scholarly journals An overview of some dating methods of mineralization

2021 ◽  
Vol 62 (2) ◽  
pp. 25-34
Author(s):  
Hung The Khuong ◽  
Keyword(s):  
Radioactive Isotope ◽  
Sulfide Minerals ◽  
Great Success ◽  
Sulfide Mineralization ◽  
Mineral Association ◽  
Hydrothermal Deposits ◽  
Dating Methods ◽  
Dating Method ◽  
Vein Deposits ◽  
Isotope System

One of the most important achievements of applying radioactive isotope in the geological study is to determine the age of mineralization. Based on the synthesis, comparison, and evaluation of the popular isotopic systems in dating mineralization, the Rb - Sr, Re - Os, and Ar - Ar dating methods are discussed in this study. The results show that the Rb - Sr dating method is likely to be successfully applied to sulfide mineralization. If the mineralization contains little or no sulfide minerals, then the method is applied to other minerals in an ore mineral association. The Re - Os dating method has shown great success when it is applied to hydrothermal deposits, especially for the molybdenite - bearing vein deposits. The limitation of the method is that when the concentration of the Os element in molybdenite is low, it is difficult to establish the Re/Os ratio in a single mineral. The Ar - Ar isotope system for dating mineralization often uses mica or feldspar minerals, which are minerals with blocking temperatures ranging from 150÷350 0C, and later metamorphic periods have higher than 350 0C often overprinted these minerals. Generally, tectonic, magmatic, and metamorphic events, which occur after mineralization, can cause difficulty in determining the age of mineralization and collecting analysis samples.

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.

The Source of Organic Matter and Its Role in Producing Reduced Sulfur for the Giant Sediment-Hosted Jinding Zinc-Lead Deposit, Lanping Basin, Yunnan, Southwest China

2021 ◽  
Author(s):  
Qing Lan ◽  
Ruizhong Hu ◽  
Xianwu Bi ◽  
Hu Liu ◽  
Jiafei Xiao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sulfate Reduction ◽  
Southwest China ◽  
Sulfide Minerals ◽  
Source Rocks ◽  
Late Triassic ◽  
Sulfide Mineralization ◽  
Solid Bitumen ◽  
Fine Grained ◽  
Reduced Sulfur

Abstract The Jinding deposit, located in the northern part of Lanping basin in southwest China, is the second largest Zn-Pb deposit in China and the third largest Mississippi Valley-type deposit identified globally. The deposit consists of several large tabular orebodies within the Jinding dome. Two stages of sulfide mineralization (sphalerite, galena, and pyrite) are identified, which are mainly hosted in the siliciclastic strata of Early Cretaceous and Paleocene age. The early sulfide minerals are mostly fine grained (<100 μm) and disseminated in the host rocks, whereas the late minerals are ty pically coarse grained (up to 1 mm in diameter) and colloform. It is estimated that about 3.17 × 106 m3 of reduced sulfur (H2S) was involved in the sulfide mineralization of the Jinding deposit, although its origin remains equivocal. Here, we investigate the biomarker signatures of organic matter and the mechanism of generation of the H2S. The organic matter in the Jinding deposit occurs mainly as petroleum filling fractures and cavities in the wall rocks and solid bitumen intergrown with sulfides or calcite. Abundant solid bitumen is also found on the surfaces of the carbonate rocks in the Sanhedong Formation as well as in the rock fractures associated with framboidal pyrite. The petrographic characteristics and maturity-related biomarker parameters show that the solid bitumen in the ores has higher thermal maturity than that in the Sanhedong Formation, suggesting that it was generated at different temperatures in the two settings. The source-related parameters suggest that the solid bitumen in the ores and Sanhedong Formation probably both originated in a mixed marine shale and carbonate environment and that the source rocks for the bitumen precursor were late Triassic marine strata. The δ34S values, ranging from –30 to –10‰ for the fine-grained and disseminated sulfide minerals and from –24.50 to –16.27‰ for the solid bitumen in the early (main) mineralization stage, suggest that H2S was generated by microbial sulfate reduction. We propose that this occurred in the Triassic strata prior to or during migration of hydrocarbons to the Jinding dome to form a H2S-enriched paleo-oil reservoir. This hypothesis is supported by the similarity of the δ34S values (–27.62 to –17.38‰) of solid bitumen in the Sanhedong Formation (the source rocks) to that of bitumen in the ores. The late-ore sulfide, however, displays significantly higher δ34S values, ranging from –8 to 0‰. We propose that the H2S of this stage was mainly generated by thermochemical sulfate reduction as a result of the interaction between hydrocarbons, sulfate, and hydrothermal fluid. The hydrocarbons were oxidized into bitumen that has δ34S values from –7.38 to –4.61‰.

APPLICATION OF 14C METHOD TO CHRONOLOGY OF THE CROATIAN DINARIC KARST—A CASE OF THE PLITVICE LAKES

Radiocarbon ◽  
2021 ◽  
pp. 1-13
Author(s):  
Ines Krajcar Bronić ◽  
Jadranka Barešić ◽  
Andreja Sironić
Keyword(s):  
Anthropogenic Impact ◽  
Present Form ◽  
Aquatic Biota ◽  
Dinaric Karst ◽  
Dating Methods ◽  
Dating Method ◽  
Isotope Analyses ◽  
Plitvice Lakes ◽  
Environmental Compartments

ABSTRACT Karst environments preserve some of the best archives of past climate, vegetation, hydrology, anthropogenic impact, and landscape evolution providing that a reliable chronology can be established. Here we present an example of the system of the Plitvice Lakes (Dinaric karst, Croatia), which is characterized by intensive tufa and lake sediment formations. The radiocarbon dating method, combined with some other dating methods and various geochemical and isotope analyses, showed that the Plitvice Lakes system in the present form has existed for about 8000 years. Older tufa deposits were dated to warm interglacial periods. A long-term comprehensive multi-proxy study showed that all environmental compartments (atmosphere, various water bodies, soil, bedrock, DIC, terrestrial and aquatic biota, and of course various secondary carbonates) must be included in order to obtain trustworthy results.

The quest for an absolute chronology in human prehistory: anthropologists, chemists and the fluorine dating method in palaeoanthropology

2009 ◽  
Vol 42 (1) ◽  
pp. 95-114 ◽  
Author(s):  
MATTHEW R. GOODRUM ◽  
CORA OLSON
Keyword(s):  
Twentieth Century ◽  
Significant Advance ◽  
Prehistoric Archaeology ◽  
Fossil Bone ◽  
Argon Dating ◽  
Early Twentieth Century ◽  
Dating Methods ◽  
Absolute Dating ◽  
Dating Method

AbstractBy the early twentieth century there was a growing need within palaeoanthropology and prehistoric archaeology to find a way of dating fossils and artefacts in order to know the age of specific specimens, but more importantly to establish an absolute chronology for human prehistory. The radiocarbon and potassium–argon dating methods revolutionized palaeoanthropology during the last half of the twentieth century. However, prior to the invention of these methods there were attempts to devise chemical means of dating fossil bone. Collaborations between Emile Rivière and Adolphe Carnot in the 1890s led to the development of the fluorine dating method, but it was not until the 1940s that this method was improved and widely implemented by Kenneth Oakley to resolve a number of problems in palaeoanthropology, including the Piltdown Man controversy. The invention of the fluorine dating method marked a significant advance in the quest for absolute dating in palaeoanthropology, but it also highlights interesting problems and issues relating to the ability of palaeoanthropologists and chemists to bring together different skills and bodies of knowledge in order successfully to develop and apply the fluorine dating method.

scholarly journals Comparison of isotope data obtained with Sm-Nd and Re-Os methods for minerals and rocks from the Ozernoe ore occurrence, Salla-Kuolajarvi belt

Vestnik MGTU ◽  
2021 ◽  
Vol 24 (1) ◽  
pp. 5-13
Author(s):  
A. A. Kalinin ◽  
T. V. Kaulina ◽  
P. A. Serov
Keyword(s):  
Radioactive Decay ◽  
Sulfide Minerals ◽  
The Other ◽  
Uneven Distribution ◽  
Sulfide Mineralization ◽  
Isotope Data

Sm-Nd isochrone, drawn for rock-forming and sulfide minerals from the Ozernoe ore occurrence, indicates albitite age of 1,759 ± 11 Ma. It shows synchronous formation of albitite and sulfide mineralization, and fully corresponds to the earlier defined age of rutile in albitite (1,757 ± 7 Ma U-Pb, n = 3, MSWD = 0.2), and Rb-Sr isochrone age 1,754 ± 39 Ma for biotite, apatite, albite, and WR. Recently published Re-Os ages of molybdenite 1,872 ± 23 Ma and chalcopyrite 1,891 ± 230 Ma indicate more ancient age of sulfide mineralization. These figures are in conflict with the age of rock-forming minerals, defined with Sm-Nd and Rb-Sr methods. The possibility of use of molybdenite from the Salla-Kuolajarvi belt for rock dating has been considered, and low reliability of Re-Os method for it has been shown. The reasons are the following: 1) extremely uneven distribution of Re in molybdenite, where Re content varies 1 wt.% even within one and the same grain, and 2) openness of the Re-Os system after molybdenite crystallization, Re is mobylized and partly removed from the mineral in the zone of hypergenesis. Removal of Re from molybdenite promotes erroneous ancient age of the molybdenite. According to the equations of radioactive decay, the age would be 110-130 Ma bigger if 5-6 % of Re is taken away. The conclusion is that molybdenite must be studied in detail, proved to be homogenous and unaltered, before it is used for Re-Os dating. In the other case the results will be not reliable.

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 Dating Recent Peat Accumulation in European Ombrotrophic Bogs

Radiocarbon ◽  
2013 ◽  
Vol 55 (3) ◽  
pp. 1763-1778 ◽  
Author(s):  
Johannes van der Plicht ◽  
Dan Yeloff ◽  
Marjolein van der Linden ◽  
Bas van Geel ◽  
Sally Brain ◽  
...  
Keyword(s):  
Binding Sites ◽  
Drainage Network ◽  
Surface Layers ◽  
Spheroidal Carbonaceous Particles ◽  
Carbonaceous Particles ◽  
Peat Deposits ◽  
Dating Methods ◽  
Dating Method ◽  
The Difference ◽  
Age Estimates

This study compares age estimates of recent peat deposits in 10 European ombrotrophic (precipitation-fed) bogs produced using the 14C bomb peak, 210Pb, 137Cs, spheroidal carbonaceous particles (SCPs), and pollen. At 3 sites, the results of the different dating methods agree well. In 5 cores, there is a clear discrepancy between the 14C bomb peak and 210Pb age estimates. In the upper layers of the profiles, the age estimates of 14C and 210Pb are in agreement. However, with increasing depth, the difference between the age estimates appears to become progressively greater. The evidence from the sites featured in the study suggests that, provided aboveground plant material (seeds, leaves) is selected for dating, the 14C bomb peak is a reliable dating method, and is not significantly affected by the incorporation of old carbon with low 14C content originating from sources including air pollution deposition or methane produced by peat decomposition. 210Pb age estimates that are too old may be explained by the enrichment of 210Pb activity in the surface layers of peat resulting from a hypothesized mechanism where rapidly infilling hollows, rich in binding sites, may scavenge 210Pb associated with dissolved organic matter passing through the hollow, as part of the surface drainage network. Until further research identifies and resolves the cause of the inaccuracy in 210Pb dating, age estimates of peat samples based only on 210Pb should be used with caution.

Aminochronology and time averaging of Quaternary land snail assemblages from colluvial deposits in the Madeira Archipelago, Portugal

2019 ◽  
Vol 92 (2) ◽  
pp. 483-496 ◽  
Author(s):  
Evan New ◽  
Yurena Yanes ◽  
Robert A.D. Cameron ◽  
Joshua H. Miller ◽  
Dinarte Teixeira ◽  
...  
Keyword(s):  
Land Snail ◽  
Time Averaging ◽  
Radiocarbon Age ◽  
Amino Acid Racemization ◽  
Madeira Archipelago ◽  
Dating Methods ◽  
Dating Method ◽  
Volcanic Islands ◽  
Geologic Record ◽  
Age Estimates

AbstractUnderstanding the properties of time averaging (age mixing) in a stratigraphic layer is essential for properly interpreting the paleofauna preserved in the geologic record. This work assesses the age and quantifies the scale and structure of time averaging of land snail-rich colluvial sediments from the Madeira Archipelago (Portugal) by dating individual shells using amino acid racemization calibrated with graphite-target and carbonate-target accelerator mass spectrometry radiocarbon methods. Gastropod shells of Actinella nitidiuscula were collected from seven sites on the volcanic islands of Bugio and Deserta Grande (Desertas Islands), where snail shells are abundant and well preserved in Quaternary colluvial deposits. Results show that the shells ranged in age from modern to ~48 cal ka BP (calibrated radiocarbon age), covering the last glacial and present interglacial periods. Snail shells retrieved from two of the colluvial sites exhibit multimillennial age mixing (>6 ka), which significantly exceeds the analytical error from dating methods and calibration. The observed multimillennial mixing of these assemblages should be taking into consideration in upcoming paleoenvironmental and paleoecological studies in the region. The extent of age mixing may also inform about the time span of colluvial deposition, which can be useful in future geomorphological studies. In addition, this study presents the first carbonate-target radiocarbon results for land snail shells and suggests that this novel, rapid, and more affordable dating method offers reliable age estimates for small land snail shells younger than ~20 cal ka BP.

scholarly journals A sedimentation study of St. Ana Lake (Romania) applying the 210Pb and 137Cs dating methods

2011 ◽  
Vol 38 (2) ◽  
pp. 93-100 ◽  
Author(s):  
Robert Begy ◽  
Alida Timar-Gabor ◽  
Janos Somlai ◽  
Constantin Cosma
Keyword(s):  
Sedimentation Rates ◽  
210Pb And 137Cs ◽  
137Cs Dating ◽  
210Po Activity ◽  
210Pb Activity ◽  
Dating Methods ◽  
Calculated Mass ◽  
Dating Method ◽  
High Resolution Gamma Spectrometry ◽  
Good Agreement

AbstractThe biggest problem with most lakes that have no contact with other water sources and are being charged by precipitation is the massive eutrophication. The aim of this work was to determine the sedimentation rate in order to evaluate the progress of eutrophication for St. Ana Lake (Ciomad Mountain near the Băile Tuşnad in Harghita County (Romania)). The concentration of 210Pb was determined by means of high resolution gamma spectrometry as well as derived from 210Po activity which was measured through alpha spectrometry; values obtained are in good agreement. For the excess 210Pb activity values between 4.0±0.5 Bq/kg and 218±20 Bq/kg have been found. As an alternative method, the 137Cs dating method was applied as well. Calculated mass sedimentation rates are in the range of 0.06±0.01 to 0.32±0.05 g/cm2 year with a mean of value of 0.15±0.02 g/cm2 year. Linear sedimentation rates yielded much higher sedimentation values (between 0.5±0.1 and 7.9±0.7 cm/year with a mean of 2.4±0.6 cm/year), due to the predominant organic matter composition and the long suspension time of the sediment. This is an indication for the process of eutrophication which will probably lead to the transformation of the lake into a peat bog.

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