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ANACONDA 2010 REVIEW | |
Below: Map and sections from Bela Csejtey's 1963 dissertation on the SE flank of the Flint Range. One of the 2010 field trips will visit this area. Click a thumbnail to enlarge (the full-size images are 6 megs for the map and 700 K for the cross sections). 
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by Ted Antonioli
Let's start with a recap of the Anaconda Conference this last summer, which in many ways built on the 2009 Conference in Philipsburg a short distance west. Once again, the weather was glorious, attendance was very high, the scenery and geology were inspiring, the topics were wide-ranging (from the Belt through a Recent extinct Bison), the food was excellent, and the Quarry beer was ice cold! In addition, four members (Bruce Cox, Dick Berg, Dean Kleinkopf, and Dave Lageson) were honored for their long service to TRGS, and a "Hammer" was awarded to Jim Sears for his outstanding contributions to regional geology. Several trips looked at the upper part of the Belt and lower part of the Cambrian section, and it became apparent that thorny interpretive problems stem from both changes in the Belt section (with whole formations like the Garnet Range disappearing eastward) and from faults that are nearly parallel to bedding. Exhibit A: the famed unconformity beneath the Cambrian photographed and described by Frank Calkins a hundred years ago, which TRGS member Don Heffington re-located, and Jeff Lonn compellingly re-interpreted as a detachment fault. Jeff also made a strong case that the Browns fault system of Csejtey (map, left) is part of the Eocene detachment system, while Yates , Follman and Antonioli presented evidence that the Hidden Lake-Twin Peaks fault system is an overthrust that has been overturned along the northern segment (supporting Reed Lewis' interpretation of this important regional structural element). But while progress (we think) was made resolving some old mysteries, new ones "outcropped". A field trip to the Cable Mountain district considered the origin of a coarse breccia that is stratabound in Belt quartzite... a facebook post from a TRGS member (Lundberg) suggested that it might be part of an impact breccia. Other interesting problems touched on in the conference included the origin of regional west- verging folds, the stratigraphic position of Missoula Group conglomerates on Cable Mountain, the relationship of the Cable strat section to the similar strata in Lost Creek to the east, and the age relationships of intrusives in Warm Springs Creek, among many others. One theme developed in both Jeff Lonn's tour-de-force session talk on the regional structure and in several field trips at the conference was the importance of Cretaceous top-to-the-west detachment faults (which were described by Jeff and Katie McDonald for the Kelly Lake quad in the Pintler Range) that must be sorted out from Cretaceous top-to-the-east overthrusts (and here) and the Eocene top-to-the-east detachment system (which was first detailed for TRGS by Mike O'Neill and others in a 2002 field trip to the Anaconda area). Mineralization which appears to be occurring along the earlier detachments was seen on a couple field trips. Trips also looked at placer (and here) and epithermal deposits south of Anaconda, and ore deposits of the Highlands south of Butte. Jumping forward to the Tertiary, another chapter of the story of the regional impact of the emergence of the Yellowstone hot spot in Miocene time - this time dealing with how the fluvial picture developed along the Big Hole River, was examined in the field during a trip led by Jim Sears and TRGS grantee Warren Roe. The entire regional Miocene story was synthesized in Jim's keynote talk. If the proceedings of the Anaconda conference are of interest, you can join (or re-up) with TRGS for $25 and receive the volume. A paypal button is enabled at the link if you prefer that method of payment. We also are grateful that many folks have chosen to donate money to TRGS for our scholarship program... 2010 set a record for both the amount awarded and the number of grantees, and we expect 2011 will mark yet another all-time-high for the program. For 2011, the summer conference will be based out of Superior, Montana.
Larry Smith is the conference organizer. We expect that field trips will
deal with exceptionally diverse geologic features ranging from the Precambrian
of far western Montana and adjoining rocks in Idaho, to a variety of structural
elements, to placer and lode mines, to Glacial Lake Missoula. Mark July
28 to 31 on your calendar. We expect fascinating geology, and very likely
huckleberries among the rocks during the field trips! ANACONDA PREVIEWFirst announcement and call for papersJuly 29 to August 1, 2010First Announcement & Call For PapersFinal Announcement & Registration Conference organizers: Ted Antonioli, >Katie McDonald TRGS's 2010 Field Conference will be held between Thursday evening, July 29, and Sunday, August 1, in Anaconda, Montana. Talks are planned for Friday morning with field trips on Friday, Saturday, and Sunday. We will be using the High School for our principal venue and will have breakfast and lunches and Friday dinner available from a student group. The TRGS barbeque will, as usual, be Saturday evening's featured event, and we have a city park reserved for Friday dinner as well. The immediate vicinity of Anaconda has complex geology that has been the focus of field work for a century and several trips are in the works to explore some diverse aspects of that geology. Some examples: Jeff Lonn will show structures of the Eocene Anaconda Metamorphic Core Complex in Lost Creek Canyon, leading a hike (for hardy souls) to the north rim of Lost Creek Canyon to examine ductile and brittle structures along the Anaconda detachment fault. Skip Yates will lead a trip that will look at structure, stratigraphy and mineralization in upper Warm Springs Creek and the vicinity of the Hidden Lake and Cable mines. Bruce Cox and Paul Antonioli are putting together a trip that will look at active mines and general geology in the Highland range south of Butte. Jim Sears of the University of Montana and his students will lead a field trip highlighting their work to test the hypothesis that the Big Hole Valley contained a Middle Miocene lake that discharged a big river that carved the Big Hole Canyon and dumped the eroded sediment into an enormous fan delta in a second Middle Miocene lake at Twin Bridges. We will have more details on all these trips (and several more!) when we send out the conference registration information in late Spring. Updated information will be posted periodically here or the TRGS facebook page. We are also posting links to papers, cross-sections, maps, and other information related to both the field conference and news of interest to Society members on the facebook page. If you would like to contribute a paper to our guidebook, please contact Bruce Cox, technical editor of this year's guidebook. There is a hard deadline of June 1 for submissions. Authors for the guidebook should refer to the Editorial Requirements (PDF). Please especially note formats - do not send texts in DOCX format, and please do not embed images in word documents - send as separate JPGs. If you would like to participate by leading a field trip, or have other questions regarding the conference, kindly contact one of the organizers, Ted Antonioli or Katie McDonald. Camping in the area is abundant, particularly at several USFS campgrounds in upper Warm Springs Creek only 10-15 minutes from town, and at Lost Creek State Park. Here are some contacts for motels in Anaconda and the surrounding area.
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