Paleovegetational Reconstruction and Implications on Formation of Oil Shale and Coal in the Lower Cretaceous Laoheishan Basin (NE China): Evidence from Palynology and Terpenoid Biomarkers

In some cases, the oil shale deposited in shallow lakes may be genetically associated with the coal-bearing successions. Although paleovegetation is an important controlling factor for the formation of oil shale- and coal-bearing successions, few studies have focused on their joint characterization. In this study, a total of twenty-one oil shale and coal samples were collected from the upper member of the Lower Cretaceous Muling Formation (K1ml2) in the Laoheishan Basin, and investigated for their bulk geochemical, maceral, palynological, and terpenoid biomarker characteristics, in order to reconstruct the paleovegetation and reveal its influence on the formation of oil shale and coal. The K1ml2 is subdivided into lower, middle, and upper units. The studied oil shale samples from the lower and upper units display a high ash yield (Ad), low total organic carbon (TOC) and sulfur (S) contents, and limited hydrocarbon generation potential. The studied coal samples from the middle unit are characterized by low Ad, and high TOC and low S values, and show significant hydrocarbon generation potential. The paleovegetation during the formation of the lower unit was dominated by mire vegetation, such as shrubs (e.g., Lygodiaceae, Schizaeaceae), tree ferns (e.g., Dicksoniaceae/Cyatheaceae), and coniferous trees (e.g., Podocarpaceae). In the middle unit interval, the paleovegetation was represented by highland vegetation (Pinaceae and Araucariaceae) and peat-forming coniferous plants (e.g., Podocarpaceae, Cupressaceae/Taxodiaceae). Various vegetation, such as herbs (e.g., Osmundaceae), shrubs (e.g., Schizaeaceae), and coniferous trees (e.g., Podocarpaceae) was prosperous during the upper unit interval. Coniferous trees could provide abundant hydrogen-rich materials (e.g., resins) to the mire/lake, which may elevate the hydrogen content in peat/lake sediments, and finally result in higher hydrocarbon generation potential in the coal than in the oil shale. Therefore, the influence of paleovegetation on the formation of oil shale and coal should be fully considered when studying oil shale- and coal-bearing successions. The results also provide guidance for further exploration studies on oil shale and coal in northeast China.

Deformation mechanisms in natural dolomite mylonites from a detachment system (Mt. Hymittos, Greece)

<p>Microstructures may be used to determine the processes, conditions and kinematics under which deformation occurred. For a given set of these variables, different microstructures are observed in various materials due to the material’s physical properties. Dolomite is a major rock forming mineral, yet the mechanics of dolomite are understudied compared to other ubiquitous minerals such as quartz, feldspar, and calcite. Our new study uses petrographic, structural and electron back scatter diffraction analyses on a series of dolomitic and calcitic mylonites to document differences in deformation styles under similar metamorphic conditions. The Attic-Cycladic Crystalline Complex, Greece, comprises a series of core complexes wherein Miocene low-angle detachment systems offset and juxtapose a footwall of high-pressure metamorphosed rocks against a low-grade hanging wall. This recent tectonic history renders the region an excellent natural laboratory for studying the interplay of the processes that accommodate deformation. The bedrock of Mt. Hymittos, Attica, preserves a pair of ductile-then-brittle normal faults dividing a tripartite tectonostratigraphy. Field observations, mineral assemblages and observable microstructures suggests the tectonic packages decrease in metamorphic grade from upper greenschist facies (~470 °C at 0.8 GPa) in the stratigraphically lowest package to sub-greenschist facies in the stratigraphically highest package. Both low-angle normal faults exhibit cataclastic fault cores that grade into the schists and marbles of their respective hanging walls. The middle and lower tectonostratigraphic packages exhibit dolomitic and calcitic marbles that experienced similar geologic histories of subduction and exhumation. The mineralogically distinct units (calcite vs. dolomite) of the middle package deformed via different mechanisms under the same conditions within the same package and may be contrasted with mineralogically similar units that deformed under higher pressure and temperature conditions in the lower package. In the middle unit, dolomitic rocks are brittlely deformed. Middle unit calcitic marble are mylonitic to ultramylonitic with average grain sizes ranging from 30 to 8 μm. These mylonites evince grain-boundary migration and grain size reduction facilitated by subgrain rotation. Within the lower package, dolomitic and calcitic rocks are both mylonitic to ultramylonitic with grain sizes ranging from 28 to 5 μm and preserve clear crystallographic preferred orientation fabrics. Calcitic mylonites exhibit deformation microstructures similar to those of the middle unit. Distinctively, the dolomitic mylonites of the lower unit reveal ultramylonite bands cross-cutting and overprinting an older coarser mylonitic fabric. Correlated missorientation angles suggest these ultramylonites show evidence for grain size reduction accommodated by microfracturing and subgrain rotation. In other samples the dolomitic ultramylonite is the dominant fabric and is overprinting and causing boudinage of veins and relict coarse mylonite zones. Isolated interstitial calcite grains within dolomite ultramylonites are signatures of localized creep-cavitation processes. Following grain size reduction, grain boundary sliding dominantly accommodated further deformation in the ultramylonitic portions of the samples as indicated by randomly distributed correlated misorientation angles. This study finds that natural deformation of dolomitic rocks may occur by different mechanisms than those identified by published experiments; notably that grain-boundary migration and subgrain rotation may be active in dolomite at much lower temperatures than previously suggested.</p>

Between the supercontinents: Mesoproterozoic Deer Trail Group, an intermediate age unit between the Mesoproterozoic Belt–Purcell Supergroup and the Neoproterozoic Windermere Supergroup in northeastern Washington, USA

Mesoproterozoic and Neoproterozoic basins in western North America record the evolving position of the Laurentian craton within two supercontinents during their growth and dismemberment: Columbia (Nuna) and Rodinia. The western-most exposures of the Columbia rift-related Belt–Purcell Supergroup are preserved in northeastern Washington, structurally overlain by the Deer Trail Group and depositionally overlying the Neoproterozoic Windermere Supergroup. It has been disputed whether the Deer Trail Group is correlative with the Belt–Purcell Supergroup, or younger. To help resolve the uncertain correlation of these units and their bearing on supercontinent evolution, we characterized the detrital zircon age populations of units from the Deer Trail Group, the Windermere Supergroup, and the Belt–Purcell Supergroup in northeastern Washington. These data show that the western part of the Columbia supercontinent (now located in Australia and eastern Antarctica) remained attached to western Laurentia and continued to supply 1600–1500 Ma detrital zircon grains to the Belt–Purcell Supergroup until after ca. 1391 Ma. The Deer Trail Group is younger than the Belt–Purcell strata, with the basal unit younger than ca. 1362 Ma and a middle unit younger than ca. 1300 Ma. The Deer Trail Group has a pre-Grenville-age provenance from the southwestern USA and possibly east Antarctica. The Buffalo Hump Formation is younger than the Deer Trail Group, with Grenville-age (ca. 1112 Ma) detrital zircon grains and a detrital zircon signature like that of the overlying Neoproterozoic Windermere Supergroup. We interpret the Deer Trail Group to have been deposited during the rift-demise of supercontinent Columbia and before the Grenville-age assembly of the supercontinent Rodinia.

Weak associativity and quasigroup units

We investigate a family of identities similar to weak associativity: x(y/y)?z = x?(y/y)z which might imply the existence of the {left, right, middle} unit in a quasigroup. A partial solution to Krapez, Shcherbacov Problem concerning such identities and consequently to similar well known Belousov's Problem is obtained. Another problem by Krapez and Shcherbacov is solved affirmatively, showing that there are many single identities determining unipotent loops among quasigroups.

Struktur Naratif Hikayat Nur Muhammad

This paper will review the narrative structure in Hikayat Nur Muhammad (HNM). The theory used is Aristotels and Abrams theory that is narrative structure of introductory unit, opening unit, middle unit and closing unit. The object of this study is the script of Nur Muhammad collection of the National Library of Jakarta with the number Bat. Gen. 378 C / Ml. 378 C. HNM is an old literary work of genre saga. HNM belongs to a kind of biographical narrative that has a narrative structure consisting of narrative units each of which has certain content categories, namely the opening unit, the middle and the cover. The introductory unit, the opening, the middle unit is the part that contains the core of the story. This unit is the most dominant and most important. The middle unit of the HNM contains the story of the patience and submission test that Nur Muhammad must undergo, the events of Nur Muhammad's creatures and dialogue with the four elements. The concluding unit is the conclusion of the image of the greatness of Nur Muhammad's character which further strengthens the image of the greatness of the Prophet Muhammad who was the beginning of this creation. Narrative Structure HNM supports the image of greatness, greatness and goodness of Nur Muhammad as a lover of God from whom created this universe.

Improvement of a Screw Drive In-Pipe Robot with Pathway Selection Mechanism to Pass Through T-Branches

This paper discusses the improvement of a screw drive in-pipe robot with a pathway selection mechanism. This robot is composed of three units: a screw driving unit called a rotator unit (front unit), a steering unit that bends the front unit (middle unit), and a stator unit to hold the whole body (rear unit). It passes not only through straight pipes but also bent pipes and T-branches by changing driving modes (screw driving mode, steering mode and rolling mode). These modes are performed by just two motors through a differential mechanism. The screw drive in-pipe robot previously developed cannot pass through certain T-branches. In this paper, the rear unit has been improved to solve this problem. Constraints on robot length in T-branches caused by this improvement are discussed, that is, installation of additional passive wheels on the rear unit and its rectangle model in the T-branch. Finally, to verify the effect of this improvement and its mobility, experiments are conducted in straight, bent and T-branch pipes.

New insights into the polyphase evolution of the Variscan suture zone: evidence from the Staré Město Belt, NE Bohemian Massif

Forming a northern continuation of the Moldanubian Thrust Zone, the Staré Město Belt comprises an E-verging thrust stack of three narrow lithotectonic units that exhibit variations in their respective P–T records. The upper and lower units form the respective margins of the hanging wall and footwall of the suture zone and are dominated by amphibolite grade metasedimentary successions. The middle unit is defined by an elongated body of MORB-like amphibolites that contains inserts of migmatized mica schists. Integrating both structural studies and pseudosection modelling in the MnNCKFMASH system shows that the present-day tectonic architecture of the Staré Město Belt is the result of a polyphase Variscan evolution. During a frontal, WNW–ESE-directed (in present-day coordinates) collision between the Bohemian Massif terranes and the Brunovistulian terrane, the metasedimentary rocks of the Staré Město Belt experienced tectonic burial to depths corresponding to 7–9 kbar. The continuous indentation and underthrusting of the Brunovistulian terrane led to top-to-the-ESE folding and uplift of these rocks to depths corresponding to 5.5–6.0 kbar at peak temperature. At depths corresponding to 5.5 kbar, the Staré Město Belt underwent subsequent dextral (top-to-the-NNE) shearing that was locally associated with nearly isobaric heating, possibly related to the emplacement of a Carboniferous tonalite body in the axial part of the Staré Město Belt. Subsequent tectonic compression resulted in the Variscan WNW-dipping metamorphic foliations becoming locally (N)NE- or ESE-dipping.

A reappraisal of the allochthonous nature of the Rosenberg slice and Stanbridge Group of southern Quebec and northwestern Vermont

The Ordovician Stanbridge Group of Quebec has long been considered an allochthonous nappe. It is an internally coherent unit that consists of lower slaty limestone overlain by slate, which is correlated with the Highgate and Morses Line formations, respectively, in Vermont. In Quebec, the basal limestones have been inferred to be thrust over Cambrian dolomites (Gorge Formation in Vermont) of the Rosenberg slice, part of the parauthochthonous shelf, although this contact is not exposed there. In the Missisquoi River gorge of Vermont, a conformable sequence of upper Gorge–Highgate–Morses Line formations is exposed. The map distribution of rock units indicates that this conformable relationship probably extends up to at least the middle unit of the Stanbridge Group. Therefore, the relationships in Vermont require that the Stanbridge Group must be part of the parauthochthonous Taconic foreland rather than a far-traveled nappe. The Rosenberg slice in Quebec forms a large anticline (Highgate anticline) whose western limb is truncated by the Rosenberg thrust. In Vermont, the anticline is internally cut by the Highgate Falls Thrust, which is an out-of-sequence thrust that decreases in displacement northwards to the International Border.