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In the first year-plus of ACS-PRF UNI, two geologic field seasons and two summers of laboratory work have been completed.

     Field work in summer 2009 was focussed on the Carrabassett and XX rivers, tributaries to the Kennebec River.  The Kennebec is a primary drainage of both late Pleistocene and current systems.  Field work consisted of:

        1) basic reconnaissance of field locations, general outcrop quality, and access;

        2) familiarization with glacial sedimentology and its terminology as applied to Maine sedimentary systems over the past several decades;

        3) search for good vertical sections exposing multiple depositional environments, such that there was potential for reconstructing a depositional history that could be tied to the known late Pleistocene-early Holocene relative sea-level history;

        4) sampling the range of late Pleistocene-early Holocene depositional environments preserved within the Kennebec drainage corridor;

        5) collection of igneous and metamorphic bedrock samples within the drainage basin.

      A total of 85 sedimentary samples were collected from ~40 sites.   An additional 20 bedrock samples were collected.  Sampling extended 150 km from above the Atlantic-St. Lawrence drainage divide to the Atlantic near the mouth of the Kennebec river.  Environments sampled include:

            peri- and pro-glacial (e.g., kame terrace, lodgement till),

            Pleistocene recessional delta,

            fluvial,

            shallow (i.e., higher-energy) shoreface,

            distal/deeper (transgressional) marine

No lacustrine samples were encountered.

     Laboratory work in summer 2009 and through most of the 2009-2010 academic year consisted of developing and refining sample processing procedures and protocols.  The sequence of processing consists of:

     partitioning and isolation of representative sub-samples

     drying sample

     weighing sample

     wet sieving sample to flush out silts and clays

     re-drying sample

     mechanical shaking of stacked sieve set to size sort the sample

     weighing size fractions (data to be used to calculate sorting parameters)

     A second round of laboratory procedures was developed and refined with the objective of separating high-density minerals from low-density minerals (i.e., “heavy minerals” from “light minerals”).  We experimented with the medium-sand, fine-sand, and very fine sand-size fractions.  The sequence of processing consists of:

           choice of centrifuge (12.5 mL versus 100 mL vials);

           8:1 mixture of lithium metatungstate liquid (density = 2.9 g/cm³) and sand sample in centrifuge vials;

           15 minutes centrifuge spin at 2500 rpm;

           freezing of the base of each vial with dry ice

           flushing out of unfrozen liquid and buoyant sand

           subsequent flushing out of remaining thawed liquid and sand

           filtering and washing of heavy mineral fraction

           retention of heavy liquid

     Field work in summer 2010 followed much the same sequence as in 2009.  Summer 2010, however, was focussed on the Penobscot River drainage extending 200 km from headwaters near the Atlantic-Saint John River drainage divide down to the Gulf of Maine.  We were disappointed to find that outcrop exposure, thickness, and diversity of environments were all less than encountered in the Kennebec drainage.

     Both heavy and light minerals have been investigated.  Since a major objective is to incorporate students into research tasks, the pace of mineral identification has been rather slow.  Light mineral

     Undergraduate students have been involved in multiple aspects of the project.  In academic year 2009-2010, chemistry major Jeff Boudreau was closely involved in all aspects of the project:  field work, all forms of lab work, and data analysis.  In addition, he started building expertise with optical mineralogy.  Starting in summer 2010, two new students, Sean Donnelly and Sue Attienese, initiated involvement with the project.  Sean was involved with field work and both Sean and Sue have been involved with lab work.

     Preliminary results were summarized by myself and undergraduate Jeff Boudreau in a conference presentation.  Jeff presented at the Geological Society of America’s joint Northeast & Southeast section annual meeting in Baltimore.  In addition, a second conference presentation with preliminary data will occur at the 18^th International Sedimentological Congress.

     Preliminary results:

• Ratio of high-density minerals (HM) to (mica + chlorite + HM) appears to decrease with increasing transport distance within the same depositional environment.

• Very fine-grained lithic fragments (volcanic and fine-grained metamorphic) significantly diminish in abundance downstream, despite that downstream areas are rich in finegrained bedrock è Fine-grained rock fragments derived from upland areas are depleted during transport.

• Quartz/Kspar/Plag and Quartz/Feldspar/Rock fragment ratios show little appreciable variation over a range of transport distances (<150 km) and depositionalenvironments è Q-K-P mechanical characteristics are so similar that any variation in Q/K/P in rock record is due to chemical alteration prior to, during, or after transport.

• Sorting within 1-6 m composite sections does not appear to correlate with transport distance è Sorting has no “memory” of transport distance.

• Sorting within 1-6 m composite sections appears to be subtly influenced by mean grain size, but not in a meaningful diagnostic relationship.