The Appalachian and Black Warrior basins represent only two of the more than 200 sedimentary basins that have developed across the North American landmass, but these basins have probably had more influence than many others in understanding the interplay between sedimentation, structure, and tectonics. This is especially true for the Appalachian Basin, which is a composite, retroarc/peripheral foreland basin that formed during five orogenies. In many ways, the Appalachian Basin is the “type” foreland basin and the “type area” for the Wilson cycle. Our understanding of the basin, and others like it worldwide, is largely the legacy of a single observation by James Hall in 1857, an observation that also effectively established the framework for the later plate-tectonic paradigm, not to mention major framework developments in structure, tectonics, isostasy, flexural modeling, stratigraphy, sedimentation, paleoclimate, and paleogeography. As preserved today, the basin is about 2050 km long with an area of nearly 536,000 km2, extending from southern Quebec in Canada to northern Alabama in the United States; it reflects the structural influence of earlier Grenvillian convergence and Rodinian dispersal, as well as the paleoclimatic, paleogeographic, eustatic, and tectonic history of eastern Laurentia/Laurussia from latest Precambrian to early Mesozoic time. The associated Black Warrior Basin, on the extreme southwest margin of the Appalachian Basin, is a peripheral foreland basin that developed during a single orogeny. It is a more local basin, and as preserved today, it is about 383 km long by 313 km wide and encompasses an area of nearly 63,900 km2. During latest Precambrian to Early Ordovician time, the recently formed, southern to southeastern Appalachian margin of Laurentia, which now includes both basins, experienced mainly synrift and postrift, passive-margin sedimentation, largely controlled by local structure, regional climate and eustasy. However, by Cambrian time, on some of the more distal outboard parts of the Laurentian margin, the initial tectonic reorganization that would ultimately produce these basins had already begun. Major development of the Appalachian foreland basin began with the advent of the Taconian orogeny at about 470 Ma near the Early-Middle Ordovician transition and continued for nearly 200 Ma during five nearly continuous orogenies that reflect closure of the Iapetus and Rheic oceans and growth of Pangea. Closure of the Iapetus and Rheic oceans reflects the transfer of several Gondwanan terranes to the eastern margin of Laurentia and eventual collision with Gondwana during Paleozoic time. Tectonic dynamics controlled the extent and shape of the basin during various orogenies, and the resulting deformational loading seems to have largely generated the accommodation space in which Appalachian sediments accumulated. Sediment thicknesses up to 13,700 m accumulated in 13 third-order (106–107 years), unconformity-bound cycles that are clearly related to Appalachian tectophases, distinct phases of tectonism controlled by sequential convergence with continental promontories during orogeny. The Black Warrior Basin, in contrast, contains two Late Paleozoic tectophase cycles generated during the Ouachita orogeny. Appalachian tectophase cycles during the Taconian and Salinic orogenies and during the succeeding Acadian, Neoacadian, and Alleghanian orogenies form the larger, second-order (107–108 years), Caledonian and Variscan-Hercynian orogenic supercycles, which generally reflect closure of the Iapetus and Rheic oceans, respectively. In most parts of the basin, the brief transitional Siluro-Devonian, Helderberg interval separates these supercycles and is represented by a thin, widespread, shallow-water, clastic, and carbonate succession with poorly developed tectophase cycles. In contrast to the relative tectonic quiescence apparent in the foreland basin during the Helderberg interval, evidence from more outboard parts of the orogen indicates that the Helderberg interval appears to represent a transitional period of uplift, magmatism, and successor-basin formation during Taconian-Salinic orogen collapse and change to collision-related, strike-slip and transpressional regimes in succeeding orogenies. The first 11 cycles in the Appalachian foreland basin mainly reflect subduction-type orogenies and typically consist of basal, dark, marine shales succeeded in ascending order by flysch-like and molasse-like units, all of which track the progress of orogeny in time and space. The last two Alleghanian cycles, in contrast, reflect collision-type orogeny and are largely composed of clastic-dominated, terrestrial or marginal-marine sediments with a strong eustatic overprint related to Gondwanan glaciation. Although Alleghanian tectonism probably continued through Late Permian time, no foreland-basin sediments younger than Early Permian age are preserved. By Late Triassic time, thermo-tectonic thickening and uplift in the Alleghanian orogen and/or delamination of the underlying Rheic slab and resulting mantle upwelling into old crustal zones of weakness caused orogen collapse and extension, ending the Iapetan or Appalachian Wilson cycle and initiating Pangean dispersal and the current Atlantic Wilson cycle. The importance of the Appalachian Basin lies not only in its “type” status as a basis for our understanding of geomorphological, structural, stratigraphic, and sedimentary parts of the plate-tectonic paradigm, but also in the fact that it contains the relatively well-preserved 545-Ma stratigraphic and sedimentary record of one complete Wilson cycle and parts of others. The larger foreland-basin/orogen area clearly shows the orogen-collapse and extension phase of the previous Laurentian or Grenvillian Wilson cycle during dispersal of the Rodinia supercontinent, as well as late-synrift, passive-margin, active-margin, and orogen-collapse phases of the Iapetan or Appalachian cycle during accretion and dispersal of the Pangean supercontinent. The foreland-basin area itself shows evidence for all the phases except orogen collapse. Nonetheless, what is particularly apparent throughout the basin’s entire history is the fact that the zigzag shape of the old Iapetan margin and the basement structural framework remaining from the previous Laurentian cycle, combined with a series of probably global tectonic events, essentially controlled development and infill of the Appalachian foreland basin. This is apparent in the timing and distribution of the 13 sedimentary cycles that largely comprise its sedimentary infill. Even so, every cycle in the basin differs, reflecting the indelible overprint of changing climatic, geographic, and eustatic regimes. The Black Warrior Basin, in contrast, is not as well understood as the Appalachian Basin. Its roughly 30-Ma history during Mississippian-Pennsylvanian time is relatively short, but that history is very instructive in that it demonstrates how flexural forces from multiple orogenies interact to generate a unique basin response within the standard tectophase model. Moreover, it shows that flexural forces generated during nearby coeval orogenies may influence the sedimentary responses in adjacent foreland basins.

The Appalachian and Black Warrior Basins: Foreland Basins in the Eastern United States

Revised sequence stratigraphy of the upper Katian Stage (Cincinnatian) strata in the Cincinnati Arch reference area: Geological and paleontological implications

Microbial biodeterioration of cultural heritage and identification of the active agents over the last two decades

Freeze-thaw cycles are important in the weathering behaviour of natural building stones in humid, cold to temperate climates. It is expected that the elevated air temperatures in urban environments, the so-called urban heat island (UHI), will have an impact on freeze-thaw weathering. In this study, the impact of the urban heat island on the potential freeze-thaw risk is assessed by parameterization of climatic data of 1 year (07/2016–06/2017) from the MOCCA (Monitoring the City's Climate and Atmosphere) project, which studies the urban heat island in Ghent, Belgium. The dose-response of Savonnieres, a French limestone often used as building stone, is investigated in laboratory and by HAM simulations. Analysis of the MOCCA data demonstrates that the urban heat island phenomenon decreases the number and intensity of freeze-thaw cycles in an urban environment with 42% and 41% respectively for the studied year in Ghent. This decrease suggests a mitigation of frost risk in urban environments. Laboratory tests and computational simulations confirm that this leads indeed to a decreased freeze-thaw risk in urban landscapes compared to the surrounding rural environment.

Impact of the urban heat island on freeze-thaw risk of natural stone in the built environment, a case study in Ghent, Belgium

The “University of Coimbra-Alta and Sofia” area was awarded the UNESCO World Heritage Site distinction in 2013 The Old Cathedral of Coimbra, a 12th-century limestone monument located in this area, has been significantly impacted during the last 800 years by physical, chemical, and biological processes This led to the significant deterioration of some of its structures and carvings, with loss of aesthetical, cultural, and historical values For this work, deteriorated spots of the walls of three semi-open chapels from the cloister of the Cathedral were sampled to ascertain their bacterial and archaeal structural diversity Based on Next-Generation Sequencing (NGS) result analysis, we report the presence of microbial populations that are well adapted to an ecosystem with harsh conditions and that can establish a diverse biofilm in most cases While it was possible to determine dominant phylogenetic groups in Archaea and Bacteria domains, there was no clear connection between specific core microbiomes and the different deterioration patterns analyzed The distribution of these archaeal and bacterial communities within the analyzed biodeterioration spots suggests they are more influenced by abiotic factors (ie, water availability, salinity, etc), although they influence (and are influenced by) the algal and fungal population composition in this ecosystem This work provides valuable information that can assist in establishing future guidelines for the preservation and conservation of this kind of historic stone monuments

https://www.mdpi.com/2076-2607/9/4/709/pdf

Bacterial and Archaeal Structural Diversity in Several Biodeterioration Patterns on the Limestone Walls of the Old Cathedral of Coimbra

Differential colonization of microbial communities inhabiting Lede stone in the urban and rural environment.

The capabilities of bacteria and archaea to alter natural building stones : a review

A restudy of the palynology of the Whirlpool Formation and Power Glen Formation in New York (USA) yielded a diverse fossil assemblage with cryptospores, glomalean fungi, acritarchs, chitinozoans, scolecodonts, and small carbonaceous fossils. These new data, and particularly the presence of the chitinozoan index fossil Hercochitina crickmayi, combined with emerging stable carbon isotope data, suggest a Late Ordovician (Katian or Hirnantian) age for these formations, which is older than their previously suggested Silurian (Rhuddanian) age.

A Late Ordovician age for the Whirlpool and Power Glen formations, New York

Water affects the susceptibility of stone to alteration by facilitating physical, chemical and biological weathering. Stone properties determine water transport and retention, but it is also expected that biofilms and extracellular polymeric substances could alter the water–stone relationship. A lot of research on this subject has been carried out on soils, but the effect on stones is understudied. For this reason, three sedimentary building stones, Ernzen, Euville and Savonnières, each with a different pore size distribution, were biofouled with cyanobacteria. Their relationship with the stone material was investigated by optical and electron microscopy, and the effect of cyanobacterial biofilms on water transport and retention was studied. The results showed that the cyanobacteria primarily colonize the building stones on the outer surface and have a limited effect on the water transport properties. They slightly reduced the capillary coefficient and drying rate of the stones, but enhanced the water content in the stone and increased water vapour sorption. They induced (near) hydrophobic conditions, but had no measurable effect on the gas permeability and water vapour diffusion. Moreover, swelling and shrinkage of the biofilms were observed, which could potentially induce physical weathering. It is expected that these changes could influence other forms of weathering, such as freeze–thaw weathering and salt weathering.

The effects of cyanobacterial biofilms on water transport and retention of natural building stones

Microbes thrive in almost every possible environment, including natural building stones. Microbial communities affect these materials which can lead to biodeterioration. Among others, air pollution, especially SO2 and NOx, is an important actor for stone degradation. This leads to crust formation and in limestone typically to gypsum crusts. There are questions if and how sulphur-oxidizing prokaryotes can play a role in crust formation, oxidizing sulphur dioxide to sulphuric acid. This study explores the microbial community inside and underneath gypsum crusts to find out who is there and how they relate to the weathering and gypsum crust formation. We studied Lede stone, a sandy limestone or calcareous sandstone, used in many historical buildings in North Western Belgium. This stone is prone to weathering and gypsum crust formation. Two historic monuments have been sampled both in the urban environment (City hall, Ghent, Belgium) and in the countryside (Castle of Berlare, Belgium). These monuments consisted of severely weathered Lede stone: the City Hall in Ghent contained very thick botryoidal gypsum crusts while the crusts in Berlare were more superficial. Stone material was collected with a flame sterilized chisel and drill chuck and was used to isolate bacteria. To desribe the prokaryotic community: DNA was extracted, 16S rRNA genes were amplified and sequenced by Illumina Mi-Seq Next Generation Sequencing (NGS). The isolation campaign gave more information on the genus and species level of the bacterial community and makes it possible to test their abilities. The isolates from the two localities differ significantly and include diverse pigmented bacteria (orange, red, pink, yellow). The pigmented bacteria might contribute to the overall rock discoloration. The impact of the prokaryotic colonization on potential crust formation will be discussed.

Laurenz Schröer

Papers

Differential colonization of microbial communities inhabiting Lede stone in the urban and rural environment.

The capabilities of bacteria and archaea to alter natural building stones : a review

A Late Ordovician age for the Whirlpool and Power Glen formations, New York

The effects of cyanobacterial biofilms on water transport and retention of natural building stones

Exploring microbial communities inhabiting gypsum crusts of weathered natural building stones