The Formation and Structure Evolution of Zechstein (Upper Permian) Salt in Northeast German Basin: A Review

The Zechstein (Upper Permian) salts are extensively distributed in the Northeast German Basin (NEGB). Their formation and movements have attracted great attention to discovering the accumulation and exploration of hydrocarbon sources, as well as the salt production. But the previous studies are validated in cases and a general view on these studies is scarce. By analyzing and integrating previous studies, the history and structure evolution of Zechstein salts were reviewed in this paper. Seven cycles of Zechstein salt (Na1, Na2, Na3, Na4, Na5, Na6, Na7) with distinct composition and thickness were deposited after a series of marine transgressions and regressions during the Upper Permian. The Na1 (300 m) locally developed in a lagoon environment. The thick Na2 (over 500 m) was widely deposited in the whole basin. The Na3, Na4, Na5, Na6 and Na7 decreased progressively in thickness and distribution. These salts should have been moved as a result of regional tectonics taking place from Triassic to Early Cenozoic, which changes the original distribution of salts, resulting in the formation of different salt structures (pillows and diapirs). Salt movement was more intensive in central and southern parts of the basin forming narrow and widely-distributed salt diapirs, while it was less intensive in the northern parts where salt pillows are the major structure. The salt meadow and saline springs are also present, which are attributed to the salinization of the groundwater. By this study, we review the history and structure development of the Zechstein salt in the NEGB by associating each individual study and figure out the common and regional characters of the salt in this region.

Material-specific high-resolution table-top extreme ultraviolet microscopy

Microscopy with extreme ultraviolet(EUV)radiation holds promise for high-resolution imaging with excellent material contrast,due to the short wavelength and numerous element-specific absorption edges available in this spectral range.At the same time,EUV radiation has significantly larger penetration depths than electrons.It thus enables a nano-scale view into complex three-dimensional structures that are important for material science,semiconductor metrology,and next-generation nano-devices.Here,we present high-resolution and material-specific microscopy at 13.5 nm wavelength.We combine a highly stable,high photon-flux,table-top EUV source with an interferometrically stabilized ptychography setup.By utilizing structured EUV illumination,we overcome the limitations of conventional EUV focusing optics and demonstrate high-resolution microscopy at a half-pitch lateral resolution of 16 nm.Moreover,we propose mixed-state orthogonal probe relaxation ptychography,enabling robust phase-contrast imaging over wide fields of view and long acquisition times.In this way,the complex transmission of an integrated circuit is precisely reconstructed,allowing for the classification of the material composition of mesoscopic semiconductor systems.