Geochemistry, Petrology, and Palynology of the Princess No. 3 Coal, Greenup County, Kentucky

The high volatile C bituminous-rank, Bolsovian-age Princess No. 3 coal, a correlative of the heavily-mined Hazard No. 7 coal and the Peach Orchard and Coalburg Lower Split coals, was investigated three sites at a mine in Greenup County, Kentucky. The coal exhibits a “dulling upwards” trend, with decreasing vitrinite and a greater tendency towards dull clarain and bone lithotypes towards the top of the coal. The relatively vitrinite-rich basal lithotype is marked by a dominance of lycopod tree spores. The palynology transitions upwards to a middle parting co-dominated by tree fern and small lycopod spores and an upper bench dominated by tree ferns with contributions from small ferns, cordaites, and calamites. The lithotypes generally have a moderate- to high-S content with a variable ash yield. Sulfur, Fe2O3, and certain siderophile elements are highest near the top of the coal. As observed in other coals, uranium and Ge are enriched at the top and bottom margins of the coal. The rare earth chemistry at the top of the coal has a significantly lighter distribution (higher LREE/HREE) than at the base of the coal

Petrology and Geochemistry of the Harlan, Kellioka, and Darby Coals from the Louellen 7.5-Minute Quadrangle, Harlan County, Kentucky

The Harlan, Kellioka, and Darby coals in Harlan County, Kentucky, have been among the highest quality coals mined in the Central Appalachians. The Middle Pennsylvanian coals are correlative with the Upper Elkhorn No. 1 to Upper Elkhorn No. 3½ coals to the northwest of the Pine Mountain thrust fault. Much of the mining traditionally was controlled by captive, steel-company-owned mines and the coal was part of the high volatile A bituminous portion of the coking coal blend. Overall, the coals are generally low-ash and low-sulfur, contributing to their desirability as metallurgical coals. We did observe variation both in geochemistry, such as individual lithologies with significant P2O5/Ba + Sr/Rare earth concentrations, and in maceral content between the lithotypes in the mine sections

Dynamic spin-lattice coupling and nematic fluctuations in NaFeAs

We use inelastic neutron scattering to study acoustic phonons and spin excitations in single crystals of NaFeAs, a parent compound of iron pnictide superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural transition at $T_s\approx 58$ K and a collinear antiferromagnetic (AF) order at $T_N\approx 45$ K. While longitudinal and out-of-plane transverse acoustic phonons behave as expected, the in-plane transverse acoustic phonons reveal considerable softening on cooling to $T_s$, and then harden on approaching $T_N$ before saturating below $T_N$. In addition, we find that spin-spin correlation lengths of low-energy magnetic excitations within the FeAs layer and along the $c$-axis increase dramatically below $T_s$, and show weak anomaly across $T_N$. These results suggest that the electronic nematic phase present in the paramagnetic tetragonal phase is closely associated with dynamic spin-lattice coupling, possibly arising from the one-phonon-two-magnon mechanism

Marine derived 87Sr/86Sr in coal, a new key to geochronology and palaeoenvironment: Elucidation of the India-Eurasia and China-Indochina collisions in Yunnan, China

Coal has formed in terrestrial and coastal-marine environments from sub-polar to equatorial regions since the Devonian. It contains detailed long-term records of contemporaneous environment, climate, and subsequent modifications. However, in general, direct chronological information in coal has been sparse. The coal investigated in the present study is from the Mile intermontane basin, Yunnan Province, China, north of an arm of the Mesozoic Tethys Ocean. The coal contains marine geochemical signatures and syngenetic gypsum, common in coastal-marine sediments. The gypsum contains marine-derived Sr and, hence, has geochronological potential. The 87Sr/86Sr record (0.708350-0.708591) in the Mile coal agrees with time-calibrated 87Sr/86Sr records of marine planktonic foraminifera obtained from core DSDP 588C, 22.25-18.27 Ma (Early Miocene). The peat of the Mile coal was deposited over 4.6 Ma., which possibly is the longest deposition of a coal bed in the world to have been found today, although this duration should include the period of non-peat deposition or erosion if present during the time of the 4.6-Ma.During this period, the regional geological structures were determined by the India-Eurasia collision, which resulted in transform faults with extensive rift structures, including the Mile rhomb-shaped graben. This structural setting enabled the flow of seawater from the South China Sea to reach inland graben structures, including that of the Mile Basin, where peat was deposited. Subsequent deformation caused by the South China-Indochina collision changed the regional structural and geographical-hydrological patterns. This affected the hydrology of the Mile Basin and resulted in its uplift to its present-day elevation of 1350 m.This study is, to our knowledge, the first to use the marine-derived 87Sr/86Sr indicator and chronometer in coal. At present, marine-influenced peats generated in coastal salt marshes extend from the Arctic Ocean (Alaska and Siberia) in the north, to Patagonia and New Zealand in the south, while mangrove forests abound in equatorial and low-latitude coastal areas. The 87Sr/86Sr record of marine-influenced coal in this study area, provides a key for the determination of age-duration-rate of geological processes in the inland basin, associated with the closure of the Tethys Ocean. Results indicate that this method has potential for providing a temporal framework for geological events and processes in other areas. These may be found near marine shore lines across the globe dating back to the Devonian. Moreover, the 87Sr/86Sr signal in marine-influenced coal can be used for correlation with the well-established 87Sr/86Sr chronology of marine planktonic foraminifera. In turn, the 87Sr/86Sr signal provides a basis for correlating terrestrial records of climate and environment contained in this type of coal and associated sediments, with those of marine sediments, such as those based on ?18O in planktonic foraminifera

Petrology, Palynology, and Geochemistry of Gray Hawk Coal (Early Pennsylvanian, Langsettian) in Eastern Kentucky, USA

This study presents recently collected data examining the organic petrology, palynology, mineralogy and geochemistry of the Gray Hawk coal bed. From the Early Pennsylvanian, Langsettian substage, Gray Hawk coal has been mined near the western edge of the eastern Kentucky portion of the Central Appalachian coalfield. While the coal is thin, rarely more than 0.5-m thick, it has a low-ash yield and a low-S content, making it an important local resource. The Gray Hawk coal palynology is dominated by Lycospora spp., and contains a diverse spectrum of small lycopods, tree ferns, small ferns, calamites, and gymnosperms. The maceral assemblages show an abundance of collotelinite, telinite, vitrodetrinite, fusinite, and semifusinite. Fecal pellet-derived macrinite, albeit with more compaction than is typically seen in younger coals, was observed in the Gray Hawk coal. The minerals in the coal are dominated by clay minerals (e.g., kaolinite, mixed-layer illite/smectite, illite), and to a lesser extent, pyrite, quartz, and iron III hydroxyl-sulfate, along with traces of chlorite, and in some cases, jarosite, szomolnokite, anatase, and calcite. The clay minerals are of authigenic and detrital origins. The occurrence of anatase as cell-fillings also indicates an authigenic origin. With the exception of Ge and As, which are slightly enriched in the coals, the concentrations of other trace elements are either close to or much lower than the averages for world hard coals. Arsenic and Hg are also enriched in the top bench of the coal and probably occur in pyrite. The elemental associations (e.g., Al2O3/TiO2, Cr/Th-Sc/Th) indicate a sediment-source region with intermediate and felsic compositions. Rare metals, including Ga, rare earth elements and Ge, are highly enriched in the coal ashes, and the Gray Hawk coals have a great potential for industrial use of these metals. The rare earth elements in the samples are weakly fractionated or are characterized by heavy-REE enrichment, indicating an input of natural waters or probably epithermal solutions

Petrology and geochemistry of the high-sulphur coals from the Upper Permian carbonate coal measures in the Heshan Coalfield, southern China

The Heshan coals, with very high organic sulphur content, are found in the Upper Permian marine carbonate successions Heshan Formation) in the Heshan Coalfield, central Guangxi, southern China. The petrography, mineralogy, and geochemistry of coals and non-coal partings from the Suhe and Lilan coal mines of the Heshan Coalfield have been investigated using proximate, petrographic, inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy with an energy-dispersive X-ray (SEM-EDX) techniques. The sulphur content in the coals (with ash less than 50%) ranges from 5.3% to 11.6%, of which more than 90% is organic sulphur, reflecting a strong marine water influence on the palaeomire. The high vitrinite reflectance (1.89–2.18%Romax) indicates that the coals in the Heshan Coalfield are mainly low-volatile bituminous coal. Microscopic observation has revealed that the coal is mainly composed of vitrinite and inertinite macerals with relatively low TPI and high GI values, suggesting an unusual, strongly alkaline palaeomire, with high pH. XRD analysis plus optical and scanning electron microscopy show that the minerals in these coals are mainly quartz, calcite, dolomite, kaolinite, illite, and pyrite, although marcasite, strengite, and feldspar, as well as some oxidised weathering products such as gypsum, are also present. Most trace elements in the Heshan coals are enriched with respect to their world mean, with Mo, U, and W highly enriched, more than 10 times their world means. The trace elements are believed to be associated either with organic compounds (Mo and U) or minerals such as aluminium–iron-silicates (Sc, Ge, and Bi), aluminium-silicates (Cs, Be, Th, Pb, Ga, and REE), iron-phosphates (Zn, Rb, and Zr), iron-sulphides (As, Cd, Cr, Cu, Ni, Tl, and V), and carbonates (Sr, Mn, and W). Abnormally high organic sulphur content, high ash yields, relatively high GI values, very low TPI values, very high U contents, and very low Th/U ratios suggest that the Heshan coals accumulated in low-lying, marine-influenced palaeomires, developed on carbonate platforms. Many of these characteristics have also been recorded in the Tertiary coals of the circum-Mediterranean coal basins, where no marine influence is present. The similarities are thought to be produced by strongly alkaline groundwater chemistry, common to both environments