排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
Rajani Nair Asha A. Juwarkar Tushar Wanjari S. K. Singh T. Chakrabarti 《Climatic change》2011,106(4):609-619
The micrometeorological technique of eddy covariance is a powerful tool for characterizing the carbon (C) budget of terrestrial
ecosystems. Eddy covariance method was used for estimating Net Ecosystem Exchange (NEE) of carbon dioxide between atmosphere
and revegetated manganese mine spoil dump at Gumgaon, India. In this paper, we analyzed the diel CO2 flux pattern and its response to various physical environmental conditions. The carbon balance of terrestrial ecosystems
is particularly sensitive to climatic changes. Study of diel pattern of CO2 flux showed that carbon uptake was dependent on sunlight. Effect of temperature and latent heat on the CO2 flux showed that rate of CO2 uptake increased proportionally, but later declined due to various factors like stomatal response, high evaporative demand,
circadian rhythm and/or a combination of all three. Net ecosystem production of revegetated land was found to be 28.196 KgC/ha/day
whereas average net carbon release by the ecosystem, through respiration was observed to be 5.433 KgC/ha/day. Thus, quantifying
net carbon (C) storage in degraded land is a necessary step in the validation of carbon sequestration estimates and in assessing
the possible role of these ecosystems in offsetting adverse impacts of fossil fuel emissions. 相似文献
2.
The Central Indian continental crust is postulated to have formed around the Archean nuclei of the Bastar Craton (Radhakrishna, 1993). Around 3.5 Ga. Old, high-Al 2 O 3 trondhjemite gneisses have been reported from the southern part of the Bastar Craton (Sarkar et al., 1993). However, neither isotopic nor geochemical evidence exists in the literature for the presence of rocks older than 2.5 Ga from the northern part of the Bastar Craton (Sarkar et al., 1990). The absence of tonalite-trondhjemite-granodiorite (TTG) suites from the Amgaon Gneisses (Rao et al., 2000), were considered to indicate substantial geochemical differences between the Amgaon gneisses and the TTG basement gneisses of the Dharwar Craton (i.e., the peninsular gneisses). Accordingly the mode of the tectonomagmatic evolutionary patterns of the Bastar Craton was considered to be different, both in time in space from the bordering Dharwar and Bundelkhand Cratons, respectively. In this communication we report the presence of high-Al 2 O 3 trondhjemite from the Amgaon gneisses, along with calc-alkaline and peraluminous granites that are geochemically similar to the late granitoids (2.5 to 2.6 Ga old) of the Dharwar Craton, suggesting that the two cratons were nearest neighbours at least during the late Archean. 相似文献
3.
Geochemistry and petrogenesis of Proterozoic granitic rocks from northern margin of the Chotanagpur Gneissic Complex (CGC) 总被引:1,自引:0,他引:1
Bhupendra S Yadav Nishchal Wanjari Talat Ahmad Rajesh Chaturvedi 《Journal of Earth System Science》2016,125(5):1041-1060
This study presents the geochemical characteristics of granitic rocks located on the northern margin of Chotanagpur Gneissic Complex (CGC), exposed in parts of Gaya district, Bihar and discusses the possible petrogenetic process and source characteristics. These granites are associated with Barabar Anorthosite Complex and Neo-proterozoic Munger–Rajgir group of rocks. The granitic litho-units identified in the field are grey, pink and porphyritic granites. On the basis of geochemical and petrographic characteristics, the grey and pink granites were grouped together as GPG while the porphyritic granites were named as PG. Both GPG and PG are enriched in SiO2, K2O, Na2O, REE (except Eu), Rb, Ba, HFSE (Nb, Y, Zr), depleted in MgO, CaO, Sr and are characterised by high Fe* values, Ga/Al ratios and high Zr saturation temperatures (GPGavg~ 861 °C and PGavg~ 835 °C). The REE patterns for GPG are moderately fractionated with an average (La/Yb)N~ 4.55 and Eu/Eu* ~ 0.58, than PG which are strongly fractionated with an average (La/Yb)N~ 31.86 and Eu/Eu* ~ 0.75. These features indicate that the granites have an A-type character. On the basis of geochemical data, we conclude that the granites are probably derived from a predominant crustal source with variable mantle involvement in a post-collisional setting. 相似文献
1