Bulletin of the Geological Society of Finland最新文献_第10页

Glacial varves at the distal slope of Pandivere-Neva ice-recessional formations in western Estonia 爱沙尼亚西部潘迪维尔-涅瓦冰川消退地层远端斜坡上的冰川裂口

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2012-06-01 DOI: 10.17741/BGSF/84.1.001

P. Talviste, T. Hang, M. Kohv

{"title":"Glacial varves at the distal slope of Pandivere-Neva ice-recessional formations in western Estonia","authors":"P. Talviste, T. Hang, M. Kohv","doi":"10.17741/BGSF/84.1.001","DOIUrl":"https://doi.org/10.17741/BGSF/84.1.001","url":null,"abstract":"The distribution and varve thickness data of Late Weichselian varved clay were analyzed to describe the proglacial sedimentary environment, ice recession and water-level changes in the Baltic Ice Lake at the distal position of Pandivere–Neva (13.5–13.1 ka BP) icerecessional formations in western Estonia. According to vertical changes in natural water content, fabric and varve thickness, four clay units were distinguished, reflecting a change in the sedimentary environment from ice-proximal to distal conditions. The varved clay complex is locally interrupted by a massive silty-clay unit, interpreted as an icedrift material during the stagnation of the glacier margin at the Pandivere–Neva line. Varve correlation gave a 294-year-long floating varve chronology. According to total varve thickness and the relation between thicknesses of seasonal layers, an about 130year period of ice-proximal conditions in the study area was followed by a rapid (within ca 20 years) change to more distal conditions. The presented varve chronology does not cover the entire period of proglacial conditions in the area, as all studied clay sections displayed an erosional discontinuity at the upper contact. In total, ca 4 m of selective post-sedimentary erosion of clay is attributed to wave erosion due to a water-level drop after the final drainage of the Baltic Ice Lake. It is concluded that the Yoldia Sea minimum level in the Pärnu area was 0 to –2 m a.s.l.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"84 1","pages":"7-19"},"PeriodicalIF":0.7,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630525","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}

引用次数: 10

Geological setting and sedimentary characteristics of the coversands distributed in the western part of the Blonie glaciolacustrine basin (Central Poland) - preliminary results 波兰中部布隆尼冰湖盆地西部覆盖地的地质背景和沉积特征——初步结果

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2012-06-01 DOI: 10.17741/BGSF/84.1.003

E. Kalińska

引用次数: 14

Geologic position of the Younger Dryas subfossil forest in the Warta River valley, central Poland 波兰中部瓦尔塔河谷新仙女木期亚化石森林的地质位置

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2012-06-01 DOI: 10.17741/BGSF/84.1.006

D. Dzieduszyńska, J. Petera-Zganiacz

引用次数: 21

The Oripää granite revisited: Elemental geochemistry, Nd isotopes, and implication to terrane boundary 重新考察Oripää花岗岩:元素地球化学、Nd同位素及其对地界的暗示

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2011-12-01 DOI: 10.17741/BGSF/83.2.003

M. Nironen, O. T. Rämö

{"title":"The Oripää granite revisited: Elemental geochemistry, Nd isotopes, and implication to terrane boundary","authors":"M. Nironen, O. T. Rämö","doi":"10.17741/BGSF/83.2.003","DOIUrl":"https://doi.org/10.17741/BGSF/83.2.003","url":null,"abstract":"The Paleoproterozoic Oripää granite in the Loimaa area in southwestern Finland (Fig. 1a; Nironen, 1999) is a small, heterogeneous leucogranite pluton that was emplaced within the synorogenic (1.89–1.87 Ga) plutonic and supracrustal rocks of the Arc complex of southern Finland at ~1.85 Ga (Kurhila et al., 2005, 2011). The Oripää granite has been considered to belong to the “microcline granites” (leucogranites) of the Late Svecofennian granite–migmatite zone (LSGM zone; Ehlers et al., 1993). In terms of its relatively radiogenic Nd isotope character (positive initial ε Nd value) and relatively old age (Rämö & Nironen, 2001; Kurhila et al., 2005) it is, however, rather different from the main leucogranite bodies of the LSGM farther south. We have analyzed new samples from the Oripää granite and its country rocks (tonalite, quartz diorite, amphibolite) for Nd isotopes and elemental geochemistry in order to further characterize the Oripää granite and the bedrock around it. Our results show that the Oripää granite is consanguineous with its immediate country rocks and that the terrane boundary marking transition from the Arc complex of western Finland to the Arc complex of southern Finland is located just north of the Oripää granite at this longitude.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"83 1","pages":"115-122"},"PeriodicalIF":0.7,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630036","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}

引用次数: 0

Rock magnetic investigations constraining relative timing for gold deposits in Finland 制约芬兰金矿相对时序的岩磁调查

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2011-12-01 DOI: 10.17741/BGSF/83.2.001

S. Mertanen, F. Karell

引用次数: 7

Estimating the distribution of strontium isotope ratios ( 87 Sr/ 86 Sr) in the Precambrian of Finland 芬兰前寒武纪锶同位素比值(87 Sr/ 86 Sr)分布的估算

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2011-12-01 DOI: 10.17741/BGSF/83.2.002

L. Kaislaniemi

引用次数: 13

Th.G. Sahama's (1910-1983) volcanological and mineralogical studies in Africa: Part II. Minerals of granitic pegmatites and other mineral occurrences of eastern and southern Africa Th.G。撒哈拉(1910-1983)在非洲的火山学和矿物学研究:第二部分。东部和南部非洲的花岗质伟晶岩矿物和其他矿物

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2011-06-01 DOI: 10.17741/BGSF/83.1.004

I. Haapala

引用次数: 4

Th.G. Sahama's (1910-1983) volcanological and mineralogical studies in Africa: Part I. Expeditions to the Virunga Volcanic Field and petrological- mineralogical studies on the Nyiragongo volcano Th.G。萨哈马(1910-1983)在非洲的火山学和矿物学研究:第一部分:维龙加火山场的考察和尼拉贡戈火山的岩石学和矿物学研究

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2011-06-01 DOI: 10.17741/BGSF/83.1.003

I. Haapala

{"title":"Th.G. Sahama's (1910-1983) volcanological and mineralogical studies in Africa: Part I. Expeditions to the Virunga Volcanic Field and petrological- mineralogical studies on the Nyiragongo volcano","authors":"I. Haapala","doi":"10.17741/BGSF/83.1.003","DOIUrl":"https://doi.org/10.17741/BGSF/83.1.003","url":null,"abstract":"The alkaline lavas of Mt. Nyiragongo in the Virunga Volcanic Field (western branch of the East African Rift), as well as the granitic pegmatites and hydrothermal mineral deposits of eastern and southern Africa, were the main research topics of Professor Th.G. Sahama (University of Helsinki) during thirty years. During several expeditions 1952–1972 to the Virunga Field, Sahama and his team collected large amounts of samples from the foot plane, flank flows, caldera walls, and the lava lake of Mt Nyiragongo, which were studied in Helsinki University and in Brussels. The lavas turned out to be feldspar-free nephelinites, leucitites and melilitites containing as major constituents nepheline, leucite, melilite, kalsilite, and clinopyroxene in varying proportions. The Nyiragongo lavas are more alkaline than the other volcanics of the Virunga Field. Sahama and his team found and described six new silicate minerals from the Nyiragongo lavas: gotzenite, combeite, kirschsteinite, trikalsilite, delhayelite, and andremeyerite, some of which locally represent the main constituents of the rocks. Sahama concluded that the Nyiragongo lavas crystallized from mantle-derived magmas without significant crustal contamination. The crustal magma chamber was layered, and the eruption started with melilite nephelinite (bergalite) magmas from the top of the chamber, followed by nepheline leucitite magmas and finally by melilite-leucite nephelinite (“nepheline-aggregate lava”) melts. Sahama’s studies aroused great international interest among petrologists and mineralogists, which has activated further systematic geochemical, mineralogical and isotopic studies in the area.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"83 1","pages":"41-55"},"PeriodicalIF":0.7,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67629873","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}

引用次数: 1

Magmatic constraints on localization of natural stone deposits in the Vehmaa rapakivi granite batholith, southwestern Finland 芬兰西南部Vehmaa rapakivi花岗岩基中天然石材矿床定位的岩浆约束

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2011-06-01 DOI: 10.17741/BGSF/83.1.002

O. Selonen, C. Ehlers, H. Luodes, F. Karell

{"title":"Magmatic constraints on localization of natural stone deposits in the Vehmaa rapakivi granite batholith, southwestern Finland","authors":"O. Selonen, C. Ehlers, H. Luodes, F. Karell","doi":"10.17741/BGSF/83.1.002","DOIUrl":"https://doi.org/10.17741/BGSF/83.1.002","url":null,"abstract":"The 1580–1570 Ma old Vehmaa rapakivi granite batholith was studied with the aim to define the geological constraints for localization of natural stone deposits in the batholith. The batholith comprises four roughly concentric granite intrusions from the margin inwards: pyterlite, coarse-grained porphyritic rapakivi granite and two types of mediumgrained porphyritic rapakivi granite. Also porphyry aplite and even-grained rapakivi granite occur. The batholith has intruded as a succession of pulses of subhorizontal sheet-like intrusions conceivably through repeated cauldron subsidence. Natural stone quarries are confined only to certain intrusions within the batholith. We show that the mediumgrained porphyritc granite body in the centre of the batholith comprises two almost identical but different intrusions, with only slightly different appearances: the inner (IG) and the outer (OG) granite. The quarries are confined to the outer intrusion which has an appearance more attractive to the market than that of the inner intrusion. The localization of the natural stone deposits in the Vehmaa batholith is a result of the magmatic history of the batholith, producing intrusions of different appearances with different commercial potential.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"83 1","pages":"25-39"},"PeriodicalIF":0.7,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67629772","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}

引用次数: 8

The Pyhäntaka formation, southern Finland: a sequence of metasandstones and metavolcanic rocks upon an intra-orogenic unconformity 芬兰南部Pyhäntaka组:在造山带内不整合上的变质砂岩和变质火山岩序列

IF 0.7 4区地球科学

Bulletin of the Geological Society of Finland Pub Date : 2011-06-01 DOI: 10.17741/BGSF/83.1.001

M. Nironen

{"title":"The Pyhäntaka formation, southern Finland: a sequence of metasandstones and metavolcanic rocks upon an intra-orogenic unconformity","authors":"M. Nironen","doi":"10.17741/BGSF/83.1.001","DOIUrl":"https://doi.org/10.17741/BGSF/83.1.001","url":null,"abstract":"Detrital zircon studies suggest that the few quartzite occurrences in southern Finland are younger than 1.87 Ga and express sedimentation after 1.89–1.87 Ga accretional deformation and metamorphism in the Svecofennian orogenic belt. Detailed field work in the high-grade metamorphic Pyhantaka area allowed to distinguish an overturned formation within metagraywackes (cordierite paragneisses) and psammites. The Pyhantaka formation has a maximum thickness of 1000 meters and consists of quartzite overlain by meta-arkose, metatuff, and metabasalt on top. An uncorformity, expressed by a weathering surface, separates the quartzite from underlying metagraywacke. The metavolcanic rocks within, stratigraphically underlying and overlying the Pyhantaka formation are mostly basalts and basaltic andesites, but a felsic volcanic rock and dacitic fragments in volcaniclastic rocks imply bimodal affinity. The quartzite was deposited during a stable intra-orogenic period probably after accretion but before 1.83–1.80 Ga collisional deformation and metamorphism in the Svecofennian orogen. Rifting during the intraorogenic period and accumulation of variable material in the rift from nearby sources by fluvial processes is a viable scenario for deposition and preservation of the Pyhantaka formation. Geochemical diagrams of the metavolcanic rocks show a scatter that is best explained by source heterogeneity and crustal contamination. Despite their (likely) postaccretion setting the basaltic rocks show arc-type characteristics due to subductionmodified lithospheric mantle sources. Because of recycling, also the paragneisses in the Pyhantaka area are geochemically similar in spite that they represent different tectonic settings. The use of elemental geochemistry alone appears to be insufficient for discriminating tectonic settings of basalts or graywackes in the Svecofennian of southern Finland where accretion and post-accretion settings were largely obliterated by late collision.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"83 1","pages":"5-23"},"PeriodicalIF":0.7,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630044","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}

引用次数: 5