Passive continental margins are tectonically inactive, but a few of them including the East India Passive Margin (EIPM) show evidences for post-breakup deformations. This unusual process prompted us to investigate the post-rift deformations on EIPM and adjacent deep-water region for understanding the possible mechanisms. Seismic reflection images of the Bay of Bengal reveal a post-rift deformation with a manifestation of extensional faults in Krishna–Godavari (K–G) basin and on flanks of the 85°E Ridge. In K–G basin, one of the rift-related faults reactivated during the Early Miocene time (~16 Ma), while on flanks of the 85°E Ridge new normal faults originated at about 6.8 Ma. From detailed analysis of fault throws, it is observed that the fault in K–G basin recorded a cumulative throw of about 900 m between the basement and Early Miocene horizon (~16 Ma), later the fault was reactivated at 6.8 Ma and continued the activity progressively until 0.3 Ma before cessation. The fault system on the margin spatially extends for about 300 km between offshore extensions of the Pranahita–Godavari graben and Nagavali–Vamshadhara shear zone. The faults on 85°E Ridge, initiated at 6.8 Ma and continued until 0.8 Ma, have cumulative throws of about 60 and 110 m on western and eastern flanks of the ridge, respectively. Back-stripping analysis of the fault from the K–G basin discloses two distinct phases of subsidence history: (i) during the first phase (120–23 Ma) the basement subsided at a rate of 46–18 m/Myr due to thermal cooling of the lithosphere, (ii) during the second phase (23 Ma–Present) rapid subsidence rate (69.56 m/Myr) of basement is noticed as a consequence of deposition of copious amounts of Bengal Fan sediments. The thick sedimentary strata exerted vertical load on underlying heterogeneous crust that led to build excessive internal stress and release through weak zones (lying at intersecting planes of heterogeneous crustal blocks). The stress, thus released through fault planes has caused the deformation of crust as well as overlying sedimentary strata.

中文翻译：

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孟加拉湾破裂后的变形：地壳对沉积物负荷的响应

被动大陆边缘在构造上是不活跃的，但包括东印度被动边缘（EIPM）在内的其中一些显示了破裂后变形的证据。这个不寻常的过程促使我们研究了EIPM和邻近深水区域的裂谷后变形，以了解可能的机制。孟加拉湾的地震反射图像显示，克里希纳-戈达瓦里（KG）盆地和85°E脊侧面的断裂断层表现为伸展断裂。在KG盆地，与裂谷有关的断层之一在中新世早期（〜16 Ma）被重新激活，而在85°E山脊的两侧，新的正断层起源于大约6.8 Ma。通过对故障抛出的详细分析，可以看出，Ｋ－Ｇ盆地的断层在基底和中新世早期水平（约１６Ｍａ）之间累积了约９００ｍ的投掷，后来断层在６．８Ｍａ处重新活化，并逐渐停止活动直到０．３Ｍａ为止。 。边缘的断层系统在Pranahita–Godavari en片的近海延伸段和Nagavali–Vamshadhara剪切带的延伸段之间在空间上延伸了约300 km。85°E脊上的断层始于6.8 Ma，一直持续到0.8 Ma，在该脊的西侧和东侧分别累积了约60 m和110 m的抛掷。KG盆地断层的反冲分析揭示了沉降历史的两个不同阶段：（i）在第一阶段（120-23 Ma），由于热作用，地下室以46-18 m / Myr的速度沉降岩石圈的冷却 （ii）在第二阶段（23 Ma-现在），由于大量孟加拉扇沉积物的沉积，基底的快速沉降速率（69.56 m / Myr）被注意到。较厚的沉积地层在下面的非均质地壳上施加垂直载荷，从而导致内部应力过大并通过薄弱区域释放（位于非均质地壳块相交平面）。通过断层平面释放的应力导致了地壳的变形以及上覆的沉积地层。较厚的沉积地层在下面的非均质地壳上施加垂直载荷，从而导致内部应力过大并通过薄弱区域释放（位于非均质地壳块相交平面）。通过断层平面释放的应力导致了地壳的变形以及上覆的沉积地层。较厚的沉积地层在下面的非均质地壳上施加垂直载荷，从而导致内部应力过大并通过薄弱区域释放（位于非均质地壳块相交平面）。通过断层平面释放的应力导致了地壳的变形以及上覆的沉积地层。