Rezente und fossile Flachmeer-absätze petrologisch betrachtet und gedeutet

Zusammenfassung Bei der Sedimentbildung im Flachmeer wird zwischen Kurzschweb (KS) im oberen durchbewegten Teil des Meeres und Langschweb (LS) des ruhigen Wassers unterschieden. Deren Grenze liegt je nach der Windwirkung zwischen 2,5 und 250 m Tiefe. Wechsel in der Größe klastischer Körner weist auf Änderung der Wasserbewegung, solcher des Kalkgehalts auf Klimaänderung hin.Bei sinkendem Meeresboden gibt es im KS-Bereich stets eine Zone, in der kontinuierlich so viel Sediment angehäuft wird, wie die Senkung beträgt. Da ohne Senkung der Absatz weiter verfrachtet würde, verdankt dies Sediment seine Entstehung der Senkung. Solch desidiertes Sediment wächst, bei gleichbleibender Tiefe des Wassers, nach unten, im Gegensatz zum ascendenten Sediment.Wo im KS-Bereich das Ausmaß von Senkung und Anhäufung gleich ist, entstehen erdgeschichtlich volldokumentäre Sedimente. Je schneller die Senkung, desto reicher und lesbarer der Inhalt. Im übrigen Teil des KS-Bereichs bedingen zahlreiche Unterbrechungen des Absatzes ein teildokumentäres Sediment. Im LS-Niederschlag fallen jene erdgeschichtlichen Ereignisse aus, die durch Wasserbewegung erkennbar werden. Da Bodenbewohner und Verdichtung die primäre Schichtung zerstören, bleibt ein erdgeschichtlich grobdokumentäres Sediment.Cyklische Sedimente entsprechen den volldokumentären.Aus den Sedimentations-Bedingungen in Ostsee, Nordsee, Mittelmeer und Golf de Gascogne werden zunächst Gesetzmäßigkeiten der Sediment-Bildung in der Flachsee abgeleitet. Daran anschließend soll versucht werden, fossile Flachsee-Ablagerungen zu deuten.Das Schrifttum, soweit nicht im Geologischen Institut Kiel vorhanden, durfte ich dankenswerterweise einsehen in den Büchereien des Instituts für Meereskunde Kiel und des Deutschen Hydrographischen Instituts Hamburg. Herrn Dr.Jarke vom letztgenannten Institut bin ich für Gedanken-Austausch und Hinweise zu besonderem Dank verpflichtet.     

Die Wittlicher Rotliegend-Senke und ihre tektonische Stellung im Rheinischen Schiefergebirge

Zusammenfassung Die Wittlicher Rotliegendsenke ist synsedimentär während des Oberrotliegenden und Zechsteins abgesunken. Der SE-Rand lagert dem flach nach NW eintauchenden Hunsrückschiefer auf; der NW-Rand wird durch eine Verwerfung gebildet, die innerhalb der Wissenbacher Schiefer liegt und der Schieferung dieser Gesteine parallel läuft.Feintektonische Untersuchungen des devonischen Rahmens der Senke lassen auch schon während der varistischen Faltung Bewegungsvorgänge erkennen, die das Einsinken der Rotliegend-Senke vorbereiten.     

Tektonische Probleme in Süd-China

Ohne Zusammenfassung     

Betrachtungen über die Grundschicht

Zusammenfassung 1. Es werden die einzelnen Vorgänge besprochen, die das eigentümliche Verhalten der Veränderlichkeit von Druck und Temperatur in ihrer vertikalen Verteilung erklären sollen. Wenn ein unteres an der Erdoberfläche vorhandenes Druckausgleichsniveau vorhanden ist und ein weiteres in grösserer Höhe, so müssen Temperaturänderungen in dem einen Niveau durch solche eines anderen ausgeglichen, kompensiert werden. Es wird gezeigt, dass dem kompensierenden Einfluss der mittleren und oberen Troposphäre ein kompensierender Einfluss der Kälte- und Wärmewellen aus dem Bereiche der Grundschicht entgegenwirkt, sodass letzten Endes das Druckausgleichsniveau nicht mehr am Erdboden liegt, sondern in eine Höhe verschoben wird, die der ungefähren Höhe der Grundschicht entspricht. — 2. Der Einfluss von Reibung und Konvektion auf die Bildung der Grundschicht wird besprochen. Die Reibung wirkt langsam und immer schichtweise. Die Konvektion wirkt rascher, aber zunächst immer nur lokal. Im Verlaufe längerer Zeit kann aber auch die Konvektion eine Homogenisierung der unteren Luftschichten bewirken, also eine Luftschicht von einem einheitlichen Charakter schaffen. Dieser Prozess wird noch verstärkt, wenn die Konvektion mit Kondensation verbunden ist. Jetzt ist eine weitere Ueberhöhung der Grundschicht möglich. Da dieser Prozess aber über weite Räume nicht von gleicher Grösse ist, wird diese Ueberhöhung vielfach gebietsweise verschieden sein. Die Grundschicht vom Böenwettertyp hat daher gewöhnlich keine einheitliche Oberfläche über weite Gebiete hinweg. — 3. Ein weiterer Faktor, der für die Bildung der Grundschicht von Bedeutung ist, ist die Strahlung. Da der Beitrag, den jeder der drei Faktoren (Reibung, Konvektion, Strahlung) zur Bildung der Grundschicht beisteuert, nicht errechnet werden kann, muss man sich zunächst mit einer qualititativen Abschätzung der Einflüsse der einzelnen an der Bildung der Grundschicht beteiligten Faktoren begnügen. Ein entsprechendes Schema wird vorgelegt und besprochen.

---

Summary 1. There are discussed individual proceedings which shall explain the characteristic behaviour of pressure, and temperature instability in their vertical distribution. When there exists equalization of pressure on a lower level near the ground, and again on a higher level, changes of temperature on one level will be compensated by such on another level. It is shown that the compensating influence of middle and upper troposphere is opposed by the compensating influence of cold, and heat waves from the ground layer, ultimately resulting in the removal of the level of pressure equalization from the ground to an altitude roughly corresponding to the height of ground layer. — 2. The influence of friction and convection on the formation of ground layer is discussed. While friction is acting slowly and by layers, convection is acting more rapidly, but only locally at first. In the long run however, also convection can produce homogeneity of the lower layers of the atmosphere, i. e. an atmospheric layer of uniform character. This process is being intensified when convection is associated with condensation. Then, another increase in height of the ground layer will be possible. However, as this process will not be of similar intensity over wide stages, the increase in height will vary locally. Therefore, generally the ground layer of the squally weather type will not possess a uniform surface extending over wide areas. — 3. Another important factor in the formation of ground layer is radiation. Since the share taken by each of the three factors (friction, convection, radiation) cannot be computed, one must be satisfied with qualitative valuation of the influence of the factors participating in the formation of ground layer. An appropriate scheme is submitted and discussed.

     

Storage-discharge characteristics of an active rock glacier catchment in the Innere Ölgrube,Austrian Alps

The active rock glacier “Innere Ölgrube” and its catchment area (Ötztal Alps, Austria) are assessed using various hydro(geo)logical tools to provide a thorough catchment characterization and to quantify temporal variations in recharge and discharge components. During the period from June 2014 to July 2018, an average contribution derived from snowmelt, ice melt and rainfall of 35.8%, 27.6% and 36.6%, respectively, is modelled for the catchment using a rainfall-runoff model. Discharge components of the rock glacier springs are distinguished using isotopic data as well as other natural and artificial tracer data, when considering the potential sources rainfall, snowmelt, ice melt and longer stored groundwater. Seasonal as well as diurnal variations in runoff are quantified and the importance of shallow groundwater within this rock glacier-influenced catchment is emphasized. Water derived from ice melt is suggested to be provided mainly by melting of two small cirque glaciers within the catchment and subordinately by melting of permafrost ice of the rock glacier. The active rock glacier is characterized by a layered internal structure with an unfrozen base layer responsible for groundwater storage and retarded runoff, a main permafrost body contributing little to the discharge (at the moment) by permafrost thaw and an active layer responsible for fast lateral flow on top of the permafrost body. Snowmelt contributes at least 1/3rd of the annual recharge. During droughts, meltwater derived from two cirque glaciers provides runoff with diurnal runoff variations; however, this discharge pattern will change as these cirque glaciers will ultimately disappear in the future. The storage-discharge characteristics of the investigated active rock glacier catchment are an example of a shallow groundwater aquifer in alpine catchments that ought to be considered when analysing (future) river runoff characteristics in alpine catchments as these provide retarded runoff during periods with little or no recharge.     

Devonian of the isle of Rügen

Summary In the Rügen area of northern Germany, Old Red Sandstones, ranging from Late Emsian to Givetian in age, unconformably overlie deformed Ordovician strata. The Middle Devonian Old Red passes conformably up into a Late Devonian carbonate facies and then into the Lower Carboniferous, apparently without a break.     

The record of impact cratering on the great volcanic shields of the Tharsis region of Mars

Mariner 9 images of the four great volcanic shields of the Tharsis region of Mars show many circular craters ranging in diameter from 100mm to 20 km. Previous attempts to date the volcanoes from their apparent impact crater densities yielded a range of results. The principal difficulty is sorting volcanic from impact craters for diameters $\text{?1}\text{km}$. Many of the observed craters are aligned in prominent linear and concentric patterns suggestive of volcanic origin. In this paper an attempt is made to date areas of shield surface, covered with high resolution images using only scattered small (?1 km) craters of probable impact origin. Craters of apparent volcanic origin are systematically excluded from the dating counts.The common measure of age, deduced for all surfaces studied, is a calculated “crater age” F′ defined as the number of craters equal to or larger than 1 km in diameter per 10⁶km². The conclusions reached from comparing surface ages and their geological settings are: (1) Lava flow terrain surfaces with ages, F′, from 180 to 490 are seen on the four great volcanoes. Summit surfaces of similar ages, F′ = 360 to 420, occur on the rims of calderas of Arsia Mons, Pavonis Mons, and Olympus Mons. The summit of Ascraeus Mons is possibly younger; F′ is calculated to be 180 for the single area which could be dated. (2) One considerably younger surface, F′ < 110, is seen on the floor of Arsia Mon's summit caldera. (3) Nearly crater free lava flow terrain surfaces seen on Olympus Mons are estimated to be less than half the age of a summit surface. The summit caldera floor is similarly young. (4) The pattern of surface ages on the volcanoes suggests that their eruption patterns are similar to those of Hawaiian basaltic shields. The youngest surfaces seem concentrated on the mid-to-lower flanks and within the summit calderas. (5) The presently imaged sample of shield surface, though incomplete, clearly shows a broad range of ages on three volcanoes—Olympus, Arsia, and Pavonis Mons.Estimated absolute ages of impact dated surfaces are obtained from two previously published estimates of the history of flux of impacting bodies on Mars. The estimated ranges of age for the observed crater populations are 0.5 to 1.2b.y. and 0.07 to 0.2b.y. Areas which are almost certainly younger, less than 0.5 or 0.07b.y., are also seen. The spans of surface age derived for the great shields are minimum estimates of their active lifetimes, apparently very long compared to those of terrestrial volcanoes.     

The GeoCitizen-approach: community-based spatial planning – an Ecuadorian case study

Over the last years, geospatial web platforms, social media, and volunteered geographic information (VGI) have opened a window of opportunity for traditional Public Participatory GIS (PPGIS) to usher in a new era. Taking advantage of these technological achievements, this paper presents a new approach for a citizen-orientated framework of spatial planning that aims at integrating participatory community work into existing decision-making structures. One major cornerstone of the presented approach is the application of a social geoweb platform (the GeoCitizen platform) that combines geo-web technologies and social media in one single tool allowing citizens to collaboratively report observations, discuss ideas, solve, and monitor problems in their living environment at a local level. This paper gives an account of an ongoing participatory land-zoning process in the Capital District of Quito, Ecuador, where the GeoCitizen platform is applied in a long-term study.     

Evolution of sedimentary environments of the middle Jiangsu coast, South Yellow Sea since late MIS 3

An evolutionary model of sedimentary environments since late Marine Isotope Stage 3 （late MIS 3, i.e., ca. 39 cal ka BP） along the middle Jiangsu coast is presented based upon a reinterpretation of core 07SR01, new correlations between adjacent published cores, and shallow seismic profiles recovered in the Xiyang tidal channel and adjacent northern sea areas. Geomorphology, sedimentology, radiocarbon dating and seismic and sequence stratigraphy are combined to confirm that environmental changes since late MIS 3 in the study area were controlled primarily by sea-level fluctuations, sediment discharge of paleo-rivers into the South Yellow Sea （SYS）, and minor tectonic subsidence, all of which impacted the progression of regional geomorphic and sedimentary environments （Le., coastal barrier island freshwater lacustrine swamp, river floodplain, coastal marsh, tidal sand ridge, and tidal channel）. This resulted in the formation of a fifth-order sequence stratigraphy, comprised of the parasequence of the late stage of the last interstadial （Para-Sq2）, including the highstand and forced regressive wedge system tracts （HST and FRWST）, and the parasequence of the postglacial period （Para-Sql）, including the transgressive and highstand system tracts （TST and HST）. The tidal sand ridges likely began to develop during the postglacial transgression as sea-level rise covered the middle Jiangsu coast at ca. 9.0 cal ka BP. These initially submerged tidal sand ridges were constantly migrating until the southward migration of the Yellow River mouth to the northern Jiangsu coast during AD 1128 to 1855. The paleo-Xiyang tidal channel that was determined by the paleo-tidal current field and significantly different from the modern one, was in existence during the Holocene transgressive maxima and lasted until AD 1128. Following the capture of the Huaihe River in AD 1128 by the Yellow River, the paleo-Xiyang tidal channel was infilled with a large amount of river-derived sediments from AD 1128 to 1855, causing the emergence of some of the previously submerged tidal sand ridges. From AD 1855 to the present, the infilled paleo-Xiyang tidal channel has undergone scouring, resulting in its modern form. The modern Xiyang tidal channel continues to widen and deepen, due both to strong tidal current scouring and anthropogenic activities.