April 2019: Newsletter

Dear RMS SEPM Supporter,


This month brings some big changes behind the scenes at the Rocky Mountain Section of the SEPM!  If you haven’t been to our homepage recently please check it out HERE!  The address hasn’t changed but just about everything else has. Ellen Wilcox, our website administrator, and the rest of the council have been working hard for the past few months to provide a more relevant, modern, and functional website for our members.  I think you will be happy with what you see.

 As part of the new functionality the way you receive these monthly reminders about our lunchtime lecture series, as well as a host of other things, will change.  Our membership team will still be coordinating email addresses and the best ways of reaching our members, however delivery of information will now come via a “newsletter” system rather than bulk mass emails.  If you’re a member, or already receiving emails from the RMS SEPM you don’t need to do anything other than add information@rmssepm.org to your list of safe emails.  If you’re not a member or would like to stay abreast of what’s happening, you can sign up for communications via the new website by entering your info in the “Subscribe” area at the bottom of our home page (www.rmssepm.org). 

 If you have any questions or comments, please let us know by using the “Contact Us” page on our website here: www.rmssepm.org/contact-us


This month we return to the Niobrara petroleum system with a look back at the classic 1998 regional study of the Niobrara by Mark Longman and Barbara Luneau.  The authors of that paper will take us through insights learned since their landmark paper, which was recognized by AAPG as such in 2013, to revisit their conclusions, provide updates on which original ideas have endured, and improvements that can be made to their original models.  Of note is new work illustrating that alternating chalk/marl facies trends were not controlled by relative changes in sea level but via a different mechanism.  Information on the lecture, including abstract and speaker biographies, may be found on our website at: RMS SEPM lunchtime lecture.  Registration for this important lecture can be done on our registration page, which is found at the bottom of the page.  Our registration page also contains links where you can sign up for our Brown Bag Lunch & Learn series, register for the April Brewery Rendezvous, renew or start your membership, and become a sponsor of our lunchtime lecture series. 


Our Next Luncheon Talk

(11:30 Reception; 11:45 Lunch; 12:15 Talk)

Tuesday, April 23rd , 2019

11:30 Reception; 11:45 Lunch; 12:15 Talk commences
Wynkoop Brewing Company
1634 18th St., Denver, CO

The cost is $25.00 for current members and $35.00 for non-members or non-current members (the added cost of which includes an annual RMS-SEPM membership).

Please Note: We now have a $10 luncheon option for recently-unemployed members

Please submit reservations by 10:00 a.m. Friday, April 19th , 2019


After the lunch reservation deadline, you may attend the talk for a $5.00 "walk-in" fee. Reservations may be secured online or by e-mail robin.swank@gmail.com or by calling Robin Swank at 720-2726697

This luncheon is generously sponsored by: 

Conundrum Geological Services

 Interested in sponsoring an upcoming luncheon? We welcome new sponsors and they will be recognized at the luncheon as well as the website.

Click https://www.rmssepm.org/sponsor-an-event to learn more

Revisiting the Upper Cretaceous Niobrara Petroleum System in the Rocky Mountain Region

Speakers: Mark Longman and Barbara Luneau


In 1998 we co-authored a regional study of the Niobrara Formation in the Rocky Mountain area. The paper slightly preceded a burst of successful horizontal drilling in the Niobrara along with much additional research that resulted in new insights into Niobrara stratigraphy and depositional processes. With this presentation, we provide an update on which of our original ideas have endured, and one that we would like to improve upon to advance understanding of the Niobrara.

Although our alphanumeric terms for intervals within the Niobrara have been largely replaced by the “A”, “B”, and “C” terminology for the chalk-rich intervals, our isopach and facies maps as well as our depositional models for both the chalk and marl facies have proved valid and useful. However, we now feel we may have erred in attributing the chalk and marl benches principally to eustatic sea level changes. That model claims that the marls represent relative lowstand events whereas the chalks represent highstands during which the influx of detrital clay into the central part of the Western Interior Seaway was limited.

We now believe that the main factor controlling chalk vs. marl deposition was the direction of current flow through the long, relatively narrow (100s of miles), north-south trending seaway. When warmer waters from the incipient Gulf of Mexico flowed northward, they brought into the seaway the abundant coccoliths, copepods, and planktonic foraminifers that form the chalkier intervals. When cooler arctic waters flowed southward in the seaway, carbonate productivity was limited and marlier, more organic-rich facies were deposited. Changes in water depth had little to do with the resulting rock types.

Evidence supporting this interpretation is three-fold. First, past core descriptions and wireline logs largely focused on intervals many feet thick to define the chalk and marl facies. Closer examination of the cores on a <1-inch scale in combination with elemental data from X-ray fluorescence reveals interfingering of the chalk and marl facies on a scale far too small to be related to global sea level changes. Second, if changes in sea level controlled the chalk/marl lithofacies, their impact should have been much greater on the relatively shallow eastern and western shelves of the seaway where a 50-ft change in sea level could have had a profound impact on deposition. Instead, the open marine carbonate-rich facies so common on the eastern shelf show no evidence for significant changes in water depth. Third, the Fort Hays Member of the Niobrara with its thicker and more apparent interfingering of cyclical chalk and marl facies has long been interpreted as the product of Milankovitch (climate) cycles rather than sea level fluctuations. The cyclicity in the Smoky Hill Member may be too fine to be Milankovitch related, although this has been suggested. However, the internal Smoky Hill Member stratigraphy shows regional trends that are unlikely to be Milankovitch or sea-level related.

April Luncheon

Luncheon Lecture

Aren’t sure if your membership has expired or if you’re not a member?   Please email membership@rmssepm.org and our membership staff will be happy to let you know.  Annual memberships are $10.00 and lifetime memberships are $75.00 for professionals; student memberships are $8.00/year.  There is also a $10 luncheon and talk option for recently unemployed members.  If you need to renew your membership, or would like to become a new member, please go to the registration page of our website, which may be found here: RMS SEPM Membership.

For information about our upcoming events, check out our calendar: