Mo deposit were a mixture of fluid containing mantle component,which is exsolved from the porphyry magma,and crustal fluid characterized by atmospheric Ar and crustal radiogenic He.The δ~(34)S values of pyrite and molybdenite range from-0.52‰ to 0.31‰,with an average of-0.12‰,indicating a magmatic origin.More mantle components were involved in the Cu-Mo deposit than in the Mo-Cu deposit in the Qulong-Jiama ore-district.     

Rare gas constraints on hydrocarbon accumulation, crustal degassing and groundwater flow in the Pannonian Basin

The isotopic composition and abundances of He, Ne and Ar have been measured in a sequence of vertically stacked gas reservoirs at Hajduszoboszlo and Ebes, in the Pannonian Basin of Hungary. The gas reservoirs occur at depths ranging from 727 to 1331 m, are CH₄ dominated and occupy a total rock volume of approximately 1.5 km³. There are systematic variations in both major species abundances and rare gas isotopic composition with depth: CO₂ and N₂ both increase from 0.47 and 1.76% to 14.1 and 30.5%, respectively, and ⁴⁰Ar/³⁶Ar and ²¹Ne/²²Ne increase systematically from 340 and 0.02990 at 727 m to 1680 and 0.04290 at 1331 m. A mantle-derived He component between 2 and 5% is present in all samples, the remainder is crustal-radiogenic He. The Ar and Ne isotope variations arise from mixing between atmosphere-derived components in groundwater, and crustally produced radiogenic Ar and Ne. The atmosphere-derived ⁴⁰Ar and ²¹Ne decreases from 85 and 97% of the total ⁴⁰Ar and ²¹Ne at 727 m to 18 and 68% at 1331 m. The deepest samples are shown to have both atmosphere-derived and radiogenic components close to the air-saturated water and radiogenic production ratios. The shallowest samples show significant fractionation of He/Ar and Ne/Ar ratios in atmosphere-derived and radiogenic rare gas components, but little or no fractionation of He/Ne ratios. This suggests that diffusive fractionation of rare gases is relatively unimportant and that rare gas solubility partitioning between CH₄ and H₂O phases controls the observed rare gas elemental abundances.The total abundance of atmosphere-derived and radiogenic rare gas components in the Hajduszoboszlo gas field place limits on the minimum volume of groundwater that has interacted with the natural gas, and the amount of crust that has degassed and supplied radiogenic rare gases. The radiogenic mass balance cannot be accounted for by steady state production either within the basin sediments or the basement complex since basin formation. The results require that radiogenic rare gases are stored at their production ratios on a regional scale and transported to the near surface with minimal fractionation. The minimum volume of groundwater required to supply the atmosphere-derived rare gases would occupy a rock volume of some 1000 km³ (assuming an average basin porosity of 5%), a factor of 670 greater than the reservoir volume. Interactions between groundwater and the Hajduszoboszlo hydrocarbons has been on a greater scale than often envisaged in models of hydrocarbon formation and migration.     

N<Subscript>2</Subscript>, Ar,and He as a tool for discriminating sources of volcanic fluids with application to Vulcano,Italy

A detailed analysis of published data on the N₂, Ar, and He content and Ar and He isotopic composition of fumarolic fluids from Vulcano crater (south Italy) supports a model with two endmembers comprising magmatic and hydrothermal fluids with correspondingly low and high H₂O content. The magmatic component with the highest ³He/⁴He and highest absolute concentrations of N₂, Ar, and He also has the lowest N₂/Ar and N₂/He ratios (∼300 and ∼500, respectively). In contrast, the hydrothermal endmember, with the lower ³He/⁴He and lower absolute N₂, Ar, and He abundances, has high N₂/Ar (∼1,000) and high N₂/He (>3,000) ratios. The hydrothermal component is also characterized by the highest ⁴⁰Ar/³⁶Ar ratios (>1,000) and is proposed to be the main carrier of metamorphic gases from the arc crust.     

Diffusive fractionation of noble gases and helium isotopes during mantle melting

The large differences in He and Ar diffusivities in silicate minerals could result in fractionation of the He/Ar ratio during melting of the mantle, producing He/Ar ratios in the primary mantle melts that are higher than those of the bulk mantle. Modeling noble gas diffusion out of the bulk mantle into fast diffusion pathways (such as fractures or melt channels) suggests that significant (order of magnitude) He/Ar fractionation will occur if the fast diffusion channels are spaced several meters apart and the noble gas residence in these diffusion channels is of the order days to weeks. In addition, the 15% difference in ³He and ⁴He diffusivities could also produce isotopic fractionation between the melt and its solid source. Modeling the behavior of He and Ar during melting shows that small increases (few %) in ³He/⁴He should be correlated with larger variations (factor of 5) in ⁴He/⁴⁰Ar. However, in order to test this hypothesis the effects of subsequent He–Ar fractionation that occur during degassing have to be corrected. I describe a scheme that can separate He/Ar variations in the primary melt from overprinted fractionation during magmatic degassing. Using the degassing-corrected data, there is a correlation between the primary melt’s ⁴He/⁴⁰Ar and ³He/⁴He in mid-ocean ridge basalts (MORBs). The slope of the correlation is consistent with the models of preferential diffusion of ³He relative to ⁴He and of ⁴He relative to ⁴⁰Ar from the solid mantle into the melt. Diffusive fractionation of noble gases during melting of the mantle can also account for low ⁴He/⁴⁰Ar ratios commonly found in residual mantle xenoliths: preferential diffusion of He relative to Ar will produce some regions of the mantle with low ⁴He/⁴⁰Ar, the complement of the high ⁴He/⁴⁰Ar ratios in basalts. Diffusive fractionation cannot, however, account for differences between the He and Ne isotopic compositions of MORBs compared with ocean island basalts (OIBs); not only are the extremely high ³He/⁴He ratios of OIBs (up to 50 Ra) difficult to produce at reasonable mantle time and lengthscales, but also the Ne isotopic compositions of MORBs and OIBs do not lie on a single mass fractionation line, therefore cannot result from diffusive fractionation of a single mantle Ne source. If preferential diffusion of He from the solid mantle into primary melts is a significant process during generation of MORBs, then it is difficult to constrain the He concentration of the mantle: He concentrations in basalts and the He flux to the ocean essentially result from extraction of He from a larger (and unknown) volume of mantle than that that produced the basalts themselves. The He concentration of the mantle cannot be constrained until more accurate estimates of the diffusion contribution are available.     

Noble gases in submarine pillow volcanic glasses

Fifteen submarine glasses from the East Pacific Rise (CYAMEX), the Kyushu-Palau Ridge (DSDP Leg 59) and the Nauru Basin (DSDP Leg 61) were analysed for noble gas contents and isotopic ratios. Both the East Pacific Rise and Kyushu-Palau Ridge samples showed Ne excess relative to Ar and a monotonic decrease from Xe to Ar when compared with air noble gas abundance. This characteristic noble gas abundance pattern (type 2, classified by Ozima and Alexander) is interpreted to be due to a two-stage degassing from a noble gas reservoir with originally atmospheric abundance. In the Kyushu-Palau Ridge sample, noble gases are nearly ten times more abundant than in the East Pacific Rise samples. This may be attributed to an oceanic crust contamination in the former mantle source.There is no correlation between the He content and that of the other noble gas in the CYAMEX samples. This suggests that He was derived from a larger region, independent from the other noble gases.Except where radiogenic isotopes are involved, all other noble gas isotopic ratios were indistinguishable from air noble gas isotopic ratios. The³He/⁴He in the East Pacific Rise shows a remarkably uniform ratio of (1.21±0.07)×10^?5, while the⁴⁰Ar/³⁶Ar ranges from 700 to 5600.     

He, Ne and Ar isotope compositions of fluid inclusions in hydrothermal sulfides from the TAG hydrothermal field Mid-Atlantic Ridge

Helium, neon and argon isotope compositions of fluid inclusions have been measured in hydrothermal sulfide samples from the TAG hydrothermal field at the Mid-Atlantic Ridge. Fluid-inclusion³He/⁴He ratios are 2.2—13.3 times the air value (Ra), and with a mean of 7.2 Ra. Comparison with the local vent fluids (³He/⁴He=7.5—8.2 Ra) and mid-ocean ridge basalt values (³He/⁴He=6—11 Ra) shows that the variation range of³He/⁴He ratios from sulfide-hosted fluid inclusions is significantly large. Values for²⁰Ne/²²Ne are from 10.2 to 11.4, which are significantly higher than the atmospheric ratio (9.8). And fluid-inclusion⁴⁰Ar/³⁶Ar ratios range from 287 to 359, which are close to the atmospheric values (295.5). These results indicate that the noble gases of fluid inclusions in hydrothermal sulfides are a mixture of mantle- and seawater-derived noble gases; the partial mantle-derived components of trapped hydrothermal fluids may be from the lower mantle; the helium of fluid inclusions is mainly from upper mantle; and the Ne and Ar components are mainly from seawater.     

Rare gas isotopic compositions in natural gases of Japan

Isotopic and elemental compositions of rare gases in various types of gas samples collected in the Japanese Islands were investigated. Excess³He was found in most samples. Many samples showed a regionally uniform high³He/⁴He ratio of about 7 times the atmospheric ratio. The He concentrations varied from 0.6 to 1800 ppm, and they were low in CO₂-rich gases and high in N₂-rich gases. Ne isotopic deviations from the atmospheric Ne were detected in most volcanic gases. The deviations and the elemental abundance patterns in volcanic gases can be explained by a mixing between two components, one is mass fractionated rare gases and the other is isotopically atmospheric and is enriched in heavy rare gas elements. Ar was a mixture of mass fractionated Ar, atmospheric Ar and radiogenic Ar, and the contribution of radiogenic⁴⁰Ar was small in all samples. Except for He, elemental abundance patterns were progressively enriched in the heavier rare gases relative to the atmosphere. Several samples were highly enriched in Kr and Xe relative to the abundance pattern of dissolution equilibrium of atmospheric rare gases in water. The component which is highly enriched in heavy rare gases may be released from sedimentary materials in the crust.     

Atmospheric noble gases in volcanic glasses from the southern Lau Basin: origin from the subducting slab?

Noble gas concentrations and isotopic compositions have been determined for four submarine volcanic glasses from the Valu Fa Ridge (VFR) in the southern Lau Basin. The samples are the least differentiated ones from this area, and they display enrichments in fluid-mobile elements similar to the nearby island arc. ³He/⁴He ratios are slightly below average MORB (6.8–7.8 times atmospheric), whereas Ne, Ar, Kr, and Xe have isotopic compositions very similar to air. Together with previously published data from the Valu Fa Ridge and other spreading segments in the Lau Basin, our data show a systematic latitudinal variation of increasing Ne, Ar, Kr, and Xe abundances from north to south as well as Ne and Ar isotopic compositions changing from MORB-like to atmosphere-like in the same direction. Moreover, isotopic compositions and noble gas abundances of the lavas correlate strongly with Ba/Nb ratios and H₂O concentrations. Based on these observations and mass balance arguments, we propose that the atmospheric noble gases come from the subducting oceanic crust and are not due to shallow contamination with air dissolved in seawater or assimilation of old crust. Our data suggest that the noble gases released from the subducting slab are atmospheric and thus contain little or no solar He and Ne. In addition to the fact that ratios of He to heavy noble gases are small in aged ocean crust, He has possibly fractionated from the other noble gases due to its higher diffusivity, and thus He transport from the subducting slab into the mantle wedge is probably insignificant. We propose that the ³He/⁴He ratios lower than MORB observed in the VFR lavas result from radiogenic ingrowth of He in a highly depleted, and hence degassed, mantle wedge after the enrichment of U and Th released from the downgoing slab.     

Mechanisms of magmatic gas loss along the Southeast Indian Ridge and the Amsterdam -St. Paul Plateau

New analyses of He, Ne, Ar and CO₂ trapped in basaltic glasses from the Southeast Indian Ridge (Amsterdam-St. Paul (ASP) region) show that ridge magmas degas by a Rayleigh distillation process. As a result, the absolute and relative noble gas abundances are highly fractionated with ⁴He/⁴⁰Ar* ratios as high as 620 compared to a production ratio of ∼3 (where ⁴⁰Ar* is ⁴⁰Ar corrected for atmospheric contamination). There is a good correlation between ⁴He/⁴⁰Ar* and the MgO content of the basalt, suggesting that the amount of gas lost from a particular magma is related to the degree of crystallization. Fractional crystallization forces oversaturation of CO₂ because CO₂ is an incompatible element. Therefore, crystallization will increase the fraction of gas lost from the magma. The He-Ar-CO₂-MgO-TiO₂ compositions of the ASP basalts are modeled as a combined fractional crystallization-fractional degassing process using experimentally determined noble gas and CO₂ solubilities and partition coefficients at reasonable magmatic pressures (2-4 kbar). The combined fractional crystallization-degassing model reproduces the basalt compositions well, although it is not possible to rule out depth of eruption as a potential additional control on the extent of degassing. The extent of degassing determines the relative noble gas abundances (⁴He/⁴⁰Ar*) and the ⁴⁰Ar*/CO₂ ratio but it cannot account for large (>factor 50) variations in He/CO₂, due to the similar solubilities of He and CO₂ in basaltic magmas. Instead, variations in CO₂/³He (≡C/³He) trapped in the vesicles must reflect similar variations in the primary magma. The controls on C/³He in mid-ocean ridge basalts (MORBs) are not known. There are no obvious correlated variations between C/³He and tracers of mantle heterogeneity (³He/⁴He, K/Ti etc.), implying that the variations in C/³He are not likely to be a feature of the mantle source to these basalts. Mixing between MORB-like sources and more enriched, high ³He/⁴He sources occurs on and near the ASP plateau, resulting in variable ³He/⁴He and K/Ti compositions (and many other tracers). Using ⁴He/⁴⁰Ar* to track degassing, we demonstrate that mixing systematics involving He isotopes are determined in large part by the extent of degassing. Relatively undegassed lavas (with low ⁴He/⁴⁰Ar*) are characterized by steep ³He/⁴He-K/Ti mixing curves, with high He/Ti ratios in the enriched magma (relative to He/Ti in the MORB magma). Degassed samples (high ⁴He/⁴⁰Ar*) on the other hand have roughly equal He/Ti ratios in both end-members, resulting in linear mixing trajectories involving He isotopes. Some degassing of ASP magmas must occur at depth, prior to magma mixing. As a result of degassing prior to mixing, mixing systematics of oceanic basalts that involve noble gas-lithophile pairs (e.g. ³He/⁴He vs. ⁸⁷Sr/⁸⁶Sr or ⁴⁰Ar/³⁶Ar vs. ²⁰⁶Pb/²⁰⁴Pb) are unlikely to reflect the noble gas composition of the mantle source to the basalts. Instead, the mixing curve will reflect the extent of gas loss from the magmas, which is in turn buffered by the pressure of combined crystallization-degassing and the initial CO₂ content.     

Primordial gases in graphite-diamond-kamacite inclusions from the Haveröureilite

Stepwise heating experiments on separated graphite-diamond-kamacite aggregates have revealed a pronounced difference in the release patterns of spallogenic³He and trapped gases. About half the³He is released at T ? 920°C, without being accompanied by significant amounts of primordial gases; the latter, together with the remaining³He, is given off only at T ? 1200°C. Acid treatment of an aliquant dissolved about 2/3 of the total Fe in the sample but did not cause a significant change in the gas concentrations. It is concluded that (a) there is no evidence for a loss of spallogenic³He from the graphite-diamond-kamacite aggregates, (b) one major constituent of the aggregates - graphite - is almost void of trapped gases, (c) kamacite is not a main carrier of the gases. This leaves diamond as the most probable site of the primordial gases.The elemental abundance pattern in the noble gases is essentially as reported previously. In particular, the excellent correlation between relative depletion factors, normalized to the cosmic abundance ratios, and the respective ionisation energies is confirmed. Other important features of the trapped gases are a²⁰Ne/²²Ne ratio of 12.3 ± 0.6, intermediate between solar wind and solar flare implanted Ne,³⁶Ar/³⁸Ar = 5.20 ± 0.06 and a measured⁴⁰Ar/³⁶Ar ratio (before blank correction) of 0.0076.Possible modes of trapping of the noble gases are discussed.     

Noble gas systematics for coexisting glass and olivine crystals in basalts and dunite xenoliths from Loihi Seamount

Noble gas isotopes including ³He/⁴He, ⁴⁰Ar/³⁶Ar and Xe isotope ratios were determined for coexisting glass and olivine crystals in tholeiitic and alkalic basalts and dunite xenoliths from Loihi Seamount.Glass and coexisting olivine crystals have similar ³He/⁴He ratios (2.8–3.4) × 10^?5, 20 to 24 times the atmospheric ratio (R_A), but different ⁴⁰Ar/³⁶Ar ratios (400–1000). Based on the results of noble gas isotope ratios and microscopic observation, some olivine crystals are xenocrysts. We conclude that He is equilibrated between glass and olivine xenocrysts, but Ar is not.The apparent high ³He/⁴He ratio (3 × 10^?5; = 21 R_A) coupled with a relatively high ⁴⁰Ar/³⁶Ar ratio (4200) for dunite xenoliths (KK 17-5) may be explained by equilibration of He between MORB-type cumulates and the host magma.Except for the dunite xenoliths, noble gas data for these Loihi samples are compatible with a model in which samples from hot spot areas may be explained by mixing between P (plume)-type and M (MORB)-type components with the addition of A (atmosphere)-type component.Excess ¹²⁹Xe has not been observed due to apparent large mass fractionation among Xe isotopes.