Development of a LOw COst TOol for studies in estuarian sediments: Application to Paleoclimatology and Paleoenvironment - LOCOTO

Funder

Organizational Unit

Publications

Algarve: a study case for global vs regional climatic changes in mid latitude estuaries during the Holocene

Publication . Veiga-Pires, C.; Mestre, Nélia; Moura, Delminda; Luis, Joaquim; Boski, T.

Located at the extreme southwestern end of the Iberian Peninsula, in the South of Portugal, the Algarve province is bordered to the north by the Alentejo province, to the east by the Guadiana River, and to the west and south by the Atlantic Ocean. Its coastal region can be divided into two different sectors: the eastern sector, which is mainly made of barrier island and lagoon system named the Ria Formosa, and the western sector mainly represented by clastic and carbonated cliffs. In each sector, we sampled long and short sedimentary cores (ca. 30m and 3m, respectively) in two different estuaries. Therefore, the different sedimentary records obtained from the four estuaries should permit to identify global vs. west-eastern regional climatic changes through the observation of several proxies. Two of these proxies are sediment color and magnetic susceptibility, which have been acquired every five centimeters along core depth, using the Colortron II spectrophotometer and SM-20 magneto-susceptometer, respectively. Sediment surfaces of short cores were also digitized using the Mustek 1200 A3 PRO Scanner. Furthermore, short cores have been sampled every five centimeters along depth in order to analyze the sediment for its major and minor elements content, its organic carbon content, and its granulometry and mineralogy. Some shell fragments have also been sampled and sent for radiocarbon radiometry or AMS dating, allowing therefore constructing some absolute chronologies for the several cores. Some relative chronologies based on digital color profiles are also being used in order to correlate sedimentary sequences between cores. All the cores are mainly composed of clay, with the existence of soil horizons at the top of the cores and frequent sand layers towards their base. Several element profiles along depths are compared, namely those regarding Sr, Ca, F, Ba, Al and Ti, as well as their ratios. First results indicate that geochemical and color data allow to identify similar sequences from west to east probably related to major climate episodes. Although, pronounced differences in mineralogy and accumulation rates from on site to another are probably due to differences, respectively, in the geochemistry of the drainage basin substratum and in the flow rate of the rivers, and therefore to local precipitation. We acknowledge FEDER and OE that financed this study through the Portuguese Foundation for Science and Technology (FCT) (POCTI/CTA/39733/2001).

2004Conference object

Open Access

An attempt to use color as a tool for high resolution correlations between estuarine sedimentary cores from Algarve (Portugal)

Publication . Mestre, Nélia; Veiga-Pires, C.

Nowadays, paleoenvironmental and climatological researches focus on studying shortterm climatic changes and one of the more sensitive environments for recording those short-term climatic variations are the high sedimentation rate of coastal regions. Accordingly, 4 estuaries from the Algarve region, south of Portugal, have been cored in order to study sedimentary and climatic variations during recent times (c.a. 5000 yrs). For this purpose, we applied sampling and analytical techniques from deep-sea studies, allowing the acquirement of almost continuous data profiles, as the color data obtained with the spectrophotometer Colortron.

2004Conference object

Open Access

An attempt to develop spectrophotometry as a proxy for sedimentary studies in estuarine environments

Publication . Veiga-Pires, C.; Mestre, Nélia; Moura, Delminda; Luis, Joaquim; Boski, T.

In deep-sea sediment studies, reﬂectance has been used as a proxy for high vs. low productivity intervals for several years. This value of the white-black scale is obtained through the use of spectrophotometers when using the CIE Lab color system, which also gives values on green-red and blue-yellow scales. In estuarine/continental sediment studies, color data are still often based on Munsell Table which does not allow to obtain numeric and continuous data and which is biased by the observer’s choice.

2004Journal article

Open Access

Regional sea level change study based on estuarine sediment color and biogeochemistry - preliminary results

Publication . Mestre, Nélia; Veiga-Pires, C.

Coastal zones play a significant role in the regional development and have been an important area for human occupation through time. The study of estuarine sediments applied to sea level changes had always been of extreme importance, as it reflects the coastal line evolution, either by local, regional or global changes.

2004-04Conference object

Open Access