Stop 5 (v.2.0) – The Day After the Day Before, Golden, CO

The day began sharply with a run up South Table Mountain with Jesse (@neotectonics), Zane (@zanejobe) and the prize-winning, Obama-meeting Rich (@rangefront). In temperatures that, even at around 0800, were heading north of 15 degrees, the start of the run was steep and hard; with pretty much no warm-up, the road and trail climb steeply, for about 250 m, up and out of Golden town centre. En route to the plateau top, we crossed the K-T boundary, which is located in a succession of Cretaceous-to-Paleocene clastics that are capped by early Paleocene (62-64 Ma) basaltic lavas. After a few stops to, ahem, take in the view, we ‘summited’, where we were rewarded with spectacular views westwards down into Golden, pinned between the plateau and the Rockies, and eastwards onto the flat plain and the sprawling city of Denver. Breath recovered, Rich gave us a brief guide to the visible geology (NEWSFLASH: it’s amazing), in addition to an overview of the somewhat surprising, at least to me, lack of seismicity in this region. I’m not sure why, but being so close to big mountains always makes me think of earthquakes. In glorious sunshine and a restorative wind, we looped around the top of the plateau before heading back down into town.

Showered and fed, I made my way to the USGS, which is based on the southern side of CSM’s campus. Rich had invited me to visit him and his group to discuss my work on normal fault structure and growth, and to show me some of the work they are doing on seismogenic hazards associated with one of my favourite normal fault systems in the world, the Wasatch Fault, Utah; see some uber-cool videos on this giant structure here. An animated 2 hours flew buy, with me extolling the benefits of a subsurface, seismic-reflection based approach to understanding fault structure and growth (see also my related GSA talk overview here and the talk itself here) and them outlining some of the challenges associated not only with constraining the ancient slip history of the Wasatch Fault (see also here), but also predicting its future behaviour. It became apparent to us all that a key issue was the how the relatively early-stage development of small normal fault systems, which is what we typically study with subsurface data, translates to seismogenic behaviour when such faults get much larger. My brain was absolutely fizzing.

 

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Time-structure map of a Late Jurassic-Early Cretaceous normal fault network, Horda Platform, Norwegian North Sea (see Duffy et al., 2015). Ancient fault systems like these are potentially geometrically, kinematically and seismogenically analogues to the Wasatch Fault, UT.

On a brain-workout ‘high’, I said goodbye to Rich, Chris and Ryan, and headed back to CSM for lunch with Jesse, Zane and Lauren Shumaker, a post-doc working in CoRE. Lunch, this time a monstrous burrito, was great, but not as great as the post-lunch geo-tour of some on-campus exposures of the latest Cretaceous (68 Ma), non-marine sandstones of the Laramie Formation. On this compact exposure, which forms part of the Dinosaur Ridge, palm fronds and truly enormous (i.e. several metre-long) logs are well-exposed on the bases of slightly overturned beds. The highlight, however, were the dinosaur trackways, which included ceratopsid (mainly Triceratops), theropods and hadrosaurs, with the absolute pinnacle being the so-called ‘trample’ areas, where the density of footprints made it look like some kind of dino-disco. It was ace. I have a real weakness for dinosaur trackways. Less so palm fronds and logs.

Having tackled seismogenic normal faulting, a burrito, and some dino trackways, I then spent an enjoyable few hours in CSM, talking to a number of research staff and students. I talked to Lauren about her past and ongoing work on some rather exotic, potentially volcanogeneic deep-water systems imaged in seismic reflection data from offshore New Zealand. We also discussed another weakness of mine, submarine gullies, which Lauren worked on during her PhD at Stanford. We’ll be keeping in touch. I then spoke to Oscar, a PEMEX-funded student working with Bruce Trudgill, about his work on salt tectonic controls on deep-water sediment dispersal in the Mexico sector of the Gulf of Mexico. Super-cool stuff, and it looks like I’ll be on his ‘committee’. Finally, I spent some time with Hiro, a PhD student working with Lesli Wood on some absolutely incredible seismic and borehole data from offshore NW Borneo. Seriously, this is possibly the most exciting subsurface dataset I have seen in several years; the 3D seismic data provide exquisite imaging of a predominantly thin-skinned, gravitationally driven deep-water fold-and-thrust belt, with the borehole data providing hard calibration of some of the syn-kinematic deep-water facies. As I became increasingly animated, I was dragged away by Bruce, Zane and Jesse to head into the Rockies for some bluegrass and booze…

We drove north-westwards up into partly snowed-covered mountains to a town called Nederland, spotting the continental divide in fading light, and twisting up through thick pine forests, which, I am assured, house mountain lions. We first hit a Crosscut Pizzeria and taphouse, a relatively new, local pizza and craft beer joint, which was rammed and evidently very popular. Joined by some of Jesse and Zane’s friends, we took on some tasty pizza and IPAs, the latter partly accounting for the hangover I am now living through. Food done, we drove the short distance to Caribou Room, a live music joint, where we watched a couple of bluegrass or, in Zane’s opinion, bluegrass-inspired bands. Apparently, the lack of a banjo was an issue. In my mind, something lacking a banjo is no bad thing. Bango-count aside, it was great, with the locals (and Zane and Jesse) getting into the waltz and Texas two-step, whilst I did battle with a whisky that was not that much smaller than a paddling pool. See comment above regarding a hangover…

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The night over, we drove back down twisty mountain roads into Golden, where I crashed. Hard. I honestly cannot recall having had as many days as much fun and educational of yesterday! Tomorrow begins the journey back home to the UK…

Author: Christopher Aiden-Lee Jackson

I am Professor of Basin Analysis @imperialcollege. I ❤️ 🏃🏿, 🚴🏿 and @basinsIC (⛏). I obsess about the tectono-stratigraphic development of sedimentary basins. Why? Because I'm hopeless at everything else.

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