检索结果-南通市图书馆

Studying Tuff Rings and Volcanic Hazards in a Tropical Setting: The Case of the Batoke Tuff Ring, Limbe, SW Region Cameroon

引用

Open Journal of Geology 2023年第8期13卷 883-899页

作者： George Teke Mafany Edison Forbuck Njei Gerald G. J. Ernst Wilson Yetoh Fantong Cheo Emmanue Suh Samuel Ndonwi Ayonghe Robert stephen John Sparks Koffi Teke Mafany stephen manga njome Institute of Geological and Mining Research Yaoundé Cameroon Department of Geology University of Buea Buea Cameroon Department of Geology University of Bamenda Bamenda Cameroon Department of Geology and Soil Science University of Ghent Ghent Belgium Department of Earth Sciences University of Bristol Bristol UK Department of Earth & Space/Physics Cypress Springs High School Houston USA

In subtropical volcanic environments, there are often few accessible outcrops. These are often highly weathered and of very poor quality. Soil development is rapid (1 cm/y) and small eruptions are unlikely to be preserved in the geological record. Reconstructing past eruptions and assessing hazards is a challenge. Here, we studied a poorly outcropping tuff ring (very poor, incomplete sections) with the best outcrop observed at a beach cliff (up to ca. 5 - 10 m high) at Batoke, to the south of Mt Cameroon volcano. Mt Cameroon has a few tuff rings, currently of unknown ages, near the SW coast of Cameroon. In the Batoke case, the sequence is dominated by gently dipping tuff beds varying in the proportion of lithics, juvenile clasts, and accretionary lapilli (acc-laps). Several beds are close-packed with acc-laps of up to 10 - 15 mm diameter. Part of the section is gullied by mud flow deposits. The rocks are highly weathered but differential weathering enhances relationships. Quantitative data can be extracted from a detailed study of outcrops’ external surfaces. The preserved section is close to where the deposits were initially thickest and where acc-laps were most abundant and largest. There is an empirical correlation between maximum acc-lap size in the thickest outcrop and eruption column height. This and the deposit features suggest that the Batoke eruption was pulsating but dominated by fallout, with a water and ice-rich eruption column reaching 10 - 15 km high. Recycling of water drops and ice-coated fine ash accumulated during eruption. At switch off, wholesale gravitational collapse of this material produced the mud flows, which gullied the previously-laid down deposits. Such ash fall and mud flows can represent a substantial hazard, e.g. they can gully down through towns and roads and cut evacuation routes. This study illustrates how, at subtropical tuff rings, it is possible to extract key data needed for hazard assessment from only 1 - 2 poor outcrops.

关键词： Batoke Tuff Ring (BTR) Accretionary Lapilli

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Studying Tuff Rings and Volcanic Hazards in a Tropical Setting: The Case of the Batoke Tuff Ring, Limbe, SW Region Cameroon

引用

Open Journal of Geology（地质学期刊） 2023年第8期

来源：博看期刊评论

在线全文

博看期刊

学校读者我要写书评

暂无评论

Tectonic evolution of the Tombel graben basement, southwestern Cameroon

引用

Episodes 2005年第1期28卷 37-41页

作者： M.S.njome C.E.Suh DepartmentofGeologyandEnvironmentalScience UniversityofBueaP.O.Box63SouthWestProvinceCameroon

Planar structures (foliations and fractures) around the Tombel graben (southwestern end of the Central African Shear zone system) have been investigated and analyzed with the aim of unraveling the tectonic evolution of the basement. The foliations show two major trends, an older N-S-trending gneissose layering of uncertain agereworked by a later Pan-African (600 + 50 Ma) NE-SW ductile trend that is contemporaneous with sinistral shearing and mylonitization. The brittle phase characterized by NW-SE-trending open and partially filled fractures is younger than the mylonitization event and although it has not been dated, it is suggested that the origin of these fractures is linked to the onset of volcanism along the Cameroon volcanic line-31 m.y. *** mylonitic foliation is recognized for the first time and supports a tectonic evolution model for the Tombel graben in which ductile non-coaxial deformation was succeeded by brittle failure.

关键词：喀麦隆西南地区构造演化 Tombel地堑地质基岩

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：