Paleogene to Quaternary geodynamical evolution of the lowland Central Amazonia inferred by weathering phases dating

2020 ◽  
Author(s):  
Cecile Gautheron ◽  
Cristiana Cabriolu ◽  
Fabiano Pupim ◽  
Mauricio Parra ◽  
Stéphane Schwartz ◽  
...  
Keyword(s):  
Amazon River ◽  
Fluvial Terraces ◽  
Left Margin ◽  
Stratigraphic Framework ◽  
Dating Methods ◽  
Central Amazonia ◽  
History Of ◽  
Dating Method ◽  
Past Conditions ◽  
Lowland Amazonia

<p>The landscape in lowland Amazonia is shaped by large rivers, whose depositional-erosive dynamics built fluvial terraces covered by upland forests. Thus, fluvial deposits distributed across lowland Amazonia are of crucial relevance since they represent the best accessible archives to study the history of environment and climate change. The timing of the assembly of the modern transcontinental Amazon River is considered a key event in the landscape evolution of Amazonia, however, proposed ages range from Miocene, early Pliocene to Pliocene/Pleistocene. Therefore, regional stratigraphic correlations need to improve to ensure a better understanding of reconstructions of past conditions in Amazonia during the Cenozoic. Yet, these are difficult due to the lack of absolute ages to constrain phases of sediment deposition or erosion and weathering. In lowland central Amazonia, past environmental conditions are recorded in the Alter do Chão and Novo Remanso Formations. Both units are dominated by sandy and highly oxidized sediments with scarce paleontological remains complicating the application of biostratigraphy dating methods. The Alter do Chão and Novo Remanso Formations are well exposed in the left margin of the Solimões-Amazon River main stem and show remarkable zones rich in supergene iron weathering products, which has been used to define the stratigraphic boundaries among the Alter do Chão Formation, Novo Remanso Formation and overlying sediments. In this study, we use the (U-Th-Sm)/He dating method on goethite and hematite grains to determine the age of iron-enrichment layers and duricrusts that mark boundary surfaces used to define the stratigraphic framework of the Alter do Chão and Novo Remanso formations. The (U-Th-Sm)/He ages allow to improve chronological constraints for both formations and to discuss the timing of fluvial terraces building and weathering conditions in central Amazonia through time.</p>

scholarly journals Multiple Dating of a Long Flowstone Profile

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 503-509 ◽  
Author(s):  
Mebus A Geyh ◽  
G J Hennig
Keyword(s):  
Growth Rate ◽  
West Germany ◽  
Spin Resonance ◽  
Dating Methods ◽  
Growth History ◽  
Order Of Magnitude ◽  
History Of ◽  
Dating Method ◽  
Closed Systems ◽  
Glacial Periods

Dense speleothem samples are considered as closed systems and are, therefore, possibilities for any dating method. Four dating methods (14C, U/Th, paleomagnetism, and electron spin resonance = ESR) were used for samples up to 1,000,000 yr old and taken along a vertical flowstone profile in the Heggen cave in West Germany. Also δ18O and δ13C analyses were carried out.The reliability of the results of each method is dependent on the diagenetic processes that took place during the complex growth history of the flowstone. Speleothem growth was interrupted during glacial periods. During interglacial periods, at least the stalagmite growth rate was greater by one order of magnitude than during interstadial periods. During the periods of low interstadial growth rate various processes might have changed the 14C, 18O, and 13C concentrations, leaching might have removed uranium, recrystallization might have moved thorium several centimeters, and increased content of radon in the cave might have exaggerated the accumulated dose (AD) at the speleothem surface. As a result, 14C ages may be too small and U/Th as well as ESR data may be too large.

scholarly journals Relative Dating of Moraines from the Arid Part of Altai: Applying of Rock Weathering and Colonization by Biota Data within the Framework of the Method

2021 ◽  
Author(s):  
Dmitrii A. Ganyushkin ◽  
Sofya N. Lesovaya ◽  
Dmitrii Y. Vlasov ◽  
Gennady P. Kopitsa ◽  
László Almásy ◽  
...  
Keyword(s):  
Biomass Accumulation ◽  
Rock Surface ◽  
Fine Earth ◽  
Fine Grained ◽  
Relative Dating ◽  
Initial Stage ◽  
Dating Methods ◽  
Rock Disintegration ◽  
History Of ◽  
Dating Method

For the Altai mountainous region, especially the arid south-eastern part, the history of glacier fluctuations in Pleistocene and Holocene is still poorly known. The key plots were located in the Kargy valley (2288-2387 m a. s. l.) that is not currently affected by glaciations. The relative dating method was applied to define Pleistocene moraine chronology and configuration in the Kargy valley. Taking into account that relative dating methods are primarily based on weathering pat-terns, the mineralogy, porosity, and specificity of biological colonization as an agent of weath-ering were obtained for the moraine samples. Three moraine groups of different age (presumably MIS 6, MIS 4, and MIS 2) were identifies based on detailed investigation of morphological features. The moraine age was indirectly confirmed by the mesostructure of the moraine samples repre-sented by fine-grained shale: the older sample is characterized by a more developed fractal sur-face than the younger one. The growth of biota (crustose lichen and micromycetes) leads to initial biomass accumulation and subsequent rock disintegration. The accumulation of autochthonous fine earth on the rock surface was considered the initial stage of fine earth formation affected by biota.

scholarly journals The ‘oldest dated document of the Cairo Genizah’ (Halper 331): The Seleucid era and sectarian Jewish calendars

2021 ◽  
pp. 1-18
Author(s):  
EVE KRAKOWSKI ◽  
SACHA STERN
Keyword(s):  
Near East ◽  
Early Medieval ◽  
Near Eastern ◽  
Dating Methods ◽  
Marriage Contract ◽  
History Of ◽  
Legal Document ◽  
Cairo Genizah ◽  
Medieval Egypt

Abstract Halper 331 is the fragment of a codex that has been styled the ‘oldest dated document of the Cairo Genizah’. It preserves the opening of a Jewish legal document dated to the year 1182 (Seleucid era), which appears to have been copied into this codex, probably as a formulary, not long after this date, in the late 9th century. In this article, the text of this fragment, in Aramaic and Hebrew, is edited, and its identification as the beginning of a marriage contract (ketubbah) is evaluated. Its Egyptian provenance is questioned, partly because the earliest evidence for the introduction of the Seleucid era by Jews in Egypt dates from the mid-10th century. The article surveys the history of Jewish dating methods in early medieval Egypt and the Near East, in an attempt to clarify this question. The specific date of the document deviates from the rabbinic calendar, but agrees with that of the contemporary Jewish Near Eastern sectarian groups of Abū ʿImrān al-Tiflīsī and Ismāʿīl al-ʿUkbarī; this document could thus uniquely attest one of these sectarian Jewish calendars.

scholarly journals A Study about the Temporal Constraints on the Martian Yardangs’ Development in Medusae Fossae Formation

2021 ◽  
Vol 13 (7) ◽  
pp. 1316
Author(s):  
Jia Liu ◽  
Zongyu Yue ◽  
Kaichang Di ◽  
Sheng Gou ◽  
Shengli Niu
Keyword(s):  
Size Distribution ◽  
Indirect Method ◽  
Common Method ◽  
Planetary Surface ◽  
Temporal Constraints ◽  
History Of Development ◽  
Long Duration ◽  
History Of ◽  
Dating Method

The age of Mars yardangs is significant in studying their development and the evolution of paleoclimate conditions. For planetary surface or landforms, a common method for dating is based on the frequency and size distribution of all the superposed craters after they are formed. However, there is usually a long duration for the yardangs’ formation, and they will alter the superposed craters, making it impossible to give a reliable dating result with the method. An indirect method by analyzing the ages of the superposed layered ejecta was devised in the research. First, the layered ejecta that are superposed on and not altered by the yardangs are identified and mapped. Then, the ages of the layered ejecta are derived according to the crater frequency and size distribution on them. These ages indicate that the yardangs ceased development by these times, and the ages are valuable for studying the evolution of the yardangs. This indirect dating method was applied to the areas of Martian yardangs in the Medusae Fossae Formation (MFF). The ages of the selected six layered ejecta range from ~0.50 Ga to ~1.5 Ga, indicating that the evolution of the corresponding yardangs had been ceased before these times. Analysis of more layered ejecta craters and superposed yardangs implies that yardangs in the MFF have a long history of development and some yardangs are still in active development.

scholarly journals Neotectonic evolution and sediment budget of the Meuse catchment in the Ardennes and the Roer Valley Rift System

2002 ◽  
Vol 81 (2) ◽  
pp. 211-215 ◽  
Author(s):  
R.T. Van Balen ◽  
R.F. Houtgast ◽  
F.M. Van der Wateren ◽  
J. Vandenberghe
Keyword(s):  
Digital Terrain Model ◽  
River System ◽  
Sediment Budget ◽  
Middle Pleistocene ◽  
Rift System ◽  
Terrain Model ◽  
Fluvial Terraces ◽  
Digital Terrain ◽  
History Of ◽  
Planation Surfaces

AbstractUsing marine planation surfaces, fluvial terraces and a digital terrain model, the amount of eroded rock volume versus time for the Meuse catchment has been computed. A comparison of the amount of eroded volume with the volume of sediment preserved in the Roer Valley Rift System shows that 12% of the eroded volume is trapped in this rift. The neotectonic uplift evolution of the Ardennes is inferred from the incision history of the Meuse River system and compared to the subsidence characteristics of the Roer Valley Rift System. Both areas are characterized by an early Middle Pleistocene uplift event.

Determination of 36Cl Production Rates Derived from the Well-Dated Deglaciation Surfaces of Whidbey and Fidalgo Islands, Washington

2001 ◽  
Vol 56 (3) ◽  
pp. 366-382 ◽  
Author(s):  
Terry W. Swanson ◽  
Marc L. Caffee
Keyword(s):  
Water Content ◽  
Ground Level ◽  
Total Production ◽  
Neutron Absorption ◽  
Production Rates ◽  
System A ◽  
History Of ◽  
Dating Method ◽  
Exposure Ages

AbstractThe 36Cl dating method is increasingly being used to determine the surface-exposure history of Quaternary landforms. Production rates for the 36Cl isotopic system, a critical component of the dating method, have now been refined using the well-constrained radiocarbon-based deglaciation history of Whidbey and Fidalgo Islands, Washington. The calculated total production rates due to calcium and potassium are 91±5 atoms 36Cl (g Ca)−1 yr−1 and are 228±18 atoms 36Cl (g K)−1 yr−1, respectively. The calculated ground-level secondary neutron production rate in air, Pf(0), inferred from thermal neutron absorption by 35Cl is 762±28 neutrons (g air)−1 yr−1 for samples with low water content (1–2 wt.%). Neutron absorption by serpentinized harzburgite samples of the same exposure age, having higher water content (8–12 wt.%), is ∼40% greater relative to that for dry samples. These data suggest that existing models do not adequately describe thermalization and capture of neutrons for hydrous rock samples. Calculated 36Cl ages of samples collected from the surfaces of a well-dated dacite flow (10,600–12,800 cal yr B.P.) and three disparate deglaciated localities are consistent with close limiting calibrated 14C ages, thereby supporting the validity of our 36Cl production rates integrated over the last ∼15,500 cal yr between latitudes of 46.5° and 51°N. Although our production rates are internally consistent and yield reasonable exposure ages for other localities, there nevertheless are significant differences between these production rates and those of other investigators.

scholarly journals Chronology of the Last Deglaciation in the Southeastern Baltic Region on the Basis of Recent OSL Dates

2010 ◽  
Vol 36 (-1) ◽  
pp. 47-54 ◽  
Author(s):  
Anto Raukas ◽  
Wojciech Stankowski ◽  
Vitālijs Zelčs ◽  
Petras Šinkunas
Keyword(s):  
Outer Zone ◽  
East European Plain ◽  
Last Deglaciation ◽  
Baltic Region ◽  
East European ◽  
The North ◽  
Dating Methods ◽  
History Of ◽  
Close Cooperation ◽  
The Last Deglaciation

Chronology of the Last Deglaciation in the Southeastern Baltic Region on the Basis of Recent OSL DatesThe study of the deglaciation chronology in the south-eastern Baltic Region belonging to the outer zone of the last Pleistocene glaciation has a long history. The Finnish investigator H. Hausen (1913) who worked in the north-western portion of the East-European Plain at the beginning of the 20thcentury was the first to attempt a reconstruction of the course of glacial retreat during the last glaciation. At that time investigators had no physical dating methods and the time scale based on varvometric method, introduced by the Swedish geologist G. de Geer (1912) who divided the deglaciation history of Scandinavia into Daniglacial, Gotiglacial and Finiglacial, each of which had different palaeoglaciological conditions. During last decades different dating methods, including14C, ESR, luminescence methods and10Be techniques have been used, but they could not help essentially improve the existing stratigraphical charts and many problems of topical interest in the history of deglaciation have not been solved yet. During last years the first two authors have studied the suitability of OSL method for the geochronological purposes, paying the most attention to the waterlaid sediments. In the first step they have found the most promising genetical varieties of glaciofluvial sediments (glaciofluvial deltas and sandurs) and in this paper they widened the study area to all three Baltic states with close cooperation with Latvian and Lithuanian colleagues. The obtained results demonstrated, that not all mineral grains in the uppermost glaciofluvial and glaciolacustrine sediments were fully bleached during the last deglaciation. Probably the older sediments also influenced to the luminescence results. It means, that stratigraphic conclusions based on single dates or their small sets are inadmissible and in each case luminiscence dating requires a verification using other methods.

14C Dating of Historical Buildings in Japan

Radiocarbon ◽  
2014 ◽  
Vol 56 (02) ◽  
pp. 691-697 ◽  
Author(s):  
Nanae Nakao ◽  
Minoru Sakamoto ◽  
Mineo Imamura
Keyword(s):  
Research Method ◽  
Radiocarbon Dating ◽  
Historical Buildings ◽  
14C Dating ◽  
History Of ◽  
Dating Method ◽  
Japanese Architecture

The radiocarbon dating method was applied to the study of Japanese traditional wooden buildings. The traditional Japanese architecture studied includes the Main Hall of Banna-ji Temple (Buddhist building), Sekisui-in of Kozan-ji Temple (noble house), Hakogi-ke house (farmhouse), and Kawai-ke house (townhouse).14C dating proved useful as a research method to better understand the history of these buildings and Japanese architecture as a whole.

scholarly journals Twisted Handaxes in Middle Pleistocene Britain and their Implications for Regional-scale Cultural Variation and the Deep History of Acheulean Hominin Groups

2019 ◽  
Vol 85 ◽  
pp. 61-81 ◽  
Author(s):  
Mark White ◽  
Nick Ashton ◽  
David Bridgland
Keyword(s):  
Settlement Patterns ◽  
Regional Scale ◽  
Middle Pleistocene ◽  
Cultural Variation ◽  
River Terrace ◽  
East Anglia ◽  
Apparent Lack ◽  
Cultural Patterning ◽  
Dating Methods ◽  
History Of

A better understood chronological framework for the Middle Pleistocene of Britain has enabled archaeologists to detect a number of temporally-restricted assemblage-types, based not on ‘culture historical’ schemes of typological progression but on independent dating methods and secure stratigraphic frameworks, especially river-terrace sequences. This includes a consistent pattern in the timing of Clactonian and Levalloisian industries, as well as a number of handaxe assemblage types that belong to different interglacial cycles. In other words, Derek Roe’s hunch that the apparent lack of coherent ‘cultural’ patterning was due to an inaccurate and inadequate chronological framework was correct. Some variation in handaxe shape is culturally significant. Here we focus on twisted ovate handaxes, which we have previously argued to belong predominantly to MIS 11. Recent discoveries have enabled us to refine our correlations. Twisted ovate assemblages are found in different regions of Britain in different substages of MIS 11 (East Anglia in MIS 11c and south of the Thames in MIS 11a), the Thames, and the MIS 11b cold interval separating the two occurrences. These patterns have the potential to reveal much about hominin settlement patterns, behaviour, and social networks during the Middle Pleistocene.

Sign in / Sign up

Export Citation Format

Share Document