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 hyd...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.展开更多
The Bonikowo Reef occurs in the central part of the Zechstein Limestone Basin in western Poland and was growing on the topmost edges of tilted blocks and/or on the top of uplifted horsts of the BrandenburgeWolsztynePo...The Bonikowo Reef occurs in the central part of the Zechstein Limestone Basin in western Poland and was growing on the topmost edges of tilted blocks and/or on the top of uplifted horsts of the BrandenburgeWolsztynePogorzela High. Its size is ca. 1.6 km^2. The Bonikowo Reef shows the thickest reef section（90.5 m） recorded in the High. The Zechstein Limestone unit is represented mostly by limestones, often thoroughly recrystallized, although the macrotextures and biota of the boundstone are identifiable in most cases. The drillcore section is a mixture of boundstones（microbial and bryozoan）, wackestones, packstones and grainstones, which often co-occur. The δ^13 C and δ^18 O values for both calcite（avg. 3.8 ± 0.8‰ and-3.4 ± 1.7‰, respectively） and dolomite（avg. 3.5 ± 0.7‰ and-5.2 ± 1.3‰, respectively） are transitional between the values previously reported for condensed sequences of the basinal facies and larger reef complexes. The biofacies of the Bonikowo Reef are very similar to those recognized in other reefs of the BrandenburgeWolsztynePogorzela High, which owe their origin to the destruction of bryozoan boundstones. The biota composition is typical and characteristic of other Zechstein Limestone reefs. However, the Bonikowo Reef demonstrates the importance of microbialites, laminar and nodose encrustations, in the growth and cohesion of the Zechstein Limestone reefs. Such encrustations abound within the Zechstein Limestone although, in many cases, the real nature of the encrustations is difficult to ascertain. These laminated encrustations show great similarity to Archaeolithoporella that is one of the most important Permian reefbuilding organisms. The encrustations considered to represent Archaeolithoporella were also previously recorded in the Zechstein Limestone of western Poland and in its stratigraphic equivalent, the Middle Magnesian Limestone of Northeast England. The lower part of the sequence shows great biofacies variability that reflects common environmental changes. The major part of the section is represented by slope depositsgrading upward into the reef, which reflects the prograding nature of reef margin. The progradation rate for the Bonikowo Reef is estimated at 400 m/My.展开更多
Encrusting foraminifers locally can play an essential reef-forming role such as in the Carnian fossiliferous Hallstatt Limestones of Austria where a dense succession of hardgrounds occurs with numerous small buildups(...Encrusting foraminifers locally can play an essential reef-forming role such as in the Carnian fossiliferous Hallstatt Limestones of Austria where a dense succession of hardgrounds occurs with numerous small buildups(up to 2 cm high)composed of sessile foraminifers.Similar foraminiferal micro-buildups occur in a 10-cm-thick bed in the basinal facies in the basal Zechstein(Upper Permian)strata in the Radlin 60 borehole,in western Poland.Foraminiferal micro-buildups of presumably columnar habit account for up to a half of the volume.The growth of columns was interrupted by hiatal surfaces,although usually the growth of columns was restored afterwards.In the upper part of the bed with foraminiferal micro-buildups,the foraminiferal encrustations become visibly less abundant,and in most cases,they have a shape of less regular masses.The bed with foraminiferal micro-buildups abounds in closely spaced discontinuity(hiatal)surfaces,occasionally encrusted by foraminifers.Tubular foraminifers in the bed with foraminiferal micro-buildups are accompanied by various encrusting organisms,possibly microbes;they are grouped under the name Palaeonubecularia.In the intercolumnar spaces,common Midiella sp.occur.During deposition,the conditions were mostly suboxic,and various types of ferruginous morphs,common in the lower part of the bed,suggest that dysoxic-anoxic interfaces produced various microaerophilic environments for iron-bacteria.The environmental conditions during the deposition of the upper part of the bed were very similar to those characterizing the starved basin environment in which the bioclastic-peloidal and oncoidal sediments in the Zechstein Limestone have been formed.In turn,the lower part of the bed registers the transition from normal(=not starved)marine conditions,with a clear chemocline,to the starved basin conditions.The deposition of the bed was coeval with the Kupferschiefer deposition based on the correlation ofδ13C curves,which implies that the previous stratigraphical concept of basal Zechstein strata has to be re-evaluated.展开更多
文摘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.
基金financed by the National Science Centre (No. DEC-2013/11/B/ST10/04949)
文摘The Bonikowo Reef occurs in the central part of the Zechstein Limestone Basin in western Poland and was growing on the topmost edges of tilted blocks and/or on the top of uplifted horsts of the BrandenburgeWolsztynePogorzela High. Its size is ca. 1.6 km^2. The Bonikowo Reef shows the thickest reef section（90.5 m） recorded in the High. The Zechstein Limestone unit is represented mostly by limestones, often thoroughly recrystallized, although the macrotextures and biota of the boundstone are identifiable in most cases. The drillcore section is a mixture of boundstones（microbial and bryozoan）, wackestones, packstones and grainstones, which often co-occur. The δ^13 C and δ^18 O values for both calcite（avg. 3.8 ± 0.8‰ and-3.4 ± 1.7‰, respectively） and dolomite（avg. 3.5 ± 0.7‰ and-5.2 ± 1.3‰, respectively） are transitional between the values previously reported for condensed sequences of the basinal facies and larger reef complexes. The biofacies of the Bonikowo Reef are very similar to those recognized in other reefs of the BrandenburgeWolsztynePogorzela High, which owe their origin to the destruction of bryozoan boundstones. The biota composition is typical and characteristic of other Zechstein Limestone reefs. However, the Bonikowo Reef demonstrates the importance of microbialites, laminar and nodose encrustations, in the growth and cohesion of the Zechstein Limestone reefs. Such encrustations abound within the Zechstein Limestone although, in many cases, the real nature of the encrustations is difficult to ascertain. These laminated encrustations show great similarity to Archaeolithoporella that is one of the most important Permian reefbuilding organisms. The encrustations considered to represent Archaeolithoporella were also previously recorded in the Zechstein Limestone of western Poland and in its stratigraphic equivalent, the Middle Magnesian Limestone of Northeast England. The lower part of the sequence shows great biofacies variability that reflects common environmental changes. The major part of the section is represented by slope depositsgrading upward into the reef, which reflects the prograding nature of reef margin. The progradation rate for the Bonikowo Reef is estimated at 400 m/My.
基金the Grant No.62.9012.2039.00.0 from Polish Geological InstituteNational Research Institute statutory funds to TMP。
文摘Encrusting foraminifers locally can play an essential reef-forming role such as in the Carnian fossiliferous Hallstatt Limestones of Austria where a dense succession of hardgrounds occurs with numerous small buildups(up to 2 cm high)composed of sessile foraminifers.Similar foraminiferal micro-buildups occur in a 10-cm-thick bed in the basinal facies in the basal Zechstein(Upper Permian)strata in the Radlin 60 borehole,in western Poland.Foraminiferal micro-buildups of presumably columnar habit account for up to a half of the volume.The growth of columns was interrupted by hiatal surfaces,although usually the growth of columns was restored afterwards.In the upper part of the bed with foraminiferal micro-buildups,the foraminiferal encrustations become visibly less abundant,and in most cases,they have a shape of less regular masses.The bed with foraminiferal micro-buildups abounds in closely spaced discontinuity(hiatal)surfaces,occasionally encrusted by foraminifers.Tubular foraminifers in the bed with foraminiferal micro-buildups are accompanied by various encrusting organisms,possibly microbes;they are grouped under the name Palaeonubecularia.In the intercolumnar spaces,common Midiella sp.occur.During deposition,the conditions were mostly suboxic,and various types of ferruginous morphs,common in the lower part of the bed,suggest that dysoxic-anoxic interfaces produced various microaerophilic environments for iron-bacteria.The environmental conditions during the deposition of the upper part of the bed were very similar to those characterizing the starved basin environment in which the bioclastic-peloidal and oncoidal sediments in the Zechstein Limestone have been formed.In turn,the lower part of the bed registers the transition from normal(=not starved)marine conditions,with a clear chemocline,to the starved basin conditions.The deposition of the bed was coeval with the Kupferschiefer deposition based on the correlation ofδ13C curves,which implies that the previous stratigraphical concept of basal Zechstein strata has to be re-evaluated.
