Digital data sets that describe aquifer characteristics of the High Plains aquifer in western Oklahoma

This data set consists of digital aquifer boundaries for the
High Plains aquifer in western Oklahoma. This area encompasses
the panhandle counties of Cimarron, Texas, and Beaver, and the
western counties of Harper, Ellis, Woodward, Dewey, and Roger
Mills. The High Plains aquifer underlies approximately 7,000
square miles of Oklahoma and is used extensively for irrigation.
The High Plains aquifer is a water-table aquifer and consists
predominately of the Tertiary-age Ogallala Formation and
overlying Quaternary-age alluvial and terrace deposits. In some
areas the aquifer is absent and the underlying Triassic,
Jurassic, or Cretaceous-age rocks are exposed at the surface.
These rocks are hydraulically connected with the aquifer in some
areas.

The High Plains aquifer is composed of interbedded sand,
siltstone, clay, gravel, thin limestones, and caliche. The
proportion of various lithological materials changes rapidly
from place to place, but poorly sorted sand and gravel
predominate. The rocks are poorly to moderately well cemented by
calcium carbonate.

The aquifer boundaries were constructed by extracting lines from
digital surficial geology data sets based on a scale of
1:125,000 for the panhandle counties and 1:250,000 for the
western counties. Some of the lines were digitized from maps in
a published water-level elevation map for 1980.

本数据集包含俄克拉荷马州西部高平原含水层（High Plains aquifer）的数字化含水层边界。该区域涵盖锡马龙（Cimarron）、德克萨斯（Texas）、比弗（Beaver）三个狭长带县，以及哈珀（Harper）、埃利斯（Ellis）、伍德沃德（Woodward）、德威（Dewey）和罗杰·米尔斯（Roger Mills）五个西部县。高平原含水层覆盖俄克拉荷马州约7000平方英里的范围，被广泛应用于灌溉。

高平原含水层为潜水含水层（water-table aquifer），主要由第三纪（Tertiary-age）奥加拉拉组（Ogallala Formation）以及上覆第四纪（Quaternary-age）冲积与阶地沉积物构成。部分区域缺失该含水层，地表直接出露下伏的三叠纪（Triassic）、侏罗纪（Jurassic）或白垩纪（Cretaceous-age）岩层；在部分区域，这些岩层与含水层存在水力连通性。

高平原含水层由互层状的砂、粉砂岩、黏土、砾石、薄层石灰岩及钙结壳（caliche）组成。不同区域的岩性物质占比变化迅速，但分选较差的砂与砾石占据主导地位。岩层的碳酸钙胶结程度从较差至中等不等。

含水层边界通过提取数字化地表地质数据集的线条构建而成，其中狭长带县采用1:125000比例尺的数据集，西部县采用1:250000比例尺的数据集。部分线条源自1980年公开出版的地下水位高程图的数字化成果。