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GEOREF RECORD

Paleoclimatologic analysis of a Late Jurassic petrified forest, southeastern Mongolia

Alysa M. Keller and Marc S. Hendrix
Paleoclimatologic analysis of a Late Jurassic petrified forest, southeastern Mongolia
Palaios (June 1997) 12 (3): 282-291

Abstract

The Late Jurassic Suihent petrified forest is located in the Gobi desert of southeastern Mongolia (43 degrees 34'54' N, 108 degrees 06'12'E). The forest is represented by well-preserved silicified trees, including in situ stumps and preferentially oriented logs, all encased in a pyroclastic surge deposit. More than 72 upright stumps and 49 horizontal logs crop out in a belt approximately 100 m wide and 720 m long. The largest stump is 1.75 m in diameter and the longest log is 13 m in length. The orientation of the logs reflects that the pyroclastic flow originated northeast of the forest. Sanidine in the ash-flow tuff has been dated at 156 + or - 0.76 Ma by (super 40) Ar/ (super 39) Ar geochronology. Forty-two samples of silicified wood were collected from the site for detailed paleoclimatologic tree-ring analysis. Cell structure is excellently preserved in seventeen wood samples. Several features of the growth rings are notable and climatologically significant. These include narrow latewood, paucity of false rings, and low man and annual sensitivity values. These characteristics indicate that growth was steady during the growing season, but ceased abruptly at the onset of unfavorable conditions, and that interannual growth was fairly consistent. Water supply was likely the limiting factor for growth. Thus, the Suihent petrified forest, which grew at a paleolatitude of 46 degrees N, provides strong evidence of a paleoclimate that was highly seasonal with a rapid cessation of the growing season. These results are consistent with the presence of a monsoonal climate in this region of central Asia during the Late Jurassic.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 12
Serial Issue: 3
Title: Paleoclimatologic analysis of a Late Jurassic petrified forest, southeastern Mongolia
Affiliation: Stanford University, Department of Geological and Environmental Sciences, Stanford, CA, United States
Pages: 282-291
Published: 199706
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 48
Accession Number: 1997-061631
Categories: StratigraphyPaleobotany
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., 1 table, sketch maps
N43°34'00" - N43°34'00", E108°05'60" - E108°05'60"
Secondary Affiliation: University of Montana, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 199720
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