Diagenesis and pyritization of crinoid ossicles

1987 ◽  
Vol 24 (12) ◽  
pp. 2486-2498 ◽  
Author(s):  
Uwe Brand ◽  
Joan O. Morrison
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Water Source ◽  
Selective Dissolution ◽  
Matter Content ◽  
Sediment Layer ◽  
Reactive Iron ◽  
Diagenetic Alteration ◽  
Diagenetic Fluids ◽  
Organic Tissue

Diagenetic alteration of original high-Mg calcite crinoid skeletal material was achieved by reaction of the calcium carbonate with isotopically light meteoric water. The light δ18O values (−10.57 ± 0.74‰, PDB) are a reflection of the water source, whereas the δ13C values (−3.49 ± 2.63‰, PDB) are a consequence of the high reactive-organic-matter content in the sediments of the Brush Creek at Sewickley, Pennsylvania. High Fe (22 970 ± 30 440 ppm) and Mn (3760 ± 1450 ppm) contents suggest further that the diagenetic fluids were reducing waters that reacted with the crinoid ossicles in the shallow-burial marine and meteoric environments.Four different types of pyrite are found within crinoid ossicles. Framboidal pyrite, aggregate pyrite, and nanopyrite are generally found in the pores of the stereom. Micropyrite, which is present in the form of octahedral, dodecahedral, and pyritohedral crystals, and nanopyrite and aggregate pyrite replace the calcitic stereom. The degree of pyritization and the pore filling increase toward the outer periphery of the crinoid ossicles. Pyrite formation of the crinoid ossicles took place in two stages. In stage I, upon death, the crinoids disarticulated and were quickly buried. In this shallow sediment layer (1–10 cm) the pore water was both undersaturated with respect to calcite and oxidizing. This brought about oxidation of the organic tissue in the stroma of the crinoids and selective dissolution of the high-Mg calcite skeletons. With further burial in stage II, in the presence of reactive organic matter local iron was solubilized, marine sulphate was reduced to sulphide, and isotopically light carbon was produced by bacterial action. Reactive iron combined with sulphur to form framboidal and nanopyrite in the pores of the stereoms. With further burial the micropyrite formed in the crinoid ossicles. Termination of the pyritization process came about with depletion of the iron and (or) sulphur, and this process proceeded very rapidly under shallow-burial conditions while the crinoids resided in the microbial sulphate-reduction zone of the marine–phreatic environment.Fossils are preserved in different stages, with brachiopod valves preserved in their original low-Mg calcite mineralogy, whereas molluscs and crinoids show the complete trend from preserved aragonite and high-Mg calcite, respectively, to diagenetic low-Mg calcite. The preservation potential of fossils is closely linked to the thermodynamic stability of the skeletal carbonate in the presence of diagenetic fluids. Carbon/sulphur ratios support the assertion that Brush Creek sediments were deposited in normal marine waters and favour generally oxic redox conditions for Pennsylvanian seawater.

scholarly journals Organic Matter Preservation in Ancient Soils of Earth and Mars

Life ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 113
Author(s):  
Adrian P. Broz
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Organic Matter Content ◽  
Clay Mineralogy ◽  
Matter Content ◽  
Published Data ◽  
Original Research ◽  
Forming Process ◽  
Soil Science Society ◽  
Diagenetic Alteration

The emerging field of astropedology is the study of ancient soils on Earth and other planetary bodies. Examination of the complex factors that control the preservation of organic matter and other biosignatures in ancient soils is a high priority for current and future missions to Mars. Though previously defined by biological activity, an updated definition of soil as planetary surfaces altered in place by biological, chemical or physical processes was adopted in 2017 by the Soil Science Society of America in response to mounting evidence of pedogenic-like features on Mars. Ancient (4.1–3.7 billion year old [Byr]) phyllosilicate-rich surface environments on Mars show evidence of sustained subaerial weathering of sediments with liquid water at circumneutral pH, which is a soil-forming process. The accumulation of buried, fossilized soils, or paleosols, has been widely observed on Earth, and recent investigations suggest paleosol-like features may be widespread across the surface of Mars. However, the complex array of preservation and degradation factors controlling the fate of biosignatures in paleosols remains unexplored. This paper identifies the dominant factors contributing to the preservation and degradation of organic carbon in paleosols through the geological record on Earth, and offers suggestions for prioritizing locations for in situ biosignature detection and Mars Sample Return across a diverse array of potential paleosols and paleoenvironments of early Mars. A compilation of previously published data and original research spanning a diverse suite of paleosols from the Pleistocene (1 Myr) to the Archean (3.7 Byr) show that redox state is the predominant control for the organic matter content of paleosols. Most notably, the chemically reduced surface horizons (layers) of Archean (2.3 Byr) paleosols have organic matter concentrations ranging from 0.014–0.25%. However, clay mineralogy, amorphous phase abundance, diagenetic alteration and sulfur content are all significant factors that influence the preservation of organic carbon. The surface layers of paleosols that formed under chemically reducing conditions with high amounts of iron/magnesium smectites and amorphous colloids should be considered high priority locations for biosignature investigation within subaerial paleoenvironments on Mars.

HEAVY METAL SPECIATION IN BOTTOM SEDIMENTS OF THE VYSHNEVOLOTSKY RESERVOIR

2018 ◽  
pp. 46-54
Author(s):  
O. A. Lipatnikova
Keyword(s):  
Heavy Metal ◽  
Organic Matter ◽  
Bottom Sediments ◽  
Metal Speciation ◽  
Organic Matter Content ◽  
Water Reservoir ◽  
Matter Content ◽  
Heavy Metal Speciation ◽  
Mobile Forms ◽  
Manganese Hydroxides

The study of heavy metal speciation in bottom sediments of the Vyshnevolotsky water reservoir is presented in this paper. Sequential selective procedure was used to determine the heavy metal speciation in bottom sediments and thermodynamic calculation — to determine ones in interstitial water. It has been shown that Mn are mainly presented in exchangeable and carbonate forms; for Fe, Zn, Pb и Co the forms are related to iron and manganese hydroxides is played an important role; and Cu and Ni are mainly associated with organic matter. In interstitial waters the main forms of heavy metal speciation are free ions for Zn, Ni, Co and Cd, carbonate complexes for Pb, fulvate complexes for Cu. Effects of particle size and organic matter content in sediments on distribution of mobile and potentially mobile forms of toxic elements have been revealed.

Physico-Chemical Properties of Soil Collected from Chandrabhaga River in Kalmeshwar, Nagpur, Maharashtra

2020 ◽  
Vol 07 (02) ◽  
pp. 1-3
Author(s):  
Amita M Watkar ◽  
Keyword(s):  
Organic Matter ◽  
Soil Quality ◽  
Agricultural Land ◽  
Organic Matter Content ◽  
Chemical Properties ◽  
Matter Content ◽  
Soil Attributes ◽  
Essential Components ◽  
Agricultural Land Management ◽  
Physical And Chemical

Soil, itself means Soul of Infinite Life. Soil is the naturally occurring unconsolidated or loose covering on the earth’s surface. Physical properties depend upon the amount, size, shape, arrangement, and mineral composition of soil particles. It also depends on the organic matter content and pore spaces. Chemical properties depend on the Inorganic and organic matter present in the soil. Soils are the essential components of the environment and foundation resources for nearly all types of land use, besides being the most important component of sustainable agriculture. Therefore, assessment of soil quality and its direction of change with time is an ideal and primary indicator of sustainable agricultural land management. Soil quality indicators refer to measurable soil attributes that influence the capacity of a soil to function, within the limits imposed by the ecosystem, to preserve biological productivity and environmental quality and promote plant, animal and human health. The present study is to assess these soil attributes such as physical and chemical properties season-wise.

scholarly journals Soil nitrogen supply of peat grasslands estimated by degree days and soil organic matter content

2020 ◽  
Vol 117 (3) ◽  
pp. 351-365
Author(s):  
J. Pijlman ◽  
G. Holshof ◽  
W. van den Berg ◽  
G. H. Ros ◽  
J. W. Erisman ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Nitrogen ◽  
Organic Matter Content ◽  
Matter Content ◽  
Nitrogen Supply ◽  
Degree Days ◽  
Soil Organic Matter Content ◽  
Soil Nitrogen Supply

scholarly journals Effect of Clay, Soil Organic Matter, and Soil pH on Initial and Residual Weed Control with Flumioxazin

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1326
Author(s):  
Calvin F. Glaspie ◽  
Eric A. L. Jones ◽  
Donald Penner ◽  
John A. Pawlak ◽  
Wesley J. Everman
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Weed Control ◽  
Soil Ph ◽  
Organic Matter Content ◽  
Amaranthus Retroflexus ◽  
Matter Content ◽  
Weed Species ◽  
Soil Organic Matter Content ◽  
Field Soils

Greenhouse studies were conducted to evaluate the effects of soil organic matter content and soil pH on initial and residual weed control with flumioxazin by planting selected weed species in various lab-made and field soils. Initial control was determined by planting weed seeds into various lab-made and field soils treated with flumioxazin (71 g ha−1). Seeds of Echinochloa crus-galli (barnyard grass), Setaria faberi (giant foxtail), Amaranthus retroflexus (redroot pigweed), and Abutilon theophrasti (velvetleaf) were incorporated into the top 1.3 cm of each soil at a density of 100 seeds per pot, respectively. Emerged plants were counted and removed in both treated and non-treated pots two weeks after planting and each following week for six weeks. Flumioxazin control was evaluated by calculating percent emergence of weeds in treated soils compared to the emergence of weeds in non-treated soils. Clay content was not found to affect initial flumioxazin control of any tested weed species. Control of A. theophrasti, E. crus-galli, and S. faberi was reduced as soil organic matter content increased. The control of A. retroflexus was not affected by organic matter. Soil pH below 6 reduced flumioxazin control of A. theophrasti, and S. faberi but did not affect the control of A. retroflexus and E. crus-galli. Flumioxazin residual control was determined by planting selected weed species in various lab-made and field soils 0, 2, 4, 6, and 8 weeks after treatment. Eight weeks after treatment, flumioxazin gave 0% control of A. theophrasti and S. faberi in all soils tested. Control of A. retroflexus and Chenopodium album (common lambsquarters) was 100% for the duration of the experiment, except when soil organic matter content was greater than 3% or the soil pH 7. Eight weeks after treatment, 0% control was only observed for common A. retroflexus and C. album in organic soil (soil organic matter > 80%) or when soil pH was above 7. Control of A. theophrasti and S. faberi decreased as soil organic matter content and soil pH increased. Similar results were observed when comparing lab-made soils to field soils; however, differences in control were observed between lab-made organic matter soils and field organic matter soils. Results indicate that flumioxazin can provide control ranging from 75–100% for two to six weeks on common weed species.

scholarly journals Assessment of Potato Farmland Soil Nutrient Based on MDS-SQI Model in the Loess Plateau

2021 ◽  
Vol 13 (7) ◽  
pp. 3957
Author(s):  
Yingying Xing ◽  
Ning Wang ◽  
Xiaoli Niu ◽  
Wenting Jiang ◽  
Xiukang Wang
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Fertility ◽  
Soil Quality ◽  
Soil Nutrients ◽  
Organic Matter Content ◽  
Soil Nutrient ◽  
Matter Content ◽  
Soil Organic Matter Content ◽  
Farmland Soil

Soil nutrients are essential nutrients provided by soil for plant growth. Most researchers focus on the coupling effect of nutrients with potato yield and quality. There are few studies on the evaluation of soil nutrients in potato fields. The purpose of this study is to investigate the soil nutrients of potato farmland and the soil vertical nutrient distributions, and then to provide a theoretical and experimental basis for the fertilizer management practices for potatoes in Loess Plateau. Eight physical and chemical soil indexes were selected in the study area, and 810 farmland soil samples from the potato agriculture product areas were analyzed in Northern Shaanxi. The paper established the minimum data set (MDS) for the quality diagnosis of the cultivated layer for farmland by principal component analysis (PCA), respectively, and furthermore, analyzed the soil nutrient characteristics of the cultivated layer adopted soil quality index (SQI). The results showed that the MDS on soil quality diagnosis of the cultivated layer for farmland soil included such indicators as the soil organic matter content, soil available potassium content, and soil available phosphorus content. The comprehensive index value of the soil quality was between 0.064 and 0.302. The SPSS average clustering process used to classify SQI was divided into three grades: class I (36.2%) was defined as suitable soil fertility (SQI < 0.122), class II (55.6%) was defined as moderate soil fertility (0.122 < SQI < 0.18), and class III (8.2%) was defined as poor soil fertility (SQI > 0.186). The comprehensive quality of the potato farmland soils was generally low. The proportion of soil nutrients in the SQI composition ranged from large to small as the soil available potassium content = soil available phosphorus content > soil organic matter content, which became the limiting factor of the soil organic matter content in this area. This study revolves around the 0 to 60 cm soil layer; the soil fertility decreased gradually with the soil depth, and had significant differences between the respective soil layers. In order to improve the soil nutrient accumulation and potato yield in potato farmland in northern Shaanxi, it is suggested to increase the fertilization depth (20 to 40 cm) and further study the ratio of nitrogen, phosphorus, and potassium fertilizer.

scholarly journals Geochemistry and Mineralogy of Lower Paleozoic Heituao Shale from Tadong Low Uplift of Tarim Basin, China: Implication for Shale Gas Development

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 635
Author(s):  
Shihu Zhao ◽  
Yanbin Wang ◽  
Yong Li ◽  
Honghui Li ◽  
Zhaohui Xu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tarim Basin ◽  
Shale Gas ◽  
Organic Matter Content ◽  
Matter Content ◽  
Mature Stage ◽  
Lower Paleozoic ◽  
Development Potential ◽  
Middle Ordovician ◽  
Average Value

Tarim Basin is the largest Petroliferous basin in China, while its shale gas development potential has not been fully revealed. The organic-rich black shale in middle Ordovician Heituao Formation from Tadong low uplift of Tarim Basin has been considered as an important source rock and has the characteristic of large thickness, high organic matter content and high thermal maturity degree. To obtain its development potential, geochemical, mineralogical and mechanics research is conducted based on Rock-Eval pyrolysis, total organic carbon (TOC), X-ray diffraction (XRD) and uniaxial compression experiments. The results show that: (1) the TOC content ranges between 0.63 and 2.51 wt% with an average value of 1.22 wt%, the Tmax values are 382–523 °C (average = 468.9 °C), and the S2 value is relatively low which ranges from 0.08 to 1.37 mg HC/g rock (averaging of 0.42 mg HC/g rock); (2) the organic matter of Heituao shale in Tadong low uplift show poor abundance as indicated by low S2 value, gas-prone property, and post mature stage (stage of dry gas). (3) Quartz is the main mineral component in Heituao shale samples, accounting for 26–94 wt% with an average of 72 wt%. Additionally, its Young’s modulus ranges from 20.0 to 23.1 GPa with an average of 21.2 GPa, Poisson’s ratio ranges between 0.11 and 0.21 (average = 0.15); (4) the fracability parameter of brittleness index (BI) ranges between 0.28 and 0.99 (averaging of 0.85), indicating good fracability potential of Heituao shale of Tadong low uplift and has the potential for shale gas development. This study reveals the shale gas accumulation potential in middle Ordovician of the Tarim Basin, and beneficial for future exploration and production practice.

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