Pub Date : 2021-04-20DOI: 10.1080/11035897.2021.1907441
E. Jarochowska, Oskar Bremer, A. Yiu, T. Märss, H. Blom, T. Mörs, V. Vajda
ABSTRACT Ludfordian strata exposed in the Burgen outlier in eastern Gotland, Sweden record a time of initial faunal recovery after a global environmental perturbation manifested in the Ludfordian Carbon Isotope Excursion (LCIE). Vertebrate microfossils in the collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, hold the key to reconstruct the dynamics of faunal immigration and diversification during the decline of the LCIE, but the stratigraphic relationships of the strata have been debated. Historically, they had been placed in the Burgsvik Formation, which included the Burgsvik Sandstone and the Burgsvik Oolite members. We revise the fauna in the Jeppsson collection and characterize key outcrops of Burgen and Kapellet. The former Burgsvik Oolite Member is here revised as the Burgen Oolite Formation. In the Burgen outlier, back-shoal facies of this formation are represented and their position in the Ozarkodina snajdri Biozone is supported. The shallow-marine position compared to the coeval strata in southern Gotland is reflected in the higher δ13Ccarb values, reaching +9.2‰. The back-shoal succession includes high-diversity metazoan reefs, which indicate a complete recovery of the carbonate producers as the LCIE declined. The impoverishment of conodonts associated with the LCIE in southern Gotland might be a product of facies preferences, as the diverse environments in the outlier yielded all 21 species known from the formation. Fish diversity also returned to normal levels as the LCIE declined, with a minimum of nine species. In line with previous reports, thelodont scales appear to dominate samples from the Burgen outlier.
{"title":"Revision of thelodonts, acanthodians, conodonts, and the depositional environments in the Burgen outlier (Ludlow, Silurian) of Gotland, Sweden","authors":"E. Jarochowska, Oskar Bremer, A. Yiu, T. Märss, H. Blom, T. Mörs, V. Vajda","doi":"10.1080/11035897.2021.1907441","DOIUrl":"https://doi.org/10.1080/11035897.2021.1907441","url":null,"abstract":"ABSTRACT Ludfordian strata exposed in the Burgen outlier in eastern Gotland, Sweden record a time of initial faunal recovery after a global environmental perturbation manifested in the Ludfordian Carbon Isotope Excursion (LCIE). Vertebrate microfossils in the collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, hold the key to reconstruct the dynamics of faunal immigration and diversification during the decline of the LCIE, but the stratigraphic relationships of the strata have been debated. Historically, they had been placed in the Burgsvik Formation, which included the Burgsvik Sandstone and the Burgsvik Oolite members. We revise the fauna in the Jeppsson collection and characterize key outcrops of Burgen and Kapellet. The former Burgsvik Oolite Member is here revised as the Burgen Oolite Formation. In the Burgen outlier, back-shoal facies of this formation are represented and their position in the Ozarkodina snajdri Biozone is supported. The shallow-marine position compared to the coeval strata in southern Gotland is reflected in the higher δ13Ccarb values, reaching +9.2‰. The back-shoal succession includes high-diversity metazoan reefs, which indicate a complete recovery of the carbonate producers as the LCIE declined. The impoverishment of conodonts associated with the LCIE in southern Gotland might be a product of facies preferences, as the diverse environments in the outlier yielded all 21 species known from the formation. Fish diversity also returned to normal levels as the LCIE declined, with a minimum of nine species. In line with previous reports, thelodont scales appear to dominate samples from the Burgen outlier.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"168 - 189"},"PeriodicalIF":1.0,"publicationDate":"2021-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2021.1907441","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45367105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-02DOI: 10.1080/11035897.2020.1822439
J. Maletz, P. Ahlberg
ABSTRACT The Dapingian and lower Darriwilian graptolite succession of the Krapperup drill core from Scania, southern Sweden, provides a detailed insight into the axonophoran (biserial) graptolites and their early Palaeozoic evolutionary changes on the Scandinavian platform. Even though earliest Darriwilian axonophorans are not represented, the succession includes faunal elements of the basal Darriwilian Arienigraptus zhejiangensis Subzone of the Levisograptus austrodentatus Biozone, followed by Levisograptus mui and Levisograptus sinicus specimens higher up in the successsion. The highest interval is referred to the Eoglyptograptus cumbrensis Biozone and bears a number of axonophoran elements, including Oelandograptus oelandicus and Undulograptus camptochilus, previously known exclusively from chemically isolated material from the island of Öland. The top of the interval investigated is below the base of a carbonate-rich interval correlated with the Komstad Limestone of Scania, indicating that the investigated interval entirely belongs to the upper part of the Tøyen Shale Formation. Pseudisograptus manubriatus and Pseudisograptus koi are not restricted to the upper Dapingian, but range into the basal Darriwilian. Arienigraptus robustus n. sp. from the uppermost Dapingian, and Arienigraptus delicatus n. sp. and Arienigraptus balticus n. sp. from the basal Darriwilian, are described as new species.
{"title":"Dapingian to lower Darriwilian (Middle Ordovician) graptolite biostratigraphy and correlation of the Krapperup drill core, Scania, Sweden","authors":"J. Maletz, P. Ahlberg","doi":"10.1080/11035897.2020.1822439","DOIUrl":"https://doi.org/10.1080/11035897.2020.1822439","url":null,"abstract":"ABSTRACT The Dapingian and lower Darriwilian graptolite succession of the Krapperup drill core from Scania, southern Sweden, provides a detailed insight into the axonophoran (biserial) graptolites and their early Palaeozoic evolutionary changes on the Scandinavian platform. Even though earliest Darriwilian axonophorans are not represented, the succession includes faunal elements of the basal Darriwilian Arienigraptus zhejiangensis Subzone of the Levisograptus austrodentatus Biozone, followed by Levisograptus mui and Levisograptus sinicus specimens higher up in the successsion. The highest interval is referred to the Eoglyptograptus cumbrensis Biozone and bears a number of axonophoran elements, including Oelandograptus oelandicus and Undulograptus camptochilus, previously known exclusively from chemically isolated material from the island of Öland. The top of the interval investigated is below the base of a carbonate-rich interval correlated with the Komstad Limestone of Scania, indicating that the investigated interval entirely belongs to the upper part of the Tøyen Shale Formation. Pseudisograptus manubriatus and Pseudisograptus koi are not restricted to the upper Dapingian, but range into the basal Darriwilian. Arienigraptus robustus n. sp. from the uppermost Dapingian, and Arienigraptus delicatus n. sp. and Arienigraptus balticus n. sp. from the basal Darriwilian, are described as new species.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"16 - 39"},"PeriodicalIF":1.0,"publicationDate":"2021-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1822439","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42515283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-02DOI: 10.1080/11035897.2020.1858959
Olof Taromi Sandström, P. Dahlqvist, M. Erlström, L. Persson, S. Kershaw, M. Calner
ABSTRACT The Hemse Group is one of the least understood stratigraphic units of the Silurian sequence of Gotland, Sweden. New results from airborne transient electromagnetic (ATEM) measurements in combination with previously published data from field studies and geophysical investigations shed new light on carbonate platform development during the early- to mid-Ludlow Hemse Group. ATEM reveals a transgressive phase that began near the Wenlock-Ludlow boundary, which resulted in deposition of marls and corresponds roughly to the Hemse limestone units a-c and the Hemse Marl NW. In this phase little or no reef development occurs. The end of the transgressive phase coincides with the weak Linde Event. The following highstand favoured extensive reef growth forming a reef barrier system of both fringing reefs and more rampiform settings with stromatoporoid biostromes and occasional biohermal buildups. The Kuppen-Snabben Unconformity Complex marks an erosional (karstic) sequence boundary and rocky shoreline and the transition from a rampiform setting with reef biostromes towards a more rimmed setting with patch reefs.
{"title":"Stratigraphy of the Gorstian and Ludfordian (upper Silurian) Hemse Group reefs on Gotland, Sweden","authors":"Olof Taromi Sandström, P. Dahlqvist, M. Erlström, L. Persson, S. Kershaw, M. Calner","doi":"10.1080/11035897.2020.1858959","DOIUrl":"https://doi.org/10.1080/11035897.2020.1858959","url":null,"abstract":"ABSTRACT The Hemse Group is one of the least understood stratigraphic units of the Silurian sequence of Gotland, Sweden. New results from airborne transient electromagnetic (ATEM) measurements in combination with previously published data from field studies and geophysical investigations shed new light on carbonate platform development during the early- to mid-Ludlow Hemse Group. ATEM reveals a transgressive phase that began near the Wenlock-Ludlow boundary, which resulted in deposition of marls and corresponds roughly to the Hemse limestone units a-c and the Hemse Marl NW. In this phase little or no reef development occurs. The end of the transgressive phase coincides with the weak Linde Event. The following highstand favoured extensive reef growth forming a reef barrier system of both fringing reefs and more rampiform settings with stromatoporoid biostromes and occasional biohermal buildups. The Kuppen-Snabben Unconformity Complex marks an erosional (karstic) sequence boundary and rocky shoreline and the transition from a rampiform setting with reef biostromes towards a more rimmed setting with patch reefs.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"71 - 83"},"PeriodicalIF":1.0,"publicationDate":"2021-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1858959","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42711236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-02DOI: 10.1080/11035897.2021.1888314
R. Kumpulainen, M. Hamilton, U. Söderlund, J. P. Nystuen
ABSTRACT The Ottfjället Dyke Swarm (ODS) is a prominent component of the Ediacaran mafic magmatism associated with opening of the Iapetus ocean, and hosted in the Särv Nappe, Middle Allochthon of the Scandinavian Caledonides. A U-Pb baddeleyite age of 596.3 ± 1.5 Ma for a thick, well preserved, plagioclase-phyric dolerite dyke in Härjedalen, Sweden, dates emplacement of the swarm. The age represents a robust, inheritance-free reference age for variably deformed and metamorphosed tholeiitic dykes in sandstone-dominated sequences of the lower part of the Middle Allochthon, representing the proximal, rifted Baltoscandian margin preceding the opening of Iapetus. The new age is within the narrow time span between 610 and 595 Ma defined by the most reliable age estimates for mafic dykes in structurally higher nappes (upper part of Middle Allochthon), representing the distal margin during the opening of Iapetus. The Ottfjället Dyke Swarm cuts the Tossåsfjället Group succession, which includes sabkha-related carbonate platform and diamictite couples, one of several correlated Neoproterozoic glaciogenic successions in Scandinavia. The intrusion age of ca. 596 Ma therefore sets a minimum age for the glaciogenic successions. It implies that Neoproterozoic glaciations in Scandinavia predate the ca. 580 Ma Gaskiers glaciation event and are probably part of the ca. 635 Ma Marinoan “Snowball-Earth”-type glaciation.
Ottfjället岩浆岩群(ODS)是埃迪卡拉纪基性岩浆活动的一个重要组成部分，与Iapetus洋的打开有关，位于斯堪的纳维亚Caledonides中Allochthon的Särv推覆体中。在瑞典Härjedalen，一个厚的、保存完好的斜长石-辉绿白云岩岩脉的U-Pb年龄为596.3±1.5 Ma，确定了虫群的就位时间。该年龄代表了中异特古统下部砂岩占主导的层序中可变变形和变质的拉斑岩脉的一个强大的、无遗传的参考年龄，代表了Iapetus打开之前的近端裂陷的巴尔托斯坎德边缘。新时代在610 - 595 Ma之间的狭窄时间跨度内，这是构造较高推覆体(中allothon上半部分)基性岩墙最可靠的年龄估计，代表了Iapetus打开时的远端边缘。Ottfjället岩脉群切割了Tossåsfjället群序列，其中包括与sabkhaa相关的碳酸盐岩台地和辉长岩对，这是斯堪的纳维亚地区几个相关的新元古代冰川序列之一。因此，约596 Ma的入侵年龄确定了冰川期演替的最小年龄。这表明斯堪的纳维亚地区新元古代冰川作用早于约580 Ma Gaskiers冰川事件，可能是约635 Ma Marinoan“雪球地球”型冰川作用的一部分。
{"title":"U-Pb baddeleyite age for the Ottfjället Dyke Swarm, central Scandinavian Caledonides: new constraints on Ediacaran opening of the Iapetus Ocean and glaciations on Baltica","authors":"R. Kumpulainen, M. Hamilton, U. Söderlund, J. P. Nystuen","doi":"10.1080/11035897.2021.1888314","DOIUrl":"https://doi.org/10.1080/11035897.2021.1888314","url":null,"abstract":"ABSTRACT The Ottfjället Dyke Swarm (ODS) is a prominent component of the Ediacaran mafic magmatism associated with opening of the Iapetus ocean, and hosted in the Särv Nappe, Middle Allochthon of the Scandinavian Caledonides. A U-Pb baddeleyite age of 596.3 ± 1.5 Ma for a thick, well preserved, plagioclase-phyric dolerite dyke in Härjedalen, Sweden, dates emplacement of the swarm. The age represents a robust, inheritance-free reference age for variably deformed and metamorphosed tholeiitic dykes in sandstone-dominated sequences of the lower part of the Middle Allochthon, representing the proximal, rifted Baltoscandian margin preceding the opening of Iapetus. The new age is within the narrow time span between 610 and 595 Ma defined by the most reliable age estimates for mafic dykes in structurally higher nappes (upper part of Middle Allochthon), representing the distal margin during the opening of Iapetus. The Ottfjället Dyke Swarm cuts the Tossåsfjället Group succession, which includes sabkha-related carbonate platform and diamictite couples, one of several correlated Neoproterozoic glaciogenic successions in Scandinavia. The intrusion age of ca. 596 Ma therefore sets a minimum age for the glaciogenic successions. It implies that Neoproterozoic glaciations in Scandinavia predate the ca. 580 Ma Gaskiers glaciation event and are probably part of the ca. 635 Ma Marinoan “Snowball-Earth”-type glaciation.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"40 - 54"},"PeriodicalIF":1.0,"publicationDate":"2021-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2021.1888314","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46930786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-02DOI: 10.1080/11035897.2020.1858341
I. Klonowska, A. Ladenberger, D. Gee, P. Jeanneret, Yuan Li
ABSTRACT Recent studies in the context of the International Continental Scientific Drilling Project “Collisional Orogeny in the Scandinavian Caledonides” have focused on the importance of the Seve Nappe Complex (SNC) for understanding the subduction history of the Baltoscandian margin during closure of the Iapetus Ocean. In the classical Åre area of western central Jämtland, granulite facies migmatites and leucogranites of the Åreskutan Nappe provide evidence of Early Silurian (c. 440 Ma) high temperature metamorphism and a previous prograde, ultra-high pressure history, with microdiamonds. New LA-ICPMS zircon isotope age investigations of the underlying amphibolite facies Lower Seve Nappes, reported here, have also identified an Early Silurian tectonothermal history with pegmatitic leucogranite (c. 443 Ma) and, at lower structural levels, another felsic intrusion of earliest Middle Ordovician age (c. 469 Ma). The latter intrudes isoclinally folded host rock amphibolites and calcareous psammitic paragneisses and is itself tightly folded. Zircons in an amphibolite proved to be highly discordant but indicate Early Silurian metamorphism during isoclinal folding. Detrital zircons in a paragneiss are dominated by Sveconorwegian populations, but also include a range of younger Neoproterozoic grains down to the Early Ediacaran (c. 600 Ma). This new evidence of early Caledonian deformation and metamorphism indicates that, as farther north in the orogen, the Seve tectonothermal history in central Jämtland probably started early in the Ordovician, or before. Subduction and accretion along the Baltoscandian outer margin occurred prior to Scandian continent-continent collision, with Siluro-Devonian emplacement of the SNC across the foreland basins onto the Baltoscandian platform.
{"title":"Timing of deformation, metamorphism and leucogranite intrusion in the lower part of the Seve Nappe Complex in central Jämtland, Swedish Caledonides","authors":"I. Klonowska, A. Ladenberger, D. Gee, P. Jeanneret, Yuan Li","doi":"10.1080/11035897.2020.1858341","DOIUrl":"https://doi.org/10.1080/11035897.2020.1858341","url":null,"abstract":"ABSTRACT Recent studies in the context of the International Continental Scientific Drilling Project “Collisional Orogeny in the Scandinavian Caledonides” have focused on the importance of the Seve Nappe Complex (SNC) for understanding the subduction history of the Baltoscandian margin during closure of the Iapetus Ocean. In the classical Åre area of western central Jämtland, granulite facies migmatites and leucogranites of the Åreskutan Nappe provide evidence of Early Silurian (c. 440 Ma) high temperature metamorphism and a previous prograde, ultra-high pressure history, with microdiamonds. New LA-ICPMS zircon isotope age investigations of the underlying amphibolite facies Lower Seve Nappes, reported here, have also identified an Early Silurian tectonothermal history with pegmatitic leucogranite (c. 443 Ma) and, at lower structural levels, another felsic intrusion of earliest Middle Ordovician age (c. 469 Ma). The latter intrudes isoclinally folded host rock amphibolites and calcareous psammitic paragneisses and is itself tightly folded. Zircons in an amphibolite proved to be highly discordant but indicate Early Silurian metamorphism during isoclinal folding. Detrital zircons in a paragneiss are dominated by Sveconorwegian populations, but also include a range of younger Neoproterozoic grains down to the Early Ediacaran (c. 600 Ma). This new evidence of early Caledonian deformation and metamorphism indicates that, as farther north in the orogen, the Seve tectonothermal history in central Jämtland probably started early in the Ordovician, or before. Subduction and accretion along the Baltoscandian outer margin occurred prior to Scandian continent-continent collision, with Siluro-Devonian emplacement of the SNC across the foreland basins onto the Baltoscandian platform.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"55 - 70"},"PeriodicalIF":1.0,"publicationDate":"2021-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1858341","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45916772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-02DOI: 10.1080/11035897.2020.1865446
J. S. Peel
ABSTRACT The ptychoparioid trilobites Eldoradia and Acrocephalops (Family Bolaspididae) are described from the middle Cambrian (Miaolingian Series) of northern Greenland (Laurentia). Eldoradia, originally described from the Secret Canyon Shale of Nevada, is recorded from south-western Wulff Land, North Greenland, where it occurs together with Modocia and Olenoides. Eldoradia caerulioris n. sp. is established. The occurrence of Eldoradia in the lower part of the Blue Cliffs Formation indicates a minimum late middle Cambrian age (Miaolingian Series, Guzhangian Stage) for the base of the formation. Type material of Acrocephalops, a relative of Eldoradia originally proposed on the basis of material from the Miaolingian Series (Wuliuan Stage) of Inglefield Land, North-West Greenland, is redescribed.
{"title":"Eldoradia and Acrocephalops (Trilobita: Bolaspididae) from the middle Cambrian (Miaolingian) of northern Greenland (Laurentia)","authors":"J. S. Peel","doi":"10.1080/11035897.2020.1865446","DOIUrl":"https://doi.org/10.1080/11035897.2020.1865446","url":null,"abstract":"ABSTRACT The ptychoparioid trilobites Eldoradia and Acrocephalops (Family Bolaspididae) are described from the middle Cambrian (Miaolingian Series) of northern Greenland (Laurentia). Eldoradia, originally described from the Secret Canyon Shale of Nevada, is recorded from south-western Wulff Land, North Greenland, where it occurs together with Modocia and Olenoides. Eldoradia caerulioris n. sp. is established. The occurrence of Eldoradia in the lower part of the Blue Cliffs Formation indicates a minimum late middle Cambrian age (Miaolingian Series, Guzhangian Stage) for the base of the formation. Type material of Acrocephalops, a relative of Eldoradia originally proposed on the basis of material from the Miaolingian Series (Wuliuan Stage) of Inglefield Land, North-West Greenland, is redescribed.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"8 - 15"},"PeriodicalIF":1.0,"publicationDate":"2021-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1865446","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41968166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-02DOI: 10.1080/11035897.2020.1858342
D. Holtstam, L. Bindi, A. Karlsson, J. Söderhielm, A. Zetterqvist
ABSTRACT Muonionalustaite, ideally Ni3(OH)4Cl2 · 4H2O, is a new mineral species (IMA 2020–010), found as a terrestrial weathering product of the Muonionalusta iron meteorite, in a fragment excavated 1.5 km NE of Lake Kitkiöjärvi in northernmost Sweden. Muonionalustaite occurs in cavities of corrosion crust, associated with taenite, goethite, maghemite, amorphous Fe-Ni oxy-hydroxides and soil mineral particles. The mineral is green in colour and transparent. It occurs as lath-like crystals up to ca. 5 μm, elongated along [010] and flattened on {001}, forming aggregates and thin crusts. The calculated density and overall refractive index are 2.67(1) g·cm−3 and 1.68, respectively. An empirical formula from point analyses is (Ni2.88Fe0.02S0.02Al0.01Si0.01)Σ2.94(OH3.73Cl2.27)Σ6.00 · 4H2O. The crystal structure was refined in the space group C2/m from powder X-ray diffraction data to R Bragg = 3.55%. The monoclinic unit-cell parameters are a = 15.018(3) Å, b = 3.1490(6) Å, c = 10.502(3) Å, β = 101.535(15)º and V = 486.62(19) Å3 for Z = 2. Muonionalustaite is isostructural with the synthetic compounds Ni3(OH)3.9Cl2.1 · 4H2O and Mg3(OH)4Cl2 · 4H2O. The strongest X-ray diffraction lines are [I(%), d(Å), hkl]: 100, 10.30, 001; 67, 5.49, 201; 31, 3.868, 202; 30, 7.36, 200 and 25, 2.409, 6‾02. Raman spectra show prominent bands at 3624, 3612, 3571 and 3507 cm−1, related to O–H-stretching vibrations of OH− groups, and in the region 450–530 cm−1 representing metal–O(H) vibration modes.
{"title":"Muonionalustaite, Ni3(OH)4Cl2·4H2O, a new mineral formed by terrestrial weathering of the Muonionalusta iron (IVA) meteorite, Pajala, Norrbotten, Sweden","authors":"D. Holtstam, L. Bindi, A. Karlsson, J. Söderhielm, A. Zetterqvist","doi":"10.1080/11035897.2020.1858342","DOIUrl":"https://doi.org/10.1080/11035897.2020.1858342","url":null,"abstract":"ABSTRACT Muonionalustaite, ideally Ni3(OH)4Cl2 · 4H2O, is a new mineral species (IMA 2020–010), found as a terrestrial weathering product of the Muonionalusta iron meteorite, in a fragment excavated 1.5 km NE of Lake Kitkiöjärvi in northernmost Sweden. Muonionalustaite occurs in cavities of corrosion crust, associated with taenite, goethite, maghemite, amorphous Fe-Ni oxy-hydroxides and soil mineral particles. The mineral is green in colour and transparent. It occurs as lath-like crystals up to ca. 5 μm, elongated along [010] and flattened on {001}, forming aggregates and thin crusts. The calculated density and overall refractive index are 2.67(1) g·cm−3 and 1.68, respectively. An empirical formula from point analyses is (Ni2.88Fe0.02S0.02Al0.01Si0.01)Σ2.94(OH3.73Cl2.27)Σ6.00 · 4H2O. The crystal structure was refined in the space group C2/m from powder X-ray diffraction data to R Bragg = 3.55%. The monoclinic unit-cell parameters are a = 15.018(3) Å, b = 3.1490(6) Å, c = 10.502(3) Å, β = 101.535(15)º and V = 486.62(19) Å3 for Z = 2. Muonionalustaite is isostructural with the synthetic compounds Ni3(OH)3.9Cl2.1 · 4H2O and Mg3(OH)4Cl2 · 4H2O. The strongest X-ray diffraction lines are [I(%), d(Å), hkl]: 100, 10.30, 001; 67, 5.49, 201; 31, 3.868, 202; 30, 7.36, 200 and 25, 2.409, 6‾02. Raman spectra show prominent bands at 3624, 3612, 3571 and 3507 cm−1, related to O–H-stretching vibrations of OH− groups, and in the region 450–530 cm−1 representing metal–O(H) vibration modes.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"1 - 7"},"PeriodicalIF":1.0,"publicationDate":"2021-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1858342","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44826708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-18DOI: 10.1080/11035897.2020.1853223
C. Öhrling, Henrik Mikko, Gustaf Peterson Becher, Carl Regnéll
ABSTRACT This study shows the occurrence of numerous iceberg imprints on the bottom of former ice-dammed lakes in Härjedalen, west-central Sweden. Discussion of the genesis of the so-called “impact crater” known as the Tor structure at Torbygget, which is located in this area, motivated an examination of the area using high-resolution digital elevation models. Previous investigations have suggested that this crater was created by a meteorite impact about 2000 years ago, forming a semi-round depression. The results of our investigation clearly indicate that the feature was formed by a grounding iceberg, scouring the bed of an ice-dammed lake during deglaciation about 11 000-10 000 cal. BP. Geomorphic evidence of an ice-dammed lake (multiple and abundant well-developed shorelines) are consistent with earlier mapping efforts in the area. Furthermore, an abundance of geomorphological traces of iceberg activity is found within the paleo-ice-dammed lake basins. Based on this we suggest that the depression at Torbygget is not an impact crater but formed by a grounded iceberg.
{"title":"Meteorite crater re-interpreted as iceberg pit in west-central Sweden","authors":"C. Öhrling, Henrik Mikko, Gustaf Peterson Becher, Carl Regnéll","doi":"10.1080/11035897.2020.1853223","DOIUrl":"https://doi.org/10.1080/11035897.2020.1853223","url":null,"abstract":"ABSTRACT This study shows the occurrence of numerous iceberg imprints on the bottom of former ice-dammed lakes in Härjedalen, west-central Sweden. Discussion of the genesis of the so-called “impact crater” known as the Tor structure at Torbygget, which is located in this area, motivated an examination of the area using high-resolution digital elevation models. Previous investigations have suggested that this crater was created by a meteorite impact about 2000 years ago, forming a semi-round depression. The results of our investigation clearly indicate that the feature was formed by a grounding iceberg, scouring the bed of an ice-dammed lake during deglaciation about 11 000-10 000 cal. BP. Geomorphic evidence of an ice-dammed lake (multiple and abundant well-developed shorelines) are consistent with earlier mapping efforts in the area. Furthermore, an abundance of geomorphological traces of iceberg activity is found within the paleo-ice-dammed lake basins. Based on this we suggest that the depression at Torbygget is not an impact crater but formed by a grounded iceberg.","PeriodicalId":55094,"journal":{"name":"Gff","volume":"143 1","pages":"84 - 91"},"PeriodicalIF":1.0,"publicationDate":"2020-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1853223","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48506048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Einführung in die Kristallographie","authors":"W. Kleber","doi":"10.1524/9783486598858","DOIUrl":"https://doi.org/10.1524/9783486598858","url":null,"abstract":"","PeriodicalId":55094,"journal":{"name":"Gff","volume":"80 1","pages":"504-505"},"PeriodicalIF":1.0,"publicationDate":"2020-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47178339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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