DEMISE OF CARNIAN PLATFORMS: LARGE SCALE GEOMETRIES

Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2012-2013
DEMISE OF CARNIAN PLATFORMS: LARGE SCALE GEOMETRIES AND MECHANISMS
OF PRECIPITATION
Ph.D. candidate: GIOVANNI GATTOLIN, III course
Tutor: Dr. NEREO PRETO
Co-tutor: Dr. ANNA BREDA
Cycle: XVI
Abstract
During the Late Triassic, a climate change known as the Carnian Pluvial Event resulted in a major crisis for carbonate
producers. The change in carbonate production led to a dramatic modification in depositional geometries. Steep clinoforms of
the high relief pre-crisis carbonate platforms were replaced by low angle ramps.
To investigate how the changes in shallow water carbonate precipitation influenced the depositional geometries of carbonate
platforms, a quantitative three dimensional acquisition (laser scanner, photogrammetry) and modeling of the geometry of
sedimentary bodies deposited before, during and after the Carnian crisis, coupled with facies analysis, was performed.
Depositional architectures and facies suggest that a phase of intermediate sedimentation, in which carbonate mounds and
detrital processes coexisted, characterized the turnover of carbonate factory across the Carnian Pluvial Event. The subsequent
ramps developed in a tidal dominated environment. Moreover, the use of three dimensional techniques enabled the succession
to be placed in a sequence stratigraphic frame.
Introduction
In the Late Anisian and Early Carnian, the carbonate platforms of the Dolomites were mainly isolated and
characterized by high relief (Bosellini 1984; Bosellini et al., 2003). Their carbonate production was
mainly dominated by microbes (microbial sensu Schlager 2003; Blendinger 1994; Russo et al. 1997;
Keim and Schlager 1999; 2001, Marangon et al. 2011). Those platforms developed characteristic
depositional geometries, with carbonate slopes steeper than the angle of repose of gravel (i.e., even more
than 35°), and often lacking clear clinoform bedding, because the slope itself was the site of primary
carbonate production.
At the end of the Early Carnian, a climatic event, known as the Carnian Pluvial Event (CPE, Simms and
Ruffel 1989; Preto et al. 2010; Dal Corso et al. 2012), caused a strong decrease in carbonate production.
Shallow water carbonate systems of the Dolomites switched from microbial dominated to carbonates with
skeletal associations and geometries typical of ramps (i.e. mainly molluscs dominated and slope angle <
1°; Preto and Hinnov 2003).
Aim
Investigate the impact of the CPE on the sedimentary environment of the Dolomites. In particular the
focus is on changes in calcium carbonate precipitation style in shallow water systems in terms of facies
and depositional geometries using a standard sedimentological approach combined with a quantitative
three dimensional acquisition (laser scanning and photogrammetric techniques) and 3D geo-modeling.
Outcrops and applied techniques
The studied outcrops are located in the Cortina d'Ampezzo area (central Dolomites, NE Italy).
Sedimentological analysis and stratigraphic section measurements were performed. The Tofana di Rozes
and the Dibona Hut are the key areas to constrain both the sedimentology and the depositional geometries
of the studied stratigraphic interval. According to outcrop conditions the geometry of the Tofana di Rozes
was acquired through photogrammetry (Fig. 1a), while at Dibona Hut a terrestrial laser scanner (LiDAR)
was used (Fig. 1b).
Data and results
On the southern walls of the Tofana di Rozes (Figs. 1a) a platform to basin transect is exposed (Preto and
Hinnov 2003; Breda et al. 2009). Here, the boundary between pre- and post-CPE deposits was identified.
It is constituted by a sharp by-pass surface on top of the last slope clinoform of the youngest generation of
Triassic high relief platforms. This surface is overlain by a series of lenticular shaped carbonate bodies
(mounds) made up of mainly microbial boundstone (Figs. 2a), interlayered and laterally onlapped by dm
1
Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2012-2013
thick beds of arenaceous grainstones with bivalves, gastropods, peloids, plant remains (Gattolin et al., in
prep).
Fig. 1a. (above) 3D photogrammetic model of the Tofana di Rozes
outcrop.
Fig. 1b. (right) 3D point cloud model of the Dibona Hut outcrop.
At Dibona Hut, arenaceous grainstones become dominant toward the top of the interval (Fig. 2b). The
complete disappearance of mounds followed the fall of sea level. This event is here documented by the
presence of a ca. 30 m thick clinostratified body (Fig. 1b), consisting of arenaceous grainstones and
presenting a series of stair stepping topsets, progressively lowered toward the basin. Its offlapping
geometry evidences an overall progradation of the shoreline along a descending, low angle trajectory
(Gattolin et al., in prep). In the neighboring, more proximal areas, the sea level fall is testified by the
presence of karstic surfaces.
Fig. 2a. Onset of mounds on the top of the last generation of
Triassic high relief platforms at Tofana di Rozes.
Fig. 2b. Mounds interfingered with arenaceous grainstones at
Dibona Hut (Gattolin et al., in prep.).
Fig. 3a. Paleotopographical scheme of the Cortina area (Gattolin et
al., 2013, modified).
2
Fig. 3b. Herringbone cross stratification at
Valparola Pass indicates a tide dominated
environment (Gattolin et al., 2013, modified).
Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2012-2013
The paleotopography that developed following the sea level fall was characterized by heights (i.e. the
demised high relief carbonate platform) and basins. In the study area the presence of an elongated marine
strait, bounded by two demised carbonate platforms, triggered tide amplification and so the onset of a tide
dominated depositional environment (Figs. 3a, b; Gattolin et al., 2013).
Because of the overlap of both climatic and eustatic events, this Triassic interval of the Dolomites was
considered one of the most challenging to interpret in terms of sequence stratigraphy. The use of virtual
3D modeling techniques enabled to carry out observations on stratal patterns and sedimentary bodies
geometries of inaccessible outcrops without the perspective distortion bias. These observations, together
with the detailed study of facies and the identification of the key stratigraphic surfaces, led to a sequence
stratigraphic interpretation of the studied succession.
References
BLENDINGER, W. 1994. The carbonate factory if Middle Triassic buildups in the Dolomites, Italy: a
quantitative analysis. Sedimentology, 41, 1147-1159.
BOSELLINI, A. 1984. Progradation geometries of carbonate platform: example from the Triassic of the
Dolomites, Northern Italy. Sedimentology, 31, 1–24.
BOSELLINI, A., GIANOLLA, P.,and STEFANI, M. 2003. Geology of the Dolomites. Episodes, 26, 181185.
BREDA, A., PRETO, N., ROGHI, G., FURIN, S., MENEGUOLO, R., RAGAZZI, E., FEDELE, P.,
GIANOLLA, P. 2009. The Carnian Pluvial Event in the Tofane area (Cortina d'Ampezzo, Dolomites,
Italy). Geo Alp, 6, 80-115.
DAL CORSO, J., MIETTO, P., NEWTON, R.J., PANCOST, R.D., PRETO, N., ROGHI, G., WIGNALL,
P.B. 2012. Discovery of a major negative delta C-13 spike in the Carnian (Late Triassic) linked to the
eruption of Wrangellia flood basalts. Geology, 40, 79-82.
GATTOLIN, G., BREDA, A., PRETO. N. 2013. Demise of Late Triassic carbonate platforms triggered
the onset of a tide-dominated depositional system in the Dolomites, Northern Italy. Sedimentary
Geology, 297, 38-49.
GATTOLIN, G., FRANCESCHI, M., PRETO, N., BREDA, A., ISOTTON, M., GIANOLLA, P.
Sequence stratigraphy after the demise of a high-relief carbonate platform: seal-level and climate
disentangled. Marine Petroleum Geology, in prep.
KEIM, L., SCHLAGER, W. 1999. Automicrite facies on steep slopes (Triassic, Dolomites, Italy). Facies,
41, 15-25.
KEIM, L., SCHLAGER, W. 2001. Quantitative compositional analysis of a Triassic carbonate platform
(Southern Alps, Italy). Sedimentary Geology, 139, 261-283.
MARANGON, A., GATTOLIN, G., DELLA PORTA, G., PRETO, N. 2011. The Latemar: A flat-topped,
steep fronted platform dominated by microbialites and synsedimentary cements. Sedimentary Geology,
240 3-4, 97-114.
PRETO, N., HINNOV, L.A. 2003. Unraveling the origin of shallow-water cyclothems in the Upper
Triassic Dürrenstein Fm. (Dolomites, Italy). Journal of Sedimentary Research, 73, 774-789.
SCHLAGER, W. 2003. Benthic carbonate factories of the Phanerozoic. International Journal of Earth
Sciences, 92, 445-464.
RUSSO, F., NERI, C., MASTANDREA, A., BARACCA, A. 1997. The mud mound nature of the
Cassian platform margins of the Dolomites. A case history: The Cipit boulders from Punta Grohmann
(Sasso Piatto Massif, Northern Italy). Facies, 36, 25-36.
SIMMS, M.J., RUFFELL, A.H. 1989. Synchroneity of climatic change and extinctions in the Late
Triassic. Geology, 17, 65–268.
3
Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2012-2013
SUMMARY OF ACTIVITIES
Courses:
R.J. ANGEL R.J. “Scientific communication”, Dipartimento di Geoscienze, Università degli Studi di Padova, 2013.
R. DI CUIA R. “Principles of image logging”, G.E.Plan Consulting, Ferrara, 2013.
MASELLI V. “Seismic and sequence stratigraphy”, Dipartimento di Geoscienze, Università degli Studi di Padova, 2013.
HELLAND-HANSEN W. “Sequence stratigraphy: principles and applications”, Dipartimento di Geoscienze, Università degli
Studi di Padova, 2012.
ASQUIER P. & GOCAD RESEARCH GROUP “SKUA 2011 quick start” and “introduction to Gocad research plugins”,
Gocad meeting post-congress courses, Nancy, 2012.
MILLI S., FONNESU F. “Processes and depositional architectures of turbidite systems”, GeoSed pre-congress course, Feltre,
2012.
CALANDRUCCIO E. “Corso di Inglese parlato”, Dipartimento di Geoscienze, Università degli Studi di Padova, 2012.
GULIK L. “Corso avanzato di Inglese scientifico”, Dipartimento di Geoscienze, Università degli Studi di Padova, 2012.
DIERNA M. “JRC 3D Reconstructor course”, Gexcel, Brescia, 2012.
SALMASO L., ARBORETTI R., CORAIN L., BONNINI S. “Statistica Applicata alla Sperimentazione Scientifica (Edizione
2011)”, Centro Studi per l'Ambiente Alpino, Università degli Studi di Padova, 2011.
PRETO N. “Petrologia dei Carbonati Avanzata”, Dipertimento di Geoscienze, Università degli Studi di Padova, 2011.
REMONDINO F., RIZZI A., MENNA F., AGUGIARO G. “Fotogrammetria e 3D Laser Scanning”, Dipartimento di
Geoscienze, Università degli Studi di Padova, 2011.
JENKYNS H.C. “Elements, Isotopes and Organic Matter in Chemostratigraphy: Applications, Limitations and Implications for
Global Environmental Change”, Dipartimento di Scienze della Terra, Università di Ferrara, 2011.
DANIELETTO E., BOESSO S. “Corso introduzione alla biblioteca” e “Gestire le bibliografie con Refworks”, Biblioteca del
Dipartimento di Geoscienze, Università degli Studi di Padova, 2011.
Communications:
GATTOLIN, G. 2013. The geometry of geologic bodies reconstructed by 3D modeling techniques. The University of
Newcastle, Australia.
DAL CORSO, J., ROGHI, G., RIGO, M., GIANOLLA, P., CAGGIATI, M., GATTOLIN, G., NEWTON, R.J., JENKYNS
H.C., PRETO, N. 2013. The Carnian Pluvial Event negative CIE at Cave del Predil (early Late Triassic, Italy): new link to
Wrangellia volcanism. Goldschmidt, Florence.
GATTOLIN, G., FRANCESCHI, M., BREDA, A., PRETO, N. 2012. Facies and geometries of carbonate platforms of the
Dolomites after the Carnian Pluvial Event (CPE). 10th GeoSed Meeting, Feltre (BL).
MARANGON, A., GATTOLIN, G., FRANCESCHI, M., PRETO, N. 2011. Il Latemar, un atollo tropicale di 240 milioni di
anni fa. Expo delle Dolomiti, Longarone (BL).
PRETO, N., DAL CORSO, J., GATTOLIN, G., ROGHI, G., BIRGEL, D., PANCOST, R., PECKMANN, J., WESTPHAL,
H. 2011. Organic compounds in shales and carbonates of the "upper Cassian beds" (Heiligkreuz Fm.) of the Dolomites: a
preliminary report. Cassian beds Workshop, Bozen.
PRETO, N., BIRGEL, D., GATTOLIN, G., MONTINARO, A., PECKMANN, J., WESTPHAL, H. 2011. Extreme
supersaturation promoted whitings in Early Triassic seawater. 28th IAS Meeting, Zaragoza.
FRANCESCHI, M., PRETO, N., GATTOLIN, G., MARANGON, A., VISEUR, S., PALERMO, D., NARDON, S. 2011. 3D
modeling of a complex carbonate platform: the case of the Latemar (Middle Triassic, Dolomites). 28th IAS Meeting,
Zaragoza.
MARANGON, A., GATTOLIN, G., FRANCESCHI, M., DELLA PORTA, G., PRETO, N. 2011. An upper Anisian microbial
platform: the Latemar (Western Dolomites, Italy). 28th IAS Meeting, Zaragoza.
4
Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2012-2013
Posters:
GATTOLIN, G., FRANCESCHI, M., PRETO, N., BREDA, A. 2013. Three-Dimensional Modeling of Dramatic Changes in
Depositional Geometries of the Late Triassic Carbonate Platforms of the Southern Alps (Italy). AAPG European Regional
Conference, Barcelona.
GIANOLLA, P., ROGHI, G., PRETO, N., BREDA, A., RIGO, M., CAGGIATI, M., DAL CORSO, J., GATTOLIN, G. 2012.
The impact of the “Carnian Pluvial Event” in the physiography of Western Tethys. 29th IAS Meeting, Schladming.
GATTOLIN, G., FRANCESCHI, M., BREDA, A., TEZA, G., PRETO, N. 2012. Three dimensional modeling of depositional
geometries. A case study from Tofane Group (Dolomites, Italy). EGU general assembly, Wien.
JALIL, N.E., BELVEDERE, M., BREDA, A., GATTOLIN, G., DYKE, G.J. 2011. A varied ichnocoenosis in the Cretaceous
Kem Kem beds of Morocco. SVP 71th annual meeting, Las Vegas.
GIANOLLA, P., STEFANI, M., PRETO, N., GATTOLIN, G., MARTELLI, A. 2011. Start-up carbonate mounds, their
selective survival, and subsequent Middle Triassic platforms in the Dolomites. 28th IAS Meeting, Zaragoza.
Publications:
GATTOLIN, G., FRANCESCHI, M., PRETO, N., BREDA, A., ISOTTON, M., GIANOLLA, P. Sequence stratigraphy after
the demise of a high-relief carbonate platform: sea-level and climate disentangled. Marine Petroleum Geology, in prep.
GATTOLIN, G., BREDA, A., PRETO, N. 2013. Demise of Late Triassic carbonate platforms triggered the onset of a tidedominated depositional system in the Dolomites, Northern Italy. Sedimentary Geology, 297, 38-49.
BELVEDERE, M., JALIL, N.E., BREDA, A., GATTOLIN, G., BOURGET, H., KHALDOUNEAND, F., DYKE, G.J.
2013. Vertebrate footprints from the Kem Kem beds (Morocco): A novel ichnological approach to faunal reconstruction.
Palaeogeography, Palaeoclimatology, Palaeoecology, 383-384, 52-58.
GRAMIGNA, P., FRANCESCHI, M., GATTOLIN, G., PRETO, N., MASSIRONI, M., RIVA, A., VISEUR, S. 2013.
Geological map of the Middle Triassic Latemar platform (Western Dolomites, Northern Italy). Journal of Maps.
MARANGON, A., GATTOLIN, G., DELLA PORTA, G., PRETO, N. 2011. The Latemar: a flat-topped, steep fronted
platform dominated by microbialites and synsedimentary cements. Sedimentary Geology, 240 (3-4), 97-114.
PRETO, N., FRANCESCHI, M., GATTOLIN, G., MASSIRONI, M., RIVA, A., GRAMIGNA, P., BERTOLDI, L.,
NARDON, S. (2011). The Latemar: a Middle Triassic polygonal fault-block platform controlled by synsedimentary
tectonics. Sedimentary Geology, 234 (1-4), 1-18.
Congresses and Workshops:
2013: AAPG European Regional Conference, Barcelona.
2012: 32nd Gocad Meeting, Nancy. 10th GeoSed Meeting, Feltre. EGU General Assembly, Wien.
2011: Workshop on the Cassian beds (Upper Triassic), Bozen.
Teaching activities:
Teaching assistant: 1 week, “Field Course in Carbonates Environments”, School of Environmental and Life Sciences, The
University of Newcastle, Australia, 2013.
Teaching assistant: 25 hours, “Laboratorio di Cartografia”, Laurea di primo livello in Scienze Geologiche, 2011 and 2012.
Co-supervisor of one MSc Thesis and one BE thesis in 2013, co-supervisor of one MSc thesis in 2012.
Other:
Visiting student at University of Newcastle, Australia, 2013.
Editor of the Rendiconti Online della Società Geologica Italiana 20th vol. , 2012.
Author of the guide-book “Evolution of carbonate platforms geometry across the Triassic in the Dolomites”, and leader of the
10th GeoSed pre-meeting excursion, 2012
Organizer of the 10th GeoSed meeting, 2012.
Awarded of the “Geosed Contributo Giovani”, 2011.
5