Deep Drill Holes Research Articles

Geophysical Methods Applied to the Mineralization Discovery of Rare-Earth Elements at the Fazenda Buriti Alkaline Complex, Goiás Alkaline Province, Brazil

In this case study, exploratory techniques were applied for the selection of potential targets for rare-earth elements (REEs) in the Fazenda Buriti Mafic–Ultramafic Complex, part of the Goiás Alkaline Province. The results of the processing and interpretation of aeromagnetic and radiometric data associated with the direct measurements of magnetic susceptibility and radiometry in rock samples collected in the study area allowed for the characterization and delimitation of the geological units. The application of Boolean logic in the radiometric data of uranium (U), thorium (Th), and the U/Th ratio allowed for the generation of a prospective map with the delimitation of two exploration targets. A 100 m deep exploratory drill hole was drilled at the main target, intercepting REE mineralization and validating the developed prospective technique. The results contributed to the detailing of a 1:25,000 scale geological map and the interpretation of shallow and deep magnetic structures. Petrophysical data allowed for the estimation of the magnetite content in the main units of the study area. The delimitation of targets with the applied method proved to be efficient after positive geochemical results for REE from the drilled rocks. The total sum of ∑REEs reached 19,629 ppm in the superficial part of the hole and 3,560 ppm in the fresh rock. Mineralogical results in two follow-up drill core samples indicated that monazite was the main REE mineral. Total REE ranged from 34,746 ppm in HG1 to 30,017 ppm in HG2, with LREEs in its majority. The bulk and clay XRD analyses indicated that monazite consisted of 5.7% (HG1) and 5.1% (HG2). The mineral abundance from the TIMA-X analysis indicated 4.2% (HG1) and 4.4% (HG2) in monazite content.

Shock petrographic and numerical modeling constraints on the morphology and size of the Morokweng impact structure, South Africa

AbstractThe 369 m deep M4 drill hole, located ~18 km NNW of the center of the 146 Ma Morokweng impact structure (MIS), intersects shocked Archean granitoid gneisses and subsidiary dolerite intrusions that are cut by faults, cataclasites and mm‐ to m‐wide suevitic and pseudotachylitic breccia dikes. The shock features in quartz in the gneisses and breccia dikes include decorated planar deformation features (PDFs), planar fractures, feather features, and toasting. Other minerals show features that may be shock‐related, such as multiple sets of planar features and alternate twin ladder structures in feldspars, kink bands in biotite, and planar features in titanite, apatite, and zircon; however, these are variably annealed and/or overprinted by hydrothermal alteration effects, and confirmation of their origin awaits further study. Universal Stage measurements of PDF sets in quartz from 12 gneissic target rocks and from lithic and mineral clasts in three suevitic and three pseudotachylitic breccia dikes reveal four dominant sets: (0001), {}, {} and {}. Based on these observations, the average peak shock pressure in these rocks is estimated at ≤16 GPa, which supports the original proximity (within one transient cavity radius) of these rocks to the point of impact. No discernible depth‐dependent shock attenuation was noted in the core. These shock levels and the elevated structural position of the rocks in the M4 core relative to the impact melt sheet intersected in drill holes closer to the center of the MIS suggest that the M4 lithologies represent part of the parautochthonous peak ring volume that subsequently experienced 1.5–2 km of post‐impact erosion before it was buried beneath younger sediments. Numerical modeling using the iSALE‐2D code suggests that the original Morokweng crater had a rim‐to‐rim diameter of between 70 and 80 km, and that the rocks in the M4 core were originally located at a depth of 7–8 km and a radial distance of 8–9 km from the point of impact.

Mineral Magnetism in Relation to Thermal Thellier Palaeointensity Experimental Results of the Deccan Basalt Flows Along the Deep Drill Hole in Western India and Their Significance

Mineral Magnetism in Relation to Thermal Thellier Palaeointensity Experimental Results of the Deccan Basalt Flows Along the Deep Drill Hole in Western India and Their Significance

Fine interpretation of magnetic data for a concealed mineral deposit: A case study of the Fe-polymetallic deposit from Western China

We interpret the magnetic anomalies for exploration and characterization of the Galinge iron polymetallic deposit, which is the largest iron polymetallic deposit in Western China. This undeveloped deposit is completely concealed by the thick Quaternary sediments, presenting an exploration challenge. A lot of drillholes have been implemented focusing on the strong magnetic anomaly centers, while the relationship between magnetite-bearing and non-magnetite-bearing drillholes is unclear, and the metallogenic regularity in the whole area needs to be further studied. The edge detection is applied on the downward continued field to resolve individual magnetite ore bodies and enhance possible concealed ore bodies. Three anomaly belts trending NE-SW with a total extension length of ∼11 km are first revealed. Combining the sharper images from the enhanced magnetic anomaly and the drillholes, we infer that the deposits would be related to the syncline structure. Forward modeling confirms the inferred three belts of the ore bodies and also shows possibly two layers deposits in which the deep layer would be located at a depth of ∼1000 m. Although the deeper deposit results in a very smooth and low amplitude magnetic anomaly, the forward modeling shows that the anomalies from both the shallow magnetite and the inferred deep one fit the observed anomaly better. One deep drillhole reveals the fact that the magnetite is existed at a depth of ∼1000 m which highlights the interpretation of the deep deposit. The results show the contribution of the fine processing techniques which would be used to distinguish zones of potentially concealed mineralization.

Timescales of mafic magmatic fractionation documented by paleosecular variation in basaltic drill core, Snake River Plain volcanic province, Idaho, USA

The timescales over which fractional crystallization and recharge work in mafic volcano-plutonic provinces is subject to great uncertainty. Currently modeled processes are subject to the scale of measurement: monogenetic basaltic fields accumulate over hundreds of thousands of years, consistent with U-Th-Ra isotopic variations that imply 50% crystallization of basic magmas on timescales of 100,000 years or more, whereas crystal diffusion modeling implies phenocryst residence times of ∼1−1000 years. Monogenetic basalts of the Snake River Plain in southern Idaho, USA, are up to 2 km thick and postdate passage over the Yellowstone−Snake River Plain hotspot. Detailed lithologic and geophysical logging of core from deep drill holes, along with chemical stratigraphy and high-resolution paleomagnetic inclination measurements, document individual eruptive units, compound lava flows, and basaltic flow groups that accumulated over 1−6 m.y. Hiatuses are commonly marked by loess or fluvial interbeds that vary from ∼0.1 m thick to 20 m thick. Radiometric (40Ar-39Ar, detrital zircon U-Pb) and paleomagnetic timescale ages show that the deepest hole (Kimama drill hole, 1912 m total depth) accumulated over ∼6 m.y. Cycles of fractional crystallization and recharge are recognized in the chemical stratigraphy as up-section shifts in major and trace elements; these fractionation cycles commonly represent 40%−50% fractionation. Individual fractionation cycles may comprise 20−40 eruptive units (8−17 lava flows) with little to no change in paleomagnetic inclination (0°−1°), whereas adjacent cycles may differ by several degrees from one another or reflect changes in polarity. Rates of paleosecular variation in Holocene lavas and sediments dated using 14C document significant shifts in magnetic inclination over short timescales, ranging from ∼0.05° to 2°/decade, with an average of ∼0.5°/decade and a minimum rate of 0.05°/decade. This implies that fractionation cycles with ≤1° variation in magnetic inclination formed on timescales of a few decades up to a few centuries (20−200 years). Thus, the lavas collectively represent only a few thousand years of eruptive activity, with major flow groups separated in time by tens to hundreds of thousands of years. We suggest that the rates defined by paleosecular variation capture the timescales of magmatic chamber evolution (fractionation/recharge) in the seismically imaged mid-crustal sill complex; in contrast, we suggest that crystal diffusion modeling captures the residence times in shallow subvolcanic magmatic chambers that underlie individual monogenetic volcanoes.

Petrogenesis and metallogenic potential of granodiorite porphyry in the Kalatag district, East Tianshan, NW China: Constraints from geochronology, mineral geochemistry, Sr–Nd–Hf–O–S isotopes and sulfide trace elements

The Hongshi epithermal Cu deposit is located in the northern margin of the Dananhu arc in the East Tianshan Orogenic Belt, NW China. The Hongshi deposit is hosted by andesite and is famous for its lode type sulfide ores. Recently, the deep drill hole exploration shows a porphyry Cu mineralization and is predominantly hosted in granodiorite porphyry in the Hongshi. As for porphyry mineralization, the metallic minerals mainly include chalcopyrite, magnetite, and pyrite, with minor amounts of molybdenite. Ore minerals occur as dense dissemination and veins. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) U–Pb dating of zircons showed that the ore-bearing granodiorite porphyry was emplaced at ca. 434 Ma, recording the early subduction of the Paleo-Tianshan oceanic plate. Major element geochemical characteristics show that granodiorite porphyry samples have A/CNK values of 1.04–1.10 and moderate Mg# values of 45–49, indicating an I-type granitoid attribute. Trace element geochemical analysis indicates that ore-bearing granodiorite porphyry samples exhibit obvious large ion lithophile elements (LILEs) enrichment, high field strength elements (HFSEs) depletion, together with mantle-like bulk Sr–Nd ((87Sr/86Sr)i = 0.706417–0.708601; εNd(t) = 6.3–7.0) and zircon Hf–O isotope signatures (εHf(t) = 15.5–21.7, δ18O = 3.8 ‰–4.7 ‰), indicating that they were generated from partial melting of metasomatized mantle by the subducted slab fluids. In situ S isotope results of pyrite (1.46 ‰–2.07 ‰) and chalcopyrite (0.79 ‰–1.93 ‰) imply that granodiorite porphyry magmas and volcanic rocks provided ore-forming components (S and metals) for porphyry Cu mineralization in the deep drill hole ZK7501. The ore-bearing granodiorite porphyry samples have high logfO2 values ranging from − 12.4 to − 10.7, corresponding to ΔFMQ values of 0.6–5.2 (FMQ is the fayalite-magnetite-quartz buffer). Zircons from granodiorite porphyry have high Ce4+/Ce3+ ratios ranging from 74 to 187 and high Ti-in-zircon temperatures (764 to 869 °C). Electron microprobe analyses (EPMA) composition results of plagioclase, apatite and amphibole reveal that granodiorite porphyry magma had systematically high oxygen fugacity, high water contents (7.6–8.4 wt%), and low Cl contents (0.08–0.27 wt%), further demonstrating that granodiorite porphyry may be beneficial to the porphyry Cu mineralization in the deep drill hole ZK7501. Pyrite in the deep drill hole ZK7501 is enriched in Co, Ni, Ag, Cu, As, and Pb, but poor in Mn, Ga, Ge, Cd, In, Sn. Mn, As, Tl, Pb and Sb in pyrite substituted Fe2+ by coupled mechanisms, while Ag and Cu can enter the mineral lattice in the form of solid solution or micro-inclusions, which was also demonstrated by LA–ICP–MS mapping and textural studies. Pyrite shows variable Co/Ni ratios ranging from 10 and 455, indicating that ore-forming fluid originated from a magmatic source. The involvement of highly oxidized magmas is fundamental for the formation of porphyry Cu mineralization in an arc tectonic setting. Additionally, water concentrations also play an important factor that controlled metal fertility of the Early Paleozoic porphyry Cu mineralization in the Kalatag district.

Preliminary discussion on pyrrhotite, gold killer in Wells-Barkerville, British Columbia, Canada

The Wells-Barkerville area of the Cariboo gold mining district is situated within the Quesnel Highlands on the eastern edge of the Interior Plateau in central British Columbia, Canada of the eastern Circum-Pacific volcanicmetallogenic belt. Recorded gold production from the area totals more than 4.0 million ounces, including an estimated 2.7 million ounces from placer mining from 101 creeks and 1.3 million ounces from lode mining. There are five principal types of lode gold deposits in the district; namely, auriferous pyrite replacement, including replacement in limestone and that in calcareous clastic rock; pyrite-quartz vein/veinlet lode gold, including strike vein, diagonal vein, orthogonal vein, and quartz veinlets; basalt-hosted auriferous pyrrhotite-pyrite lode gold; and associated gold in porphyry copper styles. This area is historically a famous gold production area in western Canada, including the initial alluvial gold and later and current lode gold. This original short article uses drilling results to illustrate that pyrrhotite in this area is the killer of gold. Wherever there is pyrrhotite, the gold grade is very poor or even contains no gold. In other words, gold grade is inversely related to pyrrhotite content. Then, the spatial distribution characteristics of the pyrrhotite anomaly zone(s) existing in this area were summarized, including the approximate thickness of zone(s). On this basis, several deep drill holes are recommended to verify whether there is considerable gold mineralization beneath the pyrrhotite anomaly zone(s).

Application of suitable methodology for control of coal fire according to its magnitude in hot strata blast-holes–an approach

ABSTRACT Coal mine fire is a common phenomenon in Indian coalfields and great concerned on safety of the person engaged in mining operations. In opencast coal mine, particularly where the extraction of previously developed coal pillars has been carried out by opencast mining method, chances of spontaneous fire became more frequent and complicated. In such prevailing situations deep holes charging and blasting operation in hot strata may create every possibility to premature detonation of explosives, which leads to fatalities. Henceforth, it is imperative to use appropriate methodology to combat the fires and make it possible for wining of coal safely. This paper highlighted a methodology adopted for safe and effective management of fire by using two different chemical additives admixed with water to bring down temperature under safe workable limit in short duration of time and also make it suitable for charging and blasting operation in hot deep drill holes. On the basis of the magnitude of fires 0.5 to1.0% concentrations of MgCl2 and CaCl2 mixed with water were applied for cooling of high temperature fire in coal bench, overburden as well as hot blast holes with encouraging results in supressing of the flames and rapid cooling of hot strata.

Ancient organic matter in black shales as a carbon source for deep subsurface life

The fluids at black schist-rich bedrock in the Fennoscandian shield have been shown to carry extensive methane (Kietäväinen and Purkamo 2015, Kietäväinen et al. 2017). The sources of methane, abiotic, microbial, thermogenic, or their mixtures, are not well understood (Etiope and Sherwood Lollar 2013, Douglas et al. 2017). While previous field and laboratory studies have concentrated on oxic degradation of relatively low metamorphic grade black shales (e.g., Matlakowska et al. 2012, Petsch et al. 2005), our goal was to explore the genetic potential of microbial communities in naturally anoxic, oligotrophic and moderately saline bedrock fluids in contact with high-metamorphic grade organic carbon containing black schist. We tested if the microbial metabolisms could explain the extensive methane detected from the fluids at black schist -rich bedrock in the Fennoscandian shield. We aimed to determine the difference between abiotic and biotic methane formation in Palaeoproteorozoic bedrock using novel methane isotopologue measurements and evaluate the ability of natural microbial communities to use black schists as a carbon source in enrichment cultures and compare these to the previously reported cultures. Two study sites, namely the Outokumpu Deep Scientific Drill Hole at depth of 1470 m and Juuka/Miihkali116 overflowing deep drill hole in Finland, were selected for comprehensive geochemical and microbiological sampling. The sampling campaign involved collecting samples for methane isotopologues, intrinsic microbial community, and fluid for inoculation of laboratory microcosms. Ground and sterilized black shists of two different maturities obtained from Finnish bedrock, 13C-labeled graphite, cellulose, acetate and CO2 were used as different carbon sources for intrinsic deep subsurface fluids, and these microcosms were incubated for 8-20 months. Subsequently, the gas phase of the microcosms was analyzed for CH4, CO2, N2O, O2, and N2 concentrations, as well as isotopic ratios of carbon in CH4 and CO2. Bacterial, archaeal and fungal communities were characterized using phylogenetic marker gene amplicon sequencing from both the intrinsic deep subsurface fluids and the microcosms after the incubation period. The results of this study indicate that methane in these sites is likely formed abiotically, as evidenced by the isotopologue data and the absence of methanogenic archaea in the microbial communities. Moreover, the gas data and isotope ratios obtained from the microcosms suggest that graphitic carbon is predominantly transformed into carbon dioxide rather than methane, further supporting the isotopologue data. Throughout the incubation period, the microbial communities within the microcosms exhibited dynamic changes. Specific microbial groups known for their capacity to utilize complex or recalcitrant organic matter and xenobiotics were observed, indicative of the challenging, oligotrophic and nutrient-deficient subsurface environments. Moreover, microbes regarded as keystone species in the deep terrestrial biosphere were observed. This study sheds light on the processes driving methane formation and the associated microbial communities in ancient black shales. The findings suggest a predominantly abiotic origin for methane in these Finnish Palaeoproterozoic bedrock formations, highlighting the potential for alternative mechanisms of microbial carbon assimilation and the importance of microbial communities in carbon cycling in subsurface ecosystems.

Conical drill bit for optimized external ventricular drain placement: a proof-of-concept study.

Despite external ventricular drain (EVD) procedures being commonplace in neurosurgical practice, suboptimal placement rates remain high, and complications are not uncommon. The angle of the EVD catheter insertion and the accuracy of the drill hole placement are major factors determining successful EVD placement that are dependent on the drill bit morphology. The standard cylindrical 2-fluted twist drill bit creates a relatively deep and narrow drill hole that requires precise positioning, has limited visibility of the drill hole bottom and restricted catheter angular adjustment range, and poses the risk of inadvertent dural puncture. To overcome the standard problems associated with EVD drill bit morphology, the authors propose novel cone-shaped drill bits for EVD placement. Conical drill bits of 30° and 45° were designed, manufactured, and tested in a simulated laboratory setting as well as in three human cadavers with intact skull, dura mater, and brain. Drill bit performance was rated by neurosurgical trainees across various domains using Likert scale-type questions. In the laboratory, maximum drilling temperatures adjacent to the drill hole were recorded and compared for the standard drill bit and the 30° and 45° conical drill bits and were not significantly different (p = 0.631 and p = 0.326, respectively). The maximum temperature recorded directly underneath the drilling site for the 45° drill bit was significantly higher than the temperature of the standard drill bit (p = 0.043). The differences between the standard and 30° drill bits were not significant (p = 0.783). Upon cadaver testing, the drilling times with 30° and 45° conical drill bits were significantly longer than those with the standard drill bit (p = 0.036 and p = 0.002, respectively). Likert scale scores were significantly higher for the conical 30° (median [IQR] 4.7 [3.3-5]) and 45° (4 [2-5]) drill bits than for the standard drill bit (1.7 [1-2.5], p < 0.0001), indicating significantly better performance. Conical drill bits used as a "rescue" strategy allowed for an EVD catheter angular adjustment range 6 to 9 times greater than that for the standard drill bit and resulted in a zero inadvertent dural puncture rate. The 30° conical drill bit can be safely used on its own or as a rescue tool to potentially achieve improved confidence, visualization, targeting, and precision of EVD placement while essentially eliminating the possibility of unintentional dural puncture with minimal increase in the total procedure time.

Application of Treatment for Deep Hole Drilling Debris in Gas-Rich Soft Coal Seams

Hole accidents occurring in the drilling process and borehole collapse encountered in gas production are obstacles standing in the way of high efficiency of gas drainage through the outburst-prone soft coal seams in China. The fundamental testing data from existing suspending agents were combined to prepare a suspension in a specific density for testing debris disposal technology considering several adverse effects. Those effects include the sizeable residual volume of drilling debris, difficult debris disposal, the low effective utilization rate of drill holes, and the unideal extraction effect in drill holes with long-distance downward drill holes. The testing outcomes indicated that the suspension-aided debris disposal could contribute to the following aspects: discharging residual drilling debris out of the drill hole, rinsing the drill hole, preventing drilling debris from filling the coal seam, providing the adequate drill hole depth, and improving the effects of gas extraction. As a result, the gas production in shallow drill holes was increased by 40%, with gas concentration elevated by 21%. In addition, the scalar quantity and extraction concentration in the gas concentration of deep drill holes were increased by 84% and 260%, respectively. This study was undertaken to provide a specific reference for debris disposal work of deep drill holes for gas-rich soft coal seams.

Digitalization of hydraulic rotary drilling process for continuously mechanical profiling of siliciclastic sedimentary rocks

Hydraulic rotary drilling can offer the essential information and core samplesa for the researches on solid earth. Recording the factual field drilling data and analyzing the hydraulic rotary coring process are challenging yet promising to utilize the massive drilling information in geophysics and geology. This paper adopts the drilling process monitoring (DPM) technique and records the four parameters of displacement, thrust pressure, upward pressure, and rotation speed in real-time series for profiling the siliciclastic sedimentary rocks along 108 m deep drillhole. The digitalization results with 107 linear zones represent the spatial distribution of drilled geomaterials including superficial deposits (fill, loess, gravelly soil), mudstone, silty mudstone, gritstone, and fine sandstone. The constant drilling speeds varying from 0.018 to 1.905 m/min present the in-situ coring resistance of drilled geomaterials. Furthermore, the constant drilling speeds can identify the strength quality of soils to hard rocks. The thickness distributions of the six basic strength quality grades are presented for all the sedimentary rocks and each individual type of the seven soil and rocks. The in-situ strength profile determined in this paper can be used to assess and evaluate the in-situ mechanical behavior of geomaterial along the drillhole and can provide a new mechanical-based assessment for determining the spatial distribution of geological strata and structures in subsurface. They are important since the same stratum at different depths can have different mechanical behavior. The results provide a novel quantitative measurement for continuously in-situ mechanical profiling by digital drilling data. The findings of the paper can offer a new and effective method for refinement and upgrading of in-situ ground investigation, and can provide researchers and engineers with a novel tool and valuable reference to digitize and utilize factual data of current drilling projects.

Analysis of Exploration Wells on Aquifer in Kaliwungu Formation and Regional Planning Recommendations

Infrastructure development in the northern coast of Java continues to take place. The study and support of subsurface geological data and the value of hydrogeological parameters is one of the important parameters to support sustainable development. The existence of well exploration reportedly can support researchers for model validation and calibration. We carried out One-Dimensional and Two-Dimensional geoelectrical acquisition along with drilling in the Kaliwungu Formation which was lined with the Halang Formation. Ten points of one dimensional geoelectrical and two lines of geoelectrical acquisition VES method (Vertical Electrical Sounding), with a depth range of 100m Schlumberger and Wenner-Schlumberger configurations for profiling have reflected the study area dominated by aquitard (silty clay) with resistivity values < 20 ohm.m. The result of VES was then followed up by analysing the value of the well logging resistivity which was compared with the lithology of the cutting results in the 108m deep drill hole. Value of hydrogeological properties was carried out by the pumping test, were pumping test analysed using pumping cooper – Jacob single well software, and the result of hydraulic conductivity value was 6 x 10-9m/s, and the transmittivity value was 5.6 x 10-7 m2/s. Based on the Farvolden Method, the safe yield value was found to be comparable to the value according to Johson which is 3-8%.

Uncovering the Leichhardt Superbasin and Kalkadoon-Leichhardt Complex in the southern Mount Isa Terrane, Australia

The parts of the Mount Isa Terrane that crop out have been instrumental in deciphering the configuration of the supercontinent Nuna. In addition, these rocks host prolific base and precious metals. Further south, the Mount Isa Terrane is buried by >800 m of Phanerozoic cover that, to date, has primarily been investigated via geophysical surveys. Here, we present zircon U-Pb and Hf isotopic data of granitoids, metabasalts and metasedimentary rocks from seven >1 km deep drill holes that provide a window into the basement geology of the southern parts of the Mount Isa Terrane. The oldest rocks, intersected in two of the drill holes, are a series of granitic gneisses dated at ca. 1865 Ma, corresponding to the Kalkadoon-Leichhardt Complex. The majority of the encountered lithology in the drill holes are metasedimentary rocks with associated volcanic rocks and intruding granitoids, which bracket the remaining stratigraphy to ca. 1800–1760 Ma, corresponding to the lower and middle parts of the Leichhardt Superbasin. The ca. 1865 Ma Kalkadoon-Leichhardt Complex and ca. 1800 Ma granitoids have unradiogenic Hf isotopic signatures that necessitate an Archean lithosphere underneath the Mount Isa Terrane. Detrital zircon from the Leichhardt Superbasin may have been derived locally but also share age and Hf isotopic signatures with the eastern and northern Gawler Craton, implying possible long-distance transport. Metamorphic events recorded in discrete zircon grains and rims reveal punctuated tectonic activity at ca. 1760–1750 Ma and ca. 1720–1710 Ma in the southern Mount Isa Terrane, related to the pre-Wonga Event and the second stage of the Wonga Orogeny. The stratigraphy and events in the southern Mount Isa Terrane can be correlated to the northern and eastern Gawler Craton in South Australia, which may only have been ∼500–1000 km from the Mount Isa Terrane at the time of deposition. Ultimately, the results from these new drill holes reveal the extent of the Mount Isa Terrane under deep sedimentary cover and strengthen the links between the North and South Australian Cratons during the protracted assembly of the supercontinent Nuna.

Biomarkers in Extreme Environments on Earth and the Search for Extraterrestrial Life in Our Solar System

Our appreciation of the potential distribution of life in the Solar System has been impacted by the discovery that organisms are able to occupy the most extreme environments on Earth. The persistence of life in the deepest parts of oceans, the deep sedimentary and crustal biosphere accessed by deep drill holes, hot springs, deserts, and polar regions has led to diverse hypotheses regarding the potential for extraterrestrial life on other planets. This chapter provides an overview on how scientists explore the habitability of other planets and moons of our Solar System and far away in outer space and how future space missions aim to find evidence for extraterrestrial life.

Early Ordovician conodonts from Barnicarndy 1 stratigraphic well of the Southern Canning Basin, Western Australia

Documented here is the systematic description of conodonts from 10 samples collected within the Nambeet Formation in Barnicarndy 1, a deep stratigraphic drillhole located within the Barnicarndy Graben on the southwestern margin of the Canning Basin, Western Australia. The fauna is represented by 22 identifiable species including a new species, Juanognathus? denticulatus sp. nov., and several age-diagnostic taxa. Three biozones extending from the upper Tremadocian to upper Floian (Lower Ordovician) are recognized in these assemblages, including the Jumudontus gananda Biozone, the Oepikodus communis Biozone and the Paroistodus proteus Biozone, all previously recorded from the Samphire Marsh Member of the Nambeet Formation. Identification of this conodont succession has enabled both precise age constraints for this sequence and correlation to other occurrences of the Samphire Marsh Member, and indicates that this unit reaches an apparent thickness of 925 m (from 1345 to 2270 m depth) in Barnicarndy 1. This newly recovered fauna can be well correlated across the basin, such as with Nambeet Formation faunas intersected in the Olympic 1 petroleum well in the northwestern Broome Platform, and from correlative carbonates on the Lennard Shelf along the northern margin of the Canning Basin. Yong Yi Zhen [ yong-yi.zhen@planning.nsw.gov.au ], Geological Survey of New South Wales, W.B. Clarke Geoscience Center, 947-953 Londonderry Road, Londonderry NSW 2753, Australia; Heidi J Allen [ heidi.allen@dmirs.wa.gov.au ]; Sarah K Martin [ sarah.martin@dmirs.wa.gov.au ], Geological Survey of Western Australia, Department of Mines, Industry Regulation and Safety, Mineral House, 100 Plain Street, East Perth WA 6004.

Ore Mineralogy, Geochemistry, and Dating (Re-Os, Ar-Ar) of the El Volcán Porphyry/Epithermal System, Maricunga Gold Belt, Northern Chile

Abstract The El Volcán gold project (8.9 Moz Au @ 0.71 g/t Au) is located in the Maricunga gold belt in northern Chile, on the flank of the large Cenozoic Copiapó Volcanic Complex. Precious metal mineralization is hosted in two zones (Dorado and Ojo de Agua) of (pervasively) altered Miocene porphyry intrusions and lava flows of andesitic to rhyolitic composition, and in breccias. The ore zones reflect an evolving magmatic-hydrothermal system with mineral assemblages of magnetite-ilmenite-pyrite-molybdenite (early), bornite-chalcopyrite-pyrite-rutile (stage I), chalcocite-chalcopyrite-enargite-fahlore-pyrite (stage II), and chalcopyrite-covellite-pyrite (stage III). Alteration is dominantly of Maricunga-style (illite-smectite-chlorite ± kaolinite), partly obscured by quartz-kaolinite-alunite ± illite ± smectite alteration. Powdery quartz-alunite-kaolinite alteration with native sulfur and cinnabar forms shallow steam-heated zones. Early K-feldspar ± biotite alteration is preserved only in small porphyry cores and in deep drill holes. Most gold is submicrometer size and is in banded quartz veinlets, which are characteristic of the Maricunga gold belt. However, some gold is disseminated in zones of pervasive quartz-kaolinite-alunite alteration, with and without banded quartz veinlets. Minor visible gold is related to disseminated chalcocite-chalcopyrite-enargite-fahlore-pyrite. The lithogeochemical database identifies a pronounced Au-Te-Re signature (&amp;gt;100× bulk crust) of the hydrothermal system. Molybdenum-rich bulk rock (100–400 ppm Mo) has an Re-Os age of 10.94 ± 0.17 Ma (2σ). 40Ar-39Ar ages on deep K-feldspar alteration and on alunite altered rock have the same age within error and yield a combined age of 11.20 ± 0.25 Ma (2σ). The formation of the El Volcán gold deposit took place during the establishment of the Chilean flat-slab setting in a time of increasing crustal thickness when hydrous magmas were formed in a mature arc setting. The vigorous nature of the hydrothermal system is expressed by abundant one-phase vapor fluid inclusions recording magmatic vapor streaming through a large rock column with a vertical extent of ≥1,500 m.

NEW TYPES OF BASIC ROCKS IN THE KORSUN-NOVOMYRHOROD ANORTHOSITE-RAPAKIVI GRANITE PLUTON AS AN INDICATOR OF ITS PETROGENESIS

Two species types of basic rocks contrasting in chemical and mineral composition were investigated within the Korsun-Novomyrhorod anorthosite-rapakivigranite pluton (KNP) of the Proterozoic age. In comparison to more typical basic rocks of KNP, the investigated rocks are presented by the extremely Fe-rich fayalite gabbroids and the most MgO enriched biotite gabbronorite. The first of them occupy a deeper level of the Horodishche massif in the central part of KNP. According to a high-Fe association of minerals and reduced or low An content in plagioclase they may represent the crystallization of a highly evolved basic melt (after anorthosite and gabbronorites separation), which were crystallized under abyssal conditions and low oxygen fugacity. Preliminary geochemical data indicate that trace elements concentration and negligible negative Eu-anomalies (0.72-0.95) are similar to most distributed basic rocks but unlike the last it is slightly differed by decreasing La/Yb and enriched in Sc (up to 118 ppm). Thus, we suppose those rocks might be crystallized as a result of mixing highly differentiated (iron and alkali enriched) melt with the early generation of anorthitic plagioclase, with subsequent dissolution of the last. Enrichment in iron of the mafic minerals and increasing of alkalinity of plagioclase in the basic rocks is consistent with the appearance of ferrodioritic melts as a product of prolonged crystalline differentiation of the initial melt. In contrast to fayalitic gabbroids, the pyroxene-biotite gabbronorites from the border zone in according to increased Mg# of the mafic minerals and rocks are obviously the least differentiated varieties of the anorthosite-gabbronorite series. The regularities in chemical composition in such type of rocks are consistent with the liquid line of dissent for basic rocks in KNP, which implies their crystallization at an earlier stage of magma ascending. By composition, such melt can be formed at an intermediate stage from slightly differentiated melt. This is indicated by enrichment in Sr (453-881 ppm) and Ba (910-930 ppm), Eu/Eu* (0.85-1.10), increased content MgO (up to 8 wt. %), Cr and V (59-193 and 169-350 ppm respectively). At the same time these rocks are enriched in Zr and Hf (378-478 and 10.3-12.02 ppm respectively), highly enriched in Rb (169-192 ppm), with moderate Nb and Ta content (14.6-18.1 and 0.91-2.84 ppm respectively) that point out to interaction and partial assimilation by crust material. Summarizing geological data of the deep drill-holes, it is possible to reveal a general direction of the mafic minerals evolution in the basic rocks and the evidences of cryptic layering. The last are quite clearly manifested both in the large gabbro-anorthosite massifs and individual intrusive bodies. We suppose that the evolution trend of mafic mineral composition are consistent with the tholeiitic trend differentiation of the primary melt with gradual increasing of iron content (under low oxygen fugacity) during differentiation and ascending in the upper crust. According to this interpretation of the inner structure of gabbro-anorthositic massifs, on the modern erosional level of KNP are often exposed the fragments of the upper (or lateral) layered series (Fe-enriched), less often the drill-holes reach up to the heads of the lower layered series.

DPM time management analysis for drilling a 200 m deep hole in ground investigation

This paper applies the drilling process monitoring (DPM) method to record and analyse the digital real-time data for the full process of the hydraulic rotary coring project along a 200 m deep drillhole. According to the DPM data, the whole drill project is divided into four periods. The working period (or the full drilling process) consists of a total of 88 roundtrips and costs a total of 76.71 hours. Each roundtrip can be classified into four sections: inserting, drilling, retrieving, and extracting processes. The time distribution of each individual process along the 200 m deep drillhole is obtained by DPM data. As the drillhole depth increases, the time of the total roundtrip, the inserting process, and the retrieving process for one roundtrip increases linearly. The ground strata, the drill machine condition, and the operators’ effectiveness determine the variations in the elapsed time of the drilling process. Furthermore, four types of malfunctions and associated time distribution can be identified by the abnormal DPM data. The factual data and results presented in the paper can quantitatively describe the time distribution of individual drilling processes and provide a digital field management method for drilling information.

Basement correlation across the southernmost Baltic Sea: Geochemical and geochronological evidence from onshore and offshore deep drill cores, northern Poland

New zircon U-Pb age measurements, whole rock major and trace element geochemistry, and Sr and Nd isotopic analyses of samples from fourteen deep drill holes that penetrated the hidden Precambrian basement of the southernmost Baltic Sea and the coastal area of northern Poland (Pomerania), make it possible to identify a two episodes of Proterozoic magmatism in that area. The basement consists of late Palaeoproterozoic deformed calc-alkaline, magnesian, I-type to A-type diorites to granites of volcanic arc affinity. U-Pb zircon geochronology documents their magmatic crystallization ages to be between 1791 ± 8 Ma and 1750 ± 5 Ma, with an episode of syn- to late-magmatic deformation recorded in thin overgrowths on zircons at about 1740 Ma. These rocks from Pomerania and its offshore area broadly correlate with the bedrock of Blekinge in southern Sweden, where most of the crust was formed at 1.77–1.75 Ga. They may thus be part of the same geological domain, extending on both sides of the present-day southern Baltic Sea, formed along a late Palaeoproterozoic active continental margin. A subordinate suite of undeformed, significantly younger A-type granites was emplaced at 1477 ± 6 Ma, 1449 ± 7 Ma and 1450 ± 9 Ma. This time interval is concurrent with emplacement of A-type granitoids on the Danish island of Bornholm as well as in Blekinge and other parts of southern Fennoscandia. However, their geochemical and isotopic data highlight a genetic diversity of these granites.