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Pennsylvanian-Permian Climatic Records From Low Latitude Rainsville Trough in Northern New Mexico

Abstract

Stratigraphic records of chemical sedimentation as well as clastic influx in a basin archives

paleoclimatic data of that region. Formation of coals are indicative of continually recurring wet

climates whereas deposition of chemical rocks i.e., evaporites and/or carbonates are linked to

document dry climates. Thus, stratigraphic records of climate-sensitive sediments provide

valuable clues to asses paleoclimatic information of that region. The repetitive occurrences of

coals versus evaporites in the subsurface Rainsville trough are utilized to reconstruct late

Paleozoic paleoclimate.

Taos-Rainsville trough, also known as the Rowe-Mora basin is one of the ancestral Rocky

Mountain (ARM) basins located near low latitude during the Pennsylvanian-Permian. Within the

Rainsville trough late Paleozoic sediments are mostly in subsurface. Therefore, available

petrophysical well log data were used for lithologic interpretation. In addition, developed Matlab

codes were used to identify coals and evaporites, and correlate them between wells. Significant

repetitive coal beds occurrences along with great clastic influxes within the Sandia and Sangre de

Cristo formations indicate seasonal wet to tropical rainy climatic condition prevailed during both

the Atokan and Wolfcampian time respectively. Dominants of marine carbonates associated with

evaporite are indicative of semiarid to arid conditions during deposition of the Desmoinesian

Porvenir Formation. The Leonardian Yeso Formation, containing of gypsum beds in the

Rainsville trough as well as throughout the New Mexico indicate an arid climate.

Climatic records show spatial and temporal variability during the Pennsylvanian-Permian time in

the low latitude North American continent. Traditionally late Paleozoic has been interpreted as a

wet climatic period that gradually became dryer during late Pennsylvanian through early

Permian. However, evaporite content in the Porvenir Formation and repetitive coals in the

Sangre de Cristo Formation within the Rainsville trough suggests significantly a dryer period

during the middle to late Pennsylvanian, which became relatively wetter at the time of the

Wolfcampian.