How to Trace out Impact-Triggered Effects Globally Scattered around Formation Boundaries: Case Uhry, North Germany (Eocene/Oligocene Boundary)

By focusing on impact-triggered phenomena having occurred synchronously with or shortly prior to formation boundaries, two glass sand pits (Upper Maastrichtian) located near Uhry, North Germany have been studied in regard to the K/T boundary throughout the last 40 years during progressive exploitation of glass sand. However, a clastic sequence of sand, mass flow and pelite deposited in a deep channel of about 10 - 12 m in depth, eroded into the glass sand, surprisingly shows an Upper Eocene/Lower Oligocene age, well defined by a Dinocyst assemblage (Chiripteridium c. galea, Enneado cysta arcuata, Areoligera tauloma = D 12na - D 14na) from a 0.5 meter thick pelite that marks the Rupelian transgression within an estuarian system running northwest/southeastward. The section exposes a high energy mass flow and formerly solid frozen angular glass sand blocks of up to a meter-size embedded in fluvial sand of the channel base. Furthermore, erratic clastics of up to 0.4 meter in diameter appear at the pelite base. The “unusual” Dinocyst assemblage is of autochthonous origin and comprises the fresh water alga Pediastrum Kawraiskyias indicator for cold climate, hitherto only known from Quaternary. Missing pollen indicate a vegetation-less hinterland. Thus, there cannot be any doubt that around the E/O b. at least one “rare event” has happened as verified by shortly before the E/O b.(33.75 Ma). In addition, a tektite strewn field along the eastern coast of the USA and micro-tektites (Gulf of Mexico, Caribbean Sea, Barbados) yield an age of ~34.4 Ma, close to the E/O b. Consequently, there does exist an extremely high probability that Uhry site hosts im-pact-triggered products at the E/O b. It should be stressed that the Upper Eocene Epoch comprises an amazingly high number of impact events during the time-span 34.2 - 37.0 Ma.


Introduction
This paper follows the spirit of both following quotations: "Since merely effects are accepted on the screen of science, it seems to be constrained to trace something quite scarce and remote if we search for "indirect effects". The trick of science insists on to admit the proof only in form of logical pointing out that means in the horizon of a "series of effects". Then, "indirect effects" can certainly never be proved, and the fore- Meeting this challenge will almost certainly demonstrate that "Convulsive Geologic Events" have greater relevance to the sedimentary record than has been previously recognized.
For checking some of the parameters listed above, two glass sand pits located atUhry Village near Braunschweig, North Germany have been studied throughout the last 25 years during the continuous sand/gravel exploitation for glass industries (Figure 1(a), [27]).

Geologic and Paleogeographic Setting
The study area is located in a transitional zone of an estuary system whose clastics were transported from southeast/east, towards the open sea situated in a northwestern direction in the time period of Cretaceous through Lower Tertiary (Figure 3(a) and Figure 3(b) [28]). Uh Uhry.
The horse shoe-like arranged huge hinterland/source area comprised the peneplained Variscan Basement and its Mesozoic overburden of Middle Germany [29], the Elbe zone [30], the Harz Mts. [29], the Flechtingen Ridge [29], and the exhumed transpressional structure of the Aller Valley zone [31].
Both pits are subjected to exploitation of kaolinite-bearing Maastrichtian glass sand deposited within both rim synclines of the Beienrode salt Diapir/Dorm Structure (Figure 1(b) and Figure 1(c), [32] [33] [34]). However, the salt ascent started fairly and abruptly around the K/T b. and continued through Paleocene [27]. So the glass sand originally covered the (later) diapir.
Lower Eocene pelite, not deposited in the pits investigated, but exposed ~2 kilometers west of them (open Parseier pit P), discordantly (20˚ -25˚) overlies the glass sand which indicates the end of diapirism around the Paleocene/Eocene b. [27].
The glass sand pits exhibit an up to 12 meters deep flat channel eroded into the glass sand ( Figure 4). Its fill exposes coarse-grained, well-sorted fluvial sand overlain with a mass flow (fanglomerate) up to 2 meters thick, hitherto unknown ( Figure 5).
The latter is preserved as channel relics but had originally a larger extension, [35]. Its pebble assemblage totally differs from that of the Pleistocene of the northern provenance.  The channel deposits are overlain with dark/grey-greenish pelite of Upper Eocene/ Lower Oligocene age, hitherto also unknown.

Biostratigraphy and Major Impacts
Biostratigraphy relates to Dinocyst assemblages of [36], is here faced with the concept of Price [23] that many formation b. coincide with major impacts ("Rare Events") affecting Plate Tectonics throughout Earth History [37]. Figure 6 summarizes the biostratigraphic and major impact data, for the relevant time span.      The following hiatus comprises the uppermost Maastrichtian, the complete Paleocene, and the Lower and Middle Eocene ( Figure 6). Whereas, in the westerly located Parseier pit (p) mentioned above (Figure 1  Suborders Acantaharia and Spumellaria [38]. Hence, the hiatus represents the K/T event and the regional "junior transgression" both around 65 Ma'in age. The Lower Eocene top coincides with another "Rare Event" whichhappened around 50 Ma ago [23].  The whole sequence described from Uhry site, is wide-spread overlain with Pleistocene moraines and fluvio-glacial deposits (Elster?/Saale Glaciation) of northern provenance ( Figure 2).

Do the Sedimentary Formations of Uhry Site Exhibit
Major Impact-Related Effects?

Upper Cretaceous Glass Sand (Maastrichtian = Walbeck F.)
As sediments of an outrunning estuary system, the kaolinite-bearing clastics (missing almost completely feldspar) reveal an extremely high compositional and textural maturity [27] [38]. The significant kaolinite content may be explained by weathering processes at the top of the Variscan Basement of Middle Germany having worked since the Permian peneplaining that surface [29]. Nevertheless, it should be inferred that kaolinite neoformation by impact-initiated nitric acid (pH-0) may play an important role during heavy rainfall and flooding via dissolution of feldspar and other silicates, even through the vadose water penetrating the porous subground. This case was discussed for the  [39].
Meter-sized "blocks" of frozen glass sand showing angular shape were obviously dislocated along joints, gliding along a short distance to be finally embedded within the basinal fluvial clastics (Figure 9). That indicates that frozen vadose pore water consolidated the glass sand during the time around the Eocene/Oligocene b. after subtropical climate hitherto dominated Central Europe that was abruptly shocked by a cold short interval (sintwinter). Since the fluvial clastics hosting the "glass sandblocks", are younger than the angle discordance, this climatic event cannot be related to the K/T Event but certainly to the Upper Eocene major impact events.
Since the uppermost Maastrichtian and the Paleocene are missing in the section, it can be concluded that the K/T transitional sequence had been eroded since the beginning of salt diapirism [27].

Lower Eocene Sand and Pelite
Reworked fine-grained laminated glass sand (St in Figure 1(a)) and some 16 meter thick dark glauconite-bearing pelite (P in Figure 1

Basinal Coarse-Grained Sand and High-Energetic Mass Flow of Post-Lower Eocene to Lower Oligocene
This clastic series hitherto unknown fills as distal part of the estuary system, a northwest running channel eroding the Maastrichtian glass sand (Figure 4). The clastics overlie the angle unconformity with basinal relics of a thin FeOOHenriched paleosol ( Figure 10). The hiatus comprises the time span from uppermost Maastrichtian to Middle Eocene ( Figure 6). The fluvial clastics expose, according to Miall [40], a broad spectrum of lithofacies types (Sh, Sp, St, Sm), and host locally blocks of (former) ice-consolidated glass sand (Figure 9).
The mass flow, up to 2 meter thick, is mainly represented as massive channel fill but has generally wider regional distribution [35]. At the channel edge, vertical and even overhang-contacts to the glass sand were exposed ( Figure 11).    covered with a thin film of soot which was reconfirmed by pit workers who occasionally find C org -enrichment within the realm of the mass flow.

Upper Eocene/Lower Oligocene Pelite and Erratic Clastics (Dropstones)
The  interval [36] for the E/O b. after a long subtropical period. Köthe [36] describes the assemblage of Dinocysts and Pediastrae as unusual. Therefore, the age of this boundary pelite coincides approximately with that of both Popigai and Cheasabreake major impacts.
The E/O b. pelite was well exposed in the Schlingmeier pit ( Figure 4) during progressive glass sand exploitation and may temporarily still be encountered in the Ewers pit in the course of further exploitation, especially in its southern part.

Discussion and Interpretation
According to Figure 6 and Figure 14, there cannot be any doubt that both Popigai and Chesabreake events caused effects of worldwide extension [26].
Regarding the temporal sequence of effects during a mega-impact ( Figures   15-17), the processes commence by spherical shockwave expansion into the rocks of the target area generating typical mineral and rock deformation [41] [42]. Seismic waves with 1/100 of impact energy, run, around the globe within Open Journal of Geology Figure 14. Frequency of impacts through earth history relating to crater, TNT-Aquivalent, bolide Ø, [26]. Figure 15. Relative temperature, impact products and consequences through time [26].  . Impact Events and their evidence from Middle Eocene to Lower Oligocene. Stratigraphy [37], age of events [23], [26], [47]- [57].
Earthquakes re-activate faulting zones, possibly triggering volcanism, and other plate tectonic processes [23]. Thus, like the Deccan Trap Flood Basalts, India effused around the K/T b. [43], the volcanic eruptions of Middle Germany (Erzgebirge, Oberlausitz: [2] meet the E/O b. [37], and therefore might be initiated by both major impacts. Furthermore, it cannot be excluded that the K/T b. event initiated the beginning of diapirism of the Beienrode Dorm Salt structure [27]. Wildfires possibly running around the globe by generating the in-flamation of woods [4] [5], represent initial processes as verified by soot layers at the base of kaolinite boundary clay ( Figure 16) and by fritted Upper Triassic dolomitic marlstones as components of the mass flow.
All these dissolution patterns relate to extreme acidity (pH~O) mainly caused by impact activation which initiates chemical reaction between the otherwise unreactive elements oxygen and nitrogen of the atmosphere to finally produce nitrous and nitric acids [14].
Furthermore, the E/O b. exhibits, in all coal pits of Middle Germany [28], the neoformation of "quartzites" possibly indicating a hiatus caused by SiO2 precipitation within unconsolidated sand [44].
As also discussed for the Early Paleozoic DISI F., Jordan, Arabian plate, it cannot be excluded that heavy acid rain may descend as vadose pore water into siliciclastic deposits to dissolve feldspar initiating herewith kaolinite neoformation [39] that might also be relevant for the Maastrichtian Uhry glass sand.  The clastics underlying the mass flow, document the beginning of increasing rainfall, as also occurred in Middle Germany, witnessed by fluvial deposits around the E/O b. [28].
The Rupelian transgression started during flash flooding. In the following time (months, yearsand even decades) gigantic volumes of ashes, dust, soot, gas and acid dominated the atmosphere and led to the adsorption of solar energy [19]. That should have initiated decrease/stop of photosynthesis and contemporaneously, the origination of "black shale facies" and mass extinction [20] [21] [22]. The latter amounts up to 39% at the K/T b. and to 12% at the E/O b. [26].
Decrease of solar energy generates a significant fall of temperature, accompanied by heavy and long-lasting snowfall (sintwinter = cosmic winter), winter ice formation, frozen vadose pore water in glass sand, erratic clastics along coastlines and in lakes, and finally darkness lasting for months, more or less to be recognized in the sedimentary record.
Temperature fall at Uhry site is reliably documented for the E/O b. ( Figure   18) by:   Formerly frozen Maastrichtian glass sand reworked as jointed angular blocks of meter size embedded in the fluvial basinal clastics (Figure 9).  Erratic clastics embedded in the transgressive Rupelianpelite (Figure 8).  The Dinocyst assemblage appears as "unusual" and comprises the freshwater alga Pediastrum kawraiskyi as indicator of cold climate, hitherto only known from the Quaternary [36].  Lack of pollen indicates vegetation-less hinterland [36].  Macroflora-bearing Rupelianpelite deposited in Middle Germany [28], document a cool period after a long-lasting subtropical climate Finally, the top portion of the E/O b. pelite exposes millimeter-thick dust deposits excellently sorted, to be understood as aerial transport via high altitude.
However, it should be inferred that mega-volcanism, as i.e. shown by the Toba volcano, Sumatra, Indonesia, [46], may produce similar evidence with regard to the mentioned patterns.
The scenario around the E/O b. does reveal such a high complexity of impact patterns which are additionally illustrated by ( Figure 17) [24]. Very probably related to the re-activation of nappes/sliding rock formations at Murillo de Galego, Pyrenees, a crater of 35 -40 Km in Ø was discovered at Azuara , in the southern foreland of the Pyrenees south of Zaragossa, generated around the E/O b./Lower Oligocene. High pressure and high temperature mineral phases indicate a major impact [57] [58].  A recent publication by Schellnhuber [59] includes a temperature curve throughout Tertiary. There appears an abrupt temperature fall at the E/O b. that may allow concluding the interdependence with the impact events which took place throughout Upper Eocene. High concentrations of ash, gas, soot, and dust having probably remained in the atmosphere/stratosphere for a W. Schneider, E. Salameh DOI: 10.4236/ojg.2018. 81002 28 Open Journal of Geology longer time span (centuries or even more) would have caused "cosmic winter" conditions (comp. [19]).

Conclusions
The period lasting from the K/T b. to the E/O b. yields a relatively high number of impact events (including tektites/micro-tektites), with their age mostly close to that of biostratigraphic boundaries ( Figure 6 and Figure 17).

Closing Statement
It is merely a question of time to encounter more effects of major impacts globally distributed around formation boundaries throughout the Earth History, keeping in mind Price's concept. However, it should be stressed that megavolcanoes and hot spot-directed Trapp basalt effusions may generate similar effects except Iridium anomalies and tektites, and that in connection with synchronous mass extinction (See also studies on the Early Paleozoic System of Jordan [39]).
Thus, Uhry site just reconfirms that, by the interplay of cosmic and terrestrial processes, Earth on the whole is sensitively concerned.