Journal of Palaeogeography最新文献

{"title":"Enrichment mechanism of organic-rich shale under tectonic–depositional differentiation: A case study from the lower Cambrian Qiongzhusi Formation, northern Sichuan Basin, China","authors":"Ming-He Zhang ,&nbsp;Bo Gao ,&nbsp;Zi-Liang Liu ,&nbsp;Jia Rong ,&nbsp;Ji-Hong Yan ,&nbsp;Muhammad Riaz ,&nbsp;Yi-Xin Luo ,&nbsp;Li-Ming Liu","doi":"10.1016/j.jop.2026.100369","DOIUrl":"10.1016/j.jop.2026.100369","url":null,"abstract":"<div><div>The Cambrian Qiongzhusi (QZS) Formation on the northern margin of the Sichuan Basin, in front of the Micang-Daba Mountains, features extensive marine fine-grained sedimentary rocks, particularly organic-rich shale. Understanding its spatial distribution, controlling factors, and enrichment mechanisms is crucial for advancing shale gas exploration in this region. However, the complex depositional and diagenetic history has led to significant heterogeneity in organic matter distribution, necessitating a comprehensive investigation. By integrating field geological surveys, drilling data, and geochemical analyses, including total organic carbon (TOC) content measurement and elemental analysis, this study systematically assesses the influence of various factors on the spatiotemporal distribution of organic-rich shale. The results indicate that the TOC content generally exceeds 2%, with organic matter abundance showing a cyclical vertical decrease. Laterally, the sedimentary zones of organic-rich shales can be classified into three types: favorable sedimentary zone, moderately sedimentary zone, and poor sedimentary zone. Moreover, the shale is thicker with higher organic matter abundance in the south and west, whereas it thins out and exhibits lower organic matter content toward the north and east. The spatial heterogeneity of organic enrichment is primarily controlled by the sedimentary paleogeographic framework, dominated by a “intracratonic sag–uplift–depression” structure, and regional tectonic evolution further accentuates these variations. Sea-level fluctuations and paleoclimate evolution govern the cyclical vertical distribution of the shale, where the abundance of plankton and bacteria contributed to organic matter accumulation, and a sufficient material supply facilitated clastic sedimentation of the QZS Formation. The organic-rich shale was influenced by warm and humid conditions, medium to high paleoproductivity, terrestrial input, and rapid deposition of organic matter occurring under deep-water reducing conditions with preservation enhanced by thick overlying cap rocks.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 3","pages":"Article 100369"},"PeriodicalIF":2.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147850292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How to prepare lithified sediments for SEM studies of palaeoclimatic interpretations","authors":"Mats O. Molén","doi":"10.1016/j.jop.2026.100347","DOIUrl":"10.1016/j.jop.2026.100347","url":null,"abstract":"<div><div>It may be difficult to prepare samples from lithified ancient deposits, i.e., mainly pre-Pleistocene sedimentary deposits, for studies of surface microtextures (SM) on quartz sand grains. Studies of SM is a major method used for palaeoclimatic interpretations and transport mechanisms for clastic sediments. Diamictites which are interpreted as tillites or sediment gravity flows are a main research area for such studies. A multi-process study documenting how SM are produced, both in nature and during laboratory processing, was performed and documented. The methods are simple, and SM can be easily analysed, and certain mineral covers can be removed. The laboratory processes did not induce any SM on the grains, except possible rare simple fractures.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 3","pages":"Article 100347"},"PeriodicalIF":2.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147850293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of the Early Paleozoic S-type granites within the Wuyi Terrane: Implications for the tectonic evolution of the South China Block","authors":"Yuan-Yuan Tang ,&nbsp;Yu Shi ,&nbsp;Guo-Dong Jin","doi":"10.1016/j.jop.2025.100320","DOIUrl":"10.1016/j.jop.2025.100320","url":null,"abstract":"<div><div>The Early Paleozoic tectonic evolution of the South China Block (SCB) remains a subject of considerable debate, particularly regarding whether it resulted from intracontinental orogeny or the subduction–collision process. The Wuyi Terrane (WYT), located at the center of the Wuyi–Yunkai orogen, plays a crucial role in understanding the petrogenesis of the Early Paleozoic magmatic products and tectonic evolution of the SCB. This study presents zircon U–Pb ages, geochemical analyses, and Lu–Hf isotopic data for the Fufang and Guixi granitic plutons located within the WYT. Zircon U–Pb dating results indicate that these granites were formed during the Early Paleozoic (ca. 437–436 Ma), and negative zircon <em>ε</em>_Hf(t) values (−20.7 to −6.2) suggest an ancient crustal source for the granites. These contemporaneous granites, characterized by peraluminous to strongly peraluminous compositions, are classified as high-K calc-alkaline to shoshonitic series and are recognized as highly fractionated S-type granites. They exhibit enrichment in Rb, Th, U, K, and Pb, while showing depletions in Ba, Sr, Nb, Ta, P, and Ti. The observed variations in Eu anomalies suggest differing source compositions and magmatic processes between the two plutons. Based on the geochemical and isotopic evidence, we propose that the Fufang granites originated from the partial melting of crustal meta-sedimentary rocks, without the contribution of mantle-derived materials, whereas the Guixi granites resulted from the partial melting of a heterogeneous crustal source predominantly composed of meta-sedimentary rocks, with a minor contribution from meta-igneous rocks. The granites underwent varying degrees of feldspar-dominated fractional crystallization throughout their magmatic evolution. In conjunction with their post-collisional geochemical characteristics and the regional tectonic frameworks, we suggest that the Early Paleozoic tectonic evolution of the SCB was characterized by intracontinental orogeny, with the formation of the Fufang and Guixi granites occurring during the intracontinental lithospheric extensional phase that followed collisional compression.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100320"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145969134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First documentation of late Silurian and earliest Devonian (Lochkovian) conodonts from biostromes and mud mounds in Truong Son Terrane of the Indochina Composite Terrane: Geological significance","authors":"Zhong-Yang Chen ,&nbsp;Mongkol Udchachon ,&nbsp;Hathaithip Thassanapak ,&nbsp;Jian-Feng Lu ,&nbsp;Xiang Fang ,&nbsp;Wen-Jie Li ,&nbsp;Clive Burrett","doi":"10.1016/j.jop.2026.100326","DOIUrl":"10.1016/j.jop.2026.100326","url":null,"abstract":"<div><div>Late Silurian to Early Devonian conodonts are first documented from the marl–limestone alternations, with biostromes and mud mounds, succession in the north of the Loei fold belt, in the Truong Son Terrane of the Indochina Composite Terrane in NE Thailand. Species found include <em>Wurmiella excavata</em>, <em>Panderodus unicostatus</em>, <em>Zieglerodina eladioi</em>, <em>Belodella resima</em>, <em>Neopanderodus aequabilis</em>, <em>Belodella anomalis</em>, and <em>Icriodus</em>? sp. indet. Seven major lithofacies of sedimentary rocks were identified and interpreted as shallower to deeper marine environments in a warm, tropical zone. The sequence was deposited to the east of a Silurian rhyolitic volcanic arc with which it interdigitates and is regarded as a part of an arc or back-arc basin. A Siluro-Devonian arc shows that this part of the Indochina Composite Terrane rifted away from Gondwana in or prior to the Silurian.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100326"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large-leaved Dryobalanops (Dipterocarpaceae) from the Miocene coal basin of Borneo: The early dispersal of the out-of-India genus in Southeast Asia","authors":"Muhammad Irfan Othman ,&nbsp;Masatoshi Sone ,&nbsp;Kien-Thai Yong ,&nbsp;Yienlim Wong ,&nbsp;László Kocsis","doi":"10.1016/j.jop.2026.100340","DOIUrl":"10.1016/j.jop.2026.100340","url":null,"abstract":"<div><div>Dipterocarpaceae is one of the most diverse tree families in the lowland rainforests of Southeast Asia, with Borneo hosting the highest species diversity and endemism. Its West Gondwanan origin in the Late Cretaceous is widely accepted; however, the timing and route of its migration to Southeast Asia remain largely unknown. One of its genera, <em>Dryobalanops</em> C.F.Gaertn., includes seven extant species that are found exclusively in Peninsular Malaysia, Sumatra, and Borneo (West Malesia floristic province). However, the genus is known to have had a broader distribution in pre-Holocene times. A fossil species, <em>Dryobalanops rajangensis</em> sp. nov., is described from the early Miocene of the Merit-Pila coal basin in Sarawak, Malaysia (Borneo), based on leaf impressions and cuticles. It is characterised by large, slightly obovate leaf blades that most closely resemble those of the modern species <em>Dryobalanops oblongifolia</em> Dyer among all its congeners. This discovery marks the earliest occurrence of the genus outside India, as it postdates the Eocene <em>Dryobalanops</em>-type pollen recently uncovered in Gujarat (West India). It further suggests that the genus had already migrated to Borneo by the early Miocene, establishing itself within the local peat swamp. This finding aligns well with the ‘out-of-India’ dispersal theory of the Dipterocarpaceae. Additionally, the Merit-Pila coal basin contains rich deposits of amber, whose resin chemistry is known to indicate dipterocarp affinity. Thus, the new fossil species may represent a botanical source of Merit-Pila amber.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100340"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147398589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multifactor controls on heterogeneous salinization in lacustrine basins: Insights from quantitative thresholds and triggering conditions","authors":"Zhen-Guo Qi ,&nbsp;Fu-Jie Jiang ,&nbsp;Fei-Long Wang ,&nbsp;Hai-Feng Yang ,&nbsp;Meng-Xing Liu ,&nbsp;Zhou Fang ,&nbsp;Xue-Yu Yao ,&nbsp;Wei-Bing Shen ,&nbsp;Tao Hu ,&nbsp;Zhao Zhao ,&nbsp;Yu-Qi Zhang ,&nbsp;Bo Yang ,&nbsp;Yu Zhang ,&nbsp;Jing-Qi Zhou ,&nbsp;Shuang Li ,&nbsp;Meng-Yang Wang ,&nbsp;Xiao-Wei Zheng","doi":"10.1016/j.jop.2026.100339","DOIUrl":"10.1016/j.jop.2026.100339","url":null,"abstract":"<div><div>Salinity plays a critical role in lake ecosystems, organic matter enrichment, and source rock formation, and holds significant implications for oil and gas exploration. Therefore, the mechanisms underlying lacustrine salinization have attracted increasing attention. Previous studies of salinization mechanisms have often focused merely on correlations between various factors and salinity. This limited scope has created a gap in the study of quantitative thresholds and triggering conditions, which impedes a comprehensive understanding of heterogeneous salinization mechanisms across temporal and spatial scales. This study investigates the multifactorial controls on heterogeneous salinization of the Paleogene strata of the Bohai Bay Basin, quantitatively elucidating their influence and identifying distinct thresholds or triggering conditions for each factor. The results show that lacustrine salinization heterogeneity is governed by multiple factors, including evaporation, marine transgression, surface runoff and hydrothermal activity: 1) evaporation is the predominant driver of salinization when climatic aridity exceeds a critical threshold (Sr/Cu &gt; 25); 2) mantle-derived hydrothermal fluids, not alone but in conjunction with formation brines, can lead to significant salinization; 3) marine transgression can cause substantial dissolved salt influx to lakes during prolonged and extensive transgression, and its salinizing effect is amplified during sustained arid climatic regimes; 4) surface runoff effectively reduces salinity, particularly near river mouths, and the dilution effect becomes significant only when the salinity exceeds 8 ‰. Collectively, evaporation and large-scale marine transgressions primarily control temporal heterogeneity in lacustrine salinization, whereas hydrothermal activity and surface runoff govern spatial heterogeneity.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100339"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Middle Llandovery (Silurian) stromatoporoids from Baingoin, Xizang (Tibet), China","authors":"Juwan Jeon ,&nbsp;Zhong-Yang Chen ,&nbsp;Guang-Xu Wang ,&nbsp;Yuan-Dong Zhang","doi":"10.1016/j.jop.2026.100336","DOIUrl":"10.1016/j.jop.2026.100336","url":null,"abstract":"<div><div>Silurian stromatoporoids from the Qinghai–Tibetan Plateau remain poorly known, with only limited documentation in this critical palaeogeographic region. We provide the first systematic description of Aeronian (Llandovery) stromatoporoids from the lower Dongka Group in Xizang (Tibet), China. Three species are described: <em>Cystostroma dongkaense</em> sp. nov., <em>Clathrodictyon shiqianense</em> Dong and Yang, 1978, and <em>Ecclimadictyon gejingae</em> sp. nov. The assemblage is dominated by clathrodictyids, continuing a global trend of clathrodictyid dominance that began in the Katian (Late Ordovician) and expanded globally during the late Hirnantian. These stromatoporoids indicate that the Lhasa terrane was situated at subtropical to tropical latitudes during the early Silurian. Shared occurrences of <em>Clathrodictyon</em> taxon from Xizang and South China indicate potential faunal connectivity between these regions during the early Silurian. This work expands the geographic and stratigraphic distribution of early Silurian stromatoporoids and also provides new insights into post-extinction recovery dynamics and the resilience of stromatoporoid calcification mechanisms after the Late Ordovician mass extinction.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100336"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Sergipe-Alagoas Basin, northeastern Brazil, as a key for the paleogeographic understanding of the central Gondwana Carboniferous","authors":"Ananda Lima Carneiro ,&nbsp;Wagner Souza-Lima","doi":"10.1016/j.jop.2026.100342","DOIUrl":"10.1016/j.jop.2026.100342","url":null,"abstract":"<div><div>Despite the increasing recognition of glaciations in Carboniferous Gondwana in recent years, there is a lack of detailed paleoclimatic and paleogeographic studies in central Gondwana. The Carboniferous successions of the Sergipe-Alagoas Basin, northeastern Brazil, presents significant geological features for understanding the sedimentary processes that occurred during this period. This study provides a paleogeographic interpretation for the Carboniferous of the Sergipe-Alagoas and adjacent basins, integrating lithostratigraphic data from boreholes and outcrops in the Carboniferous successions. The origin of this sequence was related to six glacial and interglacial paleoclimatic stages, reflecting the advance and retreat of glaciers. The first stage represented a glacial event, with extensive diamictite deposition, followed by four sequenced interglacial and glacial stages probably associated with a glaciolacustrine system, with the influence of rivers and deltas. The final stage represented the end of the glacial event and the reworking of previous deposits. The paleogeographic reconstruction proposed for the region consists of valleys controlled by Brasiliano age (Pan-African) mountain ranges, with a preferential NW–SE direction. Glacial valleys were delimited by the occurrence of diamictites from the Mulungu Member (Batinga Formation). In glacial periods, these valleys accommodated glaciers, while in interglacial periods, they were partly filled with water and became lakes. In the central portion of Gondwana, glaciation began in Visean (around 337 Ma), extending to the central east until Bashkirian (ca. 320 Ma). After this, the continents moved from the South Pole, and the ice began to melt. By the end of Sakmarian (around 290 Ma), their influences decreased considerably in this region. The age defined for the Batinga Formation, in the Sergipe-Alagoas Basin, suggests that the last glacial events in this portion of Gondwana occurred in the Westphalian.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100342"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147398584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Miocene Syzygium Gaertn. (Myrtaceae) from India and its ancestral lineages from Gondwanaland","authors":"Sadanand ,&nbsp;Harshita Bhatia ,&nbsp;Purushottam Adhikari ,&nbsp;Rashmi Srivastava ,&nbsp;Gaurav Srivastava","doi":"10.1016/j.jop.2026.100343","DOIUrl":"10.1016/j.jop.2026.100343","url":null,"abstract":"<div><div><em>Syzygium</em> is the largest woody angiosperm genus, widely distributed across tropical and subtropical regions in the Old World. Despite its ecological prominence, its fossil record remains underexplored, leading to ongoing debates about its origin and biogeographic history. This study reports eleven newly discovered <em>Syzygium</em> fossil leaves from the Early Miocene Kasauli Formation of Himachal Pradesh, India. Based on morphological and cluster analysis of 156 plant species across 21 extant angiosperm families, utilizing 22 leaf morphological characters with 79 different character states, we identified the fossil as a new species, <em>Syzygium paleosalicifolium</em> sp. nov. Additionally, we reinvestigated previously reported <em>Syzygium</em> fossils from the Paleogene and Neogene sediments of India to refine evolutionary timeline of the genus. Our findings confirmed the presence of <em>Syzygium</em> in India since at least the early Eocene, challenging hypotheses of an exclusively Australian or Southeast Asian origin. The Indian fossil record supports an East Gondwanan lineage, predating the proposed Miocene origin and diversification of the genus. Furthermore, our results suggest that <em>Syzygium</em> may have diversified earlier than the ∼51.2 Ma crown age estimated by molecular phylogenetic studies.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100343"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147398586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Glacial Trifecta: A critical look at pre-Pleistocene glacial interpretations using a Paleoproterozoic example","authors":"David K. Larue","doi":"10.1016/j.jop.2026.100344","DOIUrl":"10.1016/j.jop.2026.100344","url":null,"abstract":"<div><div>Sedimentology and stratigraphy can offer essentially unique insights into key depositional environments and processes, including tidal, wave-driven, deep-water, and fluvial systems. However, the interpretation of pre-Pleistocene glacial deposits is rife with non-unique and questionable interpretations, yet the implications of glacial events for earth history are much more profound.</div><div>Assignments of glacial environments are typically based upon interpretation of what is termed here the Glacial Trifecta, the group of three key interpretations used to recognize glaciogenic deposits: glacial till, presence of striated basement and striated and faceted clasts, and the interpretation of lonestones as dropstones. Briefly stated, uniquely distinguishing pre-Pleistocene tillites from debris flow deposits is extremely difficult or almost impossible. Striated basement and clasts can form by non-glacial mechanisms, including emplacement of olistostromes and other mass movements. Lonestones greatly resembling dropstones can form in non-glacial deep-water slope environments. When any of the features of the Glacial Trifecta appear in a geologic time period previously considered glaciogenic, they reinforce the interpretation that glaciation occurred during that time period, even though the interpreted glaciogenic period may have been defined a century ago prior to better understanding of debris flow and other sediment gravity flow mechanics, sequence stratigraphy, tectonics and sedimentation, and deep-water depositional environments.</div><div>Challenges interpreting glacial deposits in the Paleoproterozoic of the Lake Superior region are presented. Here, prior interpretations of tillite are shown to be likely examples of foliated debris flow deposits. A classification scheme for lonestones is presented, and a number of lonestones that could be misinterpreted as dropstones are described from the non-glacial Cretaceous Pigeon Point Formation and the Miocene San Onofre Breccia. Lonestones in the Paleoproterozoic of the Lake Superior region are interpreted to represent sediment gravity flow deposits.</div><div>Some have argued that the geochemistry of mudstones (the Chemical Index of Alteration, CIA) can be used as an indicator of glacial environments, but counter examples are provided from arid, tectonically active settings. An additional criterion against recognition of glacial environments is the presence of quartz arenites and quartz-rich detritus in purported glacial deposits. Future studies would benefit from focus on more rigorous testing of the Glacial Trifecta. More non-glacial analogues to the Glacial Trifecta, such as those discussed here (the Pigeon Point Formation and the San Onofre Breccia), would help future discussions concerning uncertainty in the interpretation of glacial deposits.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100344"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147398587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}