- Email: [email protected]
The late-Holocene progradation of the Mahakam Delta, Indonesia
Abstracts / Quaternary International 279-280 (2012) 9–120
temperature is above 5 C. In Europe, these are characteristic of Interglacials and found in almost any area with carbonate bedrock, from Northern England to Greece and from Western France to Poland. Their composition (95 % of CaCO3) makes them suitable for geochemical research, especially oxygen and carbon stable isotopes (d18O and d13C). These parameters have been shown to be important palaeoclimatic proxies in Holocene tufas. At decadal-scale sampling resolution, in modern and Holocene data sets, d18O of tufa records variations in d18O of regional rainfall, and in this way reflects source or amount effects (particularly continentality), and temperature depending on locality. d13C of tufa indicates moisture availability (linked to biomass type/abundance) and rainfall intensity. More recently we have been investigating the suitability of d18O and d13C as palaeoclimatic proxies in Pleistocene tufas. Using our new results from Pleistocene (mainly MIS 5) sites from Northern England (Alport), France (Caours, La Celle and Condat) and Greece (Zemeno), we can analyse regional-scale variability in climate. Latitudinal variations in stable isotopes should reflect temperature or humidity gradients, or precise respective influences of Mediterranean and Atlantic air mass as rainfall sources. MULTIPROXY RECORD OF ENVIRONMENTAL AND CLIMATIC VARIATIONS DURING THE EEMIAN FROM THE NORTHERN FRANCE CALCAREOUS TUFA OF CAOURS: COMBINING PETROGRAPHY, MALACOLOGY AND GEOCHEMISTRY
105
lowland, where during Bronze age a compound of settlements developed, representing a northern cluster of sites of the “civilization of Terramare”. Terramare were villages surrounded by a moat and a rampart, that spread all over the Po valley, during Middle and Late Bronze age (ca. 1600-1150 cal yr BC) declining then at the passage between Late and Final Bronze age. Data from recent excavation design Fondo Paviani as a central place in the context of the Valli Grandi Veronesi area and, moreover, as the only site that survived the crisis being active also during Final Bronze age. Some questions arise concerning mainly the availability and management of natural resources during the occupation of terramare and the environmental conditions for the duration of these sites and for their critical phase of abandonment. To answer these questions and to describe the environmental development of this part of the Po plain, a multi-proxies approach has been planned, based on archaeobotanical investigation (pollen, phytoliths, macroremains) on the archaeological site of Fondo Paviani. The archaeological data will be compared to palaeoecological records from a bog in the natural park of Brusà, ca. 5 km far from the site, to discriminate human impact and natural changes in the palaeosignal. The preliminary results of the pollen analysis of the peat core drilled at Brusà will be presented and then the choice of different archives and proxies will be discussed, together with the expectations about their disturbances and possibilities. THE LATE-HOLOCENE PROGRADATION OF THE MAHAKAM DELTA, INDONESIA
Julie Dabowski. Muséum national d'Histoire naturelle de Paris, France
Rory Dalman. Delft University of Technology, Netherlands
E-mail address: [email protected]
E-mail address: [email protected]
The site of Caours exhibits a calcareous tufa deposit of >10 000 m2 and up to 3.5 m thick, overlying lower terrace fluvial deposits of a Somme River (Northern France) tributary. The whole calcareous tufa sequence is attributed to the Eemian Interglacial (MIS 5e) according to its location within the Somme River terraces system, palaeontological data, and U/Th TIMS dating (average of 124 4 ky BP). Since 2005, archaeological excavations of a Middle Palaeolithic site at the base of the tufa formation have provided long stratigraphic profiles (up to 20m long), supporting multidisciplinary studies. Palaeoenvironmental data from a petrographic study and molluscs were compared to geochemical proxies recording temperature (d18O) and humidity (d13C and trace elements Mg and Sr). In thin section the main Cyanobacteria taxa precipiting tufa were identified as the fossil genus Broutinella and Ponsinella. Broutinella builds massive “cauliflower” tufas. This subaqueous facies is associated with aquatic molluscs and ostracods. Ponsinella produces the “mille-feuilles” facies with thin laminations testifying of diffuse flow periods. This facies is associated to malacofauna dominated by land snails. The cauliflower facies is dominant in the lower part of the sequence, where more pluvial conditions are suggested by d13C data. This wettest part is also the warmest according to d18O, and corresponds to the expansion of woodland molluscs. The maxima of temperature and humidity (from d 18O and d 13C) are correlated with the Climatic Optimum (highest number of forest species diversity and mollusc shells). In the upper part, the mille-feuilles facies becomes better developed as spring flow waned, based on the d 13C data. Dry conditions are also indicated by mollusc fauna which record a landscape of mainly open areas and some forest remnants. Clear environmental modifications caused by climatic changes are thus reconstructed from the tufa at Caours especially around the Interglacial Optimum.
The Mahakam Delta is an oft-cited example of a mixed fluvially and tidally influence delta. Yet the distinct separation of the tidal-dominated delta plain and the fluvial distributaries make the delta unique amongst tidally influenced deltas. The delta prograded an average of 60 km over the last 5000 years and is barely influenced by waves. The delta is characterized by a distinct, dense network of distributary and tidal channels. In order to characterize the Holocene stratigraphic architecture we describe a dataset of 10 new cores and a large survey of very high-resolution, shallow seismics. The delta was largely flooded during the Holocene Transgression, our data indicates that a small branch of fluvial distributaries was active on the current delta plain around 5 ka. Subsequently, as sea level rise slowed, the northernmost fluvial distributary built out rapidly over a period of 3 kyrs. Simultaneously the southern branch of fluvial distributaries built out slowly and reached its current position around 2 ka. The southern fluvial mouthbar deposits are significantly thicker than the northern branch, indicating a strong spatial differentiation in subsidence or a large difference in paleobathymetry. As the skeleton fluvial distributaries built out rapidly, a sheltered area was created which allowed infilling by tidedominated delta plain deposits. Most dating in the tidal channels indicate a later date than the surrounding fluvial channels. The outbuilding of the fluvial distributaries provide the shallow, sheltered and vegetated areas which allow rapid aggradation and progradation of the tide-dominated delta plain. The tidal forcing and strong bank stabilising vegetation have kept the main distributaries in place during the entire progradational event, little to no lateral shifting has occurred over the entire period despite the large number of distributaries active currently.
A MULTI-PROXIES APPROACH FOR PALAEOENVIRONMENTAL INVESTIGATION OF THE BRONZE AGE SITE OF FONDO PAVIANI AND THE VALLI GRANDI VERONESI AREA (PO VALLEY, NE ITALY)
SEDIMENTOLOGY AND GEOCHEMISTRY OF LACUSTRINE TERRACES OF THREE MIDDLE ATLAS LAKES: HOLOCENE PALEOCLIMATIC RECONSTRUCTION IN MOROCCO Brahim Damnati. UAE. Faculty of Sciences and Techniques-Tangier, Morocco E-mail address: [email protected]
Marta Dal Corso. Graduate School Human Development in Landscapes, C, Germany E-mail address: [email protected]
Palaeoenvironmental reconstructions can be carried out applying to the case-study different complementary methodologies, chosen on the basis of the requirements of the available archives and on their possibility to answer the specific objectives of research. In this case-study the application of different proxies for the environmental reconstruction of the Valli Grandi Veronesi area, in northeastern Italy, is presented. This area is a wide alluvial
At the Moroccan Middle Atlas Mountain, three lakes were used to characterize climate variability in late Holocene. The methodology is based on sedimentological, geochemical and mineralogical analysis of recent sediment and lacustrine terraces. The Lake Ifrah, is a natural lake. Waters are calc-Magnesians, relatively very alkaline and oxygenated. The Lake Afourgagh, is a karstic lake origin. Actually, its maximum depth is 1.5 m. Lake Iffer is a smaller lake sub-circular and relatively deep. Its area is 3.5 ha. Its maximum depth is 6.5 m at the center of the lake. The sedimentological and geochemical results show that the mode of actual sedimentation in
temperature is above 5 C. In Europe, these are characteristic of Interglacials and found in almost any area with carbonate bedrock, from Northern England to Greece and from Western France to Poland. Their composition (95 % of CaCO3) makes them suitable for geochemical research, especially oxygen and carbon stable isotopes (d18O and d13C). These parameters have been shown to be important palaeoclimatic proxies in Holocene tufas. At decadal-scale sampling resolution, in modern and Holocene data sets, d18O of tufa records variations in d18O of regional rainfall, and in this way reflects source or amount effects (particularly continentality), and temperature depending on locality. d13C of tufa indicates moisture availability (linked to biomass type/abundance) and rainfall intensity. More recently we have been investigating the suitability of d18O and d13C as palaeoclimatic proxies in Pleistocene tufas. Using our new results from Pleistocene (mainly MIS 5) sites from Northern England (Alport), France (Caours, La Celle and Condat) and Greece (Zemeno), we can analyse regional-scale variability in climate. Latitudinal variations in stable isotopes should reflect temperature or humidity gradients, or precise respective influences of Mediterranean and Atlantic air mass as rainfall sources. MULTIPROXY RECORD OF ENVIRONMENTAL AND CLIMATIC VARIATIONS DURING THE EEMIAN FROM THE NORTHERN FRANCE CALCAREOUS TUFA OF CAOURS: COMBINING PETROGRAPHY, MALACOLOGY AND GEOCHEMISTRY
105
lowland, where during Bronze age a compound of settlements developed, representing a northern cluster of sites of the “civilization of Terramare”. Terramare were villages surrounded by a moat and a rampart, that spread all over the Po valley, during Middle and Late Bronze age (ca. 1600-1150 cal yr BC) declining then at the passage between Late and Final Bronze age. Data from recent excavation design Fondo Paviani as a central place in the context of the Valli Grandi Veronesi area and, moreover, as the only site that survived the crisis being active also during Final Bronze age. Some questions arise concerning mainly the availability and management of natural resources during the occupation of terramare and the environmental conditions for the duration of these sites and for their critical phase of abandonment. To answer these questions and to describe the environmental development of this part of the Po plain, a multi-proxies approach has been planned, based on archaeobotanical investigation (pollen, phytoliths, macroremains) on the archaeological site of Fondo Paviani. The archaeological data will be compared to palaeoecological records from a bog in the natural park of Brusà, ca. 5 km far from the site, to discriminate human impact and natural changes in the palaeosignal. The preliminary results of the pollen analysis of the peat core drilled at Brusà will be presented and then the choice of different archives and proxies will be discussed, together with the expectations about their disturbances and possibilities. THE LATE-HOLOCENE PROGRADATION OF THE MAHAKAM DELTA, INDONESIA
Julie Dabowski. Muséum national d'Histoire naturelle de Paris, France
Rory Dalman. Delft University of Technology, Netherlands
E-mail address: [email protected]
E-mail address: [email protected]
The site of Caours exhibits a calcareous tufa deposit of >10 000 m2 and up to 3.5 m thick, overlying lower terrace fluvial deposits of a Somme River (Northern France) tributary. The whole calcareous tufa sequence is attributed to the Eemian Interglacial (MIS 5e) according to its location within the Somme River terraces system, palaeontological data, and U/Th TIMS dating (average of 124 4 ky BP). Since 2005, archaeological excavations of a Middle Palaeolithic site at the base of the tufa formation have provided long stratigraphic profiles (up to 20m long), supporting multidisciplinary studies. Palaeoenvironmental data from a petrographic study and molluscs were compared to geochemical proxies recording temperature (d18O) and humidity (d13C and trace elements Mg and Sr). In thin section the main Cyanobacteria taxa precipiting tufa were identified as the fossil genus Broutinella and Ponsinella. Broutinella builds massive “cauliflower” tufas. This subaqueous facies is associated with aquatic molluscs and ostracods. Ponsinella produces the “mille-feuilles” facies with thin laminations testifying of diffuse flow periods. This facies is associated to malacofauna dominated by land snails. The cauliflower facies is dominant in the lower part of the sequence, where more pluvial conditions are suggested by d13C data. This wettest part is also the warmest according to d18O, and corresponds to the expansion of woodland molluscs. The maxima of temperature and humidity (from d 18O and d 13C) are correlated with the Climatic Optimum (highest number of forest species diversity and mollusc shells). In the upper part, the mille-feuilles facies becomes better developed as spring flow waned, based on the d 13C data. Dry conditions are also indicated by mollusc fauna which record a landscape of mainly open areas and some forest remnants. Clear environmental modifications caused by climatic changes are thus reconstructed from the tufa at Caours especially around the Interglacial Optimum.
The Mahakam Delta is an oft-cited example of a mixed fluvially and tidally influence delta. Yet the distinct separation of the tidal-dominated delta plain and the fluvial distributaries make the delta unique amongst tidally influenced deltas. The delta prograded an average of 60 km over the last 5000 years and is barely influenced by waves. The delta is characterized by a distinct, dense network of distributary and tidal channels. In order to characterize the Holocene stratigraphic architecture we describe a dataset of 10 new cores and a large survey of very high-resolution, shallow seismics. The delta was largely flooded during the Holocene Transgression, our data indicates that a small branch of fluvial distributaries was active on the current delta plain around 5 ka. Subsequently, as sea level rise slowed, the northernmost fluvial distributary built out rapidly over a period of 3 kyrs. Simultaneously the southern branch of fluvial distributaries built out slowly and reached its current position around 2 ka. The southern fluvial mouthbar deposits are significantly thicker than the northern branch, indicating a strong spatial differentiation in subsidence or a large difference in paleobathymetry. As the skeleton fluvial distributaries built out rapidly, a sheltered area was created which allowed infilling by tidedominated delta plain deposits. Most dating in the tidal channels indicate a later date than the surrounding fluvial channels. The outbuilding of the fluvial distributaries provide the shallow, sheltered and vegetated areas which allow rapid aggradation and progradation of the tide-dominated delta plain. The tidal forcing and strong bank stabilising vegetation have kept the main distributaries in place during the entire progradational event, little to no lateral shifting has occurred over the entire period despite the large number of distributaries active currently.
A MULTI-PROXIES APPROACH FOR PALAEOENVIRONMENTAL INVESTIGATION OF THE BRONZE AGE SITE OF FONDO PAVIANI AND THE VALLI GRANDI VERONESI AREA (PO VALLEY, NE ITALY)
SEDIMENTOLOGY AND GEOCHEMISTRY OF LACUSTRINE TERRACES OF THREE MIDDLE ATLAS LAKES: HOLOCENE PALEOCLIMATIC RECONSTRUCTION IN MOROCCO Brahim Damnati. UAE. Faculty of Sciences and Techniques-Tangier, Morocco E-mail address: [email protected]
Marta Dal Corso. Graduate School Human Development in Landscapes, C, Germany E-mail address: [email protected]
Palaeoenvironmental reconstructions can be carried out applying to the case-study different complementary methodologies, chosen on the basis of the requirements of the available archives and on their possibility to answer the specific objectives of research. In this case-study the application of different proxies for the environmental reconstruction of the Valli Grandi Veronesi area, in northeastern Italy, is presented. This area is a wide alluvial
At the Moroccan Middle Atlas Mountain, three lakes were used to characterize climate variability in late Holocene. The methodology is based on sedimentological, geochemical and mineralogical analysis of recent sediment and lacustrine terraces. The Lake Ifrah, is a natural lake. Waters are calc-Magnesians, relatively very alkaline and oxygenated. The Lake Afourgagh, is a karstic lake origin. Actually, its maximum depth is 1.5 m. Lake Iffer is a smaller lake sub-circular and relatively deep. Its area is 3.5 ha. Its maximum depth is 6.5 m at the center of the lake. The sedimentological and geochemical results show that the mode of actual sedimentation in