Centennial-Scale Storage and Reworking of a Discrete Slug of Clastic Mining Sediment
學年 110
學期 1
發表日期 2021-10-10
作品名稱 Centennial-Scale Storage and Reworking of a Discrete Slug of Clastic Mining Sediment
作品名稱（其他語言）
著者 L. Allan James; Allison M. Pfeiffer; Chen-Ling J. Hung
作品所屬單位
出版者
會議名稱 GSA Connects 2021 in Portland, Oregon
會議地點 Portland, USA
摘要 Hydraulic gold mining in California between 1853 and 1884 generated an extreme, discrete pulse of highly distinctive hydraulic mining sediment (HMS). The sudden cessation of mining in 1884 provides an opportunity to study centennial-scale clastic sediment storage and reworking at the catchment scale. Initial channel aggradation in the mountains was followed by channel incision, but large volumes of HMS remain in Greenhorn Creek, a small (42 km2) unregulated mountain catchment. Two DEMs were developed to reconstruct historical surfaces (1853 pre-mining and ca.1884 maximum aggradation). Spatially distributed sediment budgets were computed for the aggradation (1853-1884) and degradation (1884-2014) periods by differencing the DEMs with a high-resolution (1-m) LiDAR DEM (2014). Sediment production, storage, and flux were extracted from the budgets. Mines in upper Greenhorn Creek produced 41×106m3 of HMS, of which 16×106m3 (38%) and 4.8×106m3 (12%) were stored in 1884 and 2014, respectively. Geomorphically, hydraulic mining was a catastrophic event that generated denudation rates of 3160 cm/kyr for the catchment, i.e., one to four orders of magnitude greater than geologic background rates. Mean annual sediment flux rates out of the catchment were 820x103m3/yr (33,039 t km-2/yr) from 1853 to 1884 and 84x103m3/yr (3,845 t km-2/yr) from 1884 to 2014. Values of sediment delivery ratios and residence times are compared for the two periods. Storage and flux rates of mining sediment decreased through time but remain high. Most storage in 2014 was in the lower catchment except for substantial storage in two cutoff valley meanders that have removed large volumes of sediment from the ‘jerky conveyor belt’ for centuries.
關鍵字
語言 en_US
收錄於
會議性質 國際
校內研討會地點 無
研討會時間 20211010~20211013
通訊作者 L. Allan James
國別 USA
公開徵稿
出版型式
出處 Geological Society of America Abstracts with Programs. Vol 53, No. 6, 2021
相關連結

機構典藏連結 ( http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/121547 )

SDGS 優質教育,潔淨水與衛生,產業創新與基礎設施,永續城市與社區,夥伴關係