Limnogeology: Progress, Challenges and Opportunities - A Tribute to Elizabeth Gierlowski-Kordesch
Limnogeology: Progress, Challenges and Opportunities - A Tribute to Elizabeth Gierlowski-Kordesch
复制标题
湖沼地质学：进步、挑战和机遇 - 向 Elizabeth Gierlowski-Kordesch 致敬
DOI：
10.1007/978-3-030-66576-0_14
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Valero-Garcés B
中科院分区：
文献类型：
--
作者：
Valero-Garcés B
墨西哥盆地是一个高海拔（海拔2240米）、大面积（9540平方公里）的构造内流盆地，发育于中东部的跨墨西哥火山带。2016年，ICDP MexiDrill项目在墨西哥盆地西南部的查尔科湖（Lake Chalco）最大深度520米处共回收了1152米的沉积物。上部309.15 m（复合层序，mc）由细粒湖相沉积物与离散可见火山灰层交替组成，下部200 m主要为火山灰相和玄武质熔岩，夹有一些河流和冲积相。最初的湖泊沉积开始于Chalco盆地，在厚的火山岩序列沉积之后，并持续到近几个世纪湖泊被排干。Chalco湖至今仍是一个浅水湖，其岩芯中主要有五种岩石类型：（1）有机质，含（i）富含有机质的粉质粘土，（ii）腐泥质粉质粘土，（iii）泥炭;（2）硅藻质，含层状、条带状和斑驳状的硅藻质粉质粘土;（3）钙质，含条带状或块状碳酸盐粉质粘土和富含介形类的地层;（4）碎屑岩，含粉质粘土、砂和砾石，由碎屑和基质支撑;（5）火山岩，如（i）火山碎屑层（火山岩和碎屑沉积物）和（ii）熔岩。根据岩石类型和磁化率值划分了18个岩性单元。在沉积环境较深的阶段，出现了层状泥岩相。碳酸盐沉积标志着更碱性，浅相。泥炭和富含有机物的粉砂在盆地湿地发育较好的时期沉积。初步的年代框架表明，湖泊序列至少跨越了过去的367 ky。硅藻相中更多的含盐硅藻组合以及碳酸盐岩型和泥炭层的出现表明间冰期湖泊水位相对较低;更频繁的淡水硅藻组合和细层迭硅藻相的出现表明冰期湖泊水位较高。MexiDrill岩心的详细地层学和岩相描述为墨西哥盆地记录的年代学和古环境研究的后续发展提供了基础。此外，中铝的沉积模式适用于在活动构造和火山背景下发育的湖泊。
The Basin of Mexico is a high elevation (2240 m asl), large (9540 km2), tectonic endorheic basin developed in the central-eastern Trans-Mexican Volcanic Belt. In 2016, the ICDP MexiDrill project recovered a total of 1152 m of sediments from a maximum depth of 520 m in Lake Chalco, in the SW of the Basin of Mexico. The upper 309.15 m (composite sequence, mc) are composed of fine-grained lacustrine sediments alternating with discrete visible tephra layers, and the lower 200 m are primarily volcaniclastic facies and basaltic lavas with some intercalated fluvial and alluvial facies. Initial lacustrine deposition started in the Chalco Basin, after the deposition of a thick volcaniclastic sequence, and continued until the lake was drained in recent centuries. Lake Chalco has remained as a shallow lake until the present day.Five main lithotypes throughout the core have been defined: (1) Organic, with (i) organic-rich silty clay, (ii) sapropelic silty clay, and (iii) peat; (2) Diatomaceous, with laminated, banded, and mottled diatomaceous silty clay; (3) Calcareous, with banded or massive carbonate silty clay and ostracod-rich layers; (4) Clastic, with silty clay, sand, and gravel, both clast and matrix-supported; and (5) Volcanic, as (i) volcaniclastic layers (tephras and clastic deposits) and (ii) lavas. Eighteen lithological units have been defined based on lithotypes and magnetic susceptibility values. Laminated diatomaceous facies occurred during phases with deeper depositional environments. Carbonate deposition marked more alkaline, shallower phases. Peat and organic-rich silts deposited during periods with better development of wetlands in the basin. The preliminary chronological framework suggests the lake sequence spans at least the last 367 ky. More saline diatom assemblages in diatomaceous facies and the occurrence of carbonate lithotypes and peat layers suggest relatively lower lake levels during interglacials; higher lake levels during glacial stages are indicated by more frequent freshwater diatom assemblages and the occurrence of finely laminated diatomaceous facies. The detailed stratigraphy and facies descriptions from the MexiDrill cores provide the basis for subsequent development of chronology and paleoenviromental studies of the Mexico basin record. Furthermore, the depositional model for Chalco is applicable to lakes developed in active tectonic and volcanic settings.