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Chronostratigraphic relations of neogene formations of the Great Hungarian Plain based on interpretation of seismic and paleomagnetic data
No abstract available.
Observations on the geology and geohydrology of the Chernobyl' nuclear accident site, Ukraine
The most higly contaminated surface areas from cesium-137 fallout from the April 1986 accident at the Chernobyl' nuclear power station in Ukraine occur within the 30-km radius evacuation zone set up around the station, and an 80-km lobe extending to the west-southwest. Lower levels of contamination extend 300 km to the west of the power station. The deposition of this radioactive dust on the surface and the subsequent entombment of the damaged reactor effectively result in the de facto establishment of an above-ground nuclear waste storage site. This site is located on a thick sedimentary sequence of loose, mostly clastic deposits, with a shallow (generally 3-5 m) water table. The geology, the presence of surface water, a shallow water table, and leaky aquifers at depth make this an unfavorable environment for the long-term containment and storage of the radioactive debris. An understanding of the general geology and hydrology of the area is important to assess the environmental impact of this unintended waste storage site, and to evaluate the potential for radionuclide migration through the soil and rock and into subsurface aquifers and nearby rivers.
Petroleum habitat of east Siberia, Russia
East Siberia comprises three petroleum provinces—Lena-Tunguska, Lena-Vilyuy, and Yenisey-Anabar—that occupy the area of the Siberian craton. Petroleum has been generated and has accumulated in Precambrian rifts beneath the sedimentary basins and, more importantly, within the section of the basin itself. The platformal deposits of the basins extend beneath overthrusts on the east and south and are covered by sedimentary rocks of the West Siberian overthrusts on the east and south and are covered by sedimentary rocks of the West Siberian province on the west. Permafrost and gas hydrate deposits are present throughout most of East Siberia. In the Lena-Tunguska province, rifts that developed during Riphean time are filled by thick sedimentary rocks, in which petroleum deposits have formed. In Early Cambrian time a barrier reef extended across the East Siberian craton from southeast to northwest. A lagoon to the west of this reef was the site of thick rhythmic salt deposits, which are the main seal for petroleum in the province. The sedimentary section of the platform cover ranges in age from Late Proterozoic to Permian. More than 25 oil and gas fields have been discovered in the province, all in Riphean through Lower Cambrian rocks. The Lena-Vilyuy province includes the Vilyuy basin and the Cis-Verkhoyansk foredeep. During Middle Devonian time, a rift formed along the axis of what was to become the Vilyuy basin. This rift is filled by Upper Devonian and Lower Carboniferous basalt, elastics, carbonates, and evaporites. During this rift stage the region that was to become the Cis-Verkhoyansk foredeep was an open geosynclinal sea. The sedimentary cover consists of Permian, coal-bearing sedimentary rocks as well as elastics from the Lower Triassic, Lower Jurassic, Lower Cretaceous, and Upper Cretaceous, the latter only in the Vilyuy basin. In the Lena-Vilyuy petroleum province as many as nine gas and gas-condensate fields have been discovered. The Yenisey-Anabar province is largely an extension of the West Siberian petroleum province. Permian sedimentary rocks are present only in the east, where they consist of elastics and some salt. The Triassic, Jurassic, and Cretaceous each are represented by thick clastic deposits. Total thickness of the sedimentary cover is up to 15 km on the west and 8 km on the east. Twelve gas and gas-condensate fields have been discovered in the western part of the province.
Kalpin transpression tectonics, northwestern Tarim Basin, western China
The paper examines the relative importance of strike-slip faulting and lateral crustal deformations in the geologic structure of a portion of the western People's Republic of China. Deformed thrust sheets in the Kalpin area of the western PRC suggest large-scale sinistral strike-slip movement on the Aheqi fault zone along the northwestern margin of the Tarim basin. The total amount of the Cenozoic sinistral strike-slip displacement is estimated to be 311 km; this is the same magnitude of slip estimated along the Altyn Tagh fault, marking the southeastern boundary of the Tarim basin. Together, the Aheqi and Altyn Tagh faults outline the Aheqi- western Kunlun-southwestern basin-Altyn transpression tectonic system.
Genesis of the West Siberian Basin and its petroleum geology: A recent interpretation
A prominent Western specialist on the geology of the oil and gas deposits of Russia provides an interpretation of the genesis of the West Siberian basin, relying, in part, on most recent Russian studies as well as information made available in 1994 evaluating the reserves of Russia's most important producing province. From Late Carboniferous through Middle Jurassic time, the region of West Siberia passed through orogenic, rift, and early platform stages. A domal high was present in the region during the orogenic stage, arising from cratonization of the Ural-Mongolian fold belt. Early Triassic rifting was part of a global rifting event and was a precursor to the subsequent crustal sagging that produced the West Siberian basin. The Early-Middle Jurassic was a time of cyclical marine and continental deposition, the sea moving back and forth from the north. The Talinskoye oil field occurs in Lower-Middle Jurassic sandstones that have the form of a river channel that extends more than 200 km. The Priobskoye field is associated with a Lower Cretaceous clinoform that has been traced N–S for more than 300 km. It is suggested that: (a) the oil in the Lower Cretaceous Neocomian sandstones was sourced by bituminous clays that interfinger with these sandstones on the west; and (b) that Upper Cretaceous Cenomanian gas was sourced in part by deeply buried Paleozoics and by overlying Upper Cretaceous Turonian clays. Predicted discoveries in West Siberia include several thousand small fields with reserves of less than 10 million tons, 250 to 300 medium-sized fields, and several large fields with 30 to 100 million tons.
Tectonic controls on ore-bearing intrusions of the Talnakh Ore Junction: Position, morphology, and ore distribution
Analysis of fifteen hundred deep boreholes permits understanding of Noril'sk-type, ore-bearing intrusions with respect to stratigraphic position, thickness, and ore distribution, and provide insights into the evolution of the Talnakh and Noril'sk ore junctions. Weakly miner-alized, Lower Talnakh-type intrusions were emplaced early in each ore junction, followed by emplacement of the ore-bearing intrusions. The morphology of the Lower Talnakh-type intrusions appears to have been controlled largely by inferred, arcuate faults; tight, N-S-trend-ing folds in the Noril'sk-Kharaelakh fault zone; and pre- Tungusskaya anticlines. The spreading and morphology of the ore-bearing intrusions were influenced by these features, but were more strongly controlled by the Noril'sk-Kharaelakh fault zone and by arcuate, thickened lenses within the Lower Talnakh-type intrusions. Host-rock characteristics strongly influenced the shapes of the ore-bearing intrusions in section and plan, the configurations of their flanking and frontal parts, and the attitudes of their peripheral sills.
Paleozoic plate-tectonic evolution of the Tarim and western Tianshan Regions, western China
The plate-tectonic evolution of the Tarim basin and nearby western Tianshan region during Paleozoic time is reconstructed in an effort to further constrain the tectonic evolution of Central Asia, providing insights into the formation and distribution of oil and gas resources. The Tarim plate developed from continental rifting that progressed during early Paleozoic time into a passive continental margin. The Yili terrane (central Tianshan) broke away from the present eastern part of Tarim and became a microcontinent located somewhere between the Junggar ocean and the southern Tianshan ocean. The southern Tianshan ocean, between the Tarim craton and the Yili terrane, was subducting beneath the Yili terrane from Silurian to Devonian time. During the Late Devonian-Early Carboniferous, the Tarim plate collided with the Yili terrane by sinistral accretional docking that resulted in a late Paleozoic deformational episode. Intracontinental shortening (A-type subduction) continued through the Permian with the creation of a magmatic belt.
Paleomagnetism of the Siberian flood basalts of the Noril'sk area: A constraint on eruption duration
The volcanic sequence of the Noril'sk area, northern Siberia, provides the most complete section of early Siberian flood-basalt volcanism. Paleomagnetic measurements for more than 4000 samples of lava and tuff indicate that nearly all of this >3500-m-thick sequence was laid down during one interval of normal magnetic polarity. Lavas of the lower third of this sequence are cut by the ore-bearing Noril'sk-I intrusion, which has an age of 251 Ma, identical to that of the Permian-Triassic boundary. Thus, the normal-polarity interval represented by this sequence is inferred to be the first of the Triassic Period. Eruption of this enormous volume of material in a relatively brief period coincident with the earth's greatest mass extinction requires that all aspects of Siberian flood-basalt volcanism be evaluated carefully as possibly contributing to that catastrophe.
Rejuvenation of the Kuqa Foreland Basin, northern flank of the Tarim Basin, northwest China
The Kuqa depression along the northern flank of the Tarim basin is filled with a thick sequence of Neogene and Quaternary coarse elastic continental sediments. This structural depression is part of a large foreland basin that lies south of the Tianshan—an orogenic belt of intracontinental convergence resulting from the northward propagation of stress following the collision of India with the southern margin of Eurasia.
Tertiary volcanic rocks from the southern Pannonian Basin, Croatia
The Tertiary volcanic rocks of the southern part of the Pannonian Basin are related to a sequence of tectonic events that occurred along the northern margin of the Dinarides when subduction ceased and after uplift of the region in middle Eocene time. The oldest rocks are andesites and dacites erupted during an Egerian to Eggenburgian marine transpression phase. In early Miocene time (about 17 Ma), rifting started, probably caused by the rise of the mantle, resulting in E-W extension and strike-slip faulting leading to formation of the Pannonian Basin. The initial rifting was accompanied by trachyandesitic volcanism of Karpathian age, followed by Badenian-age (15 to 13 Ma) volcanic activity producing basalts, andesites, and dacites. During these volcanic phases the Pannonian Basin, or the Paratethys, probably was periodically connected with the Mediterranean Sea. The final period of volcanism (about 9 to 7 Ma) produced alkalic basalts and basalts and occurred in fresh-water environments. These volcanic rocks have had a complex petrological evolution, related to an active continental margin. Egerian-Eggenburgian andesites and dacites can be explained by upper crustal assimilation with fractional crystallization (ACF) of primary basalt magma. The three younger associations originated by partial melting of rocks from both the upper mantle and the lower crust. Their evolution was accompanied by crustal contamination.
Zinc, copper, and lead geochemistry of oceanic igneous rocks - ridges, islands, and arcs
Variations in the abundances of Zn, Cu, and Pb are found to be useful in identifying tectonic regimes and separating oceanisland basalts into enriched- and depleted-source categories. The average Zn, Cu, and Pb contents of normal mid-ocean ridge basalts (N-MORB) are 84, 70, and 0.35 ppm, respectively. Differences in average Zn contents for various ridges reflect more the varying degrees of differentiation than variations of Zn content in the source rocks. At a Mg# of 70, or Mg# 70 , which is taken to represent primitive MORB, many MORB sequences converge at a Zn content of 58 ± 6 ppm, which is close to the value for primitive mantle (50 ppm) and ordinary chondrites (∼55 ppm). Values of 0.1 to 0.15 ppm Pb in MORB at Mg# 70 , best defined at the superfast-spreading Southern East Pacific Rise, are similar to estimates of Pb in the primitive mantle (0.12 to 0.18 ppm). They also are near the lower end of the range for ordinary chondrites. The very slow spreading Southwest Indian Ocean Ridge has a sequence with higher Pb contents, in addition to a more normal sequence, which has a visual best value of 0.4 ppm Pb at Mg# 70 . With the exception of the Walvis Ridge, Zn and Cu appear to be little affected by proximity to hotspots (i.e., E-MORB); however, Pb contents are higher and average about 0.6 ppm.
Undiscovered petroleum of the Brazilian interior sag basins
This paper, the second in a series dealing with undiscovered petroleum in South American basins (exclusive of Venezuela and Colombia), focuses on the four large intracratonic (or interior) sag basins of Brazil: the Solimoes, Amazonas, Parnaiba, and Parana. The smaller Chaco basin also is discussed, although in less detail. Preliminary estimates of undiscovered hydrocarbons in the five basins are 0.228 billion barrels of oil (BBO) and 11.870 trillion cubic feet of gas (TCFG). Because the mean values originally estimated by the World Energy Resources Program at the U.S. Geological Survey appear to be low when viewed in light of the recent (1983-1993) history of petroleum reserves in South America, the mean values were revised upward based on the original identified reserves. The recalculated mean values are 10.18 BBO and 20.52 TCFG. In general, exploration in these basins is in an immature stage. The Solimoes basin has the greatest initial estimated undiscovered reserves of oil (0.04 BBO), and the Parana basin has the greatest initial estimated undiscovered reserves of gas (5.08 TCFG). The most important plays in the Solimoes and structurally similar Amazonas basins are the fold and fault closures associated with the wrench systems found in the basins. The plays in the Parana basin are limited to possible structural traps linked to faultassociated closures, and possibly to some wrench-related features.
El Salvador, Chile porphyry copper deposit revisited: Geologic and geochronologic framework
The Eocene (42 to 41 Ma) El Salvador porphyry copper deposit in the Indio Muerto district, northern Chile (26° 15′ S Lat.), formerly thought to have formed at the culmination of a 9-m.y. period of episodic magmatism, is shown by new mapping, U-Pb and K-Ar geochronology, and petrologic data to have formed during the younger of two distinct but superposed magmatic events-a Paleocene (∼63 to 58 Ma) and an Eocene (44 to 41 Ma) event. In the district, high-K Paleocene volcano-plutonic activity was characterized by a variety of eruptive styles and magmatic compositions, including a collapse caldera associated with explosive rhyolitic magmatism (El Salvador trapdoor caldera), a post-collapse rhyolite dome field (Cerro Indio Muerto), and andesitic-trachyandesitic stratovolcanos (Kilometro Catorce-Los Amarillos sequence). Pre-caldera basement faults were reactivated during Paleocene volcanism as part of the collapse margin of the caldera. Beneath Cerro Indio Muerto, where the porphyry Cu deposit subsequently formed, the intersection of two major basement faults and the NNE-striking rotational axis of tilted ignimbrites of the Paleocene El Salvador caldera localized emplacement of post-collapse rhyolite domes and peripheral dikes and sills. Subsequent Eocene rhyolitic and granodioritic-dacitic porphyries intruded ~14 m.y. after cessation of Paleocene magmatism along the same NNE-striking structural belt through Cerro Indio Muerto as did the post-collapse Paleocene rhyolite domes. Eocene plutonism over a 3-m.y. period was contemporaneous with NW-SE-directed shortening associated with regional sinistral transpression along the Sierra Castillo fault, lying ∼10 km to the east. Older Eocene rhyolitic porphyries in the Indio Muerto district were emplaced between 44 and 43 Ma, and have a small uneconomic Cu center associated with a porphyry at Old Camp. The oldest granodioritic-dacitic porphyries also were emplaced at ∼44 to 43 Ma, but their petrogenetic relation to the rhyolitic porphyries and younger granodioritic-dacitic porphyries in the district is unclear. The main porphyry Cu-Mo-related granodioritic-dacitic stocks in Quebrada Turquesa on Cerro Indio Muerto intruded, cooled, and were mineralized within ∼1 m.y. between 42 and 41 Ma. Volumetrically minor late- to post-mineral porphyries are slightly more mafic than earlier granodioritic-dacitic porphyries, a compositional trend possibly repeated on several scales and more than once over the 3-million-year Eocene magmatic history of the Indio Muerto district. This compositional trend requires either addition of basaltic material into an open-system silicic magma chamber or tapping of progressively deeper levels of a vertically zoned magma chamber. Eocene porphyry magmas were more hydrous and their residual source mineralogy richer in garnet than the relatively anhydrous Paleocene rocks, whose source was rich in pyroxene. The presence of inherited zircons in Paleocene and Eocene rocks requires interaction with crustal rocks of Paleozoic and/or Proterozoic age.
Pb-isotopic systematics of lunar highland rocks (>3.9 Ga): Constraints on early lunar evolution
The present lead (Pb)-isotopic database of over 200 analyses from nearly 90 samples of non-mare basalt, lunar highland rocks (>3.9 Ga) delineate at least three isotopically distinct signatures that in some combination can be interpreted to characterize the systematics of the entire database. Two are fairly new sets of lunar data and are typical of Pb data from other solar-system objects, describing nearly linear arrays slightly above the “geochron” values, with 207 Pb/ 206 Pb values <0.9. In aggregate, those data allow a relatively new interpretation of the Pb-isotopic evolution of the Moon, helping to identify and characterize a planetary evolutionary stage not preserved by Earth rocks. From the Pb-isotopic compositions, a source 238 U/ 204 Pb (μ) value can be calculated; differences in μ values from one Pb signature to another can have important implications on the age and evolution of Moon-forming events. In particular, the U/Pb ratio is one method of measuring the fractionation between refractory and volatile elements, an important indicator when considering large-scale planetary differentiation stages. The oldest Pb signature is represented solely by ferroan anorthosite 60025, presumably a piece of the early plagioclase-rich lunar crust produced from a magma ocean, and is characterized by source μ values between 35 and 100 at ~4.43 Ga. Another prominent and uniquely lunar Pb signature, identified more than 20 years ago, is representative of many ferroan anorthosites and most high-Mg suite rocks (particularly 15415, 62237, 76535, and 78235), and is characterized by extremely high 207 Pb/ 206 Pb values (∼1.45) that require extremely high source μ values (>500). Although the age and origin of this exotic Pb is not well constrained, it is interpreted to be related to the entrapment of incompatible-element-rich (U, Th) melts within the lunar upper mantle and crust between 4.36 and 4.46 Ga (urKREEP residuum?). The latest discovered Pb signature is found only in lunar meteorites and is characterized by relatively low source μ values between 10 and 50 at 3.9 Ga. The fact that most lunar crustal rocks (>3.9 Ga) exhibit high 207 Pb/ 206 Pb values requires that they were derived from, mixed with, or contaminated by Pb produced from early-formed, high-μ sources. The ubiquity of these U-Pb characteristics in the sample collection is probably an artifact of Apollo and Luna sampling sites, all located on the near side of the Moon, which was deeply excavated during the basin-forming event(s). However, the newest Pb-isotopic data support the idea that the Moon originally had a μ value of ~8 to 35, slightly elevated from Earth values, and that progressive U-Pb fractionations occurred within the Moon during later stages of differentiation between 4.36 and 4.46 Ga.
Synthesis of crustal seismic structure and implications for the concept of a slab gap beneath Coastal California
Compilation of seismic transects across the central and northern California Coast Ranges provides evidence for the widespread tectonic emplacement beneath the margin of a slab of partially subducted oceanic lithosphere. The oceanic crust of this lithosphere can be traced landward from the former convergent margin (fossil trench), beneath the Coast Ranges, to at least as far east as the Coast Range/Great Valley boundary. Comparison of measured shear and compressional wave velocities in the middle crust beneath the Hayward fault with laboratory measurements suggests that the middle crust is a diabase (oceanic crust). Both of these observations are consistent with recent models of the high heat flow and age progression of Neogene volcanism along the Coast Ranges based on tectonic emplacement (stalling) of young, hot oceanic lithosphere beneath the margin, but appear to contradict the major predictions of the slab-gap or asthenospheric-window model. Finally, the Neogene volcanism and major strike-slip faults in the Coast Ranges occur within the thickest regions (>14 km thick) of the forearc, suggesting that the locations of Cenozoic volcanism and faulting along the margin are structurally controlled by the forearc thickness rather than being determined by the location of a broad slab gap.
Structure and metamorphism of the Franciscan Complex, Mt. Hamilton area, Northern California
Truncation of metamorphic isograds and fold axes within coherent terranes of Franciscan metagraywacke by intervening zones of melange indicate that the melange is tectonic and formed after the subduction-related metamorphism and folding. These relations are expressed in two terranes of blueschist-facies rocks of the Franciscan Complex in the Mt. Hamilton area, northern California-the Jurassic Yolla Bolly terrane and the structurally underlying Cretaceous Burnt Hills terrane. Local preservation in both terranes of basal radiolarian chert and oceanic basalt beneath continent-derived metagraywacke and argillite demonstrates thrust repetition within the coherent terranes, although these relations are scarce near Mt. Hamilton. The metagraywackes range from albite-pumpellyite blueschists to those containing well-crystallized jadeitic pyroxene, and a jadeite-in isograd can be defined in parts of the area. Primary bedding defines locally coherent structural orientations and folds within the metagraywacke units. These units are crosscut by thin zones of tectonic melange containing blocks of high-grade blueschist, serpentinite, and other exotic rocks, and a broader, but otherwise identical melange zone marks the discordant boundary between the two terranes.
Further considerations of the Ce/Yb vs. Ba/Ce plot in volcanology and tectonics
A plot of Ce/Yb vs. Ba/Ce, for locality averages, effectively separates mid-ocean ridge basalts (MORB) (Ce/Yb <10, Ba/Ce 1-4.2), oceanic island volcanics (OIV) (Ce/Yb >10, Ba/Ce <6), which are generally hotspot related, and island arc volcanics (IAV) (Ce/Yb <23, Ba/Ce >4.2). The conventional interpretation is that these three types of volcanic environments involve oceanic rift-related, large-volume partial melts (˜20-30%) of a depleted source (MORB), small volume melts (˜5% for alkalic volcanics) of enriched sources related to plumes (OIV), and melts of hydrous-enriched sources during subduction, especially for Ba (IAV). Three OIV sites, however, have average ratios that fall in the MORB field (e.g., Krafla Volcano, Iceland), and these localities also tend to have other geochemical data similar to MORB. Average ratios of Hawaiian tholeiitic shield basalts of Mauna Kea and Koolau volcanoes occupy a restricted field on a plot of Ce/Yb vs. Ba/Ce of 10-18 for Ce/Yb and 2.8-3.1 for Ba/Ce, a field toward which other shield basalts and cone-building volcanics regress. In general, post-shield alkalic rocks have higher values of Ce/Yb than do tholeiites. Peralkalic basalts (basanites, melilitites, and phonolites) have even higher values of Ce/Yb, reflecting smaller degrees of partial melting (perhaps 1-2%) and melting of sources containing phlogopite that were enriched by CO 2 -dominated fluids. The minor post-erosion nephelinitic suites of Hawaii (e.g., the Honolulu Series on Oahu, and the Koloa suite on Kauai) generally have values both greater than IAV for Ce/Yb and greater than other kinds of OIV for Ba/Ce in a part of the plot previously not found to be occupied by data. Alkali basalts of both these nephelinitic series have the lowest and similar ratios (Ce/Yb ˜ 25; Ba/Ce ˜ 10). In the Hawaiian Islands, there are two trends. One (a), where phlogopite has been interpreted to remain in the source, generally has Ba/Ce decrease away from the alkali basalts as Ce/Yb increases. The other (b), where phlogopite has been interpreted to enter the melt, occupies a field that is high in both Ce/Yb (>30) relative to IAV and in Ba/Ce (>8) relative to the OIV field. There are some exceptions, also, for IAV that plot outside the IAV field. The values of Ce/Yb in Mariana Islands samples, for example, are exceptionally low for the IAV (Ce/Yb <5 with many samples <2). Examples of two cross-chain Kasuga Islands, however, have average values of Ce/Yb considerably greater than for any other Mariana Islands data, and individual samples extend from within the IAV field into the OIV field, which may indicate a mixture of IAV and OIV sources (rather than involvement of a hotspot, these island volcanics have been interpreted as magma of OIV entrapped "plums" in an IAV "pudding" by Stern et al., 1993). Not surprisingly, continental arc volcanics (CAV) are generally similar to IAV, but with somewhat greater dispersion in Ce/Yb, perhaps representing a larger contribution of continental materials to the volcanics. Continental rift volcanics (CRV) are complex. The Antarctic rift data fall in the OIV field, and clearly define a hotspot origin for the rift with little contamination in the continental lithosphere, but most CRV data fall in the IAV field (Rio Grande rift tholeiites, Yellowstone Plateau basalts, Columbia River basalts, East African rift basalts). The Yellowstone basalt samples judged to be least crustally contaminated from other considerations (e.g., through Pb and Sr isotopes) approach closest to the OIV or hotspot field in the Ce/Yb vs. Ba/Ce plot, compatible with a hotspot origin with variable continental lithosphere interactions. The data from the Rio Grande rift have no such trend in Ce/Yb vs. Ba/Ce. Other trace element and isotopic data are suggestive of a different kind of origin, perhaps melting in the continental lithosphere from pressure release or other causes as suggested in the literature. Carbonatites, kimberlites, and ultrapotassic rocks form extreme end members for the peralkalic rocks on the continents with Ce/Yb values in the hundreds and even exceeding 1,000 in natrocarbonatite. Carbonatites and kimberlite type I, however, have Ba/Ce <8 with few exceptions. Ultrapo tassic rocks and kimberlite type II also have Ce/Yb values in the hundreds but with Ba/Ce >9. These rocks, although rare in the ocean basins (e.g., carbonatite on São Vicente Island in the Cape Verdes archipelago, Indian Ocean) plot similarly to their continental cousins. For Hawaii, the nephelinitic suites of both the Honolulu and Koloa series trend from alkali and alkali olivine basalt ratios toward higher signatures for Ce/Yb for other rock types. The Honolulu series, however, progresses towards smaller values of Ba/Ce for nephelinite-melilitite (Ce/Yb ˜ 85; Ba/Ce ˜ 5-7) near the low end of Ce/Yb found in carbonatite/kimberlite type I, whereas the Koloa series progresses toward higher Ba/Ce (Ce/Yb ˜ 65; Ba/Ce ˜ 14-15) for nephelinite-melilitite with Ce/Yb values near the lower end of kimberlite type II/ultrapotassic rocks. Carbonated phlogopitic sources have been proposed for peralkalic rocks of both oceans and continents. Carbonatites and/or kimberlites are suggested to possibly be present at depth under the Hawaiian nephelinitic series and in other OIV environments containing peralkalic suites.