May 3, 2004

REPORT ON YEAR-2004 MEETING OF SEPM CLASTIC DIAGENESIS RESEARCH GROUP (CDRG)

Fifteen participants attended the annual meeting of the Clastic Diagenesis Research Group, which was held on Sunday April 18, 2004 in Dallas. The rather low attendance was more than offset by five interesting presentations and some highly spirited discussions, which took us well past our scheduled, 4 PM conclusion.

We began the meeting at 2 PM with a period of socializing followed by news and announcements. Rob Lander volunteered a summary of the February 8-11, 2004 Hedberg conference on "Structural Diagenesis: Fundamental Advances and New Applications from a Holistic View of Mechanical and Chemical Processes", which was held in Austin, Texas.

SHORT PRESENTATIONS

Then, five individuals gave the following short (10-15 minute) presentations.

"Beard & Weyl Revisited: New Experimental Data Regarding the Controls on Depositional Porosity in Sandstones"

by Linda Bonnell (presenting), Dick Larese, & Rob Lander 

Linda Bonnell (Geocosm LLC) presented evidence from new experiments on depositional porosity of sands that challenge some of the conclusions reached by Beard and Weyl in their oft-quoted paper. One major conclusion: depositional porosity is typically higher in coarser sands than in finer sands, according to these recent experiments.

"Shallow Grain Fracturing by Compressive Stress:  Some Observations from Tectonically Active Regions"

by Art Trevena

Art Trevena (with Unocal and 2004 CDRG chairperson) presented some anecdotal evidence that extensive grain fracturing is common at relatively shallow depths in sandstones that are part of "tight" folds and thrusted folds in tectonically active regions subjected to compressive stresses.  

"Origin of Crystal Coarsening in Concretions due to Growth Competition as Shown by Prism Modeling"

by Rob Lander

Rob Lander (Geocosm LLC) presented results of computer modeling of crystal growth in concretions. His models show that commonly observed crystal fabrics in concretions can be explained by growth competition that favors crystals whose high-growth axes are oriented radially with respect to the concretion.

"Sleuthing out the volcanic connection to an early Cretaceous global anoxic event"

by Kathie Marsaglia

Kathie Marsaglia (Cal State University-Northridge) presented evidence of common volcanogenic components in Pacific Ocean deep sea sediments (ODP cores) that record an early Cretaceous global anoxic event.

"Paleo-fluid flow in faulted and fractured Aztec Sandstone, Valley of Fire, Nevada"
by Peter Eichhubl

Peter Eichhubl (Stanford University) presented evidence that explains the highly colorful oxidized and reduced zones in the Aztec Sandstone of Valley of Fire, Nevada in terms of the movements of ancient water tables and ground water flow.

CLASTIC DIAGENESIS CHALLENGE:

Offered by Kathie Marsaglia

"Clinoptilolite/heulandite occurrence in absence of volcanic components"    

"Zeolites are often unwanted diagenetic "guests" in a reservoir.  It's my experience that, in most cases, dissolved glassy components, albeit sometimes cryptic, are associated with these guests, particularly clinoptilolite/heulandite.  The challenge is to provide an example where clinoptilolite/heulandite is present in sandstone with NO possibility of volcaniclastic components within the sample or within adjacent sections. (The person presenting) the most convincing case will win a bottle of New Zealand wine."

No challengers appeared, and Kathie prevailed, hands-down. Based on the collective experience of this years’ attendees, clinoptilolite/heulandite occurrences in sandstones are always associated with volcanogenic components. But, being a great sport, Kathie offered a bottle of New Zealand wine to the group anyway!

2005 CDRG CHAIRPERSON

Kathie Marsaglia (Cal. State University –Northridge) kindly volunteered to serve as next year’s chairperson of the SEPM Clastic Diagenesis Research Group

DICUSSION TOPIC

Kitty Milliken (2003 CDRG chairperson) opened a discussion about searching for creative ideas to foster greater U.S. National Science Foundation (NSF) funding within the sedimentary geology community. There is a widespread perception that future research in sedimentary geology will suffer as petroleum-funded programs continue to shrink, unless there is additional support from governmental sources of funding, especially the NSF. While several interesting approaches were suggested, this discussion probably needs to continue.

ATTENDENCE LIST