Matti Räsänen

Matti Räsänen

Dr.

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63
Publications
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Introduction
Sedimentologic stratigraphic and paleoenvironmental work in Neogene and Quaternary shallow marine lacustrine and fluvial settings in the Neotropics. Now concentrating to Quaternary glacial geology in Scandinavia.

Publications

Publications (63)
Article
The Middle to Late Pleistocene palaeoenvironmental record from the repeatedly glaciated central and eastern Fennoscandia is poorly known. The majority of the glacial and warm interval records have been interpreted to represent only the last, Weichselian, glacial cycle (119–11.7 ka). We have revised the crucial part of the existing stratigraphic doc...
Article
Full-text available
Quaternary climatic and glacial history must be known in order to understand future environments. Reconstructions of the last Weichselian glacial cycle 117,000–11,700 years (kyr) ago propose that S Finland, adjacent Russia and the Baltic countries in the SE sector of the Eurasian Ice Sheet (EIS), were glaciated during the Middle Weichselian time [m...
Article
Full-text available
With the aim to visualize the span of time since the formation of our Universe we have set up a nature and hiking trail called `Time Trek'. The 13.7 km length of the trail corresponds to the age of the Universe, and portrays its history including events important for Earth and life. One kilometre corresponds to a billion years, and one metre to a m...
Article
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The Calabrian Stage is now formally defined by the Global Boundary Stratotype Section and Point (GSSP) at Vrica, Calabria, Italy. This GSSP had previously defined the base of the Pleistocene Series. The Calabrian becomes the second stage of the Pleistocene Series and Quaternary System, following the Gelasian. The GSSP occurs at the base of the mari...
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Full-text available
Aim Conservation and land-use planning require accurate maps of patterns in species composition and an understanding of the factors that control them. Substantial doubt exists, however, about the existence and determinants of large-area floristic divisions in Amazonia. Here we ask whether Amazonian forests are partitioned into broad-scale floristic...
Article
The carbon (C) dynamics of tropical peatlands can be of global importance, because, particularly in Southeast Asia, they are the source of considerable amounts of C released to the atmosphere as a result of land-use change and fire. In contrast, the existence of tropical peatlands in Amazonia has been documented only recently. According to a recent...
Chapter
IntroductionMethods Geological indications of marine influence in Miocene AmazoniaDiscussionConclusions AcknowledgementsReferences
Article
Full-text available
The formal stratigraphy of Late-Quaternary late- and post-glacial sediments in the Archipelago Sea, northern Baltic Sea, is revised. The Trollskär Allomember and Sandön Allomember were previously incorrectly defined as allostratigraphic units based on an acousticdiscontinuity, even though their contact is gradational in the studied sediment cores....
Conference Paper
Several studies discuss the role of the Amazon Basin in the global carbon cycle, but the existence of extensive tropical peat deposits in lowland Amazonia has been suggested only recently. These up to 5.9 m thick peat deposits documented from a floodplain environment in Western Amazonia have accumulated at high rates (0.94-4.88 mm per year) acting...
Article
The bedrock topography has contributed in a decisive way to the development of the Kokemäenjoki river and its estuary. The river is partly located in the contact of the crystalline bedrock and sandstone. In the SE section it follows the sandstone and bedrock contact and then breaks away in its own channel along the sandstone deep. Gravity line inte...
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Full-text available
The bedrock of the northern halves of North America and Europe is covered by Quaternary glacial deposits, forming a surficial overburden that is relatively thin, nonlithified, lithologically variable on a small scale (in terms of grain-size, mineralogy, texture, fabric, structure, and color), and often has a well-preserved depositional topography....
Article
The differentiation of depositional environments using the grain-size distribution patterns of estuarine channel sediments is investigated in two parallel depositional environments of different ages: the Cretaceous McMurray Formation in the Western Canadian Sedimentary Basin; and the Miocene Pebas Formation in the Amazonia foreland basin. Channel s...
Article
This paper presents a model of late-glacial and post-glacial deposition for the late-Neogene sedimentary succession of the Archipelago Sea in the northern Baltic Sea. Four genetically related facies associations are described: (i) an ice-proximal, acoustically stratified draped unit of glaciolacustrine rhythmites; (ii) an onlapping basin-fill unit...
Article
Upper Miocene strata in the Acre sub-basin, Brazil, consist dominantly of various types of inclined heterolithic stratification and pedogenic horizons. These strata were sedimentologically and ichnologically described to: (i) study different temporal controls responsible for inclined heterolithic stratification generation and their variation in a d...
Article
The congruency in the depositional origin and age of the uppermost sedimentary strata forming non-flooded rainforest ground (terra firme) in the western and central Amazon lowlands is a much debated subject. Here we conclude from the study of remote sensing imagery that active Andean foreland dynamics have played a major role in the evolution of th...
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Full-text available
An unusually long and continuous Late Quaternary sedimentary sequence has been preserved in a sedimentary basin formed in the Sokli Carbonatite Massif in eastern-central Finnish Lapland. A nearly complete sediment recovery from the central Sokli basin combinedwith palynological results from sediments not earlier recovered and an independent OSL/AMS...
Article
The Miocene palaeogeography of the western Amazonian Foreland Basin (Venezuela, Colombia, Ecuador, Peru and western Brazil) and the Paraná Basin (mainly Argentina) are contentious. Several studies have hypothesized for and against a possible connection of these epicontinental depositional systems during Miocene. However, the lack of well defined pa...
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Full-text available
A sedimentological and ichnological data set that covers the Lower-Upper Miocene sedimentary series of western Amazonian foreland basin indicates that widespread, restricted marine ingressions shaped western Amazonia throughout the Miocene. The late Lower-early Upper Miocene sedimentary series (Pebas Formation) consists of stacked, 3- to 10-m-thick...
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Vonhof, H. Landscape evolution and depositional processes in the Miocene Amazonian Pebas lake/wetland system: evidence from explora-tory boreholes in northeastern Peru. This study of the type and scales of depositional processes and landscape development in western Am-azonia during the Miocene is based on the description and interpretation of three...
Article
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A biozonation based on molluscs is proposed for Miocene deposits of western Amazonia (Peru, Colombia and Brazil), commonly referred to as the Pebas Formation. The new zonation refines existing pollen zonations and provides a key for the quick assessment of the stratigraphic position of Neogene deposits in the field. The regional distribution of twe...
Article
The Miocene Pebas Formation from the section Santa Rosa de Pichana (Loreto, Peru) was investigated using a combination of analyses of sedimentary facies, molluscan communities and taphonomy, and stable isotopes of both entire shells and growth bands in bivalves. Three sequences, comprising a succession of transgressive, maximum flooding and regress...
Article
Full-text available
Thirteen species of fossil molluscs are reported from the Solimões Formation of western Brazilian Amazonia. Based on mammalian chronology of the Solimões Formation and radiometric ages reported from coeval deposits in adjacent Peru, the age of the fauna is established as Late Miocene. The fauna includes five prosobranch gastropod species, seven pea...
Article
Miocene siliciclastic sediments of the Marañón Foreland Sub-basin in Peru record the sedimentary response to regional marine incursions into Amazonia. Contrary to previous interpretations, the Late Miocene Nauta Formation provides evidence of the last known marine incursion before the current Amazonia river basin became established. Sedimentologica...
Article
This article describes marginal marine successions in the uppermost parts of the Pebas Formation, exposed along the Marañón River in Loreto, Peru. Six main facies associations are documented: (1) mud-dominated horizontal heterolithic couplets; (2) rooted brownish mud; (3) lenticular, mud-draped, cross-stratified sand; (4,5) mud- to sand-dominated,...
Article
Full-text available
A formal stratigraphic division is proposed for the Holocene succession of the Archipelago Sea, northern Baltic Sea. Marine geological investigations, including high-resolution acoustic profiles as well as sedimentologic and stratigraphic studies, have been carried out. More than 100 km of acoustic survey lines together with 8 up to 6 m long sedime...
Article
New data from upper Miocene deposits in the Madre de Dios region, southern Peru, allow the delineation of tidal regime for the first time in western Amazonia and provide strong evidence of elevated tidal range and brackish-water influence. The results point out the insufficiency of the current depositional models and support the earlier hypothesis...
Article
The Kvarken Archipelago is situated in the centre of the Fennoscandian glacioisostatic land uplift area, with an overall net uplift rate of 8 to 8.5 mm per year. At a maintained uplift rate Finland and Sweden will become connected with a land bridge across the Kvarken strait in about 2500 years. The Bothnian Bay will then become the largest freshwa...
Article
Full-text available
Strontium, oxygen, and carbon isotope compositions of well-preserved mollusks (bivalves) indicate a dominantly freshwater depositional setting for the lower Miocene-upper Miocene Pebas Formation in Western Amazonia. Molluscan 87Sr/86Sr ratios identify different freshwater sources. Andean runoff was the dominant water source in Miocene Western Amazo...
Article
The depositional history of the Virttaankangas plain, a fan-like enlargement of the large Säkylänharju glaciofluvial ridge in SW Finland, is examined. The Säkylänharju ridge has been interpreted as having formed as an interlobate esker, and the morphology of the Virttaankangas plain as representing predominantly subaqueous glaciofluvial to glaciola...
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Full-text available
The nature of aquatic landscapes in the Miocene of western Amazonia: an integrated palaeontological and geochemical approach. Scripta Geologica, 133: 363-393, 10 fi gs, 5 tables, 2 appendices, Leiden, The Miocene Pebas Formation from the section Santa Rosa de Pichana (Loreto, Peru) was investigated using a combination of analyses of sedimentary fac...
Article
Full-text available
Sedimentary models that apply to the Middle Miocene succession in Amazonia are controversial. Although tidally-influenced sedimentary deposits have been described from several locations, the identification of brackish-water or marine facies has been hampered by limited outcrop exposure. Also, ichnological data largely have been ignored. This study...
Article
Full-text available
All geological data from Amazonian landforms imply continuous humid weathering throughout late Tertiary and Quaternary times, with all claims for arid land processes shown to be in error. Sand dunes exist only where thick deposits of sand prevent stable vegetative cover. A ground truth survey shows that proposed dune fields in the Pantanal do Mato...
Article
Boreholes from the Sokli basin in Finnish Lapland have recovered a unique sequence of diamicts interlayered with fine-grained sediments that are rich in fossils. The diamicts are interpreted as till beds deposited by the Fennoscandian Ice-Sheet. The fine-grained intercalations seem to represent a series of warm stages that include one interglacial...
Article
Lathrap introduced the concept of lateral channel migration of the meandering rivers as a potential factor for human community dynamics in the Upper Amazon. Nevertheless, the dynamics considered by Lathrap is restricted to particular floodplains. He payed no attention to a large scale fluvial phenomenom: the sudden river relocations (avulsion), whi...
Article
Late Miocene tidal sediments of Acre, Brazilian Amazonia, were deposited in an embayment or interior seaway located in the sub-Andean zone. This late Tertiary embayment system may once have connected the Caribbean with the South Atlantic. The tidal coasts of the embayment-seaway have provided an avenue for the earliest waif (over water) dispersal p...
Article
Mineral nutrient content was determined from fluvial sediments of eight different rivers in Peruvian Amazonia. Statistically significant differences between the floodplains were detected in the mean values of soil reaction, conductivity, concentrations of total phosphorus, calcium and aluminium, concentrations of extractable sodium, calcium and alu...
Article
TL dating was attempted on sediments from surficial alluvial formations of the Peruvian Amazon, a huge area for which there are few Pleistocene age determinations. The samples were collected from several locations of erosional banks carved in older alluvial deposits in order to date the Quaternary stratigraphy. The major part of the time-scale fall...
Article
Still active Sub-Andean foreland deformation is suggested to have syndepositionally modified the fluvial depositional environments in the Peruvian Amazonian foreland basin throughout Neogene-Quaternary time. Modern fluvial aggradation continues to proceed on a large scale ( c . 120 000 km ² ) in two differing depositional systems. Firstly, various...
Article
Blocked valley lakes in tectonically active upper Amazon foreland basins were investigated using satellite and radar imagery. The survey revealed that blocked valley lakes formed as a result of channel avulsions disrupting pre-existing drainage patterns, and that such lakes could be formed adjacent to either the newly formed or the abandoned floodp...
Article
The sedimentary record covering the last 150 years was studied in the productive clear water lake Pyhäjärvi in SW Finland. The lake has faced significant human-induced changes: (1) the water level was lowered by almost 2 metres in the early 1850s; (2) planktivorous coregonid fishes were successively introduced, commencing in 1908; and (3) nutrient...
Chapter
Reviews the factors which contribute to species richness in the Amazon and the characteristics of the floodplain processes in the upper section of the river. This consists of a high sediment load together with constant instability and reorganisation of the floodplain biome communities. Richness in variations in landscape can be attributed to the ri...
Article
1 We studied the recent history (1852-1982) of Lake Pyhä-järvi, south-west Finland, using both cladoceran microfossils and independent historical data. The objective of the study was to assess the impact of introduced planktivorous whitefish Coregonus lavaretus s.1. on zooplankton, especially on the main prey species Bosmina coregoni Baird s.str. 2...
Article
Haffer's refuge theory proposes that during the arid climatic phases of the late Pleistocene, tropical lowland forests of Amazonia were reduced to isolated patches contributing to the high species richness of the present-day forest. The theory was developed because no obvious historic or modern geomorphic isolation barriers were recorded in Amazoni...
Article
Vesi- ja ympäristöhallituksen julkaisuja 11. Luodon-Ojanjärven valuma-alueen maaperän ja vesistön happamuuskartoitus, 61 - 100
Article
A freshwater reservoir was dammed from the Baltic Sea in 1965. The recent sediments and the processes of accumulation in the reservoir have been investigated. The physical, chemical and diatom analyses of the sediments were carried out at 5 sampling points in order to dinstinquish the freshwater sediments from the underlying brackish sediments as w...
Article
Diatoms have been studied in an annually laminated sulphide mud which was deposited after the impoundment of the sea-bay of Gennarbyviken. It was possible to follow how the measured decrease in salinity in the basin was reflected by the diatom flora of the sediment which had been deposited concurrently

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