scholarly journals REE and Sr–Nd Isotope Characteristics of Cambrian–Ordovician Carbonate in Taebaek and Jeongseon Area, Korea

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 326
Author(s):  
Tae-Hyeon Kim ◽  
Seung-Gu Lee ◽  
Jae-Young Yu
Keyword(s):  
Depositional Environment ◽  
Sea Water ◽  
Geological Time ◽  
Nd Isotope ◽  
Diagenetic Processes ◽  
Platform Margin ◽  
Carbonate Formations ◽  
Diagenetic History ◽  
Cretaceous Period ◽  
Ree Patterns

Carbonate formations of the Cambro-Ordovician Period occur in the Taebaek and Jeongseon areas, located in the central–eastern part of the Korean Peninsula. This study analyzed the rare earth element (REE) contents and Sr–Nd isotope ratios in these carbonates to elucidate their depositional environment and diagenetic history. The CI chondrite-normalized REE patterns of the carbonates showed negative Eu anomalies (EuN/(SmN × GdN)1/2 = 0.50 to 0.81), but no Ce anomaly (Ce/Ce* = CeN/(LaN2 × NdN)1/3 = 1.01 ± 0.06). The plot of log (Ce/Ce*) against sea water depth indicates that the carbonates were deposited in a shallow-marine environment such as a platform margin. The 87Sr/86Sr ratios in both Taebaek and Jeongseon carbonates were higher than those in the seawater at the corresponding geological time. The 87Sr/86Sr ratios and the values of (La/Yb)N and (La/Sm)N suggest that the carbonates in the areas experienced diagenetic processes several times. Their 143Nd/144Nd ratios varied from 0.511841 to 0.511980. The low εNd values and high 87Sr/86Sr ratios in the carbonates may have resulted from the interaction with the hydrothermal fluid derived from the intrusive granite during the Cretaceous Period.

scholarly journals Ultrastructure, dissolution and "pyritization" of Late Quaternary and Recent echinoderms

1987 ◽  
Vol 36 ◽  
pp. 275-287
Author(s):  
Margit Jensen ◽  
Elsebeth Thomsen
Keyword(s):  
Late Pleistocene ◽  
Sea Water ◽  
Late Quaternary ◽  
Pore Space ◽  
Water Interface ◽  
Sea Stars ◽  
Northern Norway ◽  
History Of ◽  
Organic Tissue ◽  
Diagenetic History

The diagenetic history of the skeletal elements of Late Pleistocene-Holocene Ophiura sarsi from the shelf off northern Norway (Andfjorden, Malangsdjupet) is elucidated by comparison with natural and induced degradation of the skeletal elements of Recent ophiuroids (brittle stars) and asteroids (sea stars) from Danish waters. Dissolution features ("core-and-rind") in the trabeculae of fossil and Recent echinoderm stereom are initiated during death and early decay of organic tissue in the animals. The trabeculae have a polycrystal­line lamellar ultrastructure and lose their older central part during later stages of dissolution, which are dependant on undersaturation of the sea-water with regard to CaC03• The presence of undersaturated sea-water is supported by palaeoecological studies (Thomsen & Vorren 1984, 1986) implying oxygen deficient periods in the Late Pleistocene and an increased biogenic production in the Holocene. Pyrite framboids are situated in the secondary voids within the trabeculae and in the pore space of the stereom of the Late Pleistocene elements. No pyrite is observed within the polycrystalline lamellar ultrastructure of the trabeculae. The Late Pleistocene "pyritization" took place during oxygen deficient periods at the sediment-water interface or within the reduced zone of the topmost sediment.

scholarly journals GEOCHEMISTRY AND MICROFACIES OF THE RUTEH FORMATION IN THE RUTEH AREA, CENTRAL ALBORZ, IRAN

2019 ◽  
Vol 16 (32) ◽  
pp. 930-944
Author(s):  
G. BABAEE KHOU ◽  
M. H. ADABI ◽  
D. JAHANI ◽  
S. H. VAZIRI
Keyword(s):  
Depositional Environment ◽  
Facies Analysis ◽  
Minor Element ◽  
Upper Permian ◽  
Diagenetic Processes ◽  
Geochemical Study ◽  
Alborz Region ◽  
Dolomite Cement ◽  
East West

To understand microfacies, depositional environment and geochemistry of Upper Permian rocks in Alborz region, the type sections of Ruteh Formation were studied. During the Permian, the Alborz region was a part of the east-west trending Paleotethys sea. Stratigraphic studies indicate that the Ruteh Formation in Ruteh section is composed of thin to massive limestone, argillaceous limestone interbedded with shale, is overlain by distinct laterite horizon of the Elika Formation and is underlain by the disconformity by the Dorud Formation. Facies analysis and petrographic studies led to the recognition of 11 microfacies in Ruteh section. These facies were deposited in 4 facies belts such as tidal flat, lagoon, shoal and open marine sub-environment. The Permian calcareous algae in the Ruteh Formation are widespread and well documented to determine the environment and microfacies of Permian deposits. Cementation and dolomitization are the main diagenetic processes in Ruteh Formation. Based on petrographic (size and fabric) studies, 4 dolomite types such as dolomicrite, dolomicrospar, dolospar, and dolomite cement were recognized. Seawater was the main source of Mg for early diagenetic dolomite (type 1), while Mg for late diagenetic dolomite (types 2,3,4) probably were sourced by shale pressing processes and pressure solution. Major and minor element studies led to there cognition of aragonite mineralogy. The geochemical study illustrates that these carbonates were affected mostly by meteoric diagenesis, which is occurred in a semi-close to open diagenetic system.

scholarly journals Controls on Weddell Sea water mass Nd isotope signatures and their export to the subantarctic Southern Ocean

2021 ◽  
Author(s):  
Marcus Gutjahr ◽  
Huang Huang ◽  
Jörg Rickli ◽  
Gerhard Kuhn ◽  
Anton Eisenhauer
Keyword(s):  
Southern Ocean ◽  
Water Mass ◽  
Sea Water ◽  
Weddell Sea ◽  
Nd Isotope

In search of possible causes of mass extinctions

2004 ◽  
Author(s):  
Tony Hallam
Keyword(s):  
Science Fiction ◽  
High Rate ◽  
Mass Extinctions ◽  
Geological Time ◽  
Steven Spielberg ◽  
Geological Past ◽  
History Of ◽  
The Subject ◽  
Cretaceous Period ◽  
Land Vertebrates

When the subject of extinctions in the geological past comes up, nearly everyone’s thoughts turn to dinosaurs. It may well be true that these long-extinct beasts mean more to most children than the vast majority of living creatures. One could even go so far as to paraphrase Voltaire and maintain that if dinosaurs had never existed it would have been necessary to invent them, if only as a metaphor for obsolescence. To refer to a particular machine as a dinosaur would certainly do nothing for its market value. The irony is that the metaphor is now itself obsolete. The modern scientific view of dinosaurs differs immensely from the old one of lumbering, inefficient creatures tottering to their final decline. Their success as dominant land vertebrates through 165 million years of the Earth’s history is, indeed, now mainly regarded with wonder and even admiration. If, as is generally thought, the dinosaurs were killed off by an asteroid at the end of the Cretaceous, that is something for which no organism could possibly have been prepared by normal Darwinian natural selection. The final demise of the dinosaurs would then have been the result, not of bad genes, but of bad luck, to use the laconic words of Dave Raup. In contemplating the history of the dinosaurs it is necessary to rectify one widespread misconception. Outside scientific circles the view is widely held that the dinosaurs lived for a huge slice of geological time little disturbed by their environment until the final apocalypse. This is a serious misconception. The dinosaurs suffered quite a high evolutionary turnover rate, and this implies a high rate of extinction throughout their history. Jurassic dinosaurs, dominated by giant sauropods, stegosaurs, and the top carnivore Allosaurus, are quite different from those of the Cretaceous period, which are characterized by diverse hadrosaurs, ceratopsians, and Tyrannosaurus. Michael Crichton’s science-fiction novel Jurassic Park, made famous by the Steven Spielberg movies, features dinosaurs that are mainly from the Cretaceous, probably because velociraptors and Tyrannosaurus could provide more drama.

LAND-PLANT SOURCE ROCKS FOR OIL AND THEIR SIGNIFICANCE IN AUSTRALIAN BASINS

1982 ◽  
Vol 22 (1) ◽  
pp. 164 ◽  
Author(s):  
B. M. Thomas
Keyword(s):  
Depositional Environment ◽  
Land Plant ◽  
Source Rocks ◽  
Coal Measure ◽  
Terrestrial Plants ◽  
Geological Time ◽  
Close Relationship ◽  
Jurassic Coal ◽  
Paraffin Waxes ◽  
Gippsland Basin

Many Australian oils are rich in paraffin waxes which are derived from the remains of terrestrial plants. Although the land-plant contribution to oils, particularly those found in a paralic or deltaic environment, is well established, opinion is divided on the ability of non-marine coaly sediments to generate and expel commercial quantities of oil. It appears that some coal measure sequences have generated mainly gas whilst others are the source of large oil accumulations. The composition of coals deposited in Australia has varied through geological time as a result of differences in climate, geological setting, depositional environment and stage of floral evolution. Consequently, most Australian pre-Jurassic coal measure sequences are deficient in exinite macerals and are therefore mainly gas-prone. In contrast, Jurassic to Tertiary coal-rich sequences often contain abundant exinite and may have substantial potential to generate oil in commercial quantities, as demonstrated by the well-known Gippsland Basin (Bass Strait) oilfields.A similar trend is observed worldwide, where, despite the extraordinary global abundance of Late Palaeozoic coals, only minor amounts of crude oil of land-plant origin are known to be associated with them. However, there appears to be a close relationship between the occurrence of waxy, land-plant-derived crudes and coaly sediments of Cretaceous and Tertiary age. This is thought to be a result of the dominance of conifers in swamp floras of these periods, together with the evolution of the angiosperms (flowering plants) in the Late Cretaceous.

scholarly journals Consistent experimental investigation of the applicability of Biot-Gassmann’s equation in carbonates

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. WA97-WA113 ◽  
Author(s):  
Elisabeth Bemer ◽  
Youri Hamon ◽  
Mathilde Adelinet
Keyword(s):  
Carbonate Rocks ◽  
Sedimentary Facies ◽  
Solid Matrix ◽  
Acoustic Response ◽  
Velocity Measurements ◽  
S Wave ◽  
Gassmann’S Equation ◽  
Nonpolar Fluids ◽  
Carbonate Formations ◽  
Diagenetic History

Carbonate formations are characterized by multiscale heterogeneities that control their acoustic response and flow properties. At the laboratory scale, carbonate rocks do not indicate a strong correlation between P- and S-wave velocities and porosity. The velocity disparities between carbonates of similar mineralogy and porosity result from different microstructures derived from their sedimentary facies and subsequent diagenetic transformations. The still-discussed applicability of Biot-Gassmann’s equation for fluid substitution in carbonate rocks remains another key issue. We have developed an integrated experimental workflow that allows a consistent checking of the applicability of Biot-Gassmann’s equation and provides key geologic and microstructural information to understand the petroacoustic signature of carbonate rocks. The defined approach is based on the phase-velocity measurements performed in liquid-saturated conditions using polar and nonpolar fluids. It allows the identification of the whole set of parameters required by Biot-Gassmann’s equation including the bulk modulus of the solid matrix. This approach is implemented on samples representative of two different carbonate formations deposited in lacustrine and marine environments, respectively. The obtained results demonstrate the applicability of Biot-Gassmann’s equation for the two studied carbonate families and indicate the link between their petroacoustic signature and diagenetic history.

scholarly journals Supplemental Material: Apatite fingerprints on the magmatic-hydrothermal evolution of the Daheishan giant porphyry Mo deposit, NE China

2021 ◽  
Author(s):  
Pan Qu ◽  
Wubin Yang
Keyword(s):  
Wall Rock ◽  
Major And Trace Elements ◽  
Primitive Mantle ◽  
Ne China ◽  
Pb Isotope ◽  
Nd Isotope ◽  
Isotope Data ◽  
Porphyry Mo Deposit ◽  
Spider Diagrams ◽  
Ree Patterns

Figure S1: Harker diagrams illustrating major elemental variations of the porphyry and wall rock. QGP—Qiancuoluo granodioritic porphyry; QBG—Qiancuoluo biotite granodiorite; Figure S2: (a) Chondrite-normalized REE patterns and (b) primitive mantle (PM)-normalized spider diagrams of the porphyry and wall rock. Normalizing values are taken from S. Sun and McDonough (1989); Table S1: Whole-rock major and trace element compositions of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG) granites; Table S2: Whole-rock Sr-Nd compositions of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG); Table S3: Apatite major and trace elements (ppm) of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG); Table S4: Apatite Sr and Nd isotope data of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG); Table S5: Apatite U-Pb isotope data of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG).

scholarly journals Microfacies Architecture and Stratigraphic Development of the Yamama Formation, Southern Iraq

2019 ◽  
Vol 60 (5) ◽  
pp. 1115-1128
Author(s):  
Taisir Ghanem Zaki Al Mafraji ◽  
Aiad Ali Hussien Al-Zaidy
Keyword(s):  
Depositional Environment ◽  
The South ◽  
Third Order ◽  
The North ◽  
Open Sea ◽  
Sulaiy Formation ◽  
Maximum Flooding Surface ◽  
Cretaceous Period ◽  
Petrographic Study ◽  
Southern Iraq

The Yamama Formation belongs to the late Berriasian-Aptian succession, which was deposited during the Lower Cretaceous period within the main shallow marine depositional environment. Petrographic study and microfacies analysis enabled the recognition of six main microfacies for three association facies. These are the Semi-restricted, Shallow open marine and Shoal environments. The study succession represents deposition of three third order cycles, these cycles where deposited during successive episodes of relative sea level rises and still stand. The presence of shoal association facies (oolitic packstone microfaces) between the Sulaiy and Yamama formations refer to continue the deposition during the same stage, and may suggest the end of Sulaiy Formation was maximum flooding surface (mfs). The first stage started with occurrence of the shallow open marine association facies underlain by semi-restricted association and then shoal association facies. There are three cycles of this sequence consistently in the south of the study area, so that it continues to the lower part of the Ratawi Formation to be the upper contact of the Yamama Formation of a conformable and continuous in sedimentation To the north of the study area (near of Rf-1 and  Hf-5 wells) the shoal association was only shown once at the bottom of the Yamama Formation and these cycles to became unclear.  This suggest that the paleo-high was developed to the south of studied area, while the open sea was characterized the northern part.

scholarly journals Organic matter depositional microenvironment in deltaic channel deposits of Mahanadi river, Andhra Pradesh

2009 ◽  
Vol 1 (2) ◽  
pp. 180-190
Author(s):  
Anjum Farooqui ◽  
T. Karuna Karudu ◽  
D. Rajasekhara Reddy ◽  
Ravi Mishra
Keyword(s):  
Organic Matter ◽  
Depositional Environment ◽  
Sea Water ◽  
Fungal Spores ◽  
River System ◽  
Deltaic Plain ◽  
Mahanadi River ◽  
Modern Analogue ◽  
Monsoon Intensity ◽  
Channel Deposits

Quantitative and qualitative variations in microscopic plant organic matter assemblages and its preservation state in deltaic channel deposits of Mahanadi River was correlated with the depositional environment in the ecosystem in order to prepare a modern analogue for use in palaeoenvironment studies. For this, palynological and palynofacies study was carried out in 57 surface sediment samples from Birupa river System, Kathjodi-Debi River system and Kuakhai River System constituting Upper, Middle and Lower Deltaic part of Mahanadi river. Theapex of the delta shows dominance of Spirogyra algae indicating high nutrient, low energy shallow ecosystem during most of the year and recharged only during monsoons. The depositional environment is anoxic to dysoxic in the central and south-eastern part of the Middle Deltaic Plain (MDP) and Lower Deltaic Plain (LDP) indicated by high percentage of nearby palynomorphs, Particulate Organic Matter (POM) and algal or fungal spores. The northern part of the delta show high POM preservation only in the estuarine area in LDP but high Amorphous Organic Matter (MOA) in MDP. The sediment here is deposited under dysoxic to oxic fluvial conditions. Thus, the monsoon intensity, direction of fluvial discharge, and the landward extent of sea water incursion through river mouths inducing bottom water salinity play an important role in defining the magnitude of POM and its preservation in the shallow Mahanadi deltaic ecosystem.

Sign in / Sign up

Export Citation Format

Share Document