Black Limestone Research Articles

New Progress in Study of the Ore‐bearing Black Limestone of Jinding Giant Zn‐Pb Deposit, Yunnan, Southwest China

New Progress in Study of the Ore‐bearing Black Limestone of Jinding Giant Zn‐Pb Deposit, Yunnan, Southwest China

Cultural Heritage Documentation and Conservation: Three-Dimensional (3D) Laser Scanning and Geographical Information System (GIS) Techniques for Thematic Mapping of Facade Stonework of St. Nicholas Church (Pisa, Italy)

ABSTRACTThis article reports the mapping of the stones, including marbles and brick masonry, used for building the facade of the medieval Church of St. Nicholas (XI century ad), one of the most interesting churches in Pisa, due also to the nearby famous octagonal bell tower. Mapping of stone materials was performed using a computer-aided design (CAD)/geographical information system (GIS) software package for storing and processing spatial information of the ashlars, obtained using three-dimensional (3D) laser-scanning data, combined with high-resolution images, and stone-to-stone observations. Based on collected data, the facade of the Church of St. Nicholas appeared mostly composed of rocks belonging to the metamorphic Tuscan sequence, quartzites, and marbles from Mt. Pisano area. Other types of rocks were also observed, as black limestones quarried at some kilometers northwest from Pisa in the Monti d’Oltre Serchio area, white Apuan marbles and Macigno sandstones. Conversely, intarsia appeared mainly made up of serpentinite and, subordinately, red limestones laid in white Apuan and Mt. Pisano marbles.

Quaternary remagnetization of the Neoproterozoic limestone of Negash Synclinorium (Arabian–Nubian Shield, northern Ethiopia): With implications of no paleomagnetic testing for the proposed Snowball Earth events

Eighty-one paleomagnetic cores were collected from 10 locations across a black limestone unit within the core of Negash Synclinorium, northern Ethiopia in order to test the proposed Snowball Earth events for the diamictite unit of the Tambien Group. Cores were cut into two standard paleomagnetic specimens and were subjected to stepwise demagnetizations using both Thermal (TH) and alternating field (AF) techniques. Rock magnetic analyses on representative specimens were done and results revealed goethite, pyrrhotite, titano-magnetite, and titano-hematite to be the major magnetic materials carrying the magnetizations with PSD (pseudo single domain) grain size range. In most cases paleomagnetic directions are defined by a single component of magnetization, where a viscous component is present it is usually removed by heating to a temperature of ∼200°C or an AF of ∼10mT. The high stability component isolated above temperature of 200°C or AF of 15mT, defined straight line trajectories directed towards the origin and considered as the Characteristic Remanent Magnetization Direction (ChRM). The direction of magnetization of the ChRM is determined for samples with stable straight line segments by the best-fit line using the least square technique of Kirschvink (1980). In the cases of overlapping spectra and unblocking temperatures, direction of magnetization is determined by remagnetization circles of Halls (1976, 1978). When site mean ChRM directions are plotted on stereogram, their distribution is relatively clustered in geographic coordinates and the overall mean direction is Decg=358.5°, Incg=16.6° (α95=3.8°, K=162.8, N=10). After a structural restoration to the horizontal is made the directions disperse and fail the fold test of both McElhinny’s and McFadden’s tests and the mean direction is Decs=353.5°, Incs=8.8° (α95=18.9°, K=7.5, N=10). This is interpreted to result from a later remagnetization of the black limestone. All directions are normal in polarity and have mean unrestored paleomagnetic directions comparable to the Quaternary paleomagnetic directions. Virtual Geomagnetic poles (VGP) in the unrestored position is used to calculate overall mean VGP position resulting long=235.7°E, latg=84.5°N (A95=3.0°, N=10). Comparison of the obtained pole with the apparent polar wander path (APWP) curve for Africa of Besse and Courtillot (1991, 2003) and with the 2Ma reference pole of stable Africa (Kidane et al., 2003) is found to be consistent with remagnetizations during the Quaternary period. Hence supporting evidence for the proposed Snowball Earth event of the Sturtian glaciation in the Negash rocks could not, unfortunately, be obtained from paleomagnetism.

Syndeposition and epigenetic modification of the strata-bound Pb–Zn–Cu deposits associated with carbonate rocks in western Kunlun, Xinjiang, China

Lead–zinc–copper (Pb–Zn–Cu) deposits in the western Kunlun Orogen of China are mostly distributed along the Keziletao–Kusilafu fault zones in the Palaeozoic clastic–carbonate rocks, which formed in a late Palaeozoic subsidence belt at the south-west margin of the Tarim platform. Geological and geochemical studies were conducted on these deposits including detailed field observation, petrographic study, and geochemical and isotopic analyses of sulfur, lead, strontium, rhenium–osmium, and argon isotopes, as well as fluid inclusion geochemistry. The characteristics of the deposits include: (1) Except for the Tiekelike Pb–Cu deposit associated with mid-Devonian rocks, all of the other deposits were developed in the lower layers of the early Carboniferous strata. These strata mostly comprise sedimentary dolomitic limestone, sandy limestone, black limestone, and calcareous shale. (2) The ore bodies are stratiform and host veins. The stratiform ores are coeval with host rocks (yielding ore-forming ages of 331–337Ma), while the vein ore bodies are mostly massive deposits formed at 206–235Ma. The isotopic compositions of the sulfur and lead reveal that the ore-forming elements originated from various sources. (3) The mineralization in cements of brecciated ore is a veinlet type, while in the breccias it is a disseminated type. The stratoid, disseminated, and framboidal structures of the ore reveal the synsedimentary ore-formation. However, the veins, mesh-veins, and massive structures indicate late stage hydrothermal mineralization. (4) The principal metallic minerals include sphalerite, galena, and pyrite, while the secondary oxide minerals include variable distributions of cerussite, anglesite and limonite. The gangue minerals include dolomite, calcite, quartz, sericite, and gypsum, with minor chert and barite. (5) The original host rocks likely experienced dolomitization, calcitization, and minor silicification. The ore deposits underwent hydrothermal alterations, sub-greenschist facies metamorphism, and brecciation. The ore deposits may have initially formed via syndeposition in a subsidence belt along the southwest margin of the late Paleozoic Tarim platform; these deposits were further modified during later hydrothermal alteration and orogenesis during the Triassic period.

Black "marble" in the Polish architecture - characteristics and possibility of its provenance determination: the case of the Dębnik limestone

Black limestone, also known as black marble, was widely used in the Polish small-scale architecture and art of the 17th and 18th centuries. Besides the Devonian limestone from Debnik near Krakow, also popular were the Netherlandish (Wallonian), Devonian to Carboniferous limestones from the Meuse River and Schelde River valleys. This paper deals with the possibility of identifying the rocks imported to Poland. Macroscopic similarities between the Netherlandish rocks and some Debnik limestones have been highlighted for the oldest Carmelite quarry in Debnik, exploiting the best stones. The analyses include: optical microscopy, scanning electron microscopy with EDS, X-ray diffraction, X-ray fluorescence and isotope ratio mass spectrometry (13 C and 18 O stable isotopes). Carboniferous limestones from Netherlands can be identified within and distinguished from the Debnik limestone in the macroscopic observations. Differences, depending on the varieties, are associated primarily with the presence of white calcite fragments of fossils, calcite veins intersecting the rock in all directions or hardness of the limestones. Deeply black Devonian limestones from Wallonia and Debnik without macrofossils and calcite veins differ in microscopic observations considering their texture, type of microfossils and inventory of non-carbonate components. The characteristic graying and whitening of the black limestones has also been discussed as a possible feature of rock provenance.

A remarkable sea-level drop and relevant biotic responses across the Guadalupian–Lopingian (Permian) boundary in low-latitude mid-Panthalassa: Irreversible changes recorded in accreted paleo-atoll limestones in Akasaka and Ishiyama, Japan

The Capitanian (Upper Guadalupian) to Wuchiapingian (Lower Lopingian) shallow-marine limestones at Akasaka and Ishiyama in central Japan record unique aspects of the extinction-related Guadalupian–Lopingian boundary (G-LB) interval. The ca. 140m-thick Akasaka Limestone consists of the Capitanian black limestone (Unit B; 112m) and the Wuchiapingian light gray dolomitic limestone (Unit W; 21m), with a black/white striped limestone (Unit S; 9m) between them. The G-LB horizon is assigned at the base of Unit W, on the basis of the first occurrence of the Wuchiapingian fusulines. The Capitanian Unit B and the Wuchiapingian Unit W were deposited mostly in the subtidal zone of a lagoon, whereas the intervened Unit S and the lowermost Unit W were in the intertidal zone. A hiatus with a remarkable erosional feature was newly identified at the top of Unit S. These records indicate that the sea-level has dropped significantly around the G-LB to have exposed the top of the atoll complex above the sea-level. The Ishiyama Limestone, located ca. 10km to the north of the Akasaka limestone, retains almost the same depositional records. The extinction of large-tested fusuline (Yabeina) and large bivalves (Alatoconchidae) occurred in the upper part of Unit B, and the overlying 20m-thick limestone (the uppermost Unit B and Unit S) below the hiatus represents a unique barren interval. The upper half of the barren interval is more depleted in fossils than the lower half, and this likely represents a duration of the severest environmental stress(es) for the shallow-marine protists/animals on the mid-oceanic paleo-atoll complex. Small-tested fusulines re-appeared at the base of Unit W above the hiatus. These facts prove that the elimination of shallow-marine biota occurred during the Capitanian shallowing of Akasaka paleo-atoll before the subaerial exposure/erosion across the G-LB. The overall shallowing and the development of such a clear hiatus at the top of a mid-oceanic seamount, in accordance with the contemporary sea-level curve based on continental shelf records, indicates that a remarkable sea-level drop has occurred globally during the latest Capitanian. This further suggests that a cool climate likely has appeared even in the low-latitude domains in Panthalassa to cause the decline of the Middle Permian shallow-water protists/animals that adapted to warmer seawater. The Wuchiapingian biota first appeared immediately after this erosional episode, i.e., during the onset of warming after the G-LB.

Comment on “Calpionellid distribution and microfacies across the Jurassic/Cretaceous boundary in western Cuba (Sierra de los Órganos)” by López-Martínez et al. (2013)

The paper by Lopez-Martinez et al. (2013) is a new contribution to the microfossil stratigraphy of the Tithonian-Berriasian limestones in the Los Organos Succession (Pinar del Rio Province, western Cuba). This is the result of a detailed (“bedby-bed”) study of one section (San Vicente) located in the north-eastern part of the Sierra de los Organos belt (western Cuba). The description of the El Americano Member (Tithonian-Berriasian, pro parte) is extremely concise, being limited to two sentences, only (Lopez-Martinez et al. 2013), probably because this unit was previously characterized in various publications (Housa & Nuez 1972; Pszczolkowski 1978; Myczynski & Pszczolkowski 1990; Pszczolkowski 1999; Cobiella-Reguera & Oloriz 2009; Pszczolkowski & Myczynski 2010; Iturralde-Vinent & Pszczolkowski 2011). However, in this way the authors have omitted some important features of the El Americano Member. In the type section, the El Americano Member deposits were described as dark-grey to black limestones with ammonites (Housa & Nuez 1972). Unfortunately, Figure 3 (Lopez-Martinez et al. 2013) contains a serious error as the authors claim that it shows “Calpionellid and ammonite biostratigraphy of the Rancho San Vicente section according to Pszczolkowski & Myczynski (2010)”. In fact, such a figure does not exist in the cited paper. If Figure 3 of Lopez Martinez et al. (2013) was extracted from Figure 2 in Pszczolkowski & Myczynski (2010), it should not be restricted to the “Rancho San Vicente section”, as it presents the stratigraphic position of the Guaniguanico units in general, in the Los Organos and Rosario successions. The upper part of the San Vicente section is shown in Figure 10 (Pszczolkowski & Myczynski 2010), but it contains biostratigraphic data on the Upper Berriasian and Lower Valanginian limestones, only. The results of the study by Lopez-Martinez et al. (2013) include some claims and conclusions that are certainly acceptable and others which are not convincing. Only a few items can be considered here. The authors do not mention, that at San Vicente the age of the basal part of the bedded limestones named “the Artemisa Formation”, later included in the El Americano Member of the Guasasa Formation, was identified by Pop (1976, fig. 4) as Upper Tithonian (Crassicollaria Zone). Therefore, the Late Tithonian age of the boundary between the San Vicente and El Americano members in the San Vicente section was known after 1976. The new data of Lopez-Martinez et al. (2013) allow us to refine the stratigraphic position of the basal limestones of the El Americano Member in the San Vicente section as the Boneti Subzone of the Chitinoidella Zone (Upper Tithonian). However, it is not exactly true that “In previous works (Pszczolkowski 1978, 1999), the contact between the San Vicente and the El Americano Members was dated as Kimmeridgian—Tithonian” (Lopez-Martinez et al. 2013, Discussion). In Table 4 (Pszczolkowski 1978), this contact is clearly diachronous and reaches Lower Tithonian (in places); on page 63 there is a conclusion that “... the carbonate bank of Sierra de los Organos had drowned at the Middle Tithonian time which resulted in a considerable uniformity of facies all over the Cordillera de Guaniguanico (Fig. 27)”. Nevertheless, drowning of the carbonate bank had started at the Kimmeridgian-Tithonian boundary (Pszczolkowski 1999; Pszczolkowski & Myczynski 2010). Considering this, the statement of Lopez-Martinez et al. (2013), that “in more detailed work it is possible to find a diachronism in the appearance of pelagic conditions” (and so on) is true, but not new (please see Pop 1976 and Pszczolkowski 1978, 1981). The next claim on page 203 (Lopez-Martinez et al. 2013) concerns the presence of juvenile gastropods and the lack, or extreme scarcity, of adult specimens in the Tithonian limestones (Pszczolkowski & Myczynski 2010). The authors (Lopez-Martinez et al. 2013), interpret this phenomenon in the San Vicente section “as rather due to taphonomic processes, similar to the interpretations by Fernandez-Lopez & Melendez (1995), than as a consequence of low oxygenation levels”. However, it seems that gastropods are very rare in the El Americano Member of the San Vicente section (in beds No. 20 and 43, only?), or alternatively, the authors did not consider them to be important enough to illustrate at least a single specimen of these molluscs. Therefore, it is rather strange that the problem of juvenile gastropods was undertaken in the paper by Lopez-Martinez et al. (2013). Originally, the figured juvenile gastropods were found in other sections of DISCUSSION – COMMENT

ANNULATA EVENT Z PROFILU V JÁMOVÉM LŮMKU U OCHOZI U BRNA – POZNÁMKY KE KONODONTOVÉ BIOSTRATIGRAFII (FAMEN, MORAVSKÝ KRAS)

About two meters thick section of the Famennian Křtiny Limestones (Líšeň Formation) was studied in a small pit-quarry near the road leading from Brno-Líšeň to Ochoz u Brna. Conodont samples were taken from seven diff erent stratigraphical levels. A richly fossiliferous interval (about 40 cm thick) can be distinguished in the higher part of the section. This interval is characterized by abundant occurence of clymenids, bivalves, orthocone nautiloids, trilobites and other groups. Black limestone lenses (maximal thickness about 10 cm) are developed in the lowermost part of the richly fossiliferous interval. A presence of Palmatolepis glabra lepta (late morphotype), Palmatolepis minuta minuta and Palmatolepis rugosa trachytera suggests these black limestones probably represent the Lower Annulata event (Upper Palmatolepis rugosa trachytera zone). Polygnathus styriacus indicating the base of the Palmatolepis perlobata postera zone enters within about 10 centimeters thick interval of dark grey biodetritic limestones which occur closely above the black limestone lenses. The Upper Annulata event and equivalents of „Wagnerbank“ or „Annulata limestone“ were not distinguished in the studied section. This might be caused by condensed sedimentation. Grey limestones and marly limestones belonging to the higher part of the richly fossiliferous interval are placed above the base of the Palmatolepis perlobata postera zone. The studied locality might correspond to the original fossil site described by Rzehak in 1910.

Genesis of Blackened Limestone Clasts At Late Cenozoic Subaerial Exposure Surfaces, Southern Australia

Abstract Black limestone clasts are present across the globe at modern and ancient subaerial exposure surfaces, and in intertidal and supratidal environments. These problematic clasts are particularly abundant at multiple subaerial exposure surfaces across southern Australia. The genesis of such exceptionally preserved clasts can be interpreted through universal fabrics across wide geographic regions and geologic ages. Regardless of location or age, all south Australian blackened clasts studied have a similar microstructure that is dominated by porous micritic laminae and chambered tubules. Such laminae are interpreted to represent calcified root cells and occur in two different varieties: 1) micrite-walled tubules with hollow centers that are thought to represent calcification in the rhizosphere or outer surfaces of the root, and 2) tubules consistent with calcification of both the medulla and cortex, which preserved medulla, cortex, and parenchymatic cells along with xylem vessels. Preserved root fabrics are present only in the blackest clasts and are consequently thought to be the main mechanism driving limestone blackening. The dark coloration in southern Australian clasts is derived from the impregnation of partially decayed terrestrial organic substances. These organic substances were trapped in the cellular structures of roots as they calcified and were subsequently prevented from further decay and oxidation. A threshold of approximately 7-weight % organic carbon is needed in the insoluble residue to produce the distinct black coloration in limestone. This process occurs at the base of slightly organic-rich humic soil profiles where they interact with underlying carbonate bedrock (B–C soil horizon). Roots both physically and chemically (through acid secretion) corrode the underlying limestone and provide the calcium bicarbonate needed in the root calcification process. Specific semiarid flora have the ability to calcify their cellular structures, which could explain why blackened clasts occur at only some unconformities. This result means that the formation of blackened clasts via root calcification and entrapment of organics relies upon specific conditions of semiarid plants and climate along with organic soils. Such conditions would be restricted to a specific climate regime and when combined with the new proposed blackening mechanism herein could help explain their limited distribution and occurrences worldwide.

Elemental and strontium isotopic geochemistry of the soil profiles developed on limestone and sandstone in karstic terrain on Yunnan-Guizhou Plateau, China: Implications for chemical weathering and parent materials

The limestone and yellow sandstone soil profiles from SW China were measured for chemical and Sr isotope compositions of the bulk soils and their sequential leachates (labile, carbonate, and residue or silicate fraction), aiming to characterize the parent materials of the soils, to understand the soil weathering and formation processes, and to discuss the origin of the red residua (terra rossa). The studied yellow sandstone soil, yellow limestone soil, and black limestone soil show different pH values, SiO2 contents, Rb/Sr abundance ratios, and 87Sr/86Sr ratios. The sequential leachates of different soil types also have different 87Sr/86Sr and Ca/Sr ratios. The major chemical compositions of the studied soil profiles suggest that all the sandstone and limestone soils are developing at a stage that feldspar is exhausting and the clay minerals are changing from smectite to kaolinite and gibbsite. As compared with the red residua distributed in the karst region, the soils studied here show lower CIA values (58–84), but both higher Na2O/K2O (0.9–2.7) and Na2O/Al2O3 concentration ratios (0.07–0.26) on average, suggesting a lower weathering intensity than that of the red residua. The depth profiles of soil CIA values, Na2O/K2O and Rb/Sr ratios, and 87Sr/86Sr ratios indicate that the weathering intensity is slightly lower for the upper and higher for the deeper soils, which suggest that the sandstone and limestone soil profiles were formed through both accumulation and weathering of in situ weathering residue and input of external detritus or soil from upper land. During weathering of the soils, preferential release of Ca and retention of Sr in soil result in higher Ca/Sr ratios in both labile and carbonate fractions than those in the residue fractions of all soil profiles. The co-variations of Hf/Nb and Zr/Nb ratios, together with those Rb/Sr and 87Sr/86Sr ratios of limestone soils, sandstone soils, and the red residua, demonstrate that their parent materials are distinct, and support the point that the widely distributed red residua is originated from the weathering residua of both carbonate and silicate clastic rocks, and further weathering of the weathering residua resulted in intensive release of Si, Na, Ca and relative enrichment of Al, K and other immobile elements in the red residua.

Middle Permian Ostracods from the Akasaka Limestone, Gifu Prefecture, Central Japan

Samples of Middle Permian organic-rich black unconsolidated mud were collected from a fissure of black limestone in Kinshozan Mountain, Akasaka City, Gifu Prefecture, central Japan. Nine new species, one new genus and one new family are described herein: Ikeyaparchitidae Tanaka fam. nov., Gifuaparchites Tanaka and Maeda gen. nov., Aurikirkbya kinshozanensis Tanaka sp. nov., Gifuaparchites takagii Tanaka and Maeda sp. nov., Cavellina hashintotoi Tanaka and Maeda sp. nov., Bairdia nishiwakii Tanaka and Nishimura sp. nov., Bairdia akasakaensis Tanaka sp. nov., Bairdia oogakiensis Tanaka sp. nov., Bairdiacypris? hayasakai Tanaka sp. nov., Acratia? okumurai Tanaka sp. nov., and Acratia? hamadai Tanaka, Ono and Maeda sp. nov. This is the first report from Japan of a typical Panthalassa ostracod assemblage during the Middle Permian, and of which is characterized by typically endemic species.

Carbon-isotope and microfaunal stratigraphy bounding the Lower Aptian Oceanic Anoxic Event 1a in northeastern Tunisia

Using an integrated multidisciplinary approach the upper part of the Lower Cretaceous northeastern Tunisian Jebel Ammar sedimentary succession was examined in detail. The method applied included lithologic and microfacies analyses, micropalaeontology, sedimentology, variations in organic matter (OM) content and carbonate carbon stable isotope (δ13C) record. A major result was the identification in this sector of Tunisia of the Early Aptian (Bedoulian) OAE1a event in a biostratigraphically well-calibrated context, its location keyed to planktonic foraminiferal zones and isotopic stages.The most striking feature to the Jebel Ammar Aptian sequence is the presence of a 25 m interval of black limestones and marly limestones, of which the microfacies shows that these darker beds consist of wackestones with the presence of abundant radiolarians, a fair number of diversified planktonic and relatively rare benthic foraminifers, together an indication of a pelagic palaeoenvironment. The foraminiferal marker Schackoina (Leupoldina) cabri (still very rare at the beginning of its range) first occurs about six metres above the base of this interval, but becomes much more abundant in its uppermost part, together with the radially- elongate-chambered praehedbergellids. This “acme” of S. (L.) cabri is nearly contemporary with a radiolarian bloom. Rock Eval analyses show TOC values up to 4.59% and a Tmax ranging between 441 and 513 °C, which indicates an overmature OM. The δ13C isotope curve shows an evolution similar to those recognized worldwide. The lower part of the darker beds includes a marked shift in isotope values from −2.40 to +3.02 ‰/PDB. This increase is assumed to be equivalent to the isotopic C4 stage of Menegatti et al. (1998, Paleoceanography, 13, 530–545). The signature of the middle and upper part of the isotopic curve is tentatively interpreted as comprising the C5–C7 stages. The first occurrence of S. (L.) cabri is located in the upper part of C4 and its acme as well as the radiolarian bloom is situated within the span of the C7 stage. These results are fairly consistent, though with minor discrepancies, with what has been published from several parts of the North Tethyan margin and more particularly the Lower Aptian type area of southeastern France, where S. (L.) cabri first occurs at the C3/C4 stage boundary with an acme that begins in the lower part of C7.

Prolonged carbonate diagenesis under an evolving late cenozoic climate; Nullarbor Plain, southern Australia

The Nullarbor Plain in southern Australia, the largest areal karst on the globe, is a ~240,000km2 uplifted succession of Cenozoic marine carbonates whose surface has been exposed for 14 to 15m.y. The middle Miocene Nullarbor Limestone forms the upper surface of the plain and hosts a complex and prolonged record of meteoric diagenesis. Such a complete record offers unique insights into the effects of climate, tectonics, sea level, topography, and hydrology on the style and placement of numerous diagenetic events in flat low lying carbonate plains. Alteration took place during three broad phases comprising eight stages that are interpreted to have formed against a background of dramatic climate change. Middle Miocene phase one diagenesis took place under a humid climate and resulted in rapid mineral equilibration, calcite cementation, extensive karst development, and finally widespread lacustrine and palustrine sedimentation. Resultant palustrine sediments, especially terrestrial ooids, are now preserved at the surface and in underlying karst cavities. Latest middle Miocene to middle Pliocene phase two diagenesis occurred during a prolonged period (~8m.y.) of temperate climate and resulted in initial deep cave dissolution during low sea levels and later shallow cave development in the course of a high sea level. Onset of a somewhat more arid climate in the latest Pliocene led to the development of the modern desolate landscape of the Plain. This final phase of diagenesis involved creation of solution pits filled with black limestone pebbles, open and closed dolines with associated colluvium fill, and pervasive pedogenic calcrete. The Nullarbor Plain demonstrates that low lying carbonate plains can have low surficial erosion rates, precisely record relative sea level positions, be able to have extensive caves with extended periods of arrested calcite precipitation, and finally host extensive terrestrial ooid deposits. The importance of this comprehensive paragenetic record is its applicability to not only recognize unconformities in the rock record but to better appreciate the climate in which they formed.

Materiales de construcción incompatibles dentro de las esculturas estereotómicas de Avalos en el Valle de Caídos (Madrid, España)

The examination of the recently open pit in top of head of the La Piety sculpture of Avalos confirms that the external outer of Black Limestone Calatorao (BLC) composite is made by slabs 20 cm thick joined with gypsum mortars without aggregates. The analyses of these mortars samples performed by optical microscopy (OM), X-ray diffraction (XRD) and Environmental Scanning Electron Microscopy with Energies Dispersive Spectrometry (ESEM-EDS) techniques show hydrous admixtures composed by portlandite, mirabilite, ettringite, thaumasite and gypsum, all of them are well-know dangerous phases for a suitable preservation of the architectural heritage. The huge stereotomic structures have open access to the raining waters reaching the internal core of the sculptures made by concrete with weathered alkali-feldspar aggregates providing sodium to the surrounding sulfated environment facilitating the formation of hydrous calcium and sodium sulfates such as ettringite and mirabilite which reduces the inter-grains adherence.

Blackened bioclasts and bituminous impregnations in the Koněprusy Limestone (Lower Devonian), the Barrandian area, Czech Republic: implications for basin analysis

Carbonate reef talus facies of the Koněprusy Limestone (Pragian, Lower Devonian, Barrandian) locally exhibit widespread impregnation by organic matter resulting in a partial to complete blackening of the limestones. Two contrasting types of impregnation are recognized: blackening of individual carbonate fossils and bioclastic layers within the limestone originated very early during diagenesis. The blackening is due to finely dispersed organic matter and possibly some iron sulphides and clay minerals that selectively adhered to the outer layers of corals, bryozoans, and crinoid fragments, leaving other fossils unaltered. These darkened fossils are similar to black pebbles—i.e., reworked, dark to black limestone clasts and bioclasts that are known to occur exclusively in shallow-water zones of both ancient and modern carbonates. The alteration of fossil fragments may have taken place in very shallow-water environments, possibly those of saline and reducing back-reef lagoons or supratidal-intertidal zones, with organic matter being derived from decayed algae and microbes, or early vascular terrestrial plant material. Following the coloration, the blackened fossils were removed from their original position by waves or storms and transported into relatively deeper-water reef slope settings to form graded, “salt-and-pepper”-colored bioclastic beds. The presence of blackened fossils in the carbonate succession may point to episodic emergence and indicates a vanished vegetated siliciclastic hinterland that may once have existed to the west or south from the present-day erosive edge of the Barrandian Devonian strata. Subvertical veins cutting the Koněprusy Limestone and filled with black solid bitumen and blackened calcite resulted from a subsequent but substantially later diagenetic event, which is a testament of aqueous and petroleum fluid migration through the succession during deeper burial. Microthermometric characteristics of the aqueous inclusions embedded in vein calcite indicate that the veins were precipitated by brines of low to moderate salinity (0.5–9.5 wt% NaCl equiv.) with temperatures in the range of 87–116°C. The bitumen in the veins is epi-impsonite (Rr = 0.70–1.90%), which is interpreted as degraded petroleum residuum that experienced thermal alteration at around 120°C. The AFT modeling combined with fluid inclusion microthermometry and wider geological considerations indicate that the veins originated during the Variscan orogeny, most probably upon deep burial of the Lower Paleozoic strata in Carboniferous time.

Deterioration of the black Drenov Grič limestone on historical monuments (Ljubljana, Slovenia)

The black limestone from Drenov Gric quarry (Central Slovenia) is considered one of the most beautiful Slovenian natural stones due to its typical color. The limestone was characterized from mineralogical, chemical, and petrophysical points of view. Furthermore, deterioration phenomena of the limestone from two monuments exposed to indoor and outdoor environments were studied. In situ investigation of two monuments by means of monument mapping has identified several types of deterioration phenomena, such as granular disintegration, flaking, crumbling, efflorescences, crusts, and the presence of microorganisms. Samples were characterized using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS), X-Ray Powder Diffraction Analysis (XRD), porosity accessible to water under vacuum, capillary absorption, Mercury porosimetry (MIP), and Ar-sorption. Although very low values of porosity of the fresh stone as well as slow capillary kinetics were determined, both monuments showed severe deterioration as a consequence of the transport and precipitation of soluble salts within the stone.

Sublethal shell injuries in Late Devonian ammonoids (Cephalopoda) from Kattensiepen (Rhenish Mountains) doi: 10.1127/0077-7749/2011/0173

The ammonoids from the middle Famennian black limestone nodules at Kattensiepen (Rhenish Mountains) are known for their excellent preservation and show frequent sublethal shell damage of varying dimensions and of the finest detail. 76% of all specimens show traces of predation. This is the highest frequency of shell repairs known from the Palaezoic. While small individuals are less frequently affected, nearly all adult specimens of the species Platyclymenia annulata, Pl. subnautilina, Pleuroclymenia costata, and Prionoceras divisum display repaired injuries. Usually, the specimens show multiple areas of damage, which can be classified into several categories. Most of the points of damage are small, affecting only the margin of the aperture; they usually occur on both sides of the conch. Shell damage, which can be interpreted as bite marks are rare; the majority of shell injuries derive perhaps from arthropod attacks.

Weathering of the black limestone of historical monuments (Ljubljana, Slovenia): Oxygen and sulfur isotope composition of sulfate salts

Abstract The black limestone widely used in Slovenian monuments, particularly in the baroque architecture, is deteriorating extensively due to salt crystallization. Samples of soluble salts from two important historical monuments (in Ljubljana, Slovenia) were investigated in terms of their mineral and isotopic (S and O) compositions. Results revealed the presence of gypsum and soluble salts of the MgSO 4 · n H 2 O series, such as starkeyite (MgSO 4 ·4H 2 O), pentahydrite (MgSO 4 ·5H 2 O) and hexahydrite (MgSO 4 ·6H 2 O). Whereas black crusts and subflorescences consisted of gypsum, efflorescences appeared to be an assemblage of gypsum and MgSO 4 hydrates. Sample δ 18 O sulfate values varied from −1.9‰ to +5.5‰ vs. V-SMOW and δ 34 S sulfate values from −19.8‰ to +3.2‰ vs. V-CDT. The respective isotopic composition of analysed outdoor and indoor monument samples indicated different sources of contamination.

Determining the provenance of black limestone artifacts using petrography, isotopes and EPR techniques: the case of the monument of Bocco

This paper investigates the provenance of the black limestone of the monument known as Bocco, named after the king of Mauretania who presented Silla with this work as a sign of his submission to the power of Rome. A multi-method approach, comprising petrographic observations, carbon and oxygen isotope composition and electron paramagnetic resonance (EPR) spectra characteristics, was used for this purpose. The monument is part of a reconstruction of a rectangular base (approx. 8 × 2 m) which is likely to have served as the base for a bronze statuary group and is currently composed of six blocks of limestone whose exterior is engraved with a fine frieze. The results of the different analyses were compared with the data of a published database of the most important black limestone quarries exploited during Roman times in the Mediterranean area. The petrographic and physico-chemical parameters did not prove to be very effective in determining the provenance of the black limestone of Bocco; the isotopes result even raised some uncertainty as to whether all six blocks came from the same quarry, though this doubt was dispelled by the EPR data and, above all, by the evident petrographic similarity between them. Differences in the isotopic composition of the various blocks may be due to an in situ rock alteration process caused by interaction with an aqueous fluid. It was, however, impossible to determine with certainty the origin of the material of the stone artifact using the database available; it is possible that the black limestone of Bocco came from an ancient quarry that is likely to be located in north western Africa but has not yet been uncovered. An alternative hypothesis, according to which the limestone used for the monument of Bocco came from the ancient quarry of Ain el Ksir, one of the Tunisian quarries present in the database, is also discussed.

Chapter 47 The Bebedouro Formation, Una Group, Bahia (Brazil)

Abstract The Bebedouro Formation (Fm.) is a Neoproterozoic glaciogenic succession at the base of the Una Group on the São Francisco Craton. The glaciogenic sequence is composed of diamictites, pelites and sandstones with a variety of lithofacies that are grouped into four associations: (i) ice-contact, (ii) pro-glacial, (iii) ice-rafted and (iv) aeolian (extraglacial). Thus, the Bebedouro Fm. is interpreted to have been deposited in a shelf marine environment where glacio-proximal sedimentation dominated. It variably overlies Palaeoproterozoic/Archaean basement and Mesoproterozoic metasedimentary rocks of the Chapada Diamantina Group. The overlying carbonate succession (Salitre Fm.) is informally subdivided into five mappable units. Unit C, at the base, is composed of red argillaceous dolostone with typical negative δ 13 C signatures averaging –5.1‰ (VPDB). Unit B consists of grey laminated limestones that grade upward into grey dolostone with tepee structures of Unit B1; both have δ 13 C values around 0‰. The overlying Unit A consists of interbeds of greyish marl, shales and siltstones grading upward into massive black organic-rich limestone with oolitic and pisolitic beds of Unit A1. Positive δ 13 C signatures averaging +8.5‰ VPDB characterize the black limestones of Unit A1. 87 Sr/ 86 Sr ratios of well-preserved samples of these carbonate units show values of 0.70745 and 0.70765. These units can be correlated litho- and chemostratigraphically with formations of the Bambuí Group (São Francisco Basin) to the west.