{"title":"帕霍霍(Pāhoehoe)熔岩在 Mull 的 Lon Reudle 火山喷发。","authors":"Steven N. A. Walker, Joaquín A. Cortés","doi":"10.1144/sjg2023-019","DOIUrl":null,"url":null,"abstract":"The base of the Mull Lava Sequence, part of the Palaeogene British Igneous Province, contains a variety of volcanic features, e.g., small-scale filled lava tubes and toes that can be interpreted as large-scale inflated sheets from pāhoehoe lava flows. Here, we re-examine a previously reported unique outcrop found along the coastline of Lon Reudle, Mull, which can be better understood under that conceptual model. The outcrop is composed by multiple layers, with repeating porphyritic, poorly columnar jointed and vesicle-free layers, alternating with vesicle-rich layers with individual vesicles measuring up to 1 m. We reinterpret the outcrop as an individual inflated pāhoehoe lobe with an aggregated total thickness of at least 25 m. The estimated thickness of the upper crust of this lobe is 15 m, as the upper crust would account for 40-60% of the total volume of the flow, while the time required for this upper crust to form is ∼4 years. The alternation between vesicle-rich and vesicle-free layers is likely to be caused by instabilities of the suspended bubbles in the basaltic melt, forming a diapir with abundant evidence of bubble coalescence. Typical Hawaiian pāhoehoe lava flows have thickness of 1-3 metres, while in other flood basalt provinces thickness can reach up to 75-80 metres, suggesting that pāhoehoe structures are scale-independent. This is a key factor to take into account at the time of re-interpreting other lava structures that have been found in the Palaeogene British Igneous Province.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":null,"pages":null},"PeriodicalIF":0.5000,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Pāhoehoe lava emplacement in Lon Reudle, Mull.\",\"authors\":\"Steven N. A. Walker, Joaquín A. Cortés\",\"doi\":\"10.1144/sjg2023-019\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The base of the Mull Lava Sequence, part of the Palaeogene British Igneous Province, contains a variety of volcanic features, e.g., small-scale filled lava tubes and toes that can be interpreted as large-scale inflated sheets from pāhoehoe lava flows. Here, we re-examine a previously reported unique outcrop found along the coastline of Lon Reudle, Mull, which can be better understood under that conceptual model. The outcrop is composed by multiple layers, with repeating porphyritic, poorly columnar jointed and vesicle-free layers, alternating with vesicle-rich layers with individual vesicles measuring up to 1 m. We reinterpret the outcrop as an individual inflated pāhoehoe lobe with an aggregated total thickness of at least 25 m. The estimated thickness of the upper crust of this lobe is 15 m, as the upper crust would account for 40-60% of the total volume of the flow, while the time required for this upper crust to form is ∼4 years. The alternation between vesicle-rich and vesicle-free layers is likely to be caused by instabilities of the suspended bubbles in the basaltic melt, forming a diapir with abundant evidence of bubble coalescence. Typical Hawaiian pāhoehoe lava flows have thickness of 1-3 metres, while in other flood basalt provinces thickness can reach up to 75-80 metres, suggesting that pāhoehoe structures are scale-independent. This is a key factor to take into account at the time of re-interpreting other lava structures that have been found in the Palaeogene British Igneous Province.\",\"PeriodicalId\":49556,\"journal\":{\"name\":\"Scottish Journal of Geology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.5000,\"publicationDate\":\"2024-04-22\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Scottish Journal of Geology\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1144/sjg2023-019\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"GEOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Scottish Journal of Geology","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1144/sjg2023-019","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOLOGY","Score":null,"Total":0}
The base of the Mull Lava Sequence, part of the Palaeogene British Igneous Province, contains a variety of volcanic features, e.g., small-scale filled lava tubes and toes that can be interpreted as large-scale inflated sheets from pāhoehoe lava flows. Here, we re-examine a previously reported unique outcrop found along the coastline of Lon Reudle, Mull, which can be better understood under that conceptual model. The outcrop is composed by multiple layers, with repeating porphyritic, poorly columnar jointed and vesicle-free layers, alternating with vesicle-rich layers with individual vesicles measuring up to 1 m. We reinterpret the outcrop as an individual inflated pāhoehoe lobe with an aggregated total thickness of at least 25 m. The estimated thickness of the upper crust of this lobe is 15 m, as the upper crust would account for 40-60% of the total volume of the flow, while the time required for this upper crust to form is ∼4 years. The alternation between vesicle-rich and vesicle-free layers is likely to be caused by instabilities of the suspended bubbles in the basaltic melt, forming a diapir with abundant evidence of bubble coalescence. Typical Hawaiian pāhoehoe lava flows have thickness of 1-3 metres, while in other flood basalt provinces thickness can reach up to 75-80 metres, suggesting that pāhoehoe structures are scale-independent. This is a key factor to take into account at the time of re-interpreting other lava structures that have been found in the Palaeogene British Igneous Province.
期刊介绍:
Although published only since 1965, the Scottish Journal of Geology has a long pedigree. It is the joint publication of the Geological Society of Glasgow and the Edinburgh Geological Society, which prior to 1965 published separate Transactions: from 1860 in the case of Glasgow and 1863 for Edinburgh.
Traditionally, the Journal has acted as the focus for papers on all aspects of Scottish geology and its contiguous areas, including the surrounding seas. The publication policy has always been outward looking, with the Editors encouraging review papers and papers on broader aspects of the Earth sciences that cannot be discussed solely in terms of Scottish geology.
The diverse geology of Scotland continues to provide an important natural laboratory for the study of earth sciences; many seminal studies in geology have been carried out on Scottish rocks, and over the years the results of much of this work had been published in the Journal and its predecessors.
The Journal fully deserves its high reputation worldwide and intends to maintain its status in the front rank of publications in the Earth sciences.