Early Paleocene tropical forest from the Ojo Alamo Sandstone, San Juan Basin, New Mexico, USA

Flynn, Andrew G.; Peppe, Daniel J.

doi:10.1017/pab.2019.24

Cited by 24 publications

(23 citation statements)

References 85 publications

(246 reference statements)

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“…The distribution of MA values has been shown to vary between environmental and climatic regimes, and previous studies have demonstrated that MA distribution in fossil floras reflects these modern distributions in expected ways (Flynn and Peppe, 2019;Lowe et al, 2018;Peppe et al, 2018;Royer et al, 2010). The distribution of Florissant MA values is centered at higher values relative to various wet temperate sites and is lacking leaves with the extremely high MA values found in typical wet tropical sites (Fig.…”

Section: Sclerophyllymentioning

confidence: 80%

Paleoclimate and paleoecology of the latest Eocene Florissant flora of Central Colorado, U.S.A.

Allan¹,

Lowe²,

Peppe³

et al. 2019

Preprint

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The uppermost Eocene Florissant Formation of central Colorado, U.S.A. contains a diverse flora and fauna preserved in lacustrine facies and represents a key episode in Earth history immediately preceding the Eocene-Oligocene boundary. Laminated shales contain impressions of non-monocot angiosperm leaves that were used to estimate paleoecological and paleoclimatic parameters using leaf physiognomic methods including: leaf mass per area (MA), digital leaf physiognomy (DiLP), leaf margin analysis (LMA), and leaf area analysis (LAA). The majority (58%) of the morphotypes analyzed for MA suggested a semi-evergreen leaf lifespan, whereas another 27% indicated a deciduous habit and 15% an evergreen habit. There was no significant relationship between MA and insect damage based on a small subset of Florissant’s leaves. Higher MA values (~73% of leaves ≥ one-year lifespan), coupled with a tendency toward long and narrow leaf shapes and small leaf areas, indicate the existence of sclerophyllous vegetation. Using the global regression for mean annual temperature (MAT), the DiLP estimate of MAT was anomalously cold: 5.5 ± 4 °C. However, using a Northern Hemisphere regression the DiLP MAT estimate of 11.6 ± 3.3 °C was more plausible. Using DiLP, mean annual precipitation (MAP) was estimated at 740 +608/-334 mm∙yr-1, which supports dry conditions. Estimates for MAT and MAP using the univariate LMA and LAA methods overlapped within uncertainty of the DiLP results. In addition, those taxa classified as growing in wet areas (riparian) had significantly more teeth than non-riparian taxa. These paleoclimatic and paleoecological results suggest that outside the riparian forest, the Florissant flora sampled a seasonally dry temperate sclerophyllous shrubland to woodland, perhaps similar to modern chaparral forests, in the western interior of the U.S.A. just before the transition into the cooler Oligocene.

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Section: Sclerophyllymentioning

confidence: 80%

Paleoclimate and paleoecology of the latest Eocene Florissant flora of Central Colorado, U.S.A.

Allan¹,

Lowe²,

Peppe³

et al. 2019

Preprint

Self Cite

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“…Our results suggest that the rich Cenozoic macrofloras of Patagonia also carry a legacy of rich Cretaceous floras, as well as significantly earlier recovery of Paleocene species richness resulting from the persistence of most higher taxonomic levels (Supplementary Tables 1, 2). Nonetheless, an emerging body of research shows that floral diversity in the early Paleocene of the Denver and San Juan Basins can be higher relative to the more northerly WB (Johnson and Ellis 2002; Flynn and Peppe 2019; Lyson et al 2019). These studies show heterogeneity in NAM floral richness during the early Paleocene, a pattern warranting further intensive study.…”

Section: Discussionmentioning

confidence: 99%

“…1D) (Clyde et al 2014). While acknowledging work on diverse Paleocene floras from the more southerly Denver and San Juan basins (Johnson and Ellis 2002; Flynn and Peppe 2019; Lyson et al 2019), we focus on the floras of the WB for comparison, because they come from similar absolute paleolatitudes to our samples (i.e., ca. 51.3°S for the Danian Patagonian floras, ca.…”

Section: Methodsmentioning

confidence: 99%

Cretaceous–Paleogene plant extinction and recovery in Patagonia

Stiles¹,

Wilf²,

Iglesias³

et al. 2020

Paleobiology

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The Cretaceous–Paleogene (K/Pg) extinction appears to have been geographically heterogeneous for some organismal groups. Southern Hemisphere K/Pg palynological records have shown lower extinction and faster recovery than in the Northern Hemisphere, but no comparable, well-constrained Southern Hemisphere macrofloras spanning this interval had been available. Here, macrofloral turnover patterns are addressed for the first time in the Southern Hemisphere, using more than 3500 dicot leaves from the latest Cretaceous (Maastrichtian) and the earliest Paleocene (Danian) of Argentine Patagonia. A maximum ca. 90% macrofloral extinction and ca. 45% drop in rarefied species richness is estimated across the K/Pg, consistent with substantial species-level extinction and previously observed extirpation of host-specialized leaf mines. However, prior palynological and taxonomic studies indicate low turnover of higher taxa and persistence of general floral composition in the same sections. High species extinction, decreased species richness, and homogeneous Danian macrofloras across time and facies resemble patterns often observed in North America, but there are several notable differences. When compared with boundary-spanning macrofloras at similar absolute paleolatitudes (ca. 50°S or 50°N) from the Williston Basin (WB) in the Dakotas, both Maastrichtian and Danian Patagonian species richnesses are higher, extending a history of elevated South American diversity into the Maastrichtian. Despite high species turnover, our analyses also reveal continuity and expansion of leaf morphospace, including an increase in lobed and toothed species unlike the Danian WB. Thus, both Patagonian and WB K/Pg macrofloras support a significant extinction event, but they may also reflect geographically heterogeneous diversity, extinction, and recovery patterns warranting future study.

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“…Silicified stumps, wood fragments, and logs as much as 34 m long are common in the sandstones of the Ojo Alamo Sandstone. Leaf fossils are present but uncommon in the formation's claystones (Flynn and Peppe, 2019).…”

Section: Ojo Alamo Sandstonementioning

confidence: 99%

“…The overbank floodplain facies association contains sandy mudstones with interbedded fine-grained sandstones. This facies association's laterally discontinuous sand lenses, organic-rich fossil hash layers, and leaf fossils (Flynn et al, 2014;Flynn and Peppe, 2019) suggest deposition in fluvial floodplain environments (Kraus and Gwinn, 1997;Alexander and Fielding, 2006). Paleosols are uncommon; where present, they lack horizonation and are identified based solely on root traces.…”

Section: Overbank Floodplain Depositsmentioning

confidence: 99%

A physical and chemical sedimentary record of Laramide tectonic shifts in the Cretaceous-Paleogene San Juan Basin, New Mexico, USA

Hobbs

Fawcett

2021

Geosphere

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Fluvial siliciclastic rocks bracketing the Cretaceous-Paleogene (K-Pg) boundary in the San Juan Basin, New Mexico (USA), provide records of regional fluvial and tectonic evolution during the Laramide orogeny. Petrographic analyses of sandstones from the Upper Cretaceous Fruitland Formation and Kirtland Formation and the Paleocene Ojo Alamo Sandstone and Nacimiento Formation show that the rivers depositing these sediments were sourced in areas where unroofing of crystalline basement rocks took place, introducing an increasing proportion of immature detrital grains into the fluvial system through time. After the Cretaceous-Paleogene boundary, rivers deposited an increasing amount of microcline and orthoclase feldspar relative to plagioclase feldspar, suggesting a growing source in unique crystalline basement rocks. Geochemical analyses show significant differences between Al- and K-poor Upper Cretaceous sandstones and Al- and K-rich lower Paleocene sandstones in the San Juan Basin. The high proportion of sand-sized material in the Ojo Alamo Sandstone suggests that it was deposited in a basin with a low ratio of sediment supply to accommodation. However, magnetostratigraphic age constraints suggest it had a relatively high sedimentation and/or subsidence rate of as much as 0.38 m/k.y. The sediment supply must have been high in order to deposit a basin-wide coarse sand-dominated package, suggesting rapid creation of topographic relief in the San Juan uplift, the proposed source area of the Ojo Alamo fluvial system. The observed sedimentary architecture and age constraints of the Ojo Alamo Sandstone, including kilometers-wide sand bodies and limited overbank mudstones throughout most of the outcrop area, are difficult to reconcile with accepted models of aggradation and avulsion in large fluvial systems, but available age and lithologic data make difficult a complete understanding of Paleocene San Juan Basin fluvial systems and basin evolution. Here, we present new lithologic, petrographic, and thickness data from San Juan Basin K-Pg fluvial siliciclastic units and interpretations of their origins.

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Early Paleocene tropical forest from the Ojo Alamo Sandstone, San Juan Basin, New Mexico, USA

Cited by 24 publications

References 85 publications

Paleoclimate and paleoecology of the latest Eocene Florissant flora of Central Colorado, U.S.A.

Paleoclimate and paleoecology of the latest Eocene Florissant flora of Central Colorado, U.S.A.

Cretaceous–Paleogene plant extinction and recovery in Patagonia

A physical and chemical sedimentary record of Laramide tectonic shifts in the Cretaceous-Paleogene San Juan Basin, New Mexico, USA

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