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Erlanger geol. Abh., Sonderband

Erlanger geol. Abh., Sonderband

James N.P. & Clarke J.D. (Eds.) "Cool-water carbonates", SEPM. Spec. Publ.

Atti del 76° Congresso della Soc. Geol. It.

SEPM-IAS Research Conference

We describe a new terrestrial, plant-rich Fossil-Lagerstatte discovered at Magliano Vetere (Campania region, S Italy) in the middle Cenomanian of the Apennine Carbonate Platform. The deposit, 1.42 m thick, is made up of a thin-bedded interlayering of evenly laminated dolomicrites, lenticular dolorudites and carbonaceous seams, which contain well-preserved remains of terrestrial plants yielding cuticles and minor fishes. This study focuses on plant remains, to provide systematical, taphonomical and palaeoenvironmental considerations; nevertheless, a preliminary analysis carried out on fossil fishes has led to the identification of pycnodontids and teleosts. The Fossil-Lagerstatte retains sterile foliage-bearing shoots with epidermal features belonging to the genus Frenelopsis of the extinct conifer family of the Cheirolepidiaceae. Plant remains possibly represent a stable biotope, as floral composition displays no variation along the deposit. Nevertheless, episodes of harsh environmental conditions occurred as demonstrated by a fish mortality event and Ca-sulphate evaporite precipitation. Taphonomical considerations and sedimentological evidence from the encasing sediments suggest a parautochthonous deposition of fossil plants in a supratidal/intertidal mudflat, including a salt-marsh that was characterised by a restricted sea-water circulation, deposition of primary dolomite and episodical wildfires. The presence of xeromorphic features in Frenelopsis from Magliano Vetere could represent an adaptation to haline environment which was subjected to microtephra supply from a distant, orogenic volcanism. The facies evolution of the studied Fossil-Lagerstatte records a rapid regressive and a following slower transgressive trend, and constitutes the lowermost portion of a ~20 m thick interval characterised by several dolomitic plattenkalk, up to 1.50 m thick, which are separated by cyclically stacked peritidal limestones. We infer that: 1) the ~20 m thick, Plattenkalk-bearing interval represents a Sequence Boundary Zone in the stratigraphical record of the middle Cenomanian ApCP; 2) Frenelopsis thrived at the verge of an arid–semiarid climatical phase during a major pulse of relative sea-level fall.

This study reports an integrated facies analysis carried out on a new section from the Upper Aptian of the SE Matese Mts. (Civitella Licinio, northern Campania, S. Italy), which includes several decimeter-to-meter scale lacustrine intervals straddling a meter-scale plant-rich Plattenkalk. These intervals are assigned to the late Gargasian–early Clansayesian by their stratigraphic relationship with the upper Salpingoporella dinarica acme as well as lithologic and biostratigraphic supra-regional key-markers found in the Apennine Carbonate Platform (ApCP), including the Orbitolina Level. We infer that the monogeneric parautochthonous plant remains (Frenelopsis sp.) were deposited in a supratidal-to-paralic coastal mudflat close to a restricted, shallow-marine lagoon, at the verge of an arid–semiarid climatic phase. The Plattenkalk was rapidly replaced by persistent lacustrine lithofacies at the onset of a major climatic turnover (Glacial Trigger). The overlying shallow-marine deposits are capped by a deeply incised palaeokarstic surface and, in turn, by unconformable middle Clansayesian transgressive shallow-marine deposits. Interlayering of reliable lithologic indicators of palaeoclimate and High-Resolution Event Stratigraphic (HIRES) correlation of the Civitella Licinio succession with the astrochronologically tuned Mt. Faito reference section of the ApCP bring evidence of rapidly fluctuating hydroclimatic conditions (wet and arid phases) in the short (100 ky) and long (400 ky) eccentricity time band. HIRES and astrochronological age assignment to crucial key markers and humid/arid phases at Civitella Licinio permit to further refine the detailed stratigraphy of the Mt. Faito reference section and to assign the upper S. dinarica acme of the ApCP to a numerical age of 118.55–118.50 My. SEM and EDS analyses document common to abundant windblown volcanic particles (glass shards and sanidine crystals) throughout the Frenelopsis-rich Plattenkalk (~ 118.3 to ~ 118.2 My) and the encasing units, especially in the overlying brackish–lacustrine deposits. Palaeogeographic and palaeoclimatic reconstructions suggest that the pyroclastic material was probably transported by northeasterly trade winds from orogenic volcanic centers located within the Dinaridic–Carpatho-Balkan arc–trench system and have been supplied to the ApCP for a time span of ~ 3 My during the Late Aptian. A preliminary tephrostratigraphic correlation of the Upper Aptian volcaniclastic levels of the ApCP with the bentonite levels of the Vocontian Basin is proposed.

The stratigraphic signature of the global Late Aptian cooling episode and sea level lowstand has been investigated in the Mt. Faito section of the Apennine Carbonate Platform (ApCP) of southern Italy. Several, meter scale fine-grained limestone intervals with abundant quartz pseudomorphs after anhydrite and minor calcite pseudomorphs after gypsum are present in the middle-upper Gargasian straddling the marly Orbitolina Level, a regional key-marker correlative with part of the Fallot Oceanic Anoxic Event. The evaporite-rich intervals were deposited in a mudflat-saltern setting and together with frequent transgressive shallow-marine interlayers alternate quite regularly with lacustrine, paralic or very shallow-marine deposits suggestive of overall wetter conditions. Three-to-five couplets of cyclic arid–wet phases are thus identified. Their timing and duration, determined by an original cyclostratigraphically constrained age model tuned with the astrochronology from deep-water Tethyan reference sections, suggest fluctuating hydroclimatic conditions (arid/semiarid vs. wet phases) over time scales as brief as 100 and 400 ky. They are considered to reflect astronomically-induced latitudinal migrations of intertropical climate belts. A secular climate shift from arid to humid conditions, supra-regionally correlatable across the Upper Gargasian of the Tethyan realm, is dated at ~ 118.1 My. It corresponds to the onset of persistent lacustrine deposits on the partially emerged ApCP and of abundant river-borne supply of siliciclastics along the opposing Tethyan margin. The observed climate fluctuations occurred during a major ApCP subaerial exposure which lasted for ~ 4.4 My. Precise supra-regional correlations suggest that the platform exposure was glacioeustatic in origin and coeval with a long-lived Late Aptian cooling episode which interrupted the mid-Cretaceous greenhouse. Biostratigraphic and astrochronological tuning from the ApCP indicates that the glacioeustatic lowstand terminated in the earliest Albian, just above the O. reicheli key-marker.

We show that the global-scale environmental perturbations leading to the Selli OAE1a were clearly recorded in the middle Bedoulian Apulia carbonate platform at Borgo Celano, in the western Gargano Promontory (Southern Italy). The studied section (Bari Limestones), which is 72.45 m thick and spans the Late Barremian p.p. -latest Early Aptian time interval, has been logged with an average resolution of 3 samples per metre for chemostratigraphic analyses and up to 7 samples per metre for facies analysis in the aim of detailed paleocologic and paleoceanographic investigation. It contains the complete biosedimentary and chemostratigraphic record across the Selli OAE1a, as suggested by a consistent match of the observed isotope excursions with those documented in the Cismon pelagic reference section and the lack of significant non-depositional or erosional hiatuses within the chemostratigraphic Selli level: biostratigraphic and sedimentary-diagenetic analyses document a continuous record of fully subtidal conditions. Furthermore, the Borgo Celano section allows correlation of the shallow- and deep-water records without intervening stratigraphic breaks. Upper Barremian-Lower Bedoulian, chlorozoan-type carbonates showing subtidal-intertidal Milankovitch-type cyclicities characterize the lower part of the Borgo Celano section (C2 pro parte isotopic segment). Starting from the latest C2 segment, a remarkable Crisis Interval (CI) about 4 m thick shows an increasing frequency of bivalves ( Chondrodonta and requieniids), the disappearance of green algae and a reduced diversity of foraminiferal assemblages (foramol-type carbonates). This interval is sharply overlain by an interval, about 3.70 m thick, that is largely dominated by “out-of-balance” microbial limestones almost devoid of metazoans, apart from sparse, small-sized requieniids and Chondrodonta , which accompanies the C3-middle C4 isotope segment. It is interpreted to reflect a sharp hyperthermal and acidification event induced by excess p CO 2 . Starting from the upper C4 segment, less severe but still threatening environmental conditions permitted the deposition throughout the lower C5 segment of peculiar shallow-water tropical-like carbonates, which are dominated by oncoidal floatstones and microbial wackestone/packstone emphasizing the enduring influence of benthic cyanobacteria during the Selli OAE1a. Upsection guilds are dominated by foraminiferal and peloidal wackestones/packstones with sparse bivalves and green algae (upper C5-lowermost C7 isotope segments). Similarly to other carbonate platforms of the central Tethyan Realm (e.g., Apennine and Adriatic), the resilience of the Apulia carbonate platform inner shelf to the environmental perturbations that led to the coeval drowning of its margin, the starvation of its slope and to the deposition of black shales in the bounding Ionian basin is a striking supraregional feature. The inception of the resilience of the Apulia carbonate platform inner shelf is coincident with the lithostratigraphic boundary in between the Borgo Celano and Chondrodonta and requieniids members of the Bari Limestones and physically corresponds in the field with the base of a significant, 1 m thick, Chondrodonta -rich marker bed. These observations confirm the value of routinely applied field and laboratory studies for precise chemostratigraphic and bio-chronostratigraphic correlations on a regional scale. Furthermore, chemostratigraphic data presented here corroborate recent paleoceanographic and stratigraphic models proposed for the Lower Aptian across the transition between the Apulia carbonate platform and the bounding Ionian basin, and provide further elements for regional reconstructions of historical patterns.

The stratigraphic and biotic signatures of severe environmental changes across the late Early Aptian Oceanic Anoxic Event (OAE1a) in central Tethyan settings have been investigated in the almost undeformed Apulia Carbonate Platform Margin-Ionian Basin system (ACPM-IB) exposed in the Gargano Promontory (southeastern Italy). The nature of the observed Lower Aptian biofacies shifts within the investigated carbonate system are analyzed using an integrated biostratigraphic approach, based on ammonite-calibrated orbitolinids and caprinids coupled with the published δ 13 C and δ 18 O record of coeval pelagic sections of the Ionian basin (Coppitella, eastern Gargano, and Paliambela, northwestern Greece). Detailed field analysis of facies and tracing out of key biosedimentary and chemostratigraphic markers of the Lower Aptian have elucidated the evolution of the platform margin and allowed integrated correlations across the Gargano margin to basin transition. It is shown here that the global-scale environmental changes leading to the OAE1a event (i.e., fluctuations of surface-ocean temperature, available trophic resources and, above all, p CO 2 ) are matched consistently by significant shifts of the biotic associations inhabiting the ACPM. The onset of greenhouse , mesotrophic conditions in the surface ocean undergoing an increasing acidification by CO 2 excess favored the rapid spread of calcite shelled, filter feeding, eurytopic opportunist organisms (chondrodontids, ostreids, chaetetids sponges, along with minor bryozoans) as well as echinoids and orbitolinids (foramol productivity mode); this change is recorded by the deposition of a 4–6 m Crisis Interval (CI) that sharply overlies the “Urgonian”-type, rudist-rich platform margin complex (Montagna degli Angeli Limestones) formed from predominantly aragonite shelled, stenotopic organisms (mostly caprinid rudists, with minor corals and Dasycladales and Bryopsidales green algae) (chlorozoan productivity mode). The CI heralded the incipient drowning of the ACPM which occurred immediately after the deposition of a hothouse “out of balance” brachiopod ( Orbirhynchia nadiae )-cyanobacteria association (microbial productivity mode). The biostratigraphically constrained CI and the related drowning of the ACPM have been physically correlated with specific chemostratigraphic segments of the δ 13 C carb curve that is available for the facing, proximal Ionian Basin. The early (earliest ?) Late Bedoulian, greenhouse CI (early D. deshayesi – early P. cormyi zones) was deposited during the late C2 interval, whereas the early Late Bedoulian, hothouse “out-of-balance” guild and the ACPM drowning (early deshayesi zone) accompanied the subsequent negative excursion and culmination, respectively, at the very base of the Chemostratigraphic Selli Level (CSL) (latest C2 and C3 interval). These correlations permit regional to global interpretations of historical patterns and explanatory paleoeanographic and paleoecologic hypotheses; furthermore, they suggest that the Apulia shallow-water ecosystem reacted to the environmental disruptions linked with the OAE1a sooner than that of the facing open ocean. The onset of the drowning event was synchronous with the hothouse -induced bloom of the “out of balance” brachiopod-cyanobacteria association that occurred simultaneously with the pronounced negative excursion of the δ 13 C carb curve. This suggests a cause-and-effect relationship with the sudden environmental perturbations linked with the injection into the atmosphere-hydrosphere system of 13 C-depleted CO 2 . The numerical age model of the major biotic and stratigraphic events at the Lower Aptian ACPM, along with their inferred genetic processes call for different timings and causal mechanisms associated with platform demise in northern and central Tethyan settings.

Drowning successions which cap carbonate platforms and flanks bear palaeoenvironmental information which is useful for genetic stratigraphy; they constitute predictive key-markers in regional to global correlations. An Early Cretaceous platform-to-basin transition has been investigated in Apulia (southern Italy) and two drowning unconformities, dated as early Valanginian and late early Aptian, have been documented. They occur at the base of thick pelagic tongues wedging toward the platform and mark the base of two depositional sequences showing distinct transgressive–regressive cycles. Timing of drowning processes, based on biostratigraphy and dynamic stratigraphy, allows the correlation of unconformities with global-scale palae- oceanographic events marked, among others, by positive spikes of well-established δ13C curves. Drowning signatures in the Apulia carbonates fit the stratigraphic, palaeoecological and possibly geochemical evidence found in global records at the same stratigraphic levels. Moreover, it is proposed that the observed drowning events were caused by palaeoceanographic crises affecting factory productivity.

Huge megabreccias occur at the eastern margin of the Cretaceous Apulia Carbonate Platform (Gargano Promontory, southern Italy). Their stratigraphic and genetic meaning are controversial in the debated geological evolution of the Apulia Platform. New stratigraphic analyses have revealed that three distinct megabreccia levels occur within the coarse debrites that were previously interpreted to be the result of repeated collapses of a scalloped platform margin during the late Albian–Cenomanian. Each level has peculiar chronostratigraphic distribution, geometry, composition and genetic features. They are the Posta Manganaro Megabreccias (late early Aptian to late Albian pp.), Monte S. Angelo Megabreccias (early–middle Cenomanian) and Belvedere di Ruggiano Megabreccias (middle Turonian). These deposits overlie regional, tectonically enhanced unconformities of late early Aptian, late Albian and late Cenomanian age. These megabreccias, which were formed, respectively, during drowning, prograding and exposure events of the Apulia Platform, reflect important turning points in its Cretaceous geodynamic evolution.

Impressive megabreccia levels that were deposited mainly on by-pass, steep margins of carbonate platforms have usually been linked to syn-sedimentary tectonics and, more recently, to other mechanisms including sea-level low-stands. The Apulia Carbonate Platform, a main palaeogeographic domain of the Mediterranean Tethys, is characterized by huge megabreccia bodies which were deposited along its flank at various intervals during the Cretaceous. This paper deals with the stratigraphy and the genetic meaning of a peculiar early Cretaceous megabreccia level occurring on the Apulia platform margin exposed in the southern Gargano Promontory (southern Italy). The stratigraphic implications of the megabreccias within the tectonic evolution of the Apulia platform are also discussed along with a comparison with previous models. A sub-vertical blind contact separates a tectonized Berriasian shallow-water succession (Lower S. Giovanni Rotondo Limestones) from a thick rock-fall megabreccia succession pertaining to the Late Aptian–Albian Posta Manganaro Megabreccias. The contact, which is interpreted as a syn-sedimentary fault plane, is sealed by undeformed late Albian slope bioclastic sediments (lower Monte S. Angelo Rudist Limestones). Tensile tectonics downfaulted an external sector of the platform generating an articulated, steep, retreating margin. Field analysis and stratigraphic reconstructions show that the syn-tectonic wedge-shaped megabreccias partly filled an asymmetric depocenter (half-graben) resulting from the activity of a normal fault system located behind the previous prograding, low-energy, leeward margin (Montagna degli Angeli Limestones). Nevertheless, syn-sedimentary tectonics severely conditioned the composition, depositional processes and dispersal pattern of sediments supplied towards the original platform-to-basin transition (Upper Mattinata Bioclastic Limestones). This stratigraphic framework is believed to reflect a local response of the sedimentation to a late Early Cretaceous syn-sedimentary tectonic phase representing an important turning point in the evolution of the Apulia Carbonate Platform. It is supposed here that the observed tectonics, which are assumed to be related to the onset of the Austrian orogenic phase at the distant Adria plate margin, could only control the extension of the down-faulted platform. More probably, its drowning was decisively caused by the coeval global-scale Selli palaeoceanographic event (OAE 1a), which reduced the healing power of the platform by poisoning the shallow-water, sediment-donor communities. As a major causal mechanism, the OAE Selli event controlled the development of a rapid facies evolution during the late Early Aptian within the shallow-water successions of the Apulia and many other Tethyan carbonate platforms through the onset of nutrient-enriched water conditions. In this light, a stratigraphic correlation between the bases of the late Early Aptian shallow-water Orbitolina Level and the basinal Fucoid Marls is proposed. Their deposition within distinctive tracts of many platform-to-basin transitions on the southern Tethyan margin is viewed as the response of a previously pure carbonate sedimentation to the onset of environmental control on a global scale during the late Early Aptian.

Erlanger geol. Abh., Sonderband

Cisplatin and carboplatin are both active in ovarian cancer with different toxicity profiles; thus, dose intensification may be possible by combining them. The aim of the present study was to determine the maximum tolerated dose of carboplatin combined with fixed doses of cisplatin and cyclophosphamide without and with support of lenograstim. Cisplatin (60 mg/m(2)), cyclophosphamide (600 mg/m(2)) and carboplatin (starting dose 200 mg/m(2)) were given on day 1 every 3 weeks for 4 cycles. Escalated dose levels for carboplatin were planned by increments of 50 mg/m(2) per level. Lenograstim (L) (150 mu g/m(2)/day subcutaneously) was given in case of grade 4 leukopenia (levels without support) or from day 5 up to leukocyte >10,000/mm(3) after nadir (levels with support). Four levels were studied (200, 250, 250 + lenograstim, 300 + lenograstim) with 7, 7, 8, and 7 patients enrolled, respectively. Unacceptable toxicity was induced in 1 patient at the level I (grade 4 thrombocytopenia), in 4 patients at the level 2 (2 prolonged grade 2 leukopenia, 1 grade 4 leukopenia with concomitant grade 4 thrombocytopenia and 1 grade 4 thrombocytopenia), in 1 patient at the level 2 + L (grade 4 thrombocytopenia) and in 3 patients at the level 3 + L (3 grade 4 thrombocytopenia). Thus, 200 mg/m(2) and 250 mg/m(2) were defined as carboplatin MTDs without and with lenograstim support, respectively. Median total platinum (cisplatin + 1/4 carboplatin) delivered dose-intensities were 33, 32, 38 and 44 mg/m(2)/week at the four levels, respectively. Hematological toxicity was overall mild. In no case was febrile neutropenia recorded. Grade 4 thrombocytopenia was always transient and never symptomatic. Grade 3 vomiting was the only severe non-hematological toxicity reported in 5 patients. Out of 16 patients with measurable disease, 11 objective responses were obtained (5 complete and 6 partial) for an overall response rate of 69% (95% exact CL 41-89%). Recommended dose of carboplatin is 200 mg/m(2) without and 250 mg/m(2) with support of lenograstim when combined with cisplatin 60 mg/m(2) and cyclophosphamide 600 mg/m(2). Dose limiting toxicity is persistent leukopenia without and grade 4 thrombocytopenia with support of lenograstim.