Late Mesozoic and Cenozoic volcanosedimentary complexes from the submarine Vityaz Ridge,the Island Arc slope of the Kuril-Kamchatka trench,and its evolution

This paper describes the volcanosedimentary complexes of different ages (Late Cretaceous-Early Paleocene, Paleocene-Eocene (?), Oligocene-Early Miocene, and Pliocene-Pleistocene) that compose the basement and sedimentary cover of the submarine Vityaz Ridge. It was found that the Upper Cretaceous sedimentary rocks from the basement of the Vityaz Ridge (felsic) and the Lesser Kuril Ridge (mafic) have different compositions. Matrix mineral assemblages corresponding to the smectite and corrensite stages of epigenesis of Cenozoic rocks were distinguished, and a scheme of the Late Cretaceous-Pleistocene geological evolution of the region was proposed.     

Geochemistry of the submarine Vityaz Ridge at the pacific slope of the Kurile island arc

This paper reports the results of geological studies at the submarine Vityaz Ridge carried out during cruises 37 and 41 on the R/V “Akademik Lavrent’ev” in 2005 and 2006. The studied area is located at the near-island trench of the slope in the central part of the Kurile island arc. Morphologically, it consists of two parts: inner volcanic arc represented by the Great Kurile Range and outer arc corresponding to the submarine Vityaz Ridge. Diverse rocks that compose the basement and sedimentary cover of the ridge were recovered by dredging. Based on K-Ar dating and geochemistry, the volcanics were divided into Paleocene, Eocene, late Oligocene, and Pliocene-Pleistocene complexes. Each of the distinguished complexes reflects the tectonomagmatic stage in the ridge evolution. The geochemical and isotope data on the volcanics indicate the contribution of ancient crustal material in magma source and, correspondingly, the formation of this structure on the continental basement. Two-stage model ages, T_DM2, vary in a wide range from zero values in the mafic rocks to 0.77 Ga in felsic varieties, pointing to the presence of Precambrian protolith in the source of the felsic rocks of the Vityaz Ridge. The Pliocene-Pleistocene volcanics are classed with the tholeiitic, calc-alkaline, and subalkaline series, which differ in alkali contents and REE fractionation. The values of (La/Sm)_N and (La/Yb)_N ratios vary from 0.74 and 0,84 in the tholeiitic varieties to 1.19 and 1.44 in the calcalkaline and 2.32 and 3.73 in the subalkaline rocks. All three varieties occur within the same volcanic edifices and were formed during differentiation of magmatic melt that were channeled along fault zones from the mantle source slightly enriched in crustal component     

Late Vendian Complexes in the Structure of Metamorphic Basement of the Fore Range Zone,Greater Caucasus

The paper presents new data on the composition, age, and relationships (with host and overlying deposits) of intrusive rocks in the basement of the Fore Range zone (Greater Caucasus), in the Malaya Laba River Basin. The evolutionary features of intrusive units located within the Blyb metamorphic complex are described. It is shown for the first time that the lower levels of this complex are, in a structural sense, outcrops of the Late Vendian basement. The basement is composed of the Balkan Formation and a massif of quartz metadiorites that intrudes it; for the rocks of this massif, ages ranging from 549 ± 7.4 to 574.1 ± 6.7 Ma are obtained for three U–Pb datings by the SHRIMP-II method. The Herzyinan magmatic event is represented by a group of granodiorite intrusions penetrating the Blyb complex on a series of faults extending along its boundary with the Main Range zone. The obtained estimate for the U–Pb age of one of the intrusions (319 ± 3.8 Ma) corresponds to the end of the Serpukhovian stage of the Early Carboniferous.     

Systematic variations in xenocryst mineral composition at the province scale, Buffalo Hills kimberlites, Alberta, Canada

The Buffalo Hills kimberlites define a province of kimberlite magmatism occurring within and adjacent to Proterozoic crystalline basement termed the Buffalo Head Terrane in north-central Alberta, Canada. The kimberlites are distinguished by a diverse xenocryst suite and most contain some quantity of diamond. The xenocryst assemblage in the province is atypical for diamondiferous kimberlite, including an overall paucity of mantle indicator minerals and the near-absence of compositionally subcalcic peridotitic garnet (G10). The most diamond-rich bodies are distinguished by the presence of slightly subcalcic, chromium-rich garnet and the general absence of picroilmenite, with the majority forming a small cluster in the northwestern part of the province. Barren and near-barren pipes tend to occur to the south, with increasing proximity to the basement structure known as the Peace River Arch. Niobian picroilmenite, compositionally restricted low-to moderate-Cr peridotitic garnet, and megacrystal titanian pyrope occur in kimberlites closest to the arch. Major element data for clinopyroxene and trace element data for garnet from diamond-rich and diamond-poor kimberlites suggests that metasomatism of lithospheric peridotite within the diamond stability field may have caused destruction of diamond, and diamond source rocks proximal to the arch were the most affected.     

冀东青龙县一带中元古界与太古代基底滑脱构造厘定及地质意义

在区域地质调查的基础,通过构造分析、岩浆岩的分布以及构造岩的详细研究,厘定出冀 东青龙一带太古代基底与中元古界盖层之间接触为构造滑脱关系。并认为构造滑脱经历了明显的两期活动,早期为挤压体制下的逆冲—褶皱作用,中元古代地层表现为同倒转褶皱,滑脱带内发育断层泥和断层角砾岩;晚期为伸展体制下伸展滑脱作用,表现为断层泥劈理化发育,指示明显的伸展滑脱特征。研究区太古代基底与中元古界盖层滑脱构造的厘定,对于再造该区构造格局和沉积古地理格局具有重要意义     

Petrology, geochemistry and uranium mineralisation of post-collisional magmatism around Goanikontes, southern Central Zone, Damaran Orogen, Namibia

The Goanikontes area lies within the southern Central Zone of the northeast trending branch of the Damara Orogen. The cover succession around Goanikontes, which comprises Etusis to Chuos Formation metasediments, is in tectonic contact with older pre-Damaran basement rocks. The area can be divided into three structural domains with basement in the east, a northeast-plunging anticline of Damaran metasediments to the west and a high strain zone up to 1 km wide that separates them and truncates the anticline. The high strain zone has provided an important focus for the emplacement of sheeted granites adjacent to the basement-cover contact. Goanikontes is also one of several significant uranium anomalies within the Damaran Orogen, and the excellent 3D exposure of the Swakop river has provided evidence for an interpretation of the tectono-metamorphic setting of magmatism and mineralisation. The granitoids have been divided into equigranular granites and sheeted leucogranites. The sequence of emplacement of the equigranular granites is from red syenogranite (534±7 Ma) to later grey monzogranite (517±7 Ma) with foliated basement-hosted granite of probable time equivalence to the syenogranites. Each type can be distinguished on major- and trace-element geochemistry. The later sheeted leucogranites, which are volumetrically the most important, intrude both basement and cover rocks. These have been divided into six distinct types based on field characteristics and structural setting backed by geochemical data and fluid extraction analyses. The earliest type A are irregular in form, boudinaged and folded by D₃, and geochemically distinct with notably low HFSE; type B's are white, weakly foliated, folded by D₃, garnetiferous and highly peraluminous; type C are tourmaline-bearing, occasionally boudinaged and exhibit the typical sheet-form within the cover rocks. Of the post-D₃ sheets, type D, which is restricted to the high strain zone is characterised by smoky quartz, high radioactivity and often by visible betafite or beta-uranophane; type E, the dominant type within the high strain zone contains prominent oxidation haloes and type F is red in colour, coarsely pegmatitic and has the highest concentration of alkalis. The uranium-mineralised type D sheets have consistently higher fluid and CO₂ content than other sheeted leucogranites. The close correlation between sheet type and uranium abundance, supported by linear trends on LIL plots suggests that the distribution of radiogenic elements is primarily magmatic with more recent meteoric re-distribution, rather than due to substantial hydrothermal modification     

Geology and Hydrothermal Alteration of the Duobuza Gold‐Rich Porphyry Copper District in the Bangongco Metallogenetic Belt,Northwestern Tibet

The Duobuza gold‐rich porphyry copper district is located in the Bangongco metallogenetic belt in the Bangongco‐Nujiang suture zone south of the Qiangtang terrane. Two main gold‐rich porphyry copper deposits (Duobuza and Bolong) and an occurrence (135 Line) were discovered in the district. The porphyry‐type mineralization is associated with three Early Cretaceous ore‐bearing granodiorite porphyries at Duobuza, 135 Line and Bolong, and is hosted by volcanic and sedimentary rocks of the Middle Jurassic Yanshiping Formation and intermediate‐acidic volcanic rocks of the Early Cretaceous Meiriqie Group. Simultaneous emplacement and isometric distribution of three ore‐forming porphyries is explained as multi‐centered mineralization generated from the same magma chamber. Intense hydrothermal alteration occurs in the porphyries and at the contact zone with wall rocks. Four main hypogene alteration zones are distinguished at Duobuza. Early‐stage alteration is dominated by potassic alteration with extensive secondary biotite, K‐feldspar and magnetite. The alteration zone includes dense magnetite and quartz‐magnetite veinlets, in which Cu‐Fe‐bearing sulfides are present. Propylitic alteration occurs in the host basic volcanic rocks. Extensive chloritization‐silicification with quartz‐chalcopyrite or quartz‐molybdenite veinlets superimposes on the potassic alteration. Final‐stage argillic alteration overlaps on all the earlier alteration. This alteration stage is characterized by destruction of feldspar to form illite, dickite and kaolinite, with accompanying veinlets of quartz + chalcopyrite + pyrite and quartz + pyrite assemblages. Cu coexists with Au, which indicates their simultaneous precipitation. Mass balance calculations show that ore‐forming elements are strongly enriched during the above‐mentioned three alteration stages.     

The Early Baikalian crystalline complex in the basement of the Dzabkhan microcontinent of the Early Caledonian orogenic area, Central Asia

Fragments of continental blocks or microcontinents are represented in the Early Caledonian orogenic area of Central Asia (or Early Caledonian superterrane); the largest of these are the Dzabkhan and Tuva-Mongolian microcontinents, with Early and Late Precambrian crystalline basements, respectively. In the linkage zone of these microcontinents, crystalline rocks of the Tarbagatai and Songino blocks that are considered as units of the Early Precambrian ensialic basement of the superterrane are also known. They are composed of strongly metamorphosed rocks formed during the Early Baikalian orogeny about 790 to 820 Ma. U-Pb zircon dating and Nd isotope studies revealed, within the northwestern Dzabkhan microcontinent, the Dzabkhan-Mandal zone of crystalline rocks associated with the Riphean crust-forming process. The age of the gneiss substrate of this zone is estimated as 1.3 to 0.86 Ga. An early episode of metamorphism is dated at about 856 ± 2 Ma. The data available so far indicate a heterogeneous structure of the Dzabkhan microcontinent basement represented by Early Precambrian and Early and Late Baikalian crystalline formations.     

Geochemistry of granitoids from the basement of the Kuril island arc system

This paper reports the characteristics of granitoids from the Pacific slope of the Kuril island arc system, which were discovered by the authors during geological and geophysical operations in three cruises of the R/V Akademik M. Lavrent’ev. The major and trace element compositions of these rocks were determined, their role in the formation of the submarine Vityaz Ridge was evaluated, and they were compared with granitoids from the Brouton group of submarine volcanoes and xenoliths from Simushir Island and the Sea of Okhotsk. Granitoids from various structures of the basement of the Kuril island arc system are hypabyssal rocks derived from andesite magmas. Their common features are related to the formation on the continental crust under convergent geodynamic conditions involving compression due to the movement and subduction of the Pacific plate beneath the Asian continent. The problem of the basement of the Kuril island arc system was discussed, the composition and age of its rocks were determined, and the history of the geologic development of the Pacific slope of the arc starting from the Late Mesozoic was briefly described.     

Precambrian deformed granites of possible basement in the Himalayas

Granitic rocks are abundant in the Axial zone, the core of the Himalayas. The Lesser Himalayan unfossiliferous metasedimentary sequence lying to the south of the Axial zone also contains concordant sheets of granitic rocks which were earlier described either as intrusive or metamorphosed volcaniclastic sediments. These granites have yielded Precambrian radiometric ages.The Lesser Himalayan deformed granites have been demarcated and we suggest that they represent thrust wedges of the Precambrian (older than 1000 Ma) basement rocks of the Himalayas. The deformed granite sheets of the Eastern Himalayas show the development of various types of mylonite. The chemical characters of these granites vary within reasonable limits. Geochemistry and Sr isotope ratios suggest their derivation by melting from crustal material and sediments, probably greywacke, to variable degrees. From geochemical evidence it is suggested that the central crystalline rocks of the Axial zone may contain reworked Precambrian basement components. The studied granites provide evidence of a Precambrian metamorphic and anatectic event in the Himalayas.     

西大别地区韧性剪切带的卫星影像研究

对发育在西大别地区的韧性剪切带的卫星影像分析表明：异常色带及均匀的线状影像纹理是其突出的影像特征。色调异常带可区分为浅色、暗色与明暗界面三种异常类型。通过多地段、多地质体和不同构造部位的线状体方位的统计对比，叠加在早期韧性剪切带之上的后期岩石破裂被有效地分离。自相似性统计获得剪切带上的分维值Ｄ为１．０５～１．３（＞１），非剪切带上Ｄ为０．８～０．９９（＜１），Ｄ＝１基本可作为韧性剪切带与非韧性剪切带之间界定的统计标尺。     

浅析政和-大埔区域性断裂构造对地质灾害致灾因素的影响

多期次断裂构造运动的叠加,使得断裂带内的地层、岩体遭受不同程度的破坏,构造侵蚀作用使原有的地形(地貌)、地表水系等发生了根本性的改变,岩土体特征也随着发生改变。通常断裂带内的构造侵蚀、风化剥蚀作用相对比完整的断块要强烈的多。因此,断裂带成为地质灾害易发、高发区域。     

新疆哈密地区库姆塔格钼矿床地质特征和辉钼矿Re-Os同位素年龄

库姆塔格钼矿位于新疆东天山星星峡隆起区哈密库姆塔格沙垄的东侧,是一个产于基性岩中的辉钼矿矿床。区内目前已发现7条矿化体,这些矿化体围绕辉长岩与角岩/矽卡岩的接触带呈向北西突出的弧形展布。矿体内主要金属矿物有辉钼矿、黄铜矿、黄铁矿、磁铁矿等,辉钼矿、黄铜矿呈稀疏浸染状分布于辉长岩中。对辉长岩中的辉钼矿进行Re-Os同位素年龄测定,获得矿床形成的等时线年龄为(318±27)Ma,加权平均年龄为(319.1±4.5)Ma,成矿时代为早—中石炭世。这一测年结果与区域内的部分花岗岩的侵入时间一致,表明该矿床的形成与区内的酸性岩浆活动存在一定的联系,因此区内酸性岩体与中基性岩体的接触部位是寻找这类新型矿床的有利地段。库姆塔格钼矿的发现不仅打破了以往在酸性岩体内部和矽卡岩带内寻找钼矿床的勘探模式,同时也为在东天山地区内寻找铜钼多金属矿床开拓了思路。     

Structure and tectonic style of the Western Australian Shield

The Western Australian Shield consists of two large Archaean cratons that are partly covered by remnant Proterozoic sedimentary basins and partly surrounded by Proterozoic mobile belts. Archaean terrains are either granitoid-greenstone, or high-grade gneiss, the regional distribution of which influences the style of Proterozoic tectonism.Granitoid-greenstone terrains consist of thick volcanogenic sequences, now occurring as dismembered synclinal keels within voluminous granitoidand display features that are uniquely Archaean. The gneiss terrains, although severely modified and dismembered by metamorphism and plutonism, seem to display a more uniformitarian tectonic style than the granitoid-greenstones.Mounting evidence in the Yilgarn Block suggests that the gneiss terrains represent a pre-greenstone basement, which was probably very extensive, both outside and within the greenstone areas. The most extensive area of gneiss lies in a huge arc around the western part of the Yilgarn Block, creating a novel situation where older rocks seemingly “wrap around” younger rocks. It is postulated that the precursors of the two major granitoidgreenstone terrains were huge, discrete, somewhat rounded volcanic basins that developed within extensive and perhaps continuous crust. At least in the Pilbara, there is a phenomenally continuous volcanic stratigraphy. Despite the basic similarities there are sufficient differences between the two volcanic basins to suggest independent evolution, whereby similar processes operated in different places in different times.These granite—greenstone areas had largely stabilised by about 2500 m.y. and, during the Proterozoic, behaved as cratonic blocks that tended not to participate in the mobile belts. Thus, the Capricorn Orogen developed as an ensialic geosyncline, on gneiss basement, between the two cratons. Where Proterozoic sedimentary basins transgress on to the cratons, they are preserved as gently folded and virtually unmetamorphosed covers. Within the orogenic zone itself, trough sedimentation, prograde metamorphism, basement reworking, multiple deformation and granitoid emplacement were active over the period 2000-1600 m.y. Superimposed on the Capricorn Orogen is the intracratonic Bangemall Basin (about 1100-1000 m.y.) which displays patterns of cratonic deformation that relate closely to the underlying structures.Along the southeastern margin of the Yilgarn Block is the Albany-Fraser Province which developed over an interval from 1900 m.y., or older, to 1100 m.y. Tectonic zonation is expressed by a linear striping of contrasting rocks that become younger away from the Yilgarn Block. Rather than an accretionary origin, voluminous granitoid, basemeni reworkingand absence of geosynclinal sedimentation suggest a discrete zone of high crustal strain and high thermal activity, and the belt is likened to an arrested rift in a continental setting.     

Geological structure of the submarine Vityaz Ridge within the <Emphasis Type="Italic">Seismic Gap</Emphasis> area (Pacific slope of the Kurile island arc)

Results of geological research conducted by the Pacific Oceanological Institute of the Far East Division of the Russian Academy of Sciences and the Institute of Oceanology of the Russian Academy of Sciences on the submarine Vityaz Ridge during Cruise 37 of R/V Akademik M.A. Lavrentyev in 2005 are discussed. Various rocks constituting the basement and sedimentary cover of the ridge were dredged in three areas of the ridge. Based on isotope geochronology, petrogeochemical, petrographic, and paleontological data and comparison with similar rocks available from the adjacent land and Sea of Okhotsk, they are subdivided into several age complexes. Late Cretaceous, Eocene, Late Oligocene, Miocene, and Pliocene-Pleistocene complexes are defined among the igneous rocks, while volcanogenic-sedimentary rocks are united into Late Cretaceous-Early Paleocene (late Campanian-Danian), undivided Paleogene (Paleocene-Eocene?), Oligocene-early Miocene, and Pliocene-Pleistocene complexes. The obtained data on the age and formation settings of the defined complexes made it possible to reconstruct the geological evolution of the central Pacific slope of the Kurile island arc.     

Petrology and geochemistry of Mesozoic granitic rocks from the Nansha micro-block, the South China Sea: Constraints on the basement nature

There are several micro-blocks dispersed in the South China Sea (SCS), e.g., Xisha-Zhongsha block, Nansha block and Reed-Northeastern Palawan block, etc., but detailed petrological constraints on their basement nature were previously lacking. The magmatic ages for granitic rock samples from two dredge stations in the Nansha micro-block vary from 159 to 127 Ma, which are comparable to magmatic activities occurred in the northern margin (Pearl river mouth), HongKong and East China. Petrographic characteristics, major-, trace element and Sr–Nd isotopic data of nine samples from two dredged station performed in the Nansha micro-block, the SCS, are reported. Petrographically, these granitic rocks can be divided into two groups which underwent a complex history of magmatic process, i.e., tonalitic rock (Group I) and monzogranitic rock (Group II). The Rittmann index (σ) for these rocks (1.9–3.1) suggest that they belong to calc-alkaline rocks. Group I rocks which is of typical I-type, have higher contents of TiO₂, Al₂O₃, FeO, MgO, CaO, Na₂O and P₂O₅, but lower values of SiO₂ and K₂O, when compared with those of Group II with I-type characteristics. Group I rocks are produced by partial melting of older Precambrian basement with the variable influence of mantle-derived magma which results from the interaction of released fluids from the subducted slab and the overlying mantle wedge in a general convergent margin setting, and Group II rocks result from partial melting of lower crustal basic rocks (amphibolite) and/or further partial melting of the Group I rocks associated with the variable influence from the underplating mantle-derived magma resulting from lithospheric extensional regime. Both Groups I and II have undergone assimilation and fractional crystallization (AFC) processes during its petrogenesis. This study therefore demonstrates that there exists a continental basement within micro-blocks in the South China Sea, and further supports the idea that a Middle Jurassic to Mid-Cretaceous subduction zone existed across the temporary Taiwan, Palawan to Southern Vietnam, which was associated with westward to northestward convergence of the Pacific Plate during Late Mesozoic. We suggest that this subduction zone may have been connected with the paleo-Pacific plate subduction zone offshore eastern China during Mesozoic era. This study provides petrologic data for the pre-Cenozoic tectonic evolution of the South China Sea.     

Paleozoic rocks in infrastructure of the metamorphic core, the Greater Caucasus Main Range zone

Granitoid orthogneisses and migmatites are widespread in the lower, deeply metamorphosed gneiss-migmatite complex of the pre-Alpine basement (infrastructure) exposed within northern part of the Greater Caucasus Main Range zone. Like the other rocks of the complex, they have been traditionally attributed to the Proterozoic, but the U-Pb dating revealed the Late Paleozoic age of migmatites and Devonian age of orthogneiss protolith. Bodies of blastomylonitic apogranite gneisses, which are confined to boundary between gneiss-migmatite complex and overlying Makera Complex of supracrustal rocks, turned out to be of the Late Paleozoic age as well. The dating results suggest synchronism and, apparently, genetic interrelations between the high-T/low-P metamorphism and granite formation in the Main Range zone of the Greater Caucasus.     

Petrology of calc-alkaline/adakitic basement hosting A-type Neoproterozoic granites of the Malani igneous suite in Nagar Parkar,SE Sindh,Pakistan

The Nagar Parkar area contains three distinct groups of rocks, from oldest to youngest, (1) basement rocks ranging in composition from mafic to (quartz)diorite, tonalite, granite, and younger granodiorite, (2) granite plutons similar in general features to those of the Malani Igneous Suite of Rajasthan, and (3) abundant mafic, felsic and rhyolitic dykes. The basement rocks show strong brittle and local plastic deformation, and epidote amphibolite/upper greenschist facies metamorphic overprint. The chemistry of the basement rocks contrasts the commonly agreed within plate A-type character of the Neoproterozoic granites (group 2) that are emplaced into them. The basement rock association is calc-alkaline; the granodiorite displays the compositional characteristics of adakites, whereas the tonalite has intermediate composition between typical adakite and classical island arc rocks. This paper presents detailed petrography of the basement rocks and compares their geochemistry with those of the group 2 granites as well as with rocks from other tectonic environments. It is proposed that the Nagar Parkar basement is part of a 900–840 Ma magmatic arc that was deformed before it was intruded 800–700 Ma ago by the A-type continental granitic rocks followed by mafic to felsic dykes.     

Structure, age substantiation and tectonic setting of the Lower-Middle Ordovician volcanic-sedimentary and plutonic complexes of the western part of the Kyrgyz Range (Northern Tien Shan)

Among the Caledonides exposed in the western part of the Kyrgyz Range the Lower Ordovician volcanogenic-sedimentary, plutonic, and tuffaceous-terrigenous complexes were distinguished. Volcanogenic-sedimentary sequences are the Kentash Formation, composed of volcanic rocks, tuffs and subvolcanic bodies of dacitic, andesitic and basaltic composition, sandstones and tuffites with interlayers and lenses of limestone. On the basis of conodonts and U-Pb dating of zircon grains the age of this Formation is in the age interval between Late Tremadocian Stage and Early Darriwilian Stage. Differentiated volcanites are associated with ultramafic-gabbro massifs of the Kokkiya Complex of the Late Darriwilian age (U-Pb zirconology). Features of the chemical composition of rocks of the Kentash Formation and the Kokkiya Complex indicate that they formed in suprasubduction settings within the island arc with a thick heterogeneous basement. Tuffaceous-terrigenous deposits are presented by the olistostrome formation, and coarse-grained deposits of the Taldybulak and Kyzylkainar Formations. The formation of olistostrome formation is associated with the over-thrusting of Cambrian melanocratic complexes on terrigenous-carbonate and shale strata of the Upper Precambrian-Cambrian age. Deposits of the Taldybulak and Kyzylkainar Formations accumulated in the back-arc basin and on the island arc slope, made of rocks of the Kentash Formation.     

Structural geology of the eastern Nadaleen trend,Yukon Territory,Canada: Implications for recently discovered sedimentary rock-hosted gold

Recently discovered gold-rich mineral deposits in the eastern Nadaleen trend of northeastern Yukon Territory occur in unmetamorphosed Neoproterozoic carbonate and siliciclastic rocks and their location is partly controlled by structures. Regional deformation largely resulted from mid-Cretaceous NNE-vergent, thin-skinned fold-thrust activity. However, structures in the eastern Nadaleen trend are more complex and include strike-slip and reverse faults, and SSW-, W-, and E-plunging folds. Local structures are cospatial with regional geologic features, including (1) an E-striking structural triangle zone defined by oppositely dipping reverse faults that verge toward the eastern Nadaleen trend, (2) a transition zone between Paleozoic Ogilvie platform rocks in the north to Selwyn basin rocks in the south, and (3) a change in regional deformation character from west to east, whereby to the west, rocks in the south are more deformed than rocks in the north, whereas to the east, rocks show no obvious change in deformation style. The structural complexity within the eastern Nadaleen trend probably resulted from these regional geological features and was further complicated by local competency contrasts between rock units. The cospatial location of the regional geological features may have been caused by a pre-existing, W-trending subsurface basement structure. Reverse faults bounding the E-striking triangle zone may have acted as low permeability aquitards that directed mineralizing fluids up-dip into reactive carbonate stratigraphy in the eastern Nadaleen trend. Gold-rich mineral deposits in the eastern Nadaleen trend occur preferentially in SSW-plunging anticlines and near faults, both of which probably influenced the migration of mineralizing fluid.