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Journal articles
Depositional histories of vegetation and rainfall intensity in Sierra Madre Oriental Mountains (northeast Mexico) since the late Last Glacial
Abstract : An evaporite enriched sediment archive from the dry Sandia Basin located in the water-stressed western foothills
of the Sierra Madre Oriental Mountains (northeast Mexico) was studied to reconstruct depositional histories of
vegetation and rainfall intensity in orbital to millennial-scales over the last ~32.5 cal ka. Surrounding vegetation
had more C3 plants during the late last glacial and deglaciation and the expansion of more drought tolerant C4
plants occurred only after ~5 cal ka BP. Clastic minerals were sourced from different lithologies within the
watershed and their abundances helped to infer runoff dynamics and hence the rainfall intensities. Deposition of
more mixed-layer clay represented wetter intervals over the late last glacial and deglaciation. Transportation of
clastics from the nearby lithology during these wetter intervals suggested that high-intensity rainfall events were
less frequent. Response to the Heinrich stadials (H3, H2 and early H1) was mainly similar (drier) and erosion in
the watershed remained less-than-average. Transportation of more quartz-rich sediments from distal lithologies
during the late Bølling-Allerød (B/A) interstadial and between ~6.2 and 4 cal ka BP with a depositional hiatus
between ~12.7 and 6.2 cal ka BP represented the intervals of more frequent high-intensity rainfall events,
possibly related to short-lived storms. We hypothesize that the Gulf of Mexico sea surface temperature was a
principal forcing. Total annual precipitation in this region decreased but the frequency of short-lived storms
increased during the warmer Atlantic Multidecadal Oscillation (AMO) states. Warmer conditions also led to
deposition of more gypsum. Our observation, however, needs further evaluation under the modern-day greenhouse
warming scenario.
https://hal.archives-ouvertes.fr/hal-02887576
Contributor : Saravanan Govindaraj <>
Submitted on : Thursday, July 2, 2020 - 12:25:58 PM
Last modification on : Friday, May 21, 2021 - 8:20:02 PM
Contributor : Saravanan Govindaraj <>
Submitted on : Thursday, July 2, 2020 - 12:25:58 PM
Last modification on : Friday, May 21, 2021 - 8:20:02 PM