Petrology Of Sediments Research Articles

Volcanic activity drives lacustrine carbon sequestration after Oceanic Anoxic Event 1a

The Mesozoic was punctuated by relatively brief periods of anomalous warmth associated with pulses of volcanism, intensified weathering, expansive marine anoxia, and increased organic carbon burial. These are known as oceanic anoxic events (OAEs). Several OAEs have also been linked to potentially synchronous episodes of increased carbon burial in lacustrine settings, attributed to increased weathering-derived nutrient fluxes. Here we present the Early Aptian oil shale sequences of western Liaoning Province, north China, combining sediment petrology, zircon U-Pb geochronology, carbon isotope chemostratigraphy, as well inorganic and organic geochemical palaeoenvironmental proxies to assess possible causal links to OAE1a. New zircon 206Pb/238U ages (121.06 ± 0.63 Ma, 119.72 ± 0.40 Ma, and 119.9 ± 0.65 Ma) for three tuffs and δ13Corg chemostratigraphic correlation show that the western Liaoning Province oil shale interval formed shortly after widespread marine black shale deposition characteristic of OAE1a had ceased. Elevated concentrations of alginite (dinoflagellate-derived organic matter) in oil shale samples which contain micron-thick tuff layers suggest that arc volcanism in north China was the major factor driving increased lacustrine carbon burial, via volcanic ash fertilisation. This is supported by high values of Babio, C27/C29 ααα-20R steranes, C28/C29 ααα-20R steranes, 4-methylsterane index, dinosterane index, and tetramethylsterane index in these layers, which imply that the input of volcanic ash contributed to a flourishing of brackish/saline-water adapted dinoflagellates, leading to the formation of organic-rich tuff laminae. This is a novel mechanism that is distinct to the processes known to have contributed to enhanced marine organic matter burial on a global scale during OAE1a. This research not only contributes to the study of lacustrine source rocks in north China, but also provides insights into the influence of intermediate-acidic volcanic eruptions on organic carbon burial more generally.

The Surficial Basin Sediment Investigation and Its Concerned Vertebrate Fossils in Sirtwo Island, Western Part of Saguling Dam, West Java, Indonesia

In October 2021, the depreciation of the water level of dam Saguling revealed the surficial sediment where was dam up Citarum river. Sirtwo island and surroundings are part of the body sediment were arisen which is part of the sedimentary facies in the western of Bandung Lake ancient. Several vertebrate fossils were found on Sirtwo island and Pasir Benteng island. The investigation of vertebrate fossils was carried out to understand where are deposited in Bandung lake. The geological survey lead to the recognition of types of lake deposits and was divided into 5 block observations i.e., Block A, Block B, Block C, Block D, and Block E. Geographic information system was used to determine the location points where the fossil was found and is correlated with other location. The fossils fragment is identified as vertebrate fossils i.e., Bovid sp., Rusa sp., and Elephas maximus. The detail of vertebrate fossils type and sediment petrology is under further analysis. The sedimentary facies are lake deposit and is distinguished into 3 sub-facies: 1) volcanic deposit with vertebrate fossil 2) sandstone tuff without vertebrate fossil and 3) sandstone tuff with vertebrate fossil. The age of lithology is estimated between 10.000 till >135.000 Years ago and the depositional environment is interpreted into fan lake, channel, and lake bottom. This study clearly determines lithofacies in the research area which contain vertebrate fossils.

Distinguishing Depositional Setting For Sandy Deposits In Coastal Landscapes Using Grain Shape

Abstract: Several methods exist that use sediment properties to characterize depositional setting and related mechanisms of transport, including analysis of grain-size distributions, sediment petrology, micromorphology, and grain structure. Techniques that rely on electron or optical microscopy produce results with varying degrees of success and applicability. Here, a new method is presented and used to differentiate between littoral and eolian sands that were extracted from recently formed landforms, as well as landforms that are from mid to late Holocene in age. The method utilizes a standard optical microscope with a mounted digital camera, paired with freely available software (ImageJ) to characterize grain shape parameters. The method was tested on nearly 6000 sand grains from samples with varied transport histories, and it was found that grain solidity was the most distinguishable characteristic between eolian and littoral samples, differentiating them 86% of the time for calibration samples. The method was used to correctly identify the mechanism of transport for 76% of the samples. Patterns in the results indicated that this method could be extended to link potential sediment sources to various depositional basins, and future work includes testing the method in areas with a different mineralogy and/or landscape history.

The diagenetic history of Oligocene-Miocene sandstones of the Austrian north Alpine foreland basin

Diagenesis is an essential tool to reconstruct the development of reservoir rocks. Diagenetic processes - precipitation and dissolution - have an influence on pore space. The present paper aims to study the diagenetic history of deep-marine sandstones of the Austrian Alpine Foreland Basin. To reach that goal, sediment petrology and diagenetic features of more than 110 sandstone samples from water- and gas-bearing sections from gas fields within the Oligocene-Miocene Puchkirchen Group and Hall Formation has been investigated. Special emphasis was put on samples in the vicinity of the gas-water contact (GWC). The sediment petrography of sandstones of Puchkirchen Group and Hall Formation is similar; hence their diagenesis proceeded the same way. In fact, primary mineralogy was controlled by paleo-geography with increasing transport distance and diverse detrital input.Sediment petrographically, investigated sandstones from the water-bearing horizon seemed quite comparable to the gas-bearing sediments. In general, they can be classified as feldspatic litharenites to litharenites and display porosities of up to 30% and permeabilities of up to 1300 mD. The carbon and oxygen isotopic composition of bulk carbonate cements from these sandstones range from−3.8 to +2.2 and from −7.5 to +0.2‰ [VPDB]. However, near the Gas-Water Contact (GWC) a horizon with low porosities (<3%) and permeabilities (<0.1 mD) is present. This zone is completely cemented with calcite, which has a blocky/homogenous morphology. A slight, but significant negative shift in δ18O isotopy (−2.5‰) is evident.During early diagenesis the first carbonate generations formed. First a fibrous calcite and afterwards a micritic calcite precipitated. Further siliciclastic minerals, such as quartz and feldspar (K-feldspar and minor plagioclase), exhibit corroded grains. Occasionally, clay minerals (illite; smectite, chlorite) formed as rims around detrital grains. Late diagenesis is indicated by the formation of a low permeable zone at the GWC.

Detrital thermochronology and sediment petrology of the middle Siwaliks along the Muksar Khola section in eastern Nepal

Sediment derived from erosion of the Himalaya during the Miocene–Pliocene was deposited in the Himalayan foreland basin and is now exposed in the Siwalik Formation between the Main Boundary Thrust and Main Frontal Thrust. These sediments hold important information on orogenic exhumation during this time. In this preliminary study we sampled the middle Siwalik Formation in eastern Nepal along the Muksar Khola section for thermochronologic and sediment petrologic analysis. Detrital zircon fission-track thermochronology shows that the age signal of the middle Siwalik Formation of eastern Nepal has some similarities but also differences with published data for western-central Nepal. The Muksar Khola section samples show two static peaks at about 14 and >140 Ma, which is similar to the Siwalik Formation of western-central Nepal. In contrast, a signal of consistently fast exhumation was not observed in the upper middle Siwaliks in eastern Nepal. This could be related to a position of the Main Central Thrust further south, to overall less erosional exhumation of Higher Himalayan rocks, or to a reduced exposure of the underlying Lesser Himalayan units in comparison with western-central Nepal. Based on our apatite fission-track data we propose that above the section dated by Ojha et al. (2009) with magnetostratigraphy about 1000 m of overlying upper Siwalik Formation exist.

Transport of the Yakutat Terrane, Southern Alaska: Evidence from Sediment Petrology and Detrital Zircon Fission-Track and U/Pb Double Dating

Abstract Two hypotheses have been offered to account for the transport and accretion history of the Yakutat terrane in southern Alaska. To investigate these two options, we deconvolved fission-track (FT) and U/Pb ages of detrital zircons from stratigraphically coordinated samples collected in the northern Robinson Mountains into component populations. The strata of the Yakutat terrane include the Middle Eocene Kulthieth Formation, the Lower Oligocene to Lower Miocene Poul Creek Formation, and the Miocene-Pleistocene Yakataga Formation. The Kulthieth and Poul Creek formations record erosion of a simple, uniform, long-lived, nonvolcanic source terrain that crystallized from ∼50 to 220 Ma and cooled from ∼40 to 110 Ma. Miocene cooling episodes recorded in the source to the Kulthieth and Poul Creek formations are likely associated with plutons in the northern Coast Plutonic Complex and the Kuiu-Etoilin belt. The Upper Miocene to Pleistocene Yakataga Formation records erosion of rocks that crystallized from ∼5...

Holocene climate variability at multidecadal time scales detected by sedimentological indicators in a shelf core NW off Iceland

A Holocene sediment record is presented from the Djúpáll trough, situated on the inner shelf northwest of Iceland. The paleoclimatic development has been interpreted on the basis of mass accumulation rate, carbonate content, mean grain size, sediment petrology and 29 radiocarbon dates. The results demonstrate in the early Holocene (10,000–8000 cal year BP) high sediment accumulation rates attributable to the effect of enhanced sediment mobilisation under influence of a relatively low sea level and remobilisation of glacial sediments on the sparsely vegetated Vestfirdir peninsula. The data suggest that a general southward displacement of the Polar Front commenced around 5000–4000 cal year BP. A new proxy for Holocene climatic variability is presented by the basalt/plagioclase ratio in the 63–100 μm fraction. High basalt/plagioclase values are primarily related to periods of increased storminess and bottom current energy, which enhanced the transport of basaltic sediment from the coastal zone towards the outer shelf. Advection of polar waters containing basalt-rich IRD from the eastern Greenland Blosseville Kyst basalt province may also have contributed to increased basalt/plagioclase ratios. The correlation between basalt/plagioclase ratios and proxies of solar activity ( 14C production and 10Be flux) was explored and suggests that some of the centennial-scale peaks in colder climate could be related to increased nuclide production in the upper atmosphere. In addition, it was found that the Medieval Warm Period (c. 1100–700 cal year BP) was characterised by strong cyclone activity over the Iceland region. Intense atmospheric circulation during this period has been confirmed also by other studies in the northern North Atlantic region.

Ponded Sediments of the Mid-Atlantic Ridge between 22° and 23° North Latitude

Research Article| July 01, 1969 Ponded Sediments of the Mid-Atlantic Ridge between 22° and 23° North Latitude TJEERD H VAN ANDEL; TJEERD H VAN ANDEL Department of Oceanography, Oregon State University, Corvallis, Oregon Search for other works by this author on: GSW Google Scholar PAUL D KOMAR PAUL D KOMAR Scripps Institution of Oceanography, La Jolla, California Search for other works by this author on: GSW Google Scholar GSA Bulletin (1969) 80 (7): 1163–1190. https://doi.org/10.1130/0016-7606(1969)80[1163:PSOTMR]2.0.CO;2 Article history received: 13 Sep 1968 rev-recd: 12 Dec 1968 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation TJEERD H VAN ANDEL, PAUL D KOMAR; Ponded Sediments of the Mid-Atlantic Ridge between 22° and 23° North Latitude. GSA Bulletin 1969;; 80 (7): 1163–1190. doi: https://doi.org/10.1130/0016-7606(1969)80[1163:PSOTMR]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The numerous valleys of the flanks of the Mid-Atlantic Ridge are partly filled with sediment. The petrology of sediments from two such valleys (ponds) near 22° N. latitude shows that the material has been deposited by turbidity currents. The material has been derived from calcareous pelagic deposits which mantle the surrounding hills. The turbidite sequences show peculiarities which can be explained by assuming that the currents rebounded repeatedly from the pond walls. A theoretical model for the flow of these currents agrees well with density, thickness, and composition parameters that can be derived from the deposits and points to the occurrence of a hydraulic jump at the base of the slope. Adjacent valleys are separated by divides, and each valley contains an independent sedimentation unit. Good correlation exists between the volume of sediment in each valley and the size of the surrounding hill area from which the sediment was derived. Removal of 15 m of sediment from the entire region is required to account for the sediment that now fills the valleys. The oldest sediment outcropping in this region is upper Miocene, and the average sedimentation rate of the pelagic deposits can be estimated as approximately 3 mm/1000 years. In the ponds, the rate is much greater; more than 9 m of late Quaternary sediment have been found. Recently, the valleys have been faulted and partly uplifted. The accompanying earthquake activity may have initiated the turbidity currents responsible for the present rapid deposition on the valley floors. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Clay Petrology of Sediments

AbstractStudies of the Recent indicate that, at the most, somewhat less than half the clay minerals are altered to any extent in a marine environment. Probably most of this alteration is in the form of cation adsorption or reconstitution of slightly weathered illites and chlorites to their original form. There appears to be little if any evidence that the detrital basic lattice is being altered to a measurable extent in Recent marine sediments. In the near-shore environments there is usually a coincidence of clay mineral suites and environments.A major change in the clay mineral composition of sedimentary rock occurs within the Mississippian. Illite is the dominant clay mineral of the pre-Upper Mississippian sediments. Post-Lower Mississippian clay suites are more variable in composition; illite becomes less abundant and montmorillonite and kaolinite more abundant. This change is best related to a change in regional tectonics. The clay minerals seem to have no preferred lithologie associations, although owing to epigenetie alterations porous sandstones commonly have different clay mineral suites from those of adjacent shales and carbonate rocks.In many instances clay mineral facies coincide with environmental facies. As the clay mineral criteria for distinguishing any given type environment are extremely variable, it is thought that segregation of clay mineral suites by sorting is usually more effective than by diagenesis.Expanded clay minerals appear to be partially contracted by the time they have been buried to 10,000–15,000 ft. It remains to be proved whether this is caused by chemical modification of the basic lattice with burial or if the detrital clay lattice has the inherent ability to contract, without chemical rearrangement, when buried to a sufficient depth.