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Valles Caldera

Valles Caldera Scientific Core Drilling Services

Deep Coring of the Valles Caldera: Obtaining a Long-Term Paleoclimate Record from Northern New Mexico

Peter J. Fawcett and John W. Geissman University of New Mexico

Fraser Goff and Jeff Heikoop Los Alamos National Lab

Scott Anderson Northern Arizona University

Short History

The goal of this project was to obtain and analyze a deep (~100 m) sediment core from a lacustrine sequence in the Valles Caldera, northern New Mexico. Our work focused on determining the paleoenvironmental record of long-lived lakes in the caldera and developing a paleoclimatic record for this part of northern New Mexico for a substantial part of the middle Pleistocene. The core was drilled by DOSECC in May 2004 with the CS500 rig, and achieved a total depth of 82.1m. Most of this material was lacustrine clay with over 99% recovery. Recovery of the basal sands and gravels at the base of the core was significantly less, but we did capture a basal tephra that allowed for a constraining Ar-Ar age date. The core, VC-3, was archived at the LacCore Facility at the University of Minnesota and initial core description and sampling was conducted there.

Questions to be Answered

The questions we hoped to address with core VC-3 pertained to the paleoclimatic history of northern New Mexico over much longer time periods than the many late Pleistocene to Holocene records that are available in the area. In particular, we hoped to develop a long-term Pleistocene record that would span a significant portion of the middle Pleistocene, including some of the longer interglacials with a similar orbital forcing to today (e.g. MIS 11). The goal here was to examine natural climatic variability under such conditions as an analog for future climate change in the southwest.

What Samples were Collected?

We sampled the lacustrine mud portion of the core at a resolution of ~20 cm for a total of several hundred samples. The gravels were not sampled in detail, but the 3-cm thick basal tephra was sampled almost completely.

What Did We Do to the Samples?

An Ar-Ar age date of 552 ± 3 ka was obtained from the basal tephra, constraining the base of the core to the middle Pleistocene. To develop the paleoclimatic record, the lacustrine mud samples were split for a number of different analyses, conducted at multiple institutions (UNM, LacCore, LANL, NAU, UMN-Duluth). These analyses included organic carbon, C/N ratios, d13C, d15N, magnetic mineral properties (magnetic susceptibility MS, anisotropy of remanent magnetization, ARM), XRD of clay minerals, ICP OES (destructive elemental analysis) scanning XRF (non-destructive elemental analyses), compound specific dD, Methylated Branched Tetraether (MBT – a new paleotemperature analysis), pollen and charcoal content as well as a detailed sedimentologic description of the entire core.

What Did We Learn?

The 82-m deep lacustrine sediment core from the Valles Caldera, northern New Mexico reveals details of climate change over two glacial cycles in the middle Pleistocene. Core VC-3, taken from the Valle Grande, has a basal 40Ar/39Ar date of 552 ± 3 kyr from a tephra associated with the eruption of the South Mountain rhyolite which formed the lake. A variety of proxies including core sedimentology, organic carbon and carbon isotopic ratios, pollen, scanning XRF analysis and a new paleotemperature proxy, MBT (methylated branched tetraether) content of soil bacteria reveal two major warm periods above the basal tephra which we correlate with interglacials MIS 13 and MIS 11. This chronology is corroborated by the identification of two geomagnetic field ‘events’ which are correlated with globally recognized events (14α and 11α). The lacustrine record terminates at ~350 ka when the lake filled its available accommodation space behind the dam of rhyolite lava. Thus, the entire core spans two full glacial-interglacial cycles in the middle Pleistocene.

Valles Caldera Drilling

Figure 1: DOSECC CS500 rig operating in the Valle Grande, Valles Caldera, New Mexico

MBT temperature estimates show average glacial temperatures in core VC-3 of -4oC, and average interglacial temperatures of +4oC, and the general trends are well corroborated by multiple proxies including interglacial/glacial pollen ratios and lacustrine organic productivity estimates (organic carbon and Si/Ti ratios from the scanning XRF). A temperature increase of ~9oC occurs during Termination V, the largest glacial termination in the Pleistocene. Multiple proxies from VC-3 show significant structure during the two interglacials present in the core (MIS 13 and 11). Three warm substages (~ 2oC warmer) are recognized within MIS 11 based on organic productivity (Corg, Si/Ti ratios), pollen taxa, elevated charcoal from fires, and the MBT temperature estimates. These warm substages appear to be a strong response to precessional forcing in the SW continental interior even though the amplitude of eccentricity-modulated precession was at a minimum during MIS 11. These results suggest that future climate change in the SW may be characterized by similar natural temperature variability on precessional timescales, superimposed on future anthropogenic warming. Intervals of mudcrack facies representing significant drought conditions occur during or just after the warmest phases of the two interglacials. This past coupling between warm temperatures and extended drought in the SW as a natural feature of long interglacials is consistent with recent predictions of extended Dust-Bowl-like conditions in the SW as a response to global warming.

Where We Able to Answer These Questions & Why Should Society Care?

As a result of the multiple analyses and collaborations in this project, we were able to address the questions posed prior to the drilling project. We have generated a long, high-resolution terrestrial paleoclimate record for the middle Pleistocene, including important reconstructions of the variability within two long interglacials (MIS 11 and MIS 13). As these periods represent possible analogs for future climate change in the southwest, society should be very interested, particularly as the paleoclimate record appears to support the recent prediction of extended Dust-Bowl-like conditions in the SW as a response to global warming. The record also shows how vegetation and charcoal has changed in response to past climate change, potentially showing how vegetation and fire regimes might respond to future climate change.

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Figure 2: Representative core sections of glacials (MIS 14, MIS 12) and interglacials (MIS13).

 

References:

* denotes graduate student author

Fawcett, P.J., Heikoop, J., Goff, F., Anderson, R.S., Donohoo-Hurley, L., Geissman, J.W., WoldeGabriel, G., Allen, C.D., Johnson, C.M., Smith, S.J., and Fessenden-Rahn, J., 2007, Two Middle Pleistocene Glacial-Interglacial Cycles from the Valle Grande, Jemez Mountains, northern New Mexico; New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 409-417.

Johnson, C.M.*, Fawcett, P.J., and Ali, A.S., 2007, Geochemical Indicators of Redox Conditions as a Proxy for mid-Pleistocene Climate Change From a Lacustrine Sediment Core, Valles Caldera, New Mexico, New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 418-423.

Donohoo-Hurley, L.*, Geissman, J.W., Fawcett, P.J., Wawrzyniec, T., and Goff, F., 2007, A 200 kyr lacustrine record from the Valles Caldera: Insight from environmental magnetism and paleomagnetism, New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 424-432.

WoldeGabriel, G., Heikoop, J., Goff, F., Counce, D., Fawcett, P.J., and Fessenden-Rahn, J., 2007, Appraisal of post-South Mountain volcanism lacustrine sedimentation in the Valles Caldera using tephra units, New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 83-85.

 

Presentations

November 2008   Quaternary and Environmental Sciences and Department of Geology, Northern Arizona University (Fawcett)

March 2008 Valles Caldera Trust Public Forum, Albuquerque (Fawcett)

November 2007 IGPP Climate Study Group, LANL (Fawcett)

September 2007 Department of Geosciences, UNM (Fawcett)

September 2007 Fall Field Conference of the Geological Society of New Mexico, Jemez Mountains (Fawcett, Goff)

June 2007 IGPP Board Meeting, Santa Fe (Heikoop)

 

Presentation with Published Abstracts

Cisneros-Dozal, L, Heikoop, J., Fessenden, J., Fawcett, P., Kawka, O, and Sachs, J., 2007, Mid-Pleistocene lacustrine records of carbon and nitrogen elemental and isotopic data from Valles Caldera, New Mexico, USA, Eos Trans. AGU 88(52), Fall Meet. Suppl., Abstract PP43B-1253.

Dodd, J.P., Sharp, Z.D., Fawcett, P.J., Schiff, C., and Kaufman, D.S., 2007, A laser-extraction technique for oxygen isotope analysis of diatom frustules, Eos Trans. AGU 88(52), Fall Meet. Suppl., Abstract B13A-0893.

Donohoo-Hurley, L. L., Geissman, J.W., Fawcett, P. J., Wawrzniec, T. F., and Goff, F, 2005, Environmental magnetic record of lacustrine sediments of the Valles Caldera, New Mexico, New Mexico Geological Society Spring Meeting, Abstracts with Program

Donohoo-Hurley, L., Geissman, J.W., Fawcett, P.J., Wawrzyniec, T.F., and Goff, F., 2005, Preliminary results of the environmental magnetic record of Pleistocene Valles Caldera sediments, New Mexico, Geological Society of America Abstracts with Programs, Vol. 37, No. 7, p. 453

Donohoo-Hurley, L.L., Geissman, J.W., Fawcett, P.J., Wawrzyniec, T.F., and Goff, F, 2006, An environmental magnetism investigation of the Pleistocene lacustrine sediments from the Valle Grande, New Mexico, New Mexico Geological Society 2006 Spring Meeting, Socorro, NM, Abstract volume, p. 17.

Fawcett, P J., Goff, F., Heikoop, J.,Allen, C.D., Donohoo-Hurley, L., Geissman, J.W., Wawrzyniec, T.F., Johnson, C., Fessenden-Rahn,J., WoldeGabriel, G. and Schnurrenberger, D., 2005, Deep coring in the Valles Caldera, New Mexico to obtain a long-term paleoclimatic record, New Mexico Geological Society Spring Meeting, Abstracts with Program.

Fawcett, P.J. Fawcett, Werne, J., Anderson, R.S, Heikoop, J., Brown, E., Hurley, L, Smith, S., Berke, M., Soltow, H., Goff, F., Geissman, J., WoldeGabriel, G., Fessenden, J., Cisneros-Dozal, M., and Allen, C.D., 2008, Coupled Warming and Drought in the American Southwest During Long mid-Pleistocene Interglacials (MIS 11 and 13), AGU Fall Meeting, 2008.

Fawcett, P.J., Goff, F., Heikoop, J., Allen, C.D., Donohoo-Hurley, L., Geissman, J.W., Johnson, C., WoldeGabriel, G., and Fessenden-Rahn, J., 2005, Climate change over a glacial-interglacial cycle during the middle Pleistocene: A long term record from the Valles Caldera, New Mexico, Earth System Processes 2, Calgary, Alberta, GSA Specialty Meetings Abstracts with Programs No. 1, p. 33.

Fawcett, P.J., Goff, F., Heikoop, J., Allen, Craig D., , Donohoo-Hurley, L., Wawrzyniec, T.F., Geissman J.W., Fessenden-Rahn, J., WoldeGabriel, G., and Schnurrenberger, D., 2004, Deep Coring in the Valles Caldera, Northern New Mexico to Obtain a Long-Term Paleoclimatic Record, EOS Transactions, American Geophysical Union, v. 85 T43C-1346.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Donohoo-Hurley, L., Goff, F., Geissman, J.W., Johnson, C., Allen, C.D., WoldeGabriel, G., and Fessenden-Rahn, J., 2006, Two mid-Pleistocene glacial cycles from the Valles Caldera, New Mexico, 10th International Paleolimnology Symposium June 25-29, 2006, Duluth, Minnesota, USA, Abstracts Volume, p. 32.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Hurley, L., Goff, F. WoldeGabriel, G., Geissman, J., and Allen, C.D., 2007, A long middle Pleistocene climate record (MIS 14 to 9) from lacustrine sediments in the Valles Caldera, New Mexico, Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 270.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Hurley, L., Goff, F., Johnson, C., Geissman, J.W., and Allen, C.D., 2007, Two mid-Pleisocene glacial cycles (MIS 14 to 10) from lacustrine sediments in the Valles Caldera, northern New Mexico, Abstract XVII INQUA Congress Cairns Australia; Quaternary International v. 167-168, p. 114.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Hurley, L., Goff, F., Geissman, J.W., Johnson, C., WoldeGabriel, G., Allen, C.D., and Fessendeh-Rahn, J., 2006, Two mid-Pleistocene glacial cycles (MIS 14 to 10) from lacustrine sediments in the Valles Caldera, New Mexico, EOS Trans, 87(52) AGU, Fall Meet. Suppl., Abstract PP51B-1137.

Fawcett, P.J., Heikoop, J., Goff, F., Allen, C.D., Anderson, R.S., Donohoo-Hurley, L., Geismman, J.W., Johnson, C., WoldeGabriel, G., and Fessenden-Rahn, J., 2005, Climate change over a glacial-interglacial cycle from the mid Pleistocene: A lacustrine record from the Valles Caldera, New Mexico, American Geophysical Union Annual Fall Meeting. Eos Trans. AGU, 86(52), Fall Meet. Suppl., Abstract PP31A-1505

Fawcett, P.J., Heikoop, J., Goff, F., Anderson, R.S., Donohoo-Hurley, L., Geissman, J.W., Johnson, C., Allen, C.D., WoldeGabriel, G., and Fessenden-Rahn, J., 2006, A mid-Pleistocene glacial-interglacial cycle from the Valles Caldera, New Mexico, New Mexico Geological Society 2006 Spring Meeting, Socorro, NM, Abstract volume, p. 18.

Hurley, L., Geissman, J.W., Fawcett, P.J., Wawrzyniec, T., and Goff, F., 2006, An investigation of environmental magnetism of the Pleistoene Valle Grande lacustrine sediments, New Mexico, Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 199

Hurley, L.L., Geissmann, J.W., Fawcett, P., Wawrzyniec, T., and Goff, F., 2007, Environmental magnetism of mid-Pleistocene lacustrine sediments of the Valles Caldera, New Mexico, Eos Trans. AGU 88(52), Fall Meet. Suppl., Abstract GP53B-1218.

Johnson, C.M., Fawcett, P.J., and Ali, A.S., 2006, Geochemical and mineralogical indicators of redox conditions of a mid-Pleistocene lake in the Valles Caldera, New Mexico, New Mexico Geological Society 2006 Spring Meeting, Socorro, NM, p. 23.

Johnson, C.M., Fawcett, P.J., and Ali, M., 2006, Geochemical Indicators of Redox Conditions as a Proxy for mid-Pleistocene Climate Change From a Lacustrine Sediment Core, Valles Caldera, New Mexico, EOS Trans, 87(52) AGU, Fall Meet. Suppl., Abstract PP51B-1143.

 

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Figure 3: Core VC-3 Stratigraphic section, Organic Carbon (%) in siderite free fraction, bulk magnetic susceptibility (SI x 10-6) and bulk sediment density (g/cm3). Age assignments are based on Ar-Ar dates, and correlation with geomagnetic field events and glacial terminations. MBT temperature estimates (in oC) and depths given in red, within the Organic Carbon plot.