Evidence from Middle Ordovician paleosols for the predominance of alkaline groundwater at the dawn of land plant radiation
Bibliographic record
Abstract
Research Article| January 01, 2009 Evidence from Middle Ordovician paleosols for the predominance of alkaline groundwater at the dawn of land plant radiation Pierre Jutras; Pierre Jutras * 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada *E-mail: pierre.jutras@smu.ca Search for other works by this author on: GSW Google Scholar Ryan S. Quillan; Ryan S. Quillan 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada Search for other works by this author on: GSW Google Scholar Matthew J. LeForte Matthew J. LeForte 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Pierre Jutras * 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada Ryan S. Quillan 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada Matthew J. LeForte 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada *E-mail: pierre.jutras@smu.ca Publisher: Geological Society of America Received: 13 Apr 2008 Revision Received: 18 Aug 2008 Accepted: 09 Sep 2008 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2009 Geological Society of America Geology (2009) 37 (1): 91–94. https://doi.org/10.1130/G25447A.1 Article history Received: 13 Apr 2008 Revision Received: 18 Aug 2008 Accepted: 09 Sep 2008 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Pierre Jutras, Ryan S. Quillan, Matthew J. LeForte; Evidence from Middle Ordovician paleosols for the predominance of alkaline groundwater at the dawn of land plant radiation. Geology 2009;; 37 (1): 91–94. doi: https://doi.org/10.1130/G25447A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Atmospheric carbon is estimated to have been ~500 times more abundant in Hadean time than at present, and its concentration has been gradually decreasing since then due to its storage in sedimentary rocks. Consequently, rain pH has been gradually increasing through geologic time, leading to the common assumption that groundwaters are less acidic today than they were in the distant past. However, this assumption overlooks the fact that root-forming land plants increase the carbonic acid concentration in soils by one or two orders of magnitude. In the absence of rooted land plants, reactions between minerals and rainwater are known to promote alkalinity. It is hypothesized that groundwater pH must have been, on average, highest shortly before the Late Ordovician to Silurian proliferation of root-forming land plants. To verify this hypothesis, we studied the mineralogy and geochemistry of the youngest known pre-Silurian paleosols to have developed on primary rocks, and provide evidence that they have evolved in predominantly alkaline groundwaters despite warm and humid paleo-environmental conditions. Today, a lush vegetation cover would thrive in such a climate, and the system would be necessarily acidic due to large inputs of organic acids. Paired with previous observations indicating that early Paleozoic sedimentary rocks are especially rich in detrital illite and K-feldspar, there is now enough evidence to believe that there was a greater tendency for alkalinity during this time period than during previous and subsequent geologic periods. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".