AGE RE-ASSESSMENT OF THE LONGDONGSHUI MEMBER (MIDDLE DEVONIAN) IN SOUTHERN GUIZHOU ON THE BASIS BENTHIC FOSSILS
Bibliographic record
Abstract
Dushan,located in southern Guizhou,is an important area for the study of Devonian shallow marine strata.Abundant benthic fossils(corals and brachiopods)have been found in the Middle and Upper Devonian.The Longdongshui Member of the Houershan Formation was established by Wang et al.,in 1964.Based on rugose and tabulate corals and brachiopods,the Longdongshui Member has long been regarded to be of early Middle Devonian(Eifelian)age.Although no index or zonal conodont species have ever been found so far,the Eifelian age has been adopted by most geologists.However,Zhou Xiyun(1992)did not agree that the genera and species of Rugosa,Tabulata and Brachiopods from the Longdongshui Member are of Eifelian age.Afterwards,Wang et al.(1997)and Wu et al.(1997)also regarded the Longdongshui Member to be Lower Devonian in age on the basis of ichnofacies and sequence stratigraphy respectively.However,Zhu's data on the Rugosa,Tabulata and Brachiopods in 1992 are questionable.As for trace fossils and sequence stratigraphy,the former mainly reflected marine environments as well as the sedimentary facies and the latter was principally related to sea level changes or transgression-regression cycles.The Longdongshui Member is characrterized by abundant rugosa,tabulata and brachiopod fossils.The studies on the Rugosa(Yu and Liao 1978),the Tabulata(Ye and Zhou 1975;Deng 1979),and the Brachiopoda(Hou and Xian 1975;Wang and Zhu 1979)afforded considerable evidence for the age of the member.The rugose corals Utaratuia sinensis and Sociophyllum minor are similar to Utaratuia laevigata and Sociophyllum glomerulatum from the Hume Formation(Eifelian)of northwestern Canada respectively.The tabulate corals Favosites goldfussi eifelensis and Pachycanalicula barrandei from Europe are of early Middle Devonian age.Beside,the brachiopods Athyrisina squamosaeformis,Eospiriferina lachrymosa,Acrospirifer fongi and Kwangsia perfecta were found not only in the Longdongshui Member of Guizhou,but also in the Eifelian Yingtang Formantion,Yarang Formation and Baima Shale of Guangxi as well as in the upper part of the Yangmaba Formation of Sichuan.Therefore,the Longdongshui benthic fauna strongly suggests an early Middle Devonian(Eifelian)age.
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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 | 0.000 | 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) | 0.002 | 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".