Contrast of Leaf-wax Hydrogen Isotope Values in Mexico and Central America and It's Indication of Regional Environmental Controls
Abstract
The hydrogen isotope composition of leaf waxes (n-alkanes, n-alkanoic acids) has become increasingly important for environmental constructions as its fractionation values are determined by a variety of environmental factors including elevation and precipitation as well as biosynthetic variations among different vegetation types. We conducted a study focusing on investigating leaf wax hydrogen isotope values in lake sediments from Mexico and Central America and the environmental factors influencing these fractionation patterns. 156 core top samples were collected from 147 lakes across Tran-Mexican Volcanic Belt (TMVB) and the Yucatan Peninsula into northern Central America. It has been demonstrated that in tropical areas, the aridity index (ratio of mean annual precipitation to mean annual potential evaporation) can explain much of the variance in the hydrogen isotope fractionation between leaf waxes and meteoric water. In our study, local meteoric water lines suggest similar aridities in these two regions, yet the H isotopic fractionationshows a significant difference. We suggest that the differences between the H isotope fractionation in these two regions can be explained by biosynthetic differences related to distinctive vegetation distributions and their contribution to lake sediments, which are in turn related to patterns of precipitation and elevation.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP31D1682L
- Keywords:
-
- 0424 Biosignatures and proxies;
- BIOGEOSCIENCESDE: 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHYDE: 4924 Geochemical tracers;
- PALEOCEANOGRAPHY