Occurrence and breakdown of paragonite and margarite in the Greiner Schiefer Series (Zillerthal Alps,Tyrol)

Margarite and Paragonite are found coexisting in amphibolites of the Untere Schieferhülle in the area of the upper Schlegeistal (Zillerthal Alps, Northern Tyrol). These amphibolites are metamorphosed under conditions of the low grade amphibolite facies. The chemical composition of the two micas was determined by the electron microprobe. A maximum of 14 Mol-% margarite and 18 Mol-% muscovite enters into the paragonite, the margarite being entered by 20 to 50 Mol-% paragonite and a maximum of 10 Mol-% muscovite. There seems to be a solubility gap between margarite and paragonite in a range between 15 and 50 Mol-% margarite.At their margins the margarites and paragonites breakdown into a mixture of feldspar and into a fine, microscopically not identifiable phase. Plagioclases having An 28 to An 42 result from breakdown of paragonite, feldspars between An 50 and An 60 probably arose from breakdown of margarite. A definite statement on this probelem is not possible because the smallness and the inhomogeneity of the feldspar grains.Based on the experimental data concerning the stability of margarite, paragonite (±quartz, ±CO₂) and kyanite, the P-T-range of the metamorphosis is discussed.     

Synthesis and upper stability of paragonite

The mineral paragonite, NaAl₂[AlSi₃O₁₀ (OH)]₂, has been synthesized on its own composition starting from a variety of different materials. Indexed powder data and refined cell parameters are given for both the 1M and 2M₁ polymorphs obtained. The upper stability limit of paragonite is marked by its breakdown to albite + corundum + vapour. The univariant equilibria pertaining to this reaction have been established by reversing the reaction at six different pressures, the equilibrium curve running through the following intervals: 1 kb: 530°–550° C 2 kb: 555°–575° C 3 kb: 580°–600° C 5kb: 625°–640° C 6 kb: 620°–650° C 7 kb: 650°–670° C.Comparison with the upper stability limit of muscovite (Velde, 1966) shows that paragonite has a notably lower thermal stability thus explaining the field observation that paragonite is absent in many higher grade metamorphic rocks in which muscovite is still stable.The enthalpy and entropy of the paragonite breakdown reaction have been estimated. Since intermediate albites of varying structural states are in equilibrium with paragonite, corundum and H₂O along the univariant equilibrium curve, two sets of data pertaining to the entropy of paragonite (S ₂₉₈ ⁰ ) as well as the enthalpy ( H _f,298 ⁰ ) and Gibbs free energy ( G _f,298 ⁰ ) of its formation were computed, assuming (1) high albite and (2) low albite as the equilibrium phase. The values are: (1) (2) S ₂₉₈ ⁰ 67.8±3.9 cal deg^–1 gfw^–1 63.7±3.9 cal deg^–1 gfw^–1 H _f,298 ⁰ –1417.9±2.7 kcal gfw^–1 –1420.2±2.6 kcal gfw^–1 G _f,298 ⁰ –1327.4±4.0 kcal gfw^–1 –1328.5±4.0 kcal gfw^–1.Adapted from a part of the author's Habilitationsschrift accepted by the Ruhr University, Bochum (Chatterjee, 1968).     

On the “late” formation of paragonite and its breakdown in pelitic rocks of the southern Damara Orogen (Namibia)

The formation of paragonite at the transition from the low-grade to the medium-grade matamorphism and its breakdown in the presence of quartz in the upper medium grade in common metapelites is investigated.The microprobe work on the white micas from the low and medium-grade rocks yields compositional differences in respect to the celadonite substitutions and the paragonite content. The low-grade white micas are phengites having Si^[4] 6.25 to 6.44 and Al_tot 4.89 to 5.20. The paragonite component in solid solution in the phengites ranges from 11 to 17 mole %. In the transition from the low-grade to the medium-grade metamorphism, concomitant with the breakdown of chlorite, the phengites change to muscovites having Si^[4] 6.07 to 6.16 and Al_tot 5.36 to 5.56. At the same time, the amount of paragonite in solid solution increases up to 22±2 mole % and paragonite makes its first appearance as a separate mineral. The increase of the percentage of paragonite in solid solution in the muscovites is due to the drastical modal decrease of muscovite in the course of the breakdown of chlorite. The formation of paragonite is readily explained by the muscovite-paragonite solvus. Paragonite forms thin lamellae (1–20 m) interlayered with muscovite lamellae (1–40 m). The average composition is Pg_88.5Ms₇Mar_4.5. Paragonite occurs together with staurolite+biotite, kyanite+biotite, cordierite +biotite, and andalusite+biotite. In the presence of quartz, it breaks down in the lower part of the andalusite zone to andalusite and albite-rich plagioclase. At the same time, the amount of paragonite in solid solution in the muscovites decrease to 11–15 mole %. The basal spacings d(002) of the phengites and muscovites investigated show a clear dependence on the Na⁺ content and the celadonite substitutions.     

Pressure dependence of structural parameters of paragonite

The compressibility and structure of a 2M₁ paragonite with composition [Na_0.88K_0.10Ca_0.01Ba_0.01] [Al_1.97Ti_0.007Fe_0.01Mn_0.002Mg_0.006]Si_3.01Al_0.99O₁₀OH₂ were determined at pressures between 1 bar and 41 kbar, by single crystal X-ray diffraction using a Merrill-Bassett diamond anvil cell. Compressibility turned out to be largely anisotropic, linear compressibility coefficients parallel to the unit cell edges being β_a=3.5(1)·10^?4, β_b=3.6(1)·10^?4, β_c=8.3(3)·10^?4 kbar^?1 (β_a:β_b·β_c=1:1028:2.371). The isothermal bulk modulus, calculated as the reciprocal of the mean compressibility of the cell volume, was 650(20) kbar. The main features of the deformation mechanism resulting from structural refinements at pressures of 0.5, 25.4, 40.5 kbar were: –?variation in sheet thickness, showing that compression of the c parameter was mainly due to the interlayer thickness reduction from 3.07 Å at 0.5 kbar to 2.81 Å at 40.5 kbar; –?the compressibility of octahedra was greater than that of tetrahedra, the dimensional misfit between tetrahedral and octahedral sheets increased with P, so that tetrahedral rotation angel α increased from 15° at 0.5 kbar to 21.6° at 40.5 kbar; –?the basal surface corrugation (Δz) of the tetrahedral layer, due to the different dimensions of M1 and M2 octahedra and to the octahedral distortion, decreased with P (Δz=0.19 and 0.12 Å at 0.5 and 40.5 kbar respectively). Comparison of the new data on paragonite with those of a K-muscovite and a Na-rich muscovite (Comodi and Zanazzi 1995) revealed a clear trend toward decreasing of compressibility when Na substitutes for K atoms in the interlayer sites.     

A mixed-layer paragonite/phengite of low-grade metamorphic origin

A mixed-layer paragonite/phengite from low-grade metamorphic slates is described, showing strong tendency to regular mixed-layering with a paragonite/phengite ratio of about 64. It is suggested that the mixed-layer paragonite/phengite is an intermediate phase in the formation of paragonite from Na-bearing illite or montmorillonite.     

Distribution of trace elements during breakdown of mantle garnet: an example from Zabargad

Ion probe investigations on mineral phases forming the Al-Di pyroxenites from the Zabargad peridotite body indicate that porphyroclastic pyroxenes in composite mafic layers record an unusual HREE, Zr, Sc enrichment not registered by pyroxenes in spinel websterites. Orthopyroxene in the opx+sp clusters forming the inner, cpx-free zone of layered pyroxenites shows strongly fractionated REE patterns (HREE_N/LREE_N>1000; Yb>100xch) and very high Zr, Sc and Y abundances (up to 30,672 and 60ppm, respectively). In the outer, cpx-rich zone porphyroclastic clinopyroxene is strongly HREE enriched (HREE_N/LREE_N29; Yb 269xch) and displays very high Sc and Zr abundances (up to 819 and 164 ppm, respectively). It is suggested that the unusual trace element abundances are inherited from a precursor garnet. Composite pyroxenite layers are interpreted as former garnet clinopyroxenites characterized by gnt/cpx modal zoning. The sp+opx(cpx-free) assemblage in the inner part is a product of the break-down reaction of garnet upon decompression, with Ca of the original garnet completely entering the enstatite solid solution. The temperature at which the breakdown reaction occurred is estimated to be higher than 1000°C (P in the range 20–30 kbar). In the outer part, decompression caused the garnet to form a sp+opx assemblage; however, the grossularite component participated in the formation of new clinopyroxene which reacted with the clinopyroxene present in the original mode before the decompression reaction, thus forming a cpx₂+sp+opx assemblage. As a result of garnet breakdown, pyroxenes have peculiar HFSE anomalies. Progressive upwelling during the Red Sea rifting produced incomplete reaction under pl-facies conditions. The geochemical signatures of precursor garnet in pyroxenes were partially crased during the recrystallization from granular spincl-bearing to granoblastic plagioclase-bearing assemblages, being preserved only in a few porphyroclast relies. The finding of pyroxenes with trace element characteristics of precursor garnet has important geodynamic and geochemical implications. Al-Di pyroxenite layers had a long history within the mantle, before the continental lithosphere rifting and thinning took place in the region. It is suggested that Al-Di pyroxenites were formed by deep-seated tholeiitic magmatism unrelated to the Red Sea evolution, thus representing the earliest event in the Zabargad upper mantle. Garnet breakdown significantly preceded the metasomatism induced by hydrous fluids (crystallization of Ti-rich pargasite) and the later intrusion of hydrous (Cr-Di) pyroxenite dykes. During the stages of mantle evolution, the HFSE anomalies in pyroxenes varied significantly. We note that the study of HFSE anomalies in mineral phases reveals complex geochemical histories which are not recorded by the whole-rock system.     

Structural thermal behavior of paragonite and its dehydroxylate: a high-temperature single-crystal study

 The lattice constants of paragonite-2M₁, NaAl₂(AlSi₃)O₁₀(OH)₂, were determined to 800 °C by the single-crystal diffraction method. Mean thermal expansion coefficients, in the range 25–600 °C, were: α_a = 1.51(8) × 10⁻⁵, α_b = 1.94(6) × 10⁻⁵, α_c = 2.15(7) ×  10⁻⁵ °C⁻¹, and α_V = 5.9(2) × 10⁻⁵ °C⁻¹. At T higher than 600 °C, cell parameters showed a change in expansion rate due to a dehydroxylation process. The structural refinements of natural paragonite, carried out at 25, 210, 450 and 600 °C, before dehydroxylation, showed that the larger thermal expansion along the c parameter was mainly due to interlayer thickness dilatation. In the 25–600 °C range, Si,Al tetrahedra remained quite unchanged, whereas the other polyhedra expanded linearly with expansion rate proportional to their volume. The polyhedron around the interlayer cation Na became more regular with temperature. Tetrahedral rotation angle α changed from 16.2 to 12.9°. The structure of the new phase, nominally NaAl₂ (AlSi₃)O₁₁, obtained as a consequence of dehydroxylation, had a cell volume 4.2% larger than that of paragonite. It was refined at room temperature and its expansion coefficients determined in the range 25–800 °C. The most significant structural difference from paragonite was the presence of Al in fivefold coordination, according to a distorted trigonal bipyramid. Results confirm the structural effects of the dehydration mechanism of micas and dioctahedral 2:1 layer silicates. By combining thermal expansion and compressibility data, the following approximate equation of state in the PTV space was obtained for paragonite: V/V ₀ = 1 + 5.9(2) × 10⁻⁵ T(°C) − 0.00153(4) P(kbar). Received: 12 July 1999 / Revised, accepted: 7 December 1999     

The upper stability limit of the assemblage paragonite + quartz and its natural occurrences

The assemblage paragonite + quartz is encountered frequently in low- to medium-grade metamorphic rocks. With rising grade of metamorphism they react mutually to yield the condensed assemblage albite + Al₂SiO₅.The univariant curve pertaining to the equilibrium paragonite + quartz=albite + andalusite + H₂O has been located experimentally. The reversed P _{H 2 O}-T data are: 1 kb: 470–490° C 2 kb: 510–530° C 3 kb: 540–560° C 4 kb: 560–580° C 5 kb: 590–600° C The univariant curve pertaining to the equilibrium paragonite + quartz=albite + kyanite + H₂O runs through the following P _{H 2 O}-T-intervals: 5 kb: 570–625° C 6 kb: 600–630° C 7 kb: 620–640° C Thermodynamic calculations of S ₂₉₈ ⁰ , H _f,298 ⁰ and G _f,298 ⁰ of the phase paragonite from the experimental data presented above and those obtained from the equilibria of the reaction paragonite=albite + corundum + H₂O (Chatterjee, 1970), agree within the limits of uncertainty. This prompts the idea that Zen's (1969) suggestion of a possible error of approximately 7 kcal in G _f,298 ⁰ of the Al₂SiO₅ polymorphs may in fact be due to an error of similar magnitude in G _f,298 ⁰ of corundum.A best estimate of S ₂₉₈ ⁰ , H _f,298 ⁰ and G _f,298 ⁰ of paragonite based on these considerations yield: S ₂₉₈ ⁰ : 67.61±3.9 cal deg^–1 gfw^–1 H _f,298 ⁰ : –1411.4±2.7 kcal gfw^–1 G _f,298 ⁰ : –1320.9±4.0 kcal gfw^–1 These numbers will be subject to change when better thermochemical data on corundum and albite are available.In medium-grade metamorphic rocks the assemblage paragonite + quartz is commonly found in stable coexistence with such other phases as muscovite, staurolite, andalusite, kyanite, but not with cordierite or sillimanite. However, the assemblage paragonite-sillimanite has been reported to be stable in the absence of quartz. All these petrologic observations can be explained on the basis of the stability data of the phases and phase assemblages concerned.     

Genesis and solvus relations of submicroscopically intergrown paragonite and phengite in a blueschist from northern California

Electron microbeam techniques have been used to examine submicroscopically intergrown paragonite, phengite and chlorite from the South Fork Mountain Schist of the Franciscan Terrane of northern California, which was subjected to blueschist facies metamorphism. The sample also contains quartz, albite, lawsonite, and rutile. The subassemblage albite-lawsonite-rutile requires metamorphic conditions on the low-temperature side of the equilibrium albite+lawsonite+rutile=paragonite+sphene+quartz+H₂O (T<200° C and P<7.4 kbars based on thermodynamic data of Holland and Powell 1990). The white micas appear to be optically homogeneous, but back-scattered electron images can distinguish two different micas by their slight difference in contrast. Electron microprobe analyses (EMPA) of micas show Na/(Na+K) ranging from 0.2 to 0.8. The two micas are resolved by transmission electron microscopy (TEM) as packets of phengite and paragonite that range from 20 to several hundred nm in thickness. The compositions, determined by analytical electron microscopy (AEM), constrain the limbs of the phengite-paragonite solvus to values of Na/(Na+K)=<0.02 and 0.97, representing less mutual solid solution than ever reported by EMPA. The textural relations imply that the sheet silicates were derived from reactions between fluids and detrital clays and that they are in an intermediate stage of textural development. We caution that microprobe analyses of apparently homogeneous sheet silicates may yield erroneous data and lead to faulty conclusions using phengite barometry and paragonite-muscovite thermometry, especially in fine-grained rocks that formed at relatively low temperatures. Contribution no. 473 from the Mineralogical Laboratory, Department of Geological Sciences, The University of Michigan, Ann Arbor, Michigan, USA     

田岗断层产状的确定方法

搞清断层赋存状态对矿井安全生产至关重要。针对目前以范围表示方法确定断层产状存在精度不足的问题,山东崔庄煤矿通过在井下施工断层探孔,探明了田岗断层地质层位关系等情况,并运用平面投影法和矿体几何要素较准确地确定了田岗断层的产状要素,包括断层倾角、断层落差和断层走向等,从而取代了通常对断层产状较模糊的范围表示法。本研究方法原理简单,易于掌握,其计算结果比原有地质资料更加准确可靠。     

An example of identifying karst groundwater flow

 Hydrogeological investigations for the purpose of regulating the karst aquifer were carried out in the mountain massif of Kucaj in the Carpatho-Balkan range of eastern Serbia. Different geophysical methods were applied in order to identify the position of karstified zones with active circulation of karst underground streams. Especially good results were obtained by using the spontaneous potential method for the exploration and construction of boreholes and wells. In the valleys of Crni Timok and Radovanska reka the measurements have been carried out upstream along the whole width of the alluvium to the limestone periphery. A number of positive and negative anomalies have been recorded. In the centres of positive anomalies several boreholes were located: HG-19 (centre of anomaly +30 mV, total length of the biggest cavern is 9 m); HG-1 (+20 mV, cavern of 2 m); HG-15 (max. +114 mV, effective cavernousness is 17%). Received: 20 February 1995 · Accepted: 12 September 1997     

Thermal equations of state of dioctahedral micas on the join muscovite–paragonite

 Powder diffraction measurements at simultaneous high pressure and temperature on samples of 2M1 polytype of muscovite (Ms) and paragonite (Pg) were performed at the beamline ID30 of ESRF (Grenoble), using the Paris-Edinburgh cell. The bulk moduli of Ms, calculated from the least-squares fitting of V–P data on each isotherm using a second-order Birch–Murnaghan EoS, were: 57.0(6), 55.1(7), 51.1(7) and 48.9(5) GPa on the isotherms at 298, 573, 723 and 873 K, respectively. The value of (∂K _T /∂T) was −0.0146(2) GPa K⁻¹. The thermal expansion coefficient α varied from 35.7(3) × 10⁻⁶ K⁻¹ at P ambient to 20.1(3) × 10⁻⁶ K⁻¹ at P = 4 GPa [(∂α/∂P) _T = −3.9(1) × 10⁻⁶ GPa⁻¹ K⁻¹]. The corresponding values for Pg on the isotherms at 298, 723 and 823 K were: bulk moduli 59.9(5), 55.7(6) and 53.8(7) GPa, (∂K _T /∂T) −0.0109(1) GPa K⁻¹. The thermal expansion coefficient α varied from 44.1(2) × 10⁻⁶ K⁻¹ at P ambient to 32.5(2) × 10⁻⁶ K⁻¹ at P = 4 GPa [(∂α/∂P) _T = −2.9(1) × 10⁻⁶ GPa⁻¹ K⁻¹]. Thermoelastic coefficients showed that Pg is stiffer than Ms; Ms softens more rapidly than Pg upon heating; thermal expansion is greater and its variation with pressure is smaller in Pg than in Ms. Received: 28 January 2002 / Accepted: 5 April 2002     

Some critical remarks on the analysis of phengite and paragonite components in muscovite by X-ray diffractometry

In the past lattice parameters b and c of muscovite s.1. from pelitic schists have been used to determine its phengite and paragonite component. A critical review of the literature and of some new data shows, however,

that a convincing statistical correlation between these physical and chemical properties does not exist

that an eventual trend-like correlation cannot be used for a quantitative analysis of phengite and/or paragonite components in muscovite.

Obviously further factors influence the lattice parameters of muscovite s.1., besides octahedral and interlayer chemistry.     

Coexisting phengite,paragonite and margarite in metasediments of the mittlere Hohe Tauern,Austria

The assemblages phengite-paragonite, phengite-margarite and phengite-paragonitemargarite are very common in metasediments of a N-S profile in the middle sector of the Hohe Tauern. The Si⁴⁺-content of phengite shows no regular change with increasing temperature from north to south along the profile. The variations in the d ₀₀₂ basal spacings of phengite coexisting with paragonite are not only dependent on the Na⁺ content of phengite but also on the Mg²⁺+Fe²⁺ content of the micas. Neither the sodium content in phengite nor the potassium content in paragonite shows any dependence on temperature. Chemical analyses of coexisting phengite, paragonite and margarite give the extent of the three-phase-region which is characterized by a small amount of margarite in paragonite (4 Mol%), by a large quantity of Na⁺ in margarite (28 Mol% paragonite), and limited miscibility between phengite and paragonite.     

Experimental determination of the solubility of the assemblage paragonite,albite, and quartz in supercritical H2O

The concentrations of Na, Al, and Si in an aqueous fluid in equilibrium with natural albite, paragonite, and quartz have been measured between 350°C and 500°C and 1 to 2.5 kbar. Si is the dominant solute in solution and is near values reported for quartz solubility in pure H₂O. At 1 kbar the concentrations of Na and Al remain fairly constant from 350°C to 425°C but then decrease at 450°C. At 2 kbar, Na increases slightly with increasing temperature while Al remains nearly constant. Concentrations of Si, Na, and Al all increase with increasing pressure at constant temperature.The molality of Al is close to that of Na and is nearly a log unit greater than calculated molalities assuming Al(OH)⁰₃ is the dominant Al species. This indicates a Na-Al complex is the dominant Al species in solution as shown by Anderson and Burnham (1983) at higher temperature and pressure. The complex can be written as NaAl(OH)⁰₄ ± nSiO₂ where n is the number of Si atoms in the complex. The value of n is not well constrained but appears to be less than or equal to 3.The results indicate Al can be readily transported in pure H₂O solutions at temperatures and pressures as low as 350°C and 1 kbar.     

桂林附近陷落地震分布,形成及特征

隐落地震是石灰岩喀斯特区溶洞或上洞塌陷所引起的特殊类型的地震,在我国南方及西南喀斯特区域分布较为广泛,是一类低震级高烈度的地震,在震中区造成较大的震灾。本文以桂林附近喀斯特区为研究范围,从古往今来的地震记录中分析提炼出其分布、形成及特征。     

一个CSAMT非平面波效应的实例及数值分析

本文以实例结合数值模拟说明CSAMT中非平面波效应对资料解释的重要影响。实际数据测量于河南卢氏县,在同一条测线测量,发射源长度1.3 km,收发距离分别为4.5 km和7 km。通过对数据进行必要的校正后进行了光滑模型反演,为了对比反演结果,整个处理过程的参数都保持一致。反演的电阻率断面显示,两种收发距离反演的电阻率断面其异常形态基本一致;但在电阻率的数值上,4.5 km的收发距离反演的电阻率较7 km的大。分析发现上述现象主要是源的非平面波效应造成的,并通过三维正演数值模拟得到了验证。由于在有限收发距离时,计算卡尼亚视电阻率靠近源受非平面波效应影响偏大,远离源后,该视电阻率趋于平面波视电阻率。因此,为了采用目前的可控源音频大地电磁测深解释理论,要求收发距离尽可能大。否则,必须采用带源效应的真正可控源电磁反演技术完成数据分析。     

源外鼻状构造区油运移输导通道及对成藏的作用

尚家地区为一鼻状构造,位于三肇凹陷下白垩统青山口组一段油源区之外,其石油的成藏与分布主要受输导通道的控制。能否正确认识该区石油输导通道及对成藏的作用,对于指导该区石油勘探和丰富油气成藏理论均具重要意义。采用油源对比、典型油藏解剖和成藏模式的研究方法,对尚家地区石油输导过程进行了研究,将其划分为以下3个部分：① T2源断裂是三肇凹陷青山口组一段源岩生成石油向下伏下白垩统泉头组四段扶余油层、下白垩统泉头组三段杨大城子油层“倒灌”运移的输导通道;② 被T2—T2-2断裂沟通的砂体是扶余、杨大城子油层石油从三肇凹陷向尚家地区侧向运移的输导通道;③ T2—T1-1断裂是尚家地区扶余、杨大城子油层石油向上覆下白垩统姚家组葡萄花油层运移的输导通道。采用石油输导通道和石油分布之间匹配关系的研究方法,对尚家地区输导通道对石油成藏与分布中的作用进行了研究,得到T2源断裂越发育,三肇凹陷向尚家地区侧向运移的油源越充足;被T2—T2-2断裂沟通的砂体输导通道位置和能力控制着扶余、杨大城子油层和下白垩统泉头组二段石油的分布及富集程度;T2—T1-1断裂输导通道分布控制着尚家地区葡萄花油层的石油富集区域。     

Earthquake data analysis: An example from Sweden

Methods and results of earthquake data analysis are illustrated by the seismicity of Sweden in the period 1951–1976, summarizing a comprehensive research project for the past five years. Starting from the regional structural properties, methods are given for the evaluation of instrumental and macroseismic observations, including error analysis and source identification. The resulting earthquake distribution is investigated in relation to space (various types of seismicity mapping), time (periodicities) and magnitude (frequency-magnitude and energy-magnitude relations). The tectonophysical explanations of the earthquake origin are still subject to considerable uncertainty and can be treated only by way of discussions. The engineering applications, stimulated recently by the nuclear power industry, can be placed on much more reliable ground. They include calculations of seismic risk and fracture risk as well as investigations of certain phenomena of practical consequences, especially rockbursts.This review is primarily addressed to those who have use for seismological data in their work, especially geologists, tectonophysicists and engineers. It is important for them to realize how the seismological data are obtained, their reliability and their range of application. Sweden is here mainly used as an example, but the developed methods have a general applicability to any earthquake region, with proper modifications.In short, our purpose is two-fold: (1) to summarize recent research on the seismicity of Sweden: (2) to introduce all users of seismological data into methods and results.