Utz Kramar

200 years of mining activities at La Paz/San Luis Potosí/Mexico — Consequences for environment and geochemical exploration

Abstract The AgPbZnCuAu mining district of Santa Maria de La Paz has been extensively exploited for approximately 200 years. Consequences of these activities are several deposits of tailings with high As and heavy metal concentrations, which are completely unstable. The climate is semiarid and as the dumps have no protective cover, material from the dumps is dispersed by strong winds. It is also washed out during seasonally heavy rainfalls. By these processes approximately 100 km 2 of surrounding have been contaminated by dump material. The As and heavy metal content of the soils was determined as well as their level in crops (Zea Maize) from agricultural lands in the vicinity of the dumps. In the direction of prevailing winds concentrations up to 1000 ppm Zn, 400 ppm Pb, 16 ppm Cd, 550 ppm Cu and 300 As have been detected in top soils. Using fuzzy cluster analysis the different contamination sources could be identified. Grains of corn from contaminated sites showed no critical concentrations, but leaves which are also used tor fodder, have As-concentrations up to 20 ppm.

The cretaceous-tertiary transition on the shallow Saharan Platform of southern tunisia

Abstract A multidisciplinary approach to the study of a K/T boundary section on the Saharan Platform based on planktic and benthic foraminifera, calcareous nannofossils, lithology, stable isotopes, mineralogy and geochemistry reveals a biota stressed by fluctuating hyposaline, hypoxic littoral and nearshore environments, productivity changes, and a paleoclimate altering between seasonal warm to temperate and warm/humid conditions. Benthic formaminifera indicate that during the last 300 kyr of the Maastrichtian (CF1, Micula prinsii) deposition occurred in a inner neritic (littoral) environment that shallowed to a near-shore hyposaline and hypoxic environment during the last 100–200 kyr of the Maastrichtian. These conditions were accompanied by a seasonal warm to temperate climate that changed to warm/humid conditions with high rainfall, by decreasing surface productivity, and significantly decreasing planktic and benthic foraminiferal species richness. The K/T boundary is marked by an undulating erosional contact overlain by a 10 cm thick sandstone layer which is devoid of any exotic minerals or spherules. Their absence may be due to a short hiatus and the fact that the characteristic clay and red layer (zone P0) are missing. During the earliest Danian (Pla), low sea-levels prevailed with continued low oxygen, low salinity, high rainfall, high erosion and terrigenous sediment influx, accompanied by low diversity, low oxygen and low salinity tolerant species. These environmental conditions abruptly ended with erosion followed by deposition of a phosphatic siltstone layer that represents condensed sedimentation in an open (transgressive) marine environment. Above this layer, low sealevels and a return to near-shore, hyposaline and hypoxic conditions prevailed for a short interval [(base of Plc(2)] and are followed by the re-establishment of normal open marine conditions (inner neritic) comparable to the late Maastrichtian. This marine transgression is accompanied by increased productivity, and the first diversified Danian foraminiferal assemblages after the K/T boundary event and represents the return to normal biotic marine conditions. Though the K/T Seldja section represents one of the most shallow marginal sea environments studied to date for this interval, it does not represent isolated or atypical conditions. This is suggested by the similar global trends observed in sea-level fluctuations, hiatuses, as well as faunal assemblages. We conclude that on the Saharan platform of southern Tunisia, longterm environmental stresses beginning 100–200 kyr before the K/T boundary and related to climate, sea-level, nutrient, oxygen and salinity fluctuations, were the primary causes for the eventual demise of the Cretaceous fauna in the early Danian. The K/T boundary bolide impact appears to have had a relatively incidental short-term effect on this marine biota.

Advances in energy-dispersive X-ray fluorescence

Abstract Recently, two new instruments for X-ray fluorescence analysis (XRF) with interesting features for geochemical applications came to the market. Both instruments were designed to improve the peak to background ratio, the principal factor limiting the sensitivity of XRF. Total reflection XRF (TXRF) was designed to analyse extremely small sample amounts. An instrument, using polarised X-rays (P-XRF) for excitation, is designed to reduce scattered background in spectra of bulk samples. The performance of both instruments was compared with conventional XRF-methods and ICP/MS. Results for GXR-1, GXR-2, GXR-3, GXR-4 and GXR-6 obtained with TXRF and P-XRF are in good agreement with literature data. The effective amount of sample, analysed by TXRF was 200 μg only and detection limits of ~ l μg/g were achieved. P-XRF shows considerable improved detection limits (0.25–0.5 μg/g) for bulk samples for elements with atomic numbers 42–51 (Mo-Sb) compared with conventional XRF-methods.

Trace elements, stable isotopes, and clay mineralogy of the Elles II K–T boundary section in Tunisia: indications for sea level fluctuations and primary productivity

Abstract Trace elements and stable isotopes in bulk rocks and foraminifera, bulk rock and clay mineral compositions, are used as palaeoproxies to evaluate sea level fluctuations, climatic changes and variations in primary productivity across the K–T transition at Elles II in Tunisia from 1 m (∼33 kyr) below to 1 m (∼70 kyr) above the K–T boundary. Results on clay minerals, major and trace elements, stable isotopes in bulk rock samples (e.g. Ca, Cu, Zn, Rb, Sr, Zr, Ba, δ13C and δ18O), and in foraminifera (Sr/Ca, δ13C, δ18O) indicate that the latest Maastrichtian (last ∼33 kyr) in Tunisia was marked by a relatively warm, but humid climate and a rising sea level. The transgressive surface is marked by deposition of a foraminiferal packstone just below the K–T boundary followed by maximum flooding across the K–T boundary (red layer and black clay layer). Humid warm conditions accompanied the maximum flooding, along with increased total organic carbon values and rapidly decreasing primary productivity. At the K–T boundary, an impact event (Ir anomaly, Ni-rich spinels, spherules) exacerbated already stressed environmental conditions leading to the mass extinction of tropical planktic foraminifera. Increasingly more humid conditions prevailed within the lowermost Danian Zone P0 (∼50 kyr) culminating in a sea level lowstand near the top of P0. A slow recovery of the ecosystem in Zone P1a coincided with a rising sea level and gradually less humid climatic conditions.

Mapping of trace metals in urban soils

Spatial distribution maps depicting the concentrations of antimony, lead, tin, copper and zinc, and the presence of land-use units were generated for Mühlburg, a district of the City of Karlsruhe, Germany. The influence of the spatial land-use structure on the distributions of the element concentrations is statistically evaluated and discussed. The variography for Mühlburg shows an average range of 200-400 m for the spatial correlations of Sb, Pb, Sn and Zn. The variograms of Pb and Zn are characterised by hole effects at 300 m distances, i.e. the result of repeated stronger spatial correlations for certain distances between the sample sites. Most probably, this is an effect of the typical urban structure of streets, buildings, green spaces, and industry. Kriging method was used for the interpolation of Sb, Pb, Sn and Zn concentrations. Only Cu does not show a spatial correlation. In this case, the interpolation was carried out with a smoothed triangulation routine. Pollution plumes of point sources such as lead works, a bell foundry and a coal-fired thermal power station superimpose the more diffuse pollution from traffic, household heating processes, waste material disposal, etc. The trace element concentrations in soils of housing areas increase with the age of the developed area. Industrial areas show the highest level of pollution, followed by housing areas developed before 1920, traffic areas, allotments, housing areas developed between 1920 and 1980, parks and sports areas, cemetery and housing areas developed after 1980.It is demonstrated that spatial distribution maps of element concentrations indicate potential emission sources of harmful substances, even if the emission itself or the direct surrounding soil have not been analysed. The analytical tools presented enable town planners to discern areas of higher soil pollution. Detailed investigations can be focussed on these areas to evaluate the possibilities of soil usage and transfer. These methods enable one to manage urban soil in an adequate manner. For these reasons, the methods demonstrated support an urban environmental impact assessment and are a part of a sustainable urban soil management.

Late Maastrichtian paleoclimatic and paleoceanographic changes inferred from Sr/Ca ratio and stable isotopes

Abstract Milankovitch-scale cycles can be recognized in high-resolution δ13C, δ18O, Sr/Ca, mineralogical, and magnetic susceptibility data in hemipelagic sediments that span the last 700 kyr of the Maastrichtian at Elles, Tunisia. Oxygen isotope data reveal three cool periods between 65.50 and 65.55 Ma (21.5–23.5 m), 65.26 and 65.33 Ma (8–11 m), and 65.04 and 65.12 Ma (1.5–4 m), and three warm periods between 65.33 and 65.38 Ma (12–16 m), 65.12 and 65.26 Ma (4–8 m), and 65.00 and 65.04 Ma (0–1.5 m). The cool periods are characterized by small surface-to-deep temperature gradients that reflect intensive mixing of the water column. The surface-to-deep Sr/Ca gradient generally correlates with the oscillating ΔT trend (temperature difference between surface and bottom waters). The carbon isotope composition of planktonic foraminifera indicates a continuous decrease in surface bioproductivity during Late Maastrichtian. Decreasing Δ13C values (difference between the δ13C values of surface and bottom dwelling foraminifera) and the carbon isotope ratios of the planktonic species at the onset of gradual warming at 65.50 Ma reflect a reduction in surface productivity as a result of decreased upwelling that accompanied global warming and possibly increased atmospheric pCO2 related to Deccan Trap volcanism. Time series analysis applied to magnetic susceptibility, δ18O, and Sr/Ca data identifies the 20 kyr precession, 40 kyr obliquity, and 100 kyr eccentricity Milankovich cycles.

Paleoenvironment across the Cretaceous-Tertiary transition in eastern Bulgaria

The Cretaceous-Tertiary (K-T) transition in eastern Bulgaria (Bjala) was analyzed in terms of lithology, mineralogy, stable isotopes, trace elements, and planktic foraminifera. The sequence represents a boreal-Tethyan transitional setting, spans from the last 300 k.y. of the Maastrichtian (zone CF1) through the early Danian (zones P0-Plc), and contains several short hiatuses. It differs from low-latitude Tethyan sequences primarily by lower diversity assemblages, pre-K-T faunal changes, a reduced K-T dC shift, and the presence of two clay layers with platinum group element anomalies. The first clay layer marks the K-T boundary impact event, as indicated by an iridium anomaly (6.1 ppb), the mass extinction of tropical and subtropical planktic foraminifera, and cooling. The second clay layer is stratigraphically within the upper Parvularugoglobigerina eugubina (Pla) zone and contains a small Ir enrichment (0.22 ppb), a major Pd enrichment (1.34 ppb), and anomalies in Ru (0.30 ppb) and Rh (0.13 ppb) that suggest a volcanic source. Adatte, T., Keller, G., Burns, S., Stoykova, K.H., Ivanov, M.I., Vangelov, D., Kramar, U., and Stüben, D., 2002, Paleoenvironment across the Cretaceous-Tertiary transition in eastern Bulgaria, in Adatte, T., Koeberl, C., and MacLeod, K.G., eds., Catastrophic Events and Mass Extinctions: Impacts and Beyond: Boulder, Colorado, Geological Society of America Special Paper 356, p. 231–251. *E-mail: thierry.adatte@geo.unine *Present address: Department of Geosciences, 233 Morril Science Center, University of Massachusetts, Amherst, Ma 01003. INTRODUCTION Cretaceous-Tertiary (K-T) boundary studies have often concentrated on documenting the geochemical anomalies and the pattern of planktic foraminiferal species extinctions immediately below and above this boundary event in low latitudes (Fig. 1). Most of these studies reveal a major mass extinction of all tropical and subtropical species at or near the K-T boundary and iridium anomalies that have been variously attributed to the sole effects of an impact (e.g., Smit, 1990; D’Hondt et T. Adatte et al. 232 Figure 1. Paleolocations of Cretaceous-Tertiary (K-T) boundary sections that have good biostratigraphic control and relatively continuous sediment records. Note that current knowledge of K-T boundary event is primarily from sections in low-latitude northern Tethys, including Mexico, Spain, and Tunisia. Few K-T sections are currently known from middle and high latitudes. Bjala sections of Bulgaria provide critical information of this event in transitional environment between northern Tethys and boreal sea. Inset shows satellite photograph of Black Sea coast with Bjala locality, and simplified tectonic map of South Carpathian arc (modified from Preisinger et al., 1993a; Rögl et al., 1996). Ocean basins are white, continental platform is gray, continents are black (modified from MacLeod and Keller, 1991a). ODP is Ocean Drilling Program, DSDP is Deep Sea Drilling Project. al., 1996; Apellaniz et al., 1997; Olsson, 1997), or long-term environmental changes followed by an impact (e.g., Keller, 1988, 1996; Luciani, 1997; Abramovich et al., 1998). Few studies have attempted to evaluate some aspects of the K-T event on a regional or global scale, including studies of hiatus distributions (MacLeod and Keller, 1991a, 1991b), species survivorship, and records of pre-K-T extinctions (MacLeod and Keller, 1994; Abramovich et al., 1998; Pardo et al., 1999). The absence of more comprehensive integrated summary studies is largely because most K-T sections are separated by large distances (Fig. 1), and direct comparisons across latitudes are difficult due to little known regional effects, particularly in middle to high latitudes. The mass-extinction pattern of planktic foraminifera in high latitudes is quantitatively documented from a few localities in the southern ocean (e.g., Deep Sea Drilling Project [DSDP] Sites 690 and 738, Keller, 1993) and Northern Hemisphere (e.g., Denmark and Kazakhstan, Schmitz et al., 1992; Keller et al., 1993; Pardo et al., 1999; Fig. 1). These data suggest a diminished mass-extinction effect compared with low latitudes primarily because tropical and subtropical species are absent and assemblages are dominated by small species that tolerate environmental fluctuations, including Guembelitria cretacea, G. danica, G. trifolia, G. dammula, Heterohelix globulosa, H. navarroensis, H. planate, Hedbergella holmdelensis, H. monmouthensis, and Globigerinelloides aspera (MacLeod and Keller, 1994). Most of these species are also observed in Danian sediments of low latitudes, and between 4 and 12 species have been considered as survivors (e.g., Canudo, 1997; Keller, 1997; Masters, 1997; Olsson, 1997; Orue-etxebarria, 1997; Smit and Nederbragt, 1997; Luciani, 1997). Stable isotopes measured on some of these species in Danian sediments have been found to record Danian values, also suggesting that they are survivors (Barrera and Keller, 1994; Keller et al., 1993; MacLeod and Keller, 1994). Huber (1996) attributed the presence of these species in Danian sediments to reworking, citing relatively unPaleoenvironment across the Cretaceous-Tertiary transition in eastern Bulgaria 233 changed stable isotope values of Globigerinelloides multispinus across the K-T boundary at Site 738 as evidence (see also Huber et al., 1994; Keller and MacLeod, 1994). We do not argue that Danian sediments may contain reworked Maastrichtian species, as indeed any sedimentary interval may, but we disagree that the consistent presence of these small species in sections across latitudes can be attributed to reworking, and that the Danian isotopic signal of species can be explained as artifact of reworking. We suggest that these species are K-T survivors for two major reasons. (1) They are ecological generalists able to survive the K-T environmental changes, whereas the larger complex tropical and subtropical species are not. (2) Environmental effects of the K-T impact diminished into higher latitudes, as suggested by dC values that indicate a relatively minor decrease in primary productivity in high latitudes as compared with low latitudes (e.g., Keller and Lindinger, 1989; Zachos et al., 1989; Keller et al., 1993; Barrera and Keller, 1994). Environmental changes and the nature of the mass extinction between the extremes of the northern boreal sea (Denmark and Kazakhstan) and the low-latitude Tethys are still relatively unknown. This shortcoming is because K-T sequences with nearly continuous sedimentation and good microfossil preservation are very rare and currently only reported from Bjala in eastern Bulgaria (Preisinger et al., 1993a, 1993b; Rögl et al., 1996). We chose to study the Bjala sections in order to obtain a quantitative record that would allow evaluation of the mass extinction and environmental changes in this transitional environment and permit comparison with both lowand highlatitude records. To this end we analyzed the biostratigraphy, stable isotopes, bulk rock compositions, clay minerals, trace element abundances, and quantitative changes among planktic foraminiferal assemblages. PREVIOUS STUDIES IN BULGARIA The K-T boundary in eastern Bulgaria was first recognized on the basis of planktic foraminifera from boreholes (Juranov and Dzhuranov, 1983), and a subsequent search for outcrops in the vicinity of Bjala revealed a relatively complete K-T transition based on calcareous nannoplankton (Stoykova and Ivanov, 1992; Ivanov and Stoykova, 1994; Sinnyovsky and Stoykova, 1995). Geochemical and planktic foraminiferal data were given in Preisinger et al. (1993a, 1993b) and Rögl et al. (1996). In those publications the K-T biostratigraphy is based primarily on calcareous nannoplankton, the most complete sequences containing the Micula prinsii zone in the topmost 14– 17 m of the Maastrichtian, and zone NP1, spanning the basal 4 m of the Danian. The K-T boundary was recognized on the basis of a 2–3-cm-thick dark clay layer containing an Ir anomaly of 6.1 ppb (Preisinger et al., 1993a). A second, smaller Ir and Co enrichment was recognized 7–8 cm above this interval in a marly limestone layer, and was considered reworked. The first Danian nannofossil species Biantholithus sparsus and Cyclagellosphaera alta are reported from this marly limestone layer that also contains blooms of Thoracosphaera operculata and Braarudosphaera bigelowii (Preisinger et al., 1993a, 1993b; Ivanov and Stoykova, 1994). Rögl et al. (1996) reported the range of four Maastrichtian planktic foraminifer species (Hedbergella monmouthensis, Guembelitria cretacea, Racemiguembelina intermedia, Abathomphalus mayaroensis) and six undifferentiated genera in the 90 cm below the K-T boundary. They observed the first Danian species (Woodringina hornerstownensis, W. claytonensis, Globoconusa predaubjergensis) 2 cm above the base of the K-T clay layer. GEOLOGICAL SETTING AND LOCATION The studied outcrops are exposed along the Black Sea coast, close to the town of Bjala (Fig. 1). Tectonically, this area belongs to the Luda Kamchia unit of the Stara Planica zone, which is part of the High Balkan mountain range (Ivanov, 1983, 1988). The Bjala area was a well-differentiated basin characterized by rhythmic sedimentation of hemipelagic marls and marly limestones during the Late Cretaceous. Deposition of more detrital and turbiditic sediment began in the early Paleocene and appears to reflect the first pulse of alpine tectonic activity. Subsequent tectonic activity resulted in the numerous nappes, thrust folds, and faults that can now be observed in the area (Ivanov, 1988). Bjala-1 is located 800 m north of a trench leading down from the town of Bjala to the beach (Figs. 1 and 2). This section corresponds to the Bjala 2b section of Ivanov and Stoykova (1994) and Preisinger (1994), and can be observed laterally over 15–20 m. This locality represents the best exposure and structurally least disturbed outcrop of the K-T tr

Anthropogenic Pb contamination of soils, southwest Germany

Abstract Non-autochthonous Pb in soil profiles has been identified by its characteristic isotope patterns, and the degree of mobility of the Pb contamination can be estimated using these isotope patterns.

Late Maastrichtian and K/T paleoenvironment of the eastern Tethys (Israel): mineralogy, trace and platinum group elements, biostratigraphy and faunal turnovers

The late Maastrichtian to early Danian at Mishor Rotem, Israel, was examined based on geochemistry, bulk rock and clay mineralogies, biostratigraphy and lithology. This section contains four red clay layers of suspect impact or volcanic origin interbedded in chalk and marly chalks. PGE anomalies indicate that only the K/T boundary red layer has an Ir dominated PGE anomaly indicative of an impact source. The late Maastrichtian red clays have Pd dominated PGE anomalies which coincide with increased trace elements of terrigenous and volcanogenic origins. Deccan or Syrian-Turkey arc volcanism is the likely source of volcanism in these clay layers. Glauconite, goethite and translucent amber spherules are present in the clay layers, but the Si-rich spherules reported by Rosenfeld et al. [l989] could not be confirmed. The absence of Cheto smectite indicates that no altered impact glass has been present. The red layers represent condensed sedimentation on topographic highs during sea level highstands. In the Negev area, during the late Maastrichtian, the climate ranged from seasonally wet to more arid conditions during zones CF3 and CF2, with more humid wet conditions in the latest Maastrichtian zone CF1 and in the early Danian, probably linked to greenhouse conditions. Planktic foraminifera experienced relatively high stress conditions during this time as indicated by the low species richness and low abundance of globotruncanids. Times of intensified stress are indicated by the disaster opportunist Guembelitria blooms, which can be correlated to central Egypt and also to Indian Ocean localities associated with mantle plume volcanism. Marine plankton thus support the mineralogical and geochemical observations of volcanic influx and reveal the detrimental biotic effects of intense volcanism.

The Cretaceous–Tertiary (K/T) boundary transition at Coxquihui, state of Veracruz, Mexico: evidence for an early Danian impact event?

The Cretaceous – Tertiary (K/T) transition at Coxquihui, State of Veracruz, Mexico, differs from all other Mexican sections by the presence of two spherule-rich layers interbedded with pelagic marls, but lacking the characteristic siliciclastic deposit. A 1-cm-thick spherule layer is located at or near the K/T boundary and contains a small Ir enrichment of 0.2 ng/g (background values , 0.1 ng/g). The precise stratigraphic position of this spherule layer with respect to the K/T boundary is uncertain due to a hiatus that spans from to the lower Parvularugoglobigerina eugubina Zone (Pla) to the upper part of the latest Maastrichtian Plummerita hantkeninoides Zone. A 20-cm-thick marl layer separates the first spherule layer from a 60-cm-thick second spherule layer, which is also within Zone Pla. An Ir enrichment of 0.5 ng/g is present in the overlying 10-cm-thick marl layer. The stratigraphic positions of these two spherule layers and Ir enrichments are strikingly similar to those found at two other localities, Beloc in Haiti and Caribe in Guatemala, and suggest the possibility of an early Danian impact event. q 2002 Elsevier Science Ltd. All rights reserved.