Geophysical surveys of Yellowstone Lake, Wyoming
Geophysical surveys of Yellowstone Lake, Wyoming
复制标题
怀俄明州黄石湖的地球物理调查
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
R. Wold
中科院分区：
文献类型：
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作者：
R. Otis;Robert B. Smith;R. Wold
反射，折射，和古地磁数据从黄石湖，怀俄明州，被用来评估第四纪，构造，火山和冰川的历史，这个高山湖。反射数据显示，在湖的主体下有一个古基底，其中含有高达190米的沉积在侵入岩或火山岩床上的湖泊沉积物。突出的反射层被解释为对应于冰川层，侵蚀面开发期间的干燥，沉积物沉积在最近的湖泊蓄水流纹岩流。在湖南端露头的火山单元与向北俯冲到古盆地下方的反射体相关，表明黄石火山口最近沉降了至少300米。根据浅部岩心的古地磁记录推断，沉积速率为10- 13厘米/100年，并表明古基底内的沉积最多为20万年。折射数据描绘了一个1公里深，5.0公里/秒的层，解释为一个浅结晶侵入或火山层的顶部可能与黄石火山口。在地质学绘制的破火山口边界内4公里处发生的地震数量迅速减少，对应于温度梯度从200/sup 0/C/km增加到800/sup 0/C/km的区域，并被解释为反映了更深的地壳结构的边界，可能是冷却岩浆体的边缘。从高分辨率7.5千赫地震反射剖面获得的等深水深提供了详细的黄石湖水深图。«少
Reflection, refraction, and paleomagnetic data from Yellowstone Lake, Wyoming, were used to evaluate the Quaternary, tectonic, volcanic, and glacial history of this high mountain lake. Reflection data revealed a paleobasin beneath the main body of the lake containing up to 190 m of lake sediments deposited on intrusive or volcanic bedrock. Prominent reflectors are interpreted to correspond to glaciated layers, erosional surfaces developed during periods of desiccation, and sediments deposited during Recent lake impoundment by rhyolite flows. Volcanic units that outcrop at the south end of the lake are correlated with reflectors that plunge northward beneath the paleobasin, indicating at least 300 m of Recent subsidence of the Yellowstone caldera. Sedimentation rates of 10--13 cm/100 yr were deduced from paleomagnetic logs of shallow cores and suggest a maximum of 200,000 years of deposition within the paleobasin. Refraction data delineated a 1-km-deep, 5.0-km/s layer, interpreted as the top of a shallow crystalline intrusive or volcanic layer possibly associated with the Yellowstone caldera. A rapid decrease in the number of earthquakes occurring 4 km inside the geologically mapped caldera boundary corresponds to a zone of thermal gradients increasing from 200/sup 0/C/km to 800/sup 0/C/km and is interpreted to reflect the boundary ofmore » a deeper crustal structure, perhaps the edge of a cooling magma body. Contoured water depths obtained from high-resolution 7.5-kHz seismic reflection profiling provide a detailed bathymetric map of Yellowstone Lake.« less