Abstract State Geological Surveys (SGSs) in the USA play vitally important roles, providing sound, unbiased scientific information to each state and the nation. Although implementation of each survey's scientific programme has evolved differently, these organizations are often the principal drivers of economic development, and they consult on policies for protecting land and water, mitigating geologic hazards and promoting sustainable development. The SGSs are represented by the American Association of State Geologists. For more than 110 years, they have partnered with the federal government on important geoscience issues concerning topographic and geologic mapping, water, mineral and energy resources, and geologic hazards. These collaborations continue to develop and expand across multiple specialties, providing critical support to the SGSs. The future role of SGSs will depend on legislative decisions, contributions to research and development and scientific advancement, and ability to leverage support from existing and new collaborations with academia and with federal, state, county and municipal agencies. The Illinois State Geological Survey, one of the largest SGSs, has continually pursued relationships across geoscience sectors to develop a strong multidisciplinary scientific programme. Going forward, all SGSs will be challenged to develop an effective data stewardship programme to communicate with a diverse clientele.

ABSTRACT Organic matter (OM) in petroleum source rocks is a mixture of organic macerals that follow their own specific evolutionary pathways during thermal maturation. Understanding the transformation of each maceral into oil and gas with increasing thermal maturity is critical for both source rock evaluation and unconventional shale oil/gas reservoir characterization. In this study, organic petrology was used to document the reflectance, abundance, color, and fluorescence properties of primary organic macerals and solid bitumen (SB) in 14 Upper Devonian New Albany Shale samples (kerogen type II sequence) from early mature (vitrinite reflectance [VR o ] of 0.55%) to post-mature (VR o 1.42%). Micro-Fourier transform infrared (micro-FTIR) spectroscopy analyses were conducted on these samples to derive information on the evolution of the chemical structure of organic macerals and SB with increasing thermal maturity. Primary OM (amorphous organic matter, alginite, vitrinite, and inertinite) and secondary organic matter (SB) were identified in early mature samples. Amorphous organic matter (AOM) was the dominant organic component in early mature samples and was observed up to the maturity equivalent to VR o 0.79% but could not be identified at VR o 0.80%. An organic network composed of AOM and SB was observed from VR o 0.55 to 0.79%, which, together with the decrease in AOM content being accompanied by an increase in SB content, suggests that with the onset of petroleum generation, SB gradually replaced the original AOM. Alginite, represented by Tasmanites cysts, started to transform to pre-oil bitumen at a maturity corresponding to VR o 0.80%. It shows weak orange-yellow fluorescence at this maturity, a change from strong greenish-yellow fluorescence in early mature samples. Alginite could not be identified at VR o 0.89%, and generated bitumen remained in place or migrated over short distances. Petrographic observations and micro-FTIR study of alginite indicate that substantial hydrocarbon generation from alginite does not start until alginite is completely transformed to pre-oil bitumen. In contrast to AOM and alginite, vitrinite and inertinite derived from terrestrial woody materials occur as dispersed particles and do not change significantly during thermal maturation. A linear relationship between vitrinite and SB reflectance exists for the studied samples. The reflectance of vitrinite is higher than that of SB until VR o 0.99%, and at higher maturities, SB reflectance exceeds vitrinite reflectance. The inclusion of pre-oil SB converted from alginite in reflectance measurements could result in a lower average SB reflectance and, therefore, caution should be applied when using SB reflectance as an indicator of thermal maturity.

ABSTRACT Based on the interpretation of 893 finite radiocarbon ages, we have revised the time-distance diagram for the Lake Michigan Lobe of the Laurentide ice sheet in Illinois. The data set contains 507 reliable ages determined using standard benzene synthesis–liquid scintillation, including “legacy” ages determined in the 1950s and 1960s at the inception of the radiometric radiocarbon dating method. In addition, the data set includes 278 radiocarbon ages determined by accelerator mass spectrometry. We analyzed the data set based on context, precision, and accuracy to vet minimum or maximum age estimates of diachronic phases. The last glaciation in Illinois is marked by a local maximum margin in northeastern Illinois during the Marengo Phase (modal probability 28,000 cal [calibrated] yr B.P.), and subsequent glacial maximum culminating during the Shelby Phase (24,200 cal yr B.P.). From about that point, the Lake Michigan Lobe entered an overall retreat mode, with significant advances at ~22,200 and 21,100 cal yr B.P. (the Marseilles and Minooka Subphases of the Livingston Phase) and at 20,500 cal yr B.P. (Woodstock Phase). The latter age is also the conservative estimate of the onset of the lacustrine Milwaukee Phase, with referent deposits located as far north as Milwaukee, Wisconsin. This phase ended as the Lake Michigan Lobe made its final advance into Illinois during the Crown Point Phase (18,490 to ca. 16,500 cal yr B.P.), interfingering with the proglacial lacustrine Glenwood Phase deposits (16,900–15,000 cal yr B.P.).