Numerische Simulation der Entwicklungsgeschichte des zentralen Niedersächsischen Beckens unter besonderer Berücksichtigung der Erdgaslagerstätten-Bildung

The burial, erosion and temperature history of the central part of the Lower Saxony basin (west of the Weser river) was reconstructed applying 1D and 2D basin modeling. Vitrinite reflectance data, Rock-Eval pyrolysis data, the results of apatite fission track analysis as well as fluid inclusion measurements and an organicgeochemical maturity indicator (Methylphenantrene Index) were used as calibration parameters. Within the study area the observed coalification increases towards die south. In the southern part of the Lower Saxony basin mean vitrinite reflectance values greater than 4 %R$_{r}$ were established for the uppermost Carboniferous. The increasing maturity of the Carboniferous gas source rocks towards the south is accorpanied by a decrease of the coalification gradients. Hence, the observed increase of coalification with depth is lower in the south than in the north. The combination of the maturity pattern for the top Carboniferous with a structural map of the subsurface of the Lower Saxony basin suggests that single tectonic blocks, which are bordered by deep reaching faults, are characterized by a specific maturity spectrum. Most likely there are no isolated areas of high reflectivity. The thickness distribution of upper Jurassic and Cretaceous strata indicates a strong increase of accumulation rates (up to 170 m/m.y. during Wealden) towards the southern rim ot the study area. The results of the ID simulations (PDI/PC) as well as the outcome of the 2D modeling (PetroMod 3.1) - performed on the basis of two seismic cross sections - indicate that a satisfying match with the calibration data can only be realized if deep burial of the southwestem and central parts of the study area is assumed. The amounts of eroded Cretaceous Sediments in diese areas vary between 4200 and 3200 m with decreasing tendency towards the north. The calculated values of uplift match the amount derived from structural restoration of the western cross section. Estimated heat flow values during the time of maximum burial vary between 64 and 79 mW/m$^{2}$. However, an upper Cretaceous intrusion south of the study area cannot be excluded with certainty, since it is not possible to establish a coalification gradient for the southeastem-most well (only 1050 m deep). The northern part of the study area experienced maximum thermal stress during Tertiary times (additional burial of a few hundred meters in combination wich heat flow values around 75 mW/m$^{2}$), followed by a period of cooling, which is also indicated by the results of the apatite fission track analysis. Present day heat flow values amount to 75 mW/m$^{2}$ in the south and decrease gradually to 60 mW/m$^{2}$ in the north. Based on the calibrated temperature and burial history, the timing of methane generation from the Carboniferous source rocks, the gas migration and accumulation was simulated. The major phase of thermal gas generation within the southern part of die Lower Saxony basin occurred during upper Jurassic and Cretaceous times. The onset of the inversion (beginning at upper Cretaceous times) terminated the methane generation, which was never reactivated again. In the north, gas generation continued at least during early Tertiary times. Gas migration occurred mainly along deep reaching and active fault zones. The enormous tectonic stress within the southem parts led to the remigration of the methane, while in the north, due to much smaller movements along the fanlts and due to the ongoing gas generation during Tertiary times, potential traps were preserved and filled with methane. The southern part of the Lower Saxony basin is locally characterized by high CO$_{2}$ contents (up to 95 %) within the Zechstein carrier rocks. The $\delta^{13}$C signature of this gas varies between -1 and -5 $^{\circ}$/$_{\circ}$$_{\circ}$, which points to an inorganic origin. CO$_{2}$ containing springs located south of the Lower Saxony basin revealed $\delta^{13}$C values of -6,62 to -9,88 $^{\circ}$/$_{\circ}$$_{\circ}$ in Bad Oeynhausen and of -18,67 to -21,74 $^{\circ}$/$_{\circ}$$_{\circ}$ in Bad Münder. The former values could indicate a juvenile origin of the CO$_{2}$. whereas the lauer data point towards organic material as precursor. Because of the insufficient data Base, a genetic correlation between CO$_{2}$ in the Lower Saxony basin and the CO$_{2}$ containing springs is - at this time - not possible. Due to the overall geological evolution of the Lower Saxony basin as well as the spatial distribution of the CO$_{2}$ accumulations it is most likely that the generation of the CO$_{2}$ started during latest geological history and is still continuing

Breech-Loading Fire-Arm.

Patent for improvement in breech-loading fire-arms

Breech-Loading Fire-Arm

Patent for a new and improved breech-loading firearm. This design "consists in the devices for opening the breech-block and ejecting the cartridge-shell by one and the same motion that cocks the gun, and also in a spring and pitman arranged with the breech-block" (para. 2)

Bullet.

Patent for a new and improved bullet. This design calls for a cavity at the base of the bullet and a tube of flexible material to be inserted snugly into the cavity. This results in less wobbling after the bullet has been fired

Fire Arm Holder.

Patent for a new and improved pistol holster. This design "consists of a plate of malleable iron or other suitable metal, curved to conform to the waist of a person, having secured to it on the inside a spring adapted to push outward from the waist toward an auxiliary slotted countersunk plate, serving to hold the head of the screw attached to the fire-arm" (lines 19-25)

Cleaner for Gun Barrels.

Patent for a new and improved cleaner for gun barrels. This design "consists of a brush or cleaner formed in the main of spring metal, (preferably of brass,) and provided with bristles beveled at their free ends, so set in suitable holding parts as that when unconfined said bristles will move outward from a common axis and bear against the inner surface of a gun barrel when placed within the same" (lines 13-20)