Regional elevational response to glacial and mid-Holocene climate perturbations in New Mexico
Two high-resolution paleoclimate records from different environments
and elevations in New Mexico are compared to determine how synchronous
the late Quaternary climate change events were in this region. The timing
of late Pleistocene and Holocene valley and cirque moraines in the southern
Sangre de Cristo Range of northern New Mexico has been constrained by
a lake/bog record below Lake Katherine cirque. Three alpine glacial events
occurred: the termination of a late Pinedale valley glaciation just prior
to 12,120 yrs B.P. (all dates are radiocarbon years), a possible Younger
Dryas equivalent cirque glaciation (ending before 9,765 yrs B.P.), and
an early Neoglacial cirque glaciation (3,700 to 3,300 yrs B.P.). Each
of these high-elevation (> 3,200 m) glacial events is correlative with
a relative highstand in pluvial (and playa) lakes 130 km to the south
in the lower elevation Estancia Basin (~1,800 m). The final in a series
of late Pleistocene highstands of pluvial Lake Estancia terminated at
12,490 yrs B.P., with a later, smaller highstand that terminated before
9,650 yrs B.P. During the mid-Holocene, Estancia basin dried out and winds
cut nearly 100 playa basins into the Pleistocene lake floor. The blowout
basins were reoccupied by water beginning around 4,220 yrs B.P. This early
to mid-Holocene dry event is also reflected in the Sangre de Cristo range
by markedly reduced sedimentation rates. The hydrologic balance in Estancia
basin depends on winter groundwater recharge and runoff from the intermediate
elevation Manzano Mountains (~2,400 m) and evaporation in the basin itself.
The Sangre de Cristo glacial events also depend on cooler climates and
enhanced winter precipitation. We suggest that the major control on the
hydrology of both environments is the amount of winter precipitation,
with summer precipitation (e.g. early Holocene) being of secondary importance.
Comparison of these two records confirms that in the southernmost Rockies,
regional responses to climate changes associated with the last glacial
termination through the Holocene are expressed at all elevations and reflect
large-scale changes in atmospheric circulation
New Mexico Bureau of Geology & Mineral Resources
New Mexico Institute of Mining & Technology
801 Leroy Place
Socorro, NM 87801-4796
information: (575) 835-5420
fax: (575) 835-6333
http://geoinfo.nmt.edu
The New Mexico Bureau of Geology & Mineral Resources is a research and service division of:
