Paleoecology of Early Pennsylvanian vegetation on a seasonally dry tropical landscape (Tynemouth Creek Formation, New Brunswick, Canada)
TL;DR: The distribution and community ecology of Early Pennsylvanian vegetation on a seasonally dry fluvial megafan is reconstructed from plant assemblages in the Tynemouth Creek Formation of New Brunswick, Canada.
About: This article is published in Review of Palaeobotany and Palynology.The article was published on 2014-01-01. It has received 76 citations till now. The article focuses on the topics: Pennsylvanian & Fluvial.
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TL;DR: Lower-diversity worlds such as the late Paleozoic, with a rich spectrum of environmental variations, offer insights into relationships between organisms and environments that expand understanding of these phenomena and enlarge their sense of what is possible or probable as the authors look to the future.
Abstract: Premise of research. The Late Paleozoic Ice Age was the last extensive pre-Pleistocene ice age. It includes many climate changes of different intensities, permitting examination of many and varied biotic responses. The tropical Pennsylvanian Subperiod, usually visualized as one vast wetland coal forest, in fact also was dominated, periodically, by seasonally dry vegetation that, in turn, covered most of the central and western Pangean supercontinent. Equatorial wetland and dryland biomes oscillated during single glacial-interglacial cycles. This recognition changes understanding of the Coal Age tropics; examination of their spatiotemporal patterns indicates that these vegetation types responded differently to global environmental disturbances and long-term trends and points to potentially different underlying controls on evolutionary histories of their component lineages.Methodology. This study is based on the published literature and on examination of geological exposures and fossil floras, mainly from N...
147 citations
Cites background or result from "Paleoecology of Early Pennsylvanian..."
...The Atlantic Canadian coal basins have proven particularly fruitful ground for the preservation of wetland elements in otherwise seasonally dry cordaitalean-dominated habitats from the Early Pennsylvanian (Falcon-Lang et al. 2006; Bashforth et al. 2014)....
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...Bashforth et al. (2014) and Wagner (2005) also report Dicranophyllum, a probable coniferophyte (Barthel and Noll 1999), species of which persist into the Permian....
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...10D), perhaps during a change to greater rainfall seasonality at all phases of glacialinterglacial cycles (Cecil 1990; Bashforth et al. 2014), and became an increasingly important element of these kinds of assemblages (Galtier et al. 1992; Rothwell et al. 1997; Hernandez-Castillo et al. 2001b;…...
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...The most consistently present are the calamitaleans, which have been identified in wet areas surrounding lakes and streamsides or in bars within streams (Falcon-Lang et al. 2004; Falcon-Lang et al. 2012; Bashforth et al. 2014)....
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...In the Early and early Middle Pennsylvanian, such areas, dominated by cordaitaleans, are documented mainly in Atlantic Canada in central Pangea (Falcon-Lang and Scott 2000; Falcon-Lang 2003b, 2006; Falcon-Lang and Bashforth 2004; Dimitrova et al. 2011; Bashforth et al. 2014)....
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TL;DR: This paper explored the effects of seasonal and yearly variable rainfall and the resultant highly peaked discharge pattern on river morphodynamics, and presented a comparison of modern and ancient monsoonal and subtropical river deposits, by documenting the diversity of the sedimentary facies, macroforms (bar forms), and architectural elements common in ancient and modern monsoon-controlled rivers.
127 citations
TL;DR: In this article, the authors introduce the umbrella term "sedimentary surface textures" and propose a methodology for classifying such structures in the geological record, and demonstrate that morphological similarity alone does not constitute scientific proof of a common origin, and reinstates a passive descriptive terminology for sedimentary surface textures that cannot be achieved with the current MISS lexicon.
127 citations
Cites background from "Paleoecology of Early Pennsylvanian..."
...Palaeobotanical work has confirmed that most of the seasonally-inactive channels on the megafan were colonized by a “dryland” cordaitalean-rich flora, with a “wetland” flora dominated by pteridosperms and calamitaleans occupying waterhole environments where standing water remained in channels throughout the year (Bashforth et al., 2014)....
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...The formation was deposited as an aggradational megafan of seasonally-active, distributive fluvial channels that were locally sourced from the uplifted Cobequid Highlands to the south, and consists of a generally coarsening-upwards succession of mudrocks, sandstones and conglomerates (Plint and Van de Poll, 1982; Bashforth et al., 2014)....
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01 Dec 2014
TL;DR: In this article, a range of new fluvial planform and architectural styles came to prominence, including channelled-and island-braided systems, meandering and anabranching systems, and stable muddy floodplains.
Abstract: As vegetation evolved during the Palaeozoic Era, terrestrial landscapes were substantially transformed, especially during the ∼120 million year interval from the Devonian through the Carboniferous Early Palaeozoic river systems were of sheet-braided style – broad, shallow, sandbed rivers with non-cohesive and readily eroded banks Under the influence of evolving roots and trees that stabilised banks and added large woody debris to channels, a range of new fluvial planform and architectural styles came to prominence, including channelled- and island-braided systems, meandering and anabranching systems, and stable muddy floodplains River systems co-evolved with plants and animals, generating new ecospace that we infer would have promoted biological evolution By the end of the Carboniferous, most landforms characteristic of modern fluvial systems were in existence
91 citations
Cites background from "Paleoecology of Early Pennsylvanian..."
...…Carboniferous fossil accumulations occupy abandoned channels, variously reflecting enhanced preservation in meandering channels or the presence of waterholes in dryland channels (Hook and Ferm, 1988; Behrensmeyer et al., 1992; Falcon-Lang et al., 2004; Astin et al., 2010; Bashforth et al., 2014)....
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...…abundant in seasonally dry alluvial settings with periodically lowered water tables, and are represented by fragmentary records from redbeds that once were considered largely barren of plant life (Falcon-Lang, 2003, 2006; Falcon-Lang et al., 2009; DiMichele et al., 2010; Bashforth et al., 2014)....
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...nels or the presence of waterholes in dryland channels (Hook and Ferm, 1988; Behrensmeyer et al., 1992; Falcon-Lang et al., 2004; Astin et al., 2010; Bashforth et al., 2014)....
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TL;DR: In this paper, the responses of aquatic and riparian communities to hydrogeomorphic constraints along the longitudinal, transverse, vertical, and temporal dimensions of rivers are modeled as a four-dimensional framework, and the consequences for biogeomorphic structure and resilience along the four river dimensions, of feedbacks between riparian plants and hydrogeomorph processes on contrasting ecological and evolutionary timescales.
Abstract: River ecological functioning can be conceptualized according to a four-dimensional framework, based on the responses of aquatic and riparian communities to hydrogeomorphic constraints along the longitudinal, transverse, vertical and temporal dimensions of rivers. Contemporary riparian vegetation responds to river dynamics at ecological timescales, but riparian vegetation, in one form or another, has existed on Earth since at least the Middle Ordovician (c. 450 Ma) and has been a significant controlling factor on river geomorphology since the Late Silurian (c. 420 Ma). On such evolutionary timescales, plant adaptations to the fluvial environment and the subsequent effects of these adaptations on fluvial sediment and landform dynamics resulted in the emergence, from the Silurian to the Carboniferous, of a variety of contrasted fluvial biogeomorphic types where water flow, morphodynamics and vegetation interacted to different degrees. Here we identify several of these types and describe the consequences for biogeomorphic structure and stability (i.e. resistance and resilience), along the four river dimensions, of feedbacks between riparian plants and hydrogeomorphic processes on contrasting ecological and evolutionary timescales.
81 citations
Cites background from "Paleoecology of Early Pennsylvanian..."
...Woody cordaitaleans and conifers dominated drier Carboniferous episodes, forming dense forested patches in inland settings (Falcon-Lang et al., 2011; Bashforth et al., 2014)....
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References
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27 Nov 1992
TL;DR: The early Cambrian to late Ordovician warm mode has been studied in this paper, where the authors present a chronology of climate change in the Cenozoic climate change Bibliography Index.
Abstract: Preface Introduction 1. The early Cambrian to late Ordovician warm mode 2. The late Ordovician to early Silurian cool mode 3. The late Silurian to early Carboniferous warm mode 4. The early Carboniferous to late Permian cool mode 5. The late Permian to middle Jurassic warm mode 6. The middle Jurassic to early Cretaceous cool mode 7. The late Cretaceous to early Tertiary warm mode 8. The Cenozoic cool mode: early Eocene - late Miocene 9. The Cenozoic cool mode: late Miocene - Holocene 10. Causes and chronology of climate change Bibliography Index.
839 citations
TL;DR: In this article, the authors present a literature dataset that represents more than 1500 bedrock and Quaternary fluvial bodies for which width (W) and thickness (T) are recorded.
Abstract: The three-dimensional geometry of fluvial channel bodies and valley fills has received much less attention than their internal structure, despite the fact that many subsurface analyses draw upon the geometry of suitable fluvial analogues. Although channel-body geometry has been widely linked to base-level change and accommodation, few studies have evaluated the influence of local geomorphic controls. To remedy these deficiencies, we review the terminology for describing channel-body geometry, and present a literature dataset that represents more than 1500 bedrock and Quaternary fluvial bodies for which width (W) and thickness (T) are recorded. Twelve types of channel bodies and valley fills are distinguished based on their geomorphic setting, geometry, and internal structure, and log-log plots of W against T are presented for each type. Narrow and broad ribbons (W/T 1000, respectively) are distinguished. The dataset allows an informed selection of analogues for subsurface applications, and spreadsheets and graphs can be downloaded from a data repository. Mobile-channel belts are mainly the deposits of braided and low-sinuosity rivers, which may exceed 1 km in composite thickness and 1300 km in width. Their overwhelming dominance throughout geological time reflects their link to tectonic activity, exhumation events, and high sediment supply. Some deposits that rest on flat-lying bedrock unconformities cover areas > 70,000 km2. In contrast, meandering river bodies in the dataset are < 38 m thick and < 15 km wide, and the organized flow conditions necessary for their development may have been unusual. They do not appear to have built basin-scale deposits. Fixed channels and poorly channelized systems are divided into distributary systems (channels on megafans, deltas, and distal alluvial fans, and in crevasse systems and avulsion deposits), through-going rivers, and channels in eolian settings. Because width/maximum depth of many modern alluvial channels is between 5 and 15, these bodies probably record an initial aspect ratio followed by modest widening prior to filling or avulsion. The narrow form (W/T typically < 15) commonly reflects bank resistance and rapid filling, although some are associated with base-level rise. Exceptionally narrow bodies (W/T locally < 1) may additionally reflect unusually deep incision, compactional thickening, filling by mass-flow deposits, balanced aggradation of natural levees and channels, thawing of frozen substrates, and channel reoccupation. Valley fills rest on older bedrock or represent a brief hiatus within marine and alluvial successions. Many bedrock valley fills have W/T < 20 due to deep incision along tectonic lineaments and stacking along faults. Within marine and alluvial strata, upper Paleozoic valley fills appear larger than Mesozoic examples, possibly reflecting the influence of large glacioeustatic fluctuations in the Paleozoic. Valley fills in sub-glacial and proglacial settings are relatively narrow (W/T as low as 2.5) due to incision from catastrophic meltwater flows. The overlap in dimensions between channel bodies and valley fills, as identified by the original authors, suggests that many braided and meandering channel bodies in the rock record occupy paleovalleys. Modeling has emphasized the importance of avulsion frequency, sedimentation rate, and the ratio of channel belt and floodplain width in determining channel-body connectedness. Although these controls strongly influence mobile channel belts, they are less effective in fixed-channel systems, for which many database examples testify to the influence of local geomorphic factors that include bank strength and channel aggradation. The dataset contains few examples of highly connected suites of fixed-channel bodies, despite their abundance in many formations. Whereas accommodation is paramount for preservation, its influence is mediated through geomorphic factors, thus complicating inferences about base-level controls.
633 citations
TL;DR: In this paper, the Late Palaeozoic Ice Age comprised at least eight discrete glacial intervals (each 1-8 Ma in duration) separated by nonglacial intervals of comparable duration, and illustrate a pattern of increasing climatic austerity and increasingly widespread glacial ice from initial onset until an acme in the late Early Permian.
Abstract: Stratigraphic and sedimentological data from New South Wales and Queensland, eastern Australia, indicate that the Late Palaeozoic Ice Age comprised at least eight discrete glacial intervals (each 1–8 Ma in duration, here termed ‘glaciations’), separated by nonglacial intervals of comparable duration. These events spanned an interval from mid-Carboniferous ( c . 327 Ma) to the early Late Permian ( c . 260 Ma), and illustrate a pattern of increasing climatic austerity and increasingly widespread glacial ice from initial onset until an acme in the late Early Permian, followed by an opposite trend towards the final demise of glaciation in the Late Permian. The alternating glacial–nonglacial motif suggests that the Late Palaeozoic Ice Age was considerably more dynamic than previously thought. These patterns are remarkably consistent with recent interpretations of palaeofloral change, eustatic sea-level fluctuations and CO 2 –climate–glaciation relationships for this interval of time. The detailed record of alternating glacial and nonglacial climate mode disclosed herein may facilitate more closely resolved evaluations of stratigraphic records elsewhere, notably in far-field, ice-distal, northern hemisphere successions.
437 citations
TL;DR: In this paper, a review summarizes evidence for the timing, extent, and behavior of continental ice on Pangea in addition to the climate and ecosystem response to repeated transitions between glacial and interglacial conditions.
Abstract: The late Paleozoic icehouse was the longest-lived ice age of the Phanerozoic, and its demise constitutes the only recorded turnover to a greenhouse state. This review summarizes evidence for the timing, extent, and behavior of continental ice on Pangea in addition to the climate and ecosystem response to repeated transitions between glacial and interglacial conditions. Combined empirical and climate modeling studies argue for a dynamic ice age characterized by discrete periods of glaciation separated by periods of ice contraction during intermittent warmings, moderate-size ice sheets emanating from multiple ice centers throughout southern Gondwana, possible glaciation of the Northern Hemisphere, and atmospheric CO2 as a primary driver of both ice sheet and climate variability. The glacioeustatic response to fluctuations of these smaller ice sheets was likely less extreme than previously suggested. Modeling studies, stratigraphic relationships, and changes in both the geographic patterns and community compositions of marine fauna and terrestrial flora indicate the potential for strong responses to high-latitude glacial conditions in both ocean circulation and low-latitude climate. The forcings and feedbacks of these linkages, as well as existing climate paradoxes, define research targets for future studies of the late Paleozoic.
434 citations