Spatiotemporal history of fault–fluid interaction in the Hurricane fault, western USA
<p>The Hurricane fault is a <span class="inline-formula">∼250</span> km long, west-dipping, segmented normal fault zone located along the transition between the Colorado Plateau and the Basin and Range tectonic provinces in the western USA. Extensive evidence o...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-11-01
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| Series: | Solid Earth |
| Online Access: | https://se.copernicus.org/articles/11/1969/2020/se-11-1969-2020.pdf |
| Summary: | <p>The Hurricane fault is a <span class="inline-formula">∼250</span> km long,
west-dipping, segmented normal fault zone located along the transition
between the Colorado Plateau and the Basin and Range tectonic provinces in the western USA. Extensive evidence of fault–fluid interaction includes calcite
mineralization and veining. Calcite vein carbon (<span class="inline-formula"><i>δ</i><sup>13</sup></span>C<span class="inline-formula"><sub>VPDB</sub></span>)
and oxygen (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>VPDB</sub></span>) stable isotope ratios range from
<span class="inline-formula">−4.5</span> ‰ to 3.8 ‰ and from <span class="inline-formula">−22.1</span> ‰ to <span class="inline-formula">−1.1</span> ‰,
respectively. Fluid inclusion microthermometry constrains paleofluid
temperatures and salinities from 45 to 160 <span class="inline-formula"><sup>∘</sup></span>C and from 1.4 wt % to 11.0 wt %
as NaCl, respectively. These data suggest mixing between two primary fluid
sources, including infiltrating meteoric water (<span class="inline-formula">70±10</span> <span class="inline-formula"><sup>∘</sup></span>C, <span class="inline-formula">∼1.5</span> wt % NaCl, <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>VSMOW</sub></span>
<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>∼</mo><mo>-</mo><mn mathvariant="normal">10</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="70a5751a08a5782d3837653a833a8611"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="se-11-1969-2020-ie00001.svg" width="32pt" height="10pt" src="se-11-1969-2020-ie00001.png"/></svg:svg></span></span> ‰) and sedimentary brine (<span class="inline-formula">100±25</span> <span class="inline-formula"><sup>∘</sup></span>C, <span class="inline-formula">∼11</span> wt % NaCl, <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>VSMOW</sub></span> <span class="inline-formula">∼</span> 5 ‰). Interpreted
carbon sources include crustal- or magmatic-derived CO<span class="inline-formula"><sub>2</sub></span>, carbonate
bedrock, and hydrocarbons. Uranium–thorium (U–Th) dates from five calcite vein samples indicate
punctuated fluid flow and fracture healing at <span class="inline-formula">539±10.8</span> (<span class="inline-formula">1<i>σ</i></span>),
<span class="inline-formula">287.9±5.8</span>, <span class="inline-formula">86.2±1.7</span>, and <span class="inline-formula">86.0±0.2</span> ka in the upper
500 m of the crust. Collectively, data predominantly from the footwall
damage zone imply that the Hurricane fault imparts a strong influence on the
regional flow of crustal fluids and that the formation of veins in the
shallow parts of the fault damage zone has important implications for the
evolution of fault strength and permeability.</p> |
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| ISSN: | 1869-9510 1869-9529 |