ARTICLE | doi:10.20944/preprints202303.0518.v1
Subject: Arts And Humanities, Theater Keywords: Mesoproterozoic; Neoproterozoic; Baltica; Amazonia; detrital zircon; Volyn-Orsha basin
Online: 30 March 2023 (02:53:28 CEST)
We used LA-ICP-MS U-Pb data for detrital zircon to constrain the Maximum Depositional Age (MDA) and provenance of clastic sedimentary rocks of the Volyn-Orsha sedimentary basin, which filled an elongated (~625×250 km) depression in SW Baltica and attained ~900 m in thickness. Eighty-six zircons out of one hundred and three yielded concordant dates, with most of them (86 %) falling in the time interval between 1655 ± 3 and 1044 ± 16 Ma and clustering in two peaks at ca. 1630 and 1230 Ma. The remaining zircons yielded dates older than 1800 Ma. The MDA is defined by a tight group of three zircons with a weighted average age of 1079 ± 8 Ma. This age corresponds to the time of a clockwise ~90° rotation of Baltica and the formation of the Grenvillian – Sveconorwegian – Sunsas orogenic belts. Subsidence was facilitated by the presence of eclogites derived from subducted oceanic crust. The sediments of the Orsha sub-basin in the northeastern part of the basin were derived from the local crystalline basement, whereas the sediments in the Volyn sub-basin, extending to the margin of Baltica, were transported from the orogen between Laurentia, Baltica, and Amazonia.
ARTICLE | doi:10.20944/preprints202309.0841.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: SWAT model; surface runoff; deforestation; land use change; Amazonia; Peru
Online: 13 September 2023 (07:29:17 CEST)
The watershed hydrologic conditions in the Madre de Dios (MDD) basin in the Peruvian Amazon have been irreversibly impacted by deforestation and changes in land use cover. These changes have also had detrimental effects on the geomorphology, water quality, and aquatic habitat within the basin. However, there is a scarcity of hydrological modeling studies in this area primarily due to the limited availability of hydrometeorological data. The primary objective of this study was to examine how deforestation impacts the hydrological conditions in the MDD basin. By implementing the Soil and Water Assessment Tool (SWAT) model, this study determined that replacing 12% of the evergreen broadleaf forest area with bare land resulted in an significant increase in surface runoff by 38% monthly, a reduction of evapotranspiration by 1% annually, and an average monthly streamflow increase of 12%. Changes in spatial patterns reveal that the primary impacted watershed is the Inambari River subbasin, a significant tributary of the Madre de Dios River. This area experiences an annual average surge of 187% in surface runoff generation while witnessing an annual average reduction of 8% in evapotranspiration.These findings have important implications, as they can contribute to instances of flooding and extreme inundation events, which have already occurred in the MDD region.
ARTICLE | doi:10.20944/preprints201905.0214.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Amazonia, Upland lakes, Serra dos Carajás, Palaeoenvironmental reconstruction, Quaternary, Geology
Online: 16 May 2019 (15:31:44 CEST)
Upland lakes (ULs) of the Carajás, southeastern Amazonia, have been intensively studied to their evolution during the Quaternary, as well as the development of the associated biota. In this review, several classical and modern approaches from structural geology to the pollen rain and sedimentary data which cover an area of around 41,300 km2 were compiled. Multi-elemental geochemistry indicates that the detrital sediments derived from weathered crusts and soils, while the sedimentary organic matter represent autochthonous (siliceous sponge spicules, algae, macrophytes) and allochthonous (C3 plants and freshwater DOC) sources. Modern pollen rain suggests that even small lakes and canga areas can reflect forest signal, which depends on the topographic control and prevailing wind direction on pollen deposition. Integrated data of the sedimentary cores indicate that the active lakes never dried up during the last 50 ka cal BP. However, subaerial exposure occurs on filled lakes such as ST02 Lake during the LGM, LB3 and R2 lakes at the mid-Holocene due to drier paleoclimate conditions. Considering the organic proxies, only LB3 Lake presents expansion of C4 canga (montane savanna) plants since ULs of the Serra da Bocaína does not present siderites. Siderite formation on ULs deposits also points to drier paleoenviromental conditions, interrupting predominantly wet conditions. However, there is no evidence for widespread expansion of savanna into Southeastern Amazonia during the late Pleistocene and Holocene.
SHORT NOTE | doi:10.20944/preprints202004.0501.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Economic recession; SARS-CoV-2; Deforestation; Climate Change; Amazonia Integrity; Green Bonds
Online: 29 April 2020 (05:05:33 CEST)
The severity of the ongoing COVID-19 outbreak demand from countries to adopt extreme measurements of social isolation to stop the spread and flatten the curve of contamination. Although social isolation measures may have negative impacts on economy, historically it has been showed to be more effective in saving lives and less damaging to economy than not adopting these measurements during a viral pandemic. In Brazil, despite the positioning of the president against social isolation due to the consequent economic recession, the rapid spread of the virus has worried the governors of the Brazilian states, which are thus managing stringent social isolation measurements to avoid the advance of the virus. Since one of the main strategies to guarantee progress and economic growth in Brazil has been the exploitation of natural resources from the Amazonia biome, here we discuss the importance of this biome to Brazilian economy during the post-pandemic recession and highlights potential strategies to burst the economy without promoting Amazonia destruction. We show that, together with the REDD+ and the Amazon Fund, the Forest bonds represents good strategies to burst Brazilian economy in a sustainable way, showing that it is possible to improve the commodities without increasing Amazonia deforestation or the greenhouse gases emissions. Amazonia is a biome of global importance for the avoidance of another global crisis, which will occur if we reach the climatic tipping point of 1.5°C. Thus, governmental actions should go towards its preservation, not exploitation and depletion. The commitment of the government with environmental conservation is paramount so that these economic strategies have positive results, especially in a post-pandemic scenario, where the economy will be extremely weakened. The COVID-19 brings us a lesson regarding how our attitudes can impact the world, and what we can expect from a global crisis. Perhaps we can apply these lessons and focus on change our economy towards a sustainable direction to avoid another global crisis in the years to come.