Geochemical data (major and minor oxides, trace elements including REE, and Sr, Nd, Pb, and O isotopes) have been obtained on a number of flow sequences and plutonic and volcanic complexes of the DVP by numerous groups since the early 1970’s. Evaluation of these data has led to the classification of the basalts and other rock types, inferences on their mantle sources, parental magmas and the numerous magmatic differentiation and crustal contamination processes that have caused the observed diversity. The DVP is predominantly composed of quartz- and hypersthenenormative tholeiitic basalts in the plateau regions (Western Ghats and adjoining central and eastern parts (Malwa and Mandla)). However, along the ENE-WSW-trending Narmada-Tapi rift zones, the N-S to NNW-SSE-trending Western coastal tract, the Cambay rift zone, and the Saurashtra peninsula and Kutch regions, the DVP shows considerable diversity in terms of structures, presence of dyke swarms and dyke clusters, and intrusive and extrusive centres with diverse rock types. Based on the geochemical and isotopic variations observed in the twelve different formations of basalts from the Western Ghats, it has been established that the least contaminated basalts among the Deccan Basalt Group lavas are represented by the Ambenali Formation of the Wai sub-group (c. 500 m thick), with εNd(t) = +8 to + 2, (87Sr/86Sr)t = 0.7040–0.7044 and (206Pb/204Pb)0 = 18.0 ± 0.5, average Ba/Zr = 0.3, and Zr/Nb = 14.4, indicating a depleted T-MORB-like mantle source. Slight enrichment in (87Sr/86Sr)t ratios (0.705), and εNd(t) = (+5 to −5) and depletion in (206Pb/204Pb)0 = 18.5–17.0 and δ18O = +6.2 to +8.3 ‰ as observed in the Mahabaleshwar Formation, that overlies the Ambenali Formation, indicate an enriched or metasomatised lithospheric mantle source. Such uncontaminated magmas appear to have been variably contaminated by a variety of crustal rocks (gneisses, shales, schists, amphibolites and granulites) as indicated in the εNd(t) vs. (87Sr/86Sr)t plots of all other eight formations that underlie these two formations. The flows of the Bushe Formation from the Western Ghats and one dyke from the Tapi rift zone represent the most crustally contaminated rock types with εNd(t) = −10 to −20.2 and (87Sr/86Sr)t = 0.713–0.72315 and very high (208Pb/204Pb)0 = 41.4, (207Pb/204Pb)0 = 16.03 and (206Pb/204Pb)0 = 20.93. Combined Sr-Nd-Pb, TiO2, MgO, Zr/Y and primitive mantle — normalised plots of basalts from flow sequences that are far away (c. 400–700 km) from the Western Ghats (e.g. Toranmal, Mhow, Chikaldara, Jabalpur and others) indicate their chemical similarity to those of the Western Ghats, especially Poladpur and Ambenali formations, except for some differences in the Pb-isotope ratios. Such features suggest either lithological continuity of flows over long distances from a single eruptive source or their coeval eruption from multiple sources providing basalts of analogous geochemistry. The DVP provides a plethora of crustal contamination processes such as assimilation and quasi- equilibrium crystallization (AEC) in the MgO-rich samples of the Western Ghats (e.g. Bushe) during emplacement or ascent, and assimilation- fractionation crystallisation (AFC-type) in intrusive and/or volcanic complexes (e.g., Phenai Mata, Pavagadh, Mumbai Island) in crustal magma chambers of the refilled, tapped and fractionated (RTF)- type. Operation of such RTF-magma chamber processes within the Mahabaleshwar sequence (c. 1200 m) indicates the complexities introduced in the magmatic process and hence in geochemical interpretations of such thick flow sequences. High- and low-pressure experimental petrological studies have led to petrogenetic models which indicate the production of primary melts of picritic compositions (c. 16% MgO), by 15–30% melting of an Fe-rich lherzolitic source at c. 2–3 GPa (c. 60–100 km depths). These melts evolved through olivine-fractionation near the Moho and then gabbroic fractionation within the shallow-intermediate crust (c. 6 km below the surface under c. 2 kb pressure) to produce the most dominant quartz- and hypersthene-normative tholeiitic basalts. In some rare cases (e.g., borehole sequence of Saurashtra, Pavagadh and others), the primary picritic liquids that formed at mantle depths, and the spinel-peridotie mantle-nodule- hosting melanephelinites from Kutch, have erupted without much modification. They occur spatially in close proximity to deep faults or rifts (e.g Narmada, Cambay, Kutch and others) which have apparently facilitated their rapid ascent and eruption without significant pause or modification during transport. εNd(t) vs. (87Sr/86Sr)t, chondrite- and primitive-mantle normalized variations in the picritic rocks and basalts of the DVP indicate several types of mantle sources such as transitional-midocean-ridge basalt (T-MORB), Ocean Island basalt (OIB)/Reunion- type of peridotitic compositions either metasomatised or normal. Geodynamic and plate-tectonic considerations during the emplacement of the DVP envisage both an asthenospheric- plume source (Reunion) and continental rift-related volcanism with eclogitic sources. The role of dual sources, capable of producing large volumes of basalts through near-total melting seem to provide the answer to DVP’s enigma of production of large volumes of lava in very short time as observed in the Western Ghats and the contiguous plateau, and also the extreme diversity in rock types found in the western parts from peridotitic-sources. Age data based on Ar-Ar, U-Pb, Re-Os isotopes, constrained by paleomagnetic data for the whole of DVP conforming to C30N-C29R-29N, indicate a protracted period of volcanism from 69.5 Ma (Upper Cretaceous) to 62 Ma (Palaeocene) including polychronous complexes (e.g. Mundwara, Sarnu-Dandali, Rajasthan). Based on precise U-Pb age data on zircons, it has been shown that the whole sequence of the Western Ghats with ten formations (c.1.8 km thick) erupted over a short period of time (< 1 Ma). The most dominant volcanic phase, however, represented by the Wai Subgroup, consisting of the Poladpur, Ambenali and Mahabaleshwar formations (c. 1.1 km thick) contain an estimated volume of c. 439,000 km3 of lavas that erupted over a short span of c. 700, 000 years. The precise timing of such large eruptions with reference to the Cretaceous-Palaeogene (K-Pg) boundary with or without links to the Chicxulub meteorite impact are being debated vigorously. In addition, the quantity of gases released (Cl, F, CO2, SO2 and others) during such large eruptions of the DVP and their influence on the mass extinctions of biota including the dinosaurs appear to be closely linked. Economic aspects of the DVP include deposits of hydrothermal fluorite and REE, Y, Nb, Ba and Sr mineralisatiom (e.g. Amba Dongar) and REE (e.g. Kamthai). Residual laterite and bauxite and fertile soils (e.g., Maharashtra, Madhya Pradesh and Gujarat) support the Al- industry and a robust agrarian sector. The DVP has also been a rich source for building materials. Indications for possible resources of native copper, PGE’s and micro-diamonds have also been indicated.

中文翻译：

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印度德干火山省 (DVP)：回顾

自 1970 年代初以来，许多研究小组已经获得了 DVP 的许多流动序列以及深成岩和火山岩复合体的地球化学数据（主要和次要氧化物，包括 REE 在内的痕量元素，以及 Sr、Nd、Pb 和 O 同位素）。对这些数据的评估导致了玄武岩和其他岩石类型的分类，对其地幔来源、母岩浆以及导致观察到的多样性的众多岩浆分异和地壳污染过程的推断。DVP 主要由高原地区（西高止山脉和毗邻的中部和东部地区（马尔瓦和曼德拉））中的石英和超变质拉斑玄武岩组成。然而，沿着 ENE-WSW 走向的 Narmada-Tapi 裂谷带、NS 到 NNW-SSE 走向的西部沿海地区、Cambay 裂谷带、和 Saurashtra 半岛和 Kutch 地区，DVP 在结构、岩脉群和岩脉簇的存在以及具有不同岩石类型的侵入和喷出中心方面表现出相当大的多样性。根据在西高止山脉的 12 种不同玄武岩地层中观察到的地球化学和同位素变化，已经确定德干玄武岩组熔岩中污染最少的玄武岩由 Wai 亚组的 Ambenali 组代表（c. 500 m 厚），εNd(t) = +8 至 + 2，(87Sr/86Sr)t = 0.7040–0.7044 和 (206Pb/204Pb)0 = 18.0 ± 0.5，平均 Ba/Zr = 0.3，Zr/Nb = 14.4，表明耗尽的 T-MORB 样地幔源。(87Sr/86Sr)t 比率 (0.705) 和 εNd(t) = (+5 至 -5) 略有富集，(206Pb/204Pb)0 = 18.5–17.0 和 δ18O = +6.2 至 +8。3 ‰ 如在位于 Ambenali 组之上的 Mahabaleshwar 组所观察到的，表明岩石圈地幔源富集或交代。这种未受污染的岩浆似乎受到各种地壳岩石（片麻岩、页岩、片岩、角闪岩和麻粒岩）的不同污染，如所有其他八种地层的 εNd(t) vs. (87Sr/86Sr)t 图所示。这两个阵型。来自西高止山脉的布什组流和来自塔皮裂谷带的一处岩脉代表了地壳污染最严重的岩石类型，εNd(t) = -10 至 -20.2 和 (87Sr/86Sr)t = 0.713-0.72315 且非常高(208Pb/204Pb)0 = 41.4，(207Pb/204Pb)0 = 16.03 和 (206Pb/204Pb)0 = 20.93。结合 Sr-Nd-Pb、TiO2、MgO、Zr/Y 和原始地幔——来自远处流动序列的玄武岩的归一化图（c. 距西高止山脉（例如 Toranmal、Mhow、Chikaldara、Jabalpur 等）400-700 公里）表明它们与西高止山脉的化学相似，尤其是 Poladpur 和 Ambenali 地层，除了 Pb 同位素比率的一些差异。这些特征表明，要么是来自单个喷发源的长距离流动的岩性连续性，要么是来自提供类似地球化学性质的玄武岩的多个源的同时喷发。DVP 提供了大量的地壳污染过程，例如在西高止山脉（例如 Bushe）就位或上升过程中富含 MgO 的样品中的同化和准平衡结晶（AEC），以及同化-分馏结晶（AFC 型）侵入性和/或火山复合体（例如，Phenai Mata、Pavagadh、孟买岛）在地壳岩浆室中的再充填、挖掘和分馏 (RTF) 型。在 Mahabaleshwar 层序（约 1200 米）内运行这种 RTF-岩浆室过程表明在岩浆过程中引入了复杂性，因此在这种厚流层序的地球化学解释中。高压和低压实验岩石学研究已经产生了岩石成因模型，该模型表明通过 15-30% 的富铁锂辉石源在约 15-30% 的熔化，产生了苦味酸成分（约 16% MgO）的初级熔体。2-3 GPa（深度约 60-100 公里）。这些熔体通过莫霍面附近的橄榄石分馏演化，然后在浅中地壳内（在约 2 kb 压力下地表以下约 6 公里处）进行辉长岩分馏，以产生最主要的石英和超硬质拉斑玄武岩。在一些罕见的情况下（例如，Saurashtra、Pavagadh 和​​其他的钻孔序列），在地幔深处形成的主要苦味酸液体，以及来自 Kutch 的尖晶石-橄榄岩-地幔-结核-含黑云母岩，在没有太多修改的情况下喷发。它们在空间上发生在靠近深断层或裂谷（例如纳尔马达、坎贝、卡奇等）的地方，这些断层或裂谷显然促进了它们的快速上升和喷发，而在运输过程中没有明显的停顿或修改。εNd(t) vs. (87Sr/86Sr)t，DVP 的苦质岩和玄武岩中球粒陨石和原始地幔的归一化变化表明了几种类型的地幔来源，如过渡中洋脊玄武岩 (T-MORB)，大洋岛玄武岩 (OIB)/Reunion 型橄榄岩成分交代或正常。DVP 就位期间的地球动力学和板块构造考虑同时设想了软流圈羽流源（留尼汪）和具有榴辉岩源的大陆裂谷相关火山活动。双重来源的作用，能够通过几乎完全熔化产生大量玄武岩，似乎为 DVP 在西高止山脉和毗连高原观察到的在极短的时间内产生大量熔岩之谜提供了答案，并且在橄榄岩源的西部地区发现的岩石类型极其多样化。基于 Ar-Ar、U-Pb、Re-Os 同位素的年龄数据，受整个 DVP 符合 C30N-C29R-29N 的古地磁数据约束，表明从 69.5 Ma（上白垩纪）到 62 Ma 的火山活动期延长（古新世）包括多时复合体（例如 Mundwara、Sarnu-Dandali、Rajasthan）。根据锆石的精确 U-Pb 年龄数据，表明西高止山脉的 10 个地层（约 1.8 公里厚）的整个序列在短时间内（< 1 Ma）喷发。然而，最主要的火山阶段，由 Wai 亚群代表，由 Poladpur、Ambenali 和 Mahabaleshwar 地层（约 1.1 公里厚）组成，估计体积约为 c。439,000 平方公里的熔岩在 c. 的短时间内喷发。700, 000 年。参照白垩纪-古近纪 (K-Pg) 边界，无论是否与希克苏鲁伯陨石撞击有关，这种大规模喷发的准确时间正在激烈辩论中。此外，释放的气体量（Cl、F、CO2、SO2 和其他）在 DVP 如此大的喷发期间与它们对包括恐龙在内的生物群的大规模灭绝的影响似​​乎密切相关。DVP 的经济方面包括热液萤石和 REE、Y、Nb、Ba 和 Sr 矿化（例如 Amba Dongar）和 REE（例如 Kamthai）的矿床。残留的红土和铝土矿以及肥沃的土壤（例如马哈拉施特拉邦、中央邦和古吉拉特邦）支持着铝工业和强大的农业部门。DVP 也是建筑材料的丰富来源。还指出了天然铜、PGE 和微金刚石的可能资源的迹象。中央邦和古吉拉特邦）支持铝工业和强大的农业部门。DVP 也是建筑材料的丰富来源。还指出了天然铜、PGE 和微金刚石的可能资源的迹象。中央邦和古吉拉特邦）支持铝工业和强大的农业部门。DVP 也是建筑材料的丰富来源。还指出了天然铜、PGE 和微金刚石的可能资源的迹象。